Servlet

• 概念：运行在服务器端的小程序
• server applet 的缩写
• Servlet就是一个接口，定义了Java类被浏览器访问到(tomcat识别)的规则。
  • servlet是一个规则
• 将来我们自定义一个类，实现Servlet接口，复写方法。

理解：我们曾经使用mian方法调用类、接口等，现在我们使用tomcat服务器来调用

快速入门

1. 创建JavaEE项目
2. 定义一个类，实现Servlet接口
3. 实现接口中的抽象方法

package com.bao.demo1;import javax.servlet.*;
import java.io.IOException;public class ServletDemo1 implements Servlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {}@Overridepublic ServletConfig getServletConfig() {return null;}@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("hello,servlet");}@Overridepublic String getServletInfo() {return null;}@Overridepublic void destroy() {}
}

1. 在web.xml中配置Servlet

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"version="4.0"><!--配置Servlet --><servlet><servlet-name>demo1</servlet-name><servlet-class>com.bao.web.servlet.ServletDemo1</servlet-class></servlet><servlet-mapping><servlet-name>demo1</servlet-name><url-pattern>/demo1</url-pattern></servlet-mapping><!--配置Servlet --><!--<servlet><servlet-name>demo2</servlet-name><servlet-class>com.bao.web.servlet.ServletDemo2</servlet-class>&lt;!&ndash;指定Servlet的创建时机1.第一次被访问时创建* <load-on-startup>的值为负数2.在服务器启动时，创建* <load-on-startup>的值为0或正整数&ndash;&gt;<load-on-startup>-5</load-on-startup></servlet><servlet-mapping><servlet-name>demo2</servlet-name><url-pattern>/demo2</url-pattern></servlet-mapping>-->
</web-app>

执行原理

1. 当服务器接受到客户端浏览器的请求后，会解析请求URL路径，获取访问的Servlet的资源路径
2. 查找web.xml文件，是否有对应的<url-pattern>标签体内容。
3. 如果有，则再找到对应的<servlet-class>全类名
4. tomcat会将字节码文件加载进内存，并且创建其对象
5. 调用其方法

Servlet中的生命周期方法

1. 被创建：执行init方法，只执行一次* Servlet什么时候被创建？* 默认情况下，第一次被访问时，Servlet被创建* 可以配置执行Servlet的创建时机。* 在<servlet>标签下配置1. 第一次被访问时创建(默认)* <load-on-startup>的值为负数2. 在服务器启动时，创建* <load-on-startup>的值为0或正整数* Servlet的init方法，只执行一次，说明一个Servlet在内存中只存在一个对象，Servlet是单例的* 多个用户同时访问时，可能存在线程安全问题。* 解决：尽量不要在Servlet中定义成员变量。即使定义了成员变量，也不要对修改值2. 提供服务：执行service方法，执行多次* 每次访问Servlet时，Service方法都会被调用一次。
3. 被销毁：执行destroy方法，只执行一次* Servlet被销毁时执行。服务器关闭时，Servlet被销毁* 只有服务器正常关闭时，才会执行destroy方法。* destroy方法在Servlet被销毁之前执行，一般用于释放资源
4. getServletConfig和getServletInfo方法了解即可* getServletConfig():获取ServletConfig对象，也就是Servlet的配置对象* getServletInfo():获取Servlet的一些信息，版本，作者等

package com.bao.web.servlet;import javax.servlet.*;
import java.io.IOException;public class ServletDemo1 implements Servlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {System.out.println("init.......");}@Overridepublic ServletConfig getServletConfig() {return null;}@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("hello,servlet");}@Overridepublic String getServletInfo() {return null;}@Overridepublic void destroy() {System.out.println("destroy......");}
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"version="4.0"><!--配置Servlet --><!--<servlet><servlet-name>demo1</servlet-name><servlet-class>com.bao.web.servlet.ServletDemo1</servlet-class></servlet><servlet-mapping><servlet-name>demo1</servlet-name><url-pattern>/demo1</url-pattern></servlet-mapping>--><!--配置Servlet --><servlet><servlet-name>demo1</servlet-name><servlet-class>com.bao.web.servlet.ServletDemo1</servlet-class><!--指定Servlet的创建时机1.第一次被访问时创建* <load-on-startup>的值为负数2.在服务器启动时，创建* <load-on-startup>的值为0或正整数--><load-on-startup>-1</load-on-startup></servlet><servlet-mapping><servlet-name>demo1</servlet-name><url-pattern>/demo1</url-pattern></servlet-mapping>
</web-app>

Servlet3.0

* 好处：* 支持注解配置。可以不需要web.xml了。* 步骤：1. 创建JavaEE项目，选择Servlet的版本3.0以上，可以不创建web.xml2. 定义一个类，实现Servlet接口3. 复写方法4. 在类上使用@WebServlet注解，进行配置

package com.bao.web.servlet;import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import java.io.IOException;@WebServlet("/demo2")//资源路径
public class ServletDemo2 implements Servlet {@Overridepublic void init(ServletConfig servletConfig) throws ServletException {}@Overridepublic ServletConfig getServletConfig() {return null;}@Overridepublic void service(ServletRequest servletRequest, ServletResponse servletResponse) throws ServletException, IOException {System.out.println("servlet2");}@Overridepublic String getServletInfo() {return null;}@Overridepublic void destroy() {}
}

Servlet的体系结构

Servlet -- 接口|
GenericServlet -- 抽象类|
HttpServlet  -- 抽象类* GenericServlet：将Servlet接口中其他的方法做了默认空实现，只将service()方法作为抽象* 将来定义Servlet类时，可以继承GenericServlet，实现service()方法即可* 但是开发中还是不会继承该类，而是会继承HttpServlet* HttpServlet：对http协议的进行了封装，简化了操作* 前端发送请求会使用get或post方法，而该类复写service时，进行了请求方法类型的判断，简化了操作* 继承HttpServlet的步骤1. 定义类继承HttpServlet2. 复写doGet/doPost方法

• 查看HttpSetvlet类的service方法

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Servlet相关配置

1. urlPatterns:Servlet访问路径1. 一个Servlet可以定义多个访问路径 ： @WebServlet({"/d4","/dd4","/ddd4"})2. 路径定义规则：1. /xxx：路径匹配2. /xxx/xxx:多层路径，目录结构3. *.do：扩展名匹配

package com.bao.web.servlet;import javax.servlet.*;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;//@WebServlet("/demo2")
//@WebServlet({"/demo2","/demo3","/demo4"})
//@WebServlet("/demo/demo2")
//@WebServlet("/demo/*")
//@WebServlet("/*")//优先级最低
//@WebServlet("*.do")
@WebServlet("*.abc")
/*1、扩展名可以随便写2、注意不要加正斜杠*/public class ServletDemo2 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("doGet......");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {System.out.println("doPost......");}
}

Http：请求消息

概念

Hyper Text Transfer Protocol 超文本传输协议* 传输协议：定义了，客户端和服务器端通信时，发送数据的格式* 特点：1. 基于TCP/IP的高级协议2. 默认端口号:803. 基于请求/响应模型的:一次请求对应一次响应4. 无状态的：每次请求之间相互独立，不能交互数据* 历史版本：* 1.0：每一次请求响应都会建立新的连接* 1.1：建立连接后复用连接

请求消息数据格式

1. 请求行请求方式 请求url 请求协议/版本GET /login.html  HTTP/1.1* 请求方式：* HTTP协议有7中请求方式，常用的有2种* GET：1. 请求参数在请求行中，在url后。2. 请求的url长度有限制的3. 不太安全* POST：1. 请求参数在请求体中2. 请求的url长度没有限制的3. 相对安全2. 请求头：客户端浏览器告诉服务器一些信息请求头名称: 请求头值（多个值用逗号隔开）* 常见的请求头：1. Host：哪台计算机2. User-Agent：浏览器告诉服务器，我访问你使用的浏览器版本信息* 可以在服务器端获取该头的信息，解决浏览器的兼容性问题3. Referer：http://localhost/login.html* 告诉服务器，我(当前请求)从哪里来？* 作用：1. 防盗链：2. 统计工作：* 了解请求头：4. Connection：表示状态，活着的，可以复用链接5. Accept：作为浏览器告诉服务器我可以接收信息的格式6. Accept-Language：我可以支持的语言环境7. Accept-Encoding：我可以接收的压缩格式3. 请求空行空行，就是用于分割POST请求的请求头和请求体的。4. 请求体(正文)：* 当请求方式为post时才会有* 封装POST请求消息的请求参数的* 完整的请求消息（字符串格式）：POST /httpDemo1/HttpTest1 HTTP/1.1Host: localhost:8080User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:83.0) Gecko/20100101 Firefox/83.0Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2Accept-Encoding: gzip, deflateContent-Type: application/x-www-form-urlencodedContent-Length: 13Origin: http://localhost:8080Connection: keep-aliveReferer: http://localhost:8080/httpDemo1/Cookie: JSESSIONID=7663BFB4D313E801E2B1C1F43F2F19C0; Idea-bd098543=aa75eb7c-b393-4a74-9e81-ea97b66571d6Upgrade-Insecure-Requests: 1Pragma: no-cacheCache-Control: no-cacheusername=zhangsan

Request

原理

1)tomcat服务器会根据请求url中的资源路径，创建对应的class对象(加载进内存)2)tomcat服务器，会创建request和response对象，request对象中封装请求消息数据3)tomcat将request和response两个对象传递给service方法，并且调用service方法4)程序员可以通过request对象获取请求消息数据，通过response对象设置响应消息数据5)服务器在给浏览器做出响应之前，先会从response对象拿程序员设置的响应消息数据理解：request和response对象是由服务器创建的，我们只是来使用它们request对象是来获取请求消息，response对象是来设置响应消息

图解

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request对象继承体系

 ServletRequest      --  接口| 继承HttpServletRequest    -- 接口|  实现org.apache.catalina.connector.RequestFacade 类(tomcat编写的)理解：tomcat编写RequestFacade类并且实现了HttpServletRequest接口

request功能

获取请求消息数据

获取请求行数据

* GET /RequestDemo1/demo1?name=zhangsan HTTP/1.1
* 方法：1. 获取请求方式 ：GET* String getMethod()  2. (*)获取虚拟目录：/RequestDemo1* String getContextPath()3. 获取Servlet路径: /demo1* String getServletPath()4. 获取get方式请求参数：name=zhangsan* String getQueryString()5. (*)获取请求URI：/RequestDemo1/demo1* String getRequestURI():      /RequestDemo1/demo1* StringBuffer getRequestURL()  :http://localhost/RequestDemo1/demo1* URL:统一资源定位符 ： http://localhost/RequestDemo1/demo1   中华人民共和国* URI：统一资源标识符 : /RequestDemo1/demo1                   共和国6. 获取协议及版本：HTTP/1.1* String getProtocol()7. 获取客户机的IP地址：* String getRemoteAddr()

代码演示

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html><head><title>$Title$</title></head><body><form action="/RequestTest/requestDemo1" method="post"><input type="text" name="username"><input type="submit" value="提交"></form></body>
</html>

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//1. 获取请求方式 ：GETString method = req.getMethod();System.out.println(method);//2.(*)获取虚拟目录：/RequestTestString contextPath = req.getContextPath();System.out.println(contextPath);//3. 获取Servlet的资源路径: /requestDemo1String servletPath = req.getServletPath();System.out.println(servletPath);//4. 获取get方式请求参数：username=zhangsanString queryString = req.getQueryString();System.out.println(queryString);//5.(*)获取请求URI：/RequestTest/requestDemo1String requestURI = req.getRequestURI();//获取请求URL：http://localhost:8080/RequestTest/requestDemo1StringBuffer requestURL = req.getRequestURL();System.out.println(requestURI);System.out.println(requestURL);//6. 获取协议及版本：HTTP/1.1String protocol = req.getProtocol();System.out.println(protocol);//7. 获取客户机的IP地址：0:0:0:0:0:0:0:1(ipv6的表现形式，相当于127.0.0.1，为本机地址)String remoteAddr = req.getRemoteAddr();System.out.println(remoteAddr);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

获取请求头数据

* 方法：* (*)String getHeader(String name):通过请求头的名称获取请求头的值* Enumeration<String> getHeaderNames():获取所有的请求头名称* Enumeration对象类似于迭代器

代码演示

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;@WebServlet("/HttpTest1")
public class HttpTest1 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//演示获取所有请求头数据//1.获取所有请求头名称Enumeration<String> headerNames = req.getHeaderNames();//2.遍历while(headerNames.hasMoreElements()){//获取请求头的名称String name = headerNames.nextElement();//根据名称获取请求头的值String value = req.getHeader(name);System.out.println(name+"---"+value);}//演示获取某个请求头数据：user-agentString agent = req.getHeader("user-agent");//判断agent的浏览器版本if(agent.contains("Chrome")){//谷歌System.out.println("谷歌...");}else if(agent.contains("Firefox")){//火狐System.out.println("火狐...");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}}

获取请求体数据

* 请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数
* 步骤：
1. 获取流对象*  BufferedReader getReader()：获取字符输入流，只能操作字符数据*  ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据* 在文件上传知识点后讲解
2. 再从流对象中拿数据

代码演示

regist.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>注册页面</title>
</head>
<body><form action="/httpDemo1/requestDemo1" method="post"><input type="text" placeholder="请输入用户名" name="username"><br><input type="text" placeholder="请输入密码" name="password"><br><input type="submit" value="注册">
</form></body>
</html>

RequestDemo1

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取请求消息体--请求参数//1.获取字符流BufferedReader br = request.getReader();//2.读取数据String line = null;while((line = br.readLine()) != null){System.out.println(line);}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

其他功能

获取请求参数通用方式

不论get还是post请求方式都可以使用下列方法来获取请求参数

1. String getParameter(String name):根据参数名称获取参数值    username=zs&password=123
2. String[] getParameterValues(String name):根据参数名称获取参数值的数组  hobby=xx&hobby=game
3. Enumeration<String> getParameterNames():获取所有请求的参数名称
4. Map<String,String[]> getParameterMap():获取所有参数的map集合

* 中文乱码问题：* get方式：tomcat 8 已经将get方式乱码问题解决了* post方式：会乱码
* 解决：* 在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");* request.setCharacterEncoding("utf-8")：用来确保发往服务器的参数的编码格式，设置从request中取得的值或从数据库中取出的值

代码

<html lang="en"><head><meta charset="UTF-8"><title>注册页面</title></head><body><form action="/RequestTest/requestDemo2" method="post"><input type="text" placeholder="请输入用户名" name="username"><br><input type="text" placeholder="请输入密码" name="password"><br><input type="checkbox" name="hobby" value="game">游戏<input type="checkbox" name="hobby" value="study">学习<input type="checkbox" name="hobby" value="run">跑步<br><input type="submit" value="注册"></form></body>
</html>

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;
import java.util.Set;@WebServlet("/requestDemo2")
public class RequestDemo2 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//post 获取请求参数//解决乱码问题request.setCharacterEncoding("utf-8");//根据参数名称获取参数值String username = request.getParameter("username");//System.out.println("post");System.out.println(username);System.out.println("--------------------");//根据参数名称获取参数值的数组String[] hobbies = request.getParameterValues("hobby");for (String hobby : hobbies) {System.out.println(hobby);}System.out.println("--------------------");//获取所有请求的参数名称/*Enumeration<String> parameterNames = request.getParameterNames();while(parameterNames.hasMoreElements()){String name = parameterNames.nextElement();System.out.println(name);String value = request.getParameter(name);System.out.println(value);System.out.println("----------------");}*/// 获取所有参数的map集合Map<String, String[]> parameterMap = request.getParameterMap();//遍历Set<String> keyset = parameterMap.keySet();for (String name : keyset) {System.out.println(name);//通过键获取值String[] values = parameterMap.get(name);for (String value : values) {System.out.println(value);}System.out.println("----");}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//get 获取请求参数
/*//根据参数名称获取参数值String username = request.getParameter("username");System.out.println("get");System.out.println(username);*/this.doPost(request,response);}
}

请求转发

一种在服务器内部的资源跳转方式

步骤：1. 通过request对象获取请求转发器对象：RequestDispatcher getRequestDispatcher(String path)2. 使用RequestDispatcher对象来进行转发：forward(ServletRequest request, ServletResponse response) 特点：1. 浏览器地址栏路径不发生变化2. 只能转发到当前服务器内部资源中。3. 转发是一次请求4. 转发时不需要加虚拟目录

package com.bao.web.servlet;import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;
import java.util.Set;@WebServlet("/requestDemo3")
public class RequestDemo3 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Demo3...........");//转发到demo4资源
//        RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo4");RequestDispatcher requestDispatcher = request.getRequestDispatcher("https://www.baidu.com/");//404requestDispatcher.forward(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/requestDemo4")
public class RequestDemo4 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("Demo4.........");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

共享数据

* 域对象：一个有作用范围的对象，可以在范围内共享数据
* request域：代表一次请求的范围，一般用于请求转发的多个资源中共享数据
* 方法：1. void setAttribute(String name,Object obj):存储数据2. Object getAttitude(String name):通过键获取值3. void removeAttribute(String name):通过键移除键值对

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/requestDemo5")
public class RequestDemo5 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//存储数据到request域中request.setAttribute("msg","hello");request.removeAttribute("msg");request.getRequestDispatcher("/requestDemo6").forward(request,response);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/requestDemo6")
public class RequestDemo6 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取数据Object msg = request.getAttribute("msg");System.out.println(msg);System.out.println("demo6被访问了。。。");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

获取ServletContext

* 方法：ServletContext getServletContext()

代码演示

package com.bao.web.servlet;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/requestDemo7")
public class RequestDemo7 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取servletContextServletContext servletContext = request.getServletContext();System.out.println(servletContext);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

案例：用户登录

注意

8. login.html中form表单的action路径的写法* 虚拟目录+Servlet的资源路径9. BeanUtils工具类，简化数据封装* 用于封装JavaBean的1. JavaBean：标准的Java类1. 要求：1. 类必须被public修饰2. 必须提供空参的构造器3. 成员变量必须使用private修饰4. 提供公共setter和getter方法2. 功能：封装数据2. 概念：成员变量：定义在类中方法外的变量属性：setter和getter方法截取后首字母小写的产物例如：getUsername() --> Username--> username3. 方法：populate(Object obj , Map map):将map集合的键值对信息，封装到对应的JavaBean对象中

用户登录案例需求

1.编写login.html登录页面username & password 两个输入框
2.使用Druid数据库连接池技术,操作mysql数据库中user表
3.使用JDBCUtils工具类
4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

创建表

CREATE TABLE USER(   id INT PRIMARY KEY AUTO_INCREMENT,username VARCHAR(32) UNIQUE NOT NULL,password VARCHAR(32) NOT NULL,gender VARCHAR(32) NOT NULL
);

创建页面

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>登录</title>
</head>
<body>
<form action="/LoginCase/loginServlet" method="post">用户名:<input type="text" name="username"> <br>密码:<input type="password" name="password"><br><input type="submit" value="登录"></form>
</body>
</html>

后台代码

User

package com.bao.domain;/*** 用户的实体类*/
public class User {private int id;private String username;private String password;private String gender;public void setHehe(String gender){this.gender = gender;}public String getHehe(){return gender;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +", gender='" + gender + '\'' +'}';}
}

JDBCUtils

package com.bao.utils;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;/*** JDBC工具类 使用Durid连接池*/
public class JDBCUtils {private static DataSource ds ;static {try {//1.加载配置文件Properties pro = new Properties();//使用ClassLoader加载配置文件，获取字节输入流InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");pro.load(is);//2.初始化连接池对象ds = DruidDataSourceFactory.createDataSource(pro);} catch (IOException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}}/*** 获取连接池对象*/public static DataSource getDataSource(){return ds;}/*** 获取连接Connection对象*/public static Connection getConnection() throws SQLException {return  ds.getConnection();}/*** 释放资源*/public static void close(Statement stmt, Connection conn) {close(null, stmt, conn);}public static void close(ResultSet rs, Statement stmt, Connection conn) {if (rs != null) {try {rs.close();} catch (SQLException e) {e.printStackTrace();}}if (stmt != null) {try {stmt.close();} catch (SQLException e) {e.printStackTrace();}}if (conn != null) {try {conn.close();//归还连接} catch (SQLException e) {e.printStackTrace();}}}
}

LoginServlet

package com.bao.web.servlet;import com.bao.dao.UserDao;
import com.bao.domain.User;
import org.apache.commons.beanutils.BeanUtils;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//1.设置编码req.setCharacterEncoding("utf-8");//2.获取所有请求参数Map<String, String[]> map = req.getParameterMap();//3.创建User对象User loginUser = new User();//3.2使用BeanUtils封装try {BeanUtils.populate(loginUser,map);//自动将map集合中的数据封装到user中} catch (IllegalAccessException e) {e.printStackTrace();} catch (InvocationTargetException e) {e.printStackTrace();}//4.调用UserDao的login方法UserDao dao = new UserDao();User user = dao.login(loginUser);//5.判断userif(user == null){//登录失败req.getRequestDispatcher("/failServlet").forward(req,resp);}else{//登录成功//存储数据req.setAttribute("user",user);//转发req.getRequestDispatcher("/successServlet").forward(req,resp);}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

FailServlet

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//给页面写一句话//设置编码response.setContentType("text/html;charset=utf-8");//输出response.getWriter().write("登录失败，用户名或密码错误");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

SuccessServlet

package com.bao.web.servlet;import com.bao.domain.User;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;public class SuccessServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//获取request域中共享的user对象User user = (User) req.getAttribute("user");if(user != null){//给页面写一句话//设置编码resp.setContentType("text/html;charset=utf-8");//输出resp.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}
}

UserDao

package com.bao.dao;import com.bao.domain.User;
import com.bao.util.JDBCUtils;import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;/*** 操作数据库中User表的类*/
public class UserDao {/*** 登录方法** @param loginUser 只有用户名和密码* @return user包含用户全部数据, 没有查询到，返回null*/public User login(User loginUser) {User user = new User();try {//1.编写sqlString sql = "select * from user where username = ? and password = ?";//2.得到连接Connection connection = JDBCUtils.getConnection();//3.获取preparedStatement对象PreparedStatement preparedStatement = connection.prepareStatement(sql);//4.给占位符赋值preparedStatement.setString(1, loginUser.getUsername());preparedStatement.setString(2, loginUser.getPassword());//5.得到返回值ResultSet resultSet = preparedStatement.executeQuery();while (resultSet.next()) {user.setId(resultSet.getInt(1));user.setUsername(resultSet.getString(2));user.setPassword(resultSet.getString(3));user.setHehe(resultSet.getString(4));return user;}} catch (SQLException e) {e.printStackTrace();}return null;}
}

druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql:///db3?characterEncoding=utf-8
username=root
password=root
# 初始化连接数量
initialSize=5
# 最大连接数
maxActive=10
# 最大等待时间
maxWait=3000

Http：响应消息

概念

服务器端发送给客户端的数据

响应消息数据格式

1. 响应行1. 组成：协议/版本 响应状态码 状态码描述2. 响应状态码：服务器告诉客户端浏览器本次请求和响应的一个状态。1. 状态码都是3位数字 2. 分类：1. 1xx：服务器接收客户端消息，但没有接受完成，等待一段时间后，发送1xx状态码2. 2xx：成功。代表：2003. 3xx：重定向。代表：302(重定向)，304(访问缓存)4. 4xx：客户端错误。* 重点：* 404（请求路径没有对应的资源） * 405：请求方式没有对应的doXxx方法5. 5xx：服务器端错误。* 重点：500(服务器内部出现异常)2. 响应头：1. 格式：头名称： 值2. 常见的响应头：1. Content-Type：服务器告诉客户端本次响应体数据格式以及格式2. Content-disposition：服务器告诉客户端以什么格式打开响应体数据* 值：* in-line:默认值,在当前页面内打开* attachment;filename=xxx：以附件形式打开响应体。文件下载3. 响应空行4. 响应体:传输的数据* 完整响应字符串格式HTTP/1.1 200 OKdate: Sat, 19 Dec 2020 07:42:36 GMTcontent-type: text/html; charset=UTF-8server: nginxvary: Origin,Accept-Encodingcontent-encoding: gzipexpires: Sat, 19 Dec 2020 07:42:35 GMTcache-control: no-cachex-cache-webcdn: MISS from ks-sccd-cmcc-w-02X-Firefox-Spdy: h2<html><head><title>$Title$</title></head><body>hello , response</body></html>

Response

功能：设置响应消息

1. 设置响应行1. 格式：HTTP/1.1 200 ok2. 设置状态码：setStatus(int sc) 2. 设置响应头：setHeader(String name, String value) 3. 设置响应体：* 使用步骤：1. 获取输出流* 字符输出流：PrintWriter getWriter()* 字节输出流：ServletOutputStream getOutputStream()2. 使用输出流，将数据输出到客户端浏览器

案例：重定向

概述

* 重定向是什么：资源跳转的方式* 重定向的特点:redirect1. 地址栏发生变化2. 重定向可以访问其他站点(服务器)的资源3. 重定向是两次请求。不能使用request对象来共享数据* 转发的特点：forward1. 转发地址栏路径不变2. 转发只能访问当前服务器下的资源3. 转发是一次请求，可以使用request对象来共享数据

代码演示

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;/*** 重定向*/@WebServlet("/responseDemo1")
public class ResponseDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//需求：访问/responseDemo1，会自动跳转到/responseDemo2资源System.out.println("demo1........");
/*//1. 设置状态码为302response.setStatus(302);//2.设置响应头locationresponse.setHeader("location","/ResponseTest1/responseDemo2");
*///简单的重定向方法response.sendRedirect("/ResponseTest1/responseDemo2");
//        response.sendRedirect("https://www.baidu.com/");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/responseDemo2")
public class ResponseDemo2 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {System.out.println("demo2........");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

路径写法

1. 相对路径：通过相对路径不可以确定唯一资源* 如：./index.html* 不以/开头，以.开头路径* 规则：找到当前资源和目标资源之间的相对位置关系* ./：当前目录* ../:后退一级目录
2. 绝对路径：通过绝对路径可以确定唯一资源* 如：http://localhost/ResponseTest1/responseDemo2        /ResponseTest1/responseDemo2* 以/开头的路径* 规则：判断请求从哪里发出的* (从客户端发出)给客户端浏览器使用：需要加虚拟目录(项目的访问路径)* 建议虚拟目录动态获取：request.getContextPath()* <a> , <form> 重定向...* (服务器内部跳转)给服务器使用：不需要加虚拟目录* 转发路径

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><h1>相对路径</h1><h1>找到当前资源和目标资源之间的相对位置关系</h1><P>当前资源:location.htmlhttp://localhost/ResponseTest1/location.html</P><P>目标资源:responseDemo2http://localhost/ResponseTest1/responseDemo2</P><a href="./responseDemo2">相对路径：responseDemo2</a><br><a href="responseDemo2">相对路径："./"可以省略-responseDemo2</a><hr><h1>绝对路径</h1><a href="/ResponseTest1/responseDemo2">绝对路径：需要加虚拟目录-responseDemo2</a></body>
</html>

案例：服务器输出字符数据到浏览器

* 步骤：1. 获取字符输出流2. 输出数据* 注意：* 乱码问题：1. 获取流PrintWriter pw = response.getWriter();获取的流的默认编码是ISO-8859-12. 设置该流的默认编码response.setCharacterEncoding("utf-8");作用是告诉servlet用utf-8转码，而不是用默认的iso8859-13. 告诉浏览器响应体使用的编码简单的形式：在获取流之前设置设置编码response.setContentType("text/html;charset=utf-8");作用是让浏览器用utf-8来解析返回的数据

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;@WebServlet("/responseDemo3")
public class ResponseDemo3 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//流的默认编码字符集为：ISO-8859-1，我们把它设置为utf-8，需要在获取流前设置response.setCharacterEncoding("utf-8");//告诉浏览器，服务器发送的消息体数据的编码。建议浏览器使用该编码解码
//        response.setHeader("content-type","text/html;charset=utf-8");//简单的形式，设置编码response.setContentType("text/html;charset=utf-8");//1.获取字符输出流PrintWriter pw = response.getWriter();//2.输出数据
//        pw.write("<h1>hello response</h1>");pw.write("你好,我好,response");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

案例：服务器输出字节数据到浏览器

* 步骤：1. 获取字节输出流2. 输出数据

package com.bao.web.servlet;import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/responseDemo4")
public class ResponseDemo4 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//        response.setContentType("text/html;charset=utf-8");//1.获取字节输出流ServletOutputStream sos = response.getOutputStream();//2.输出数据sos.write("你好吗".getBytes());//与浏览器编码字符集相同不需要转码
//        sos.write("你好".getBytes("utf-8"));}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

ServletContext

概念

ServletContext代表整个web应用，可以和程序的容器(服务器)来通信
理解：ServletContext官方叫servlet上下文。服务器会为每一个工程创建一个对象，这个对象就是ServletContext对象。这个对象全局唯一，而且工程内部的所有servlet都共享这个对象。所以叫全局应用程序共享对象。

图解

[外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-Ony7KUgE-1626836820552)(02Servlet&HTTP&Request&Response-image/u=3004351408,463413229&fm=11&gp=0.jpg)]

获取

1. 通过request对象获取request.getServletContext();
2. 通过HttpServlet获取this.getServletContext();

package com.bao.web.servletcontext;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/servletContextDemo1")
public class ServletContextDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1. 通过request对象获取ServletContext context1 = request.getServletContext();//2. 通过HttpServlet获取ServletContext context2 = this.getServletContext();System.out.println(context1);System.out.println(context2);System.out.println(context1 == context2);//true}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

功能

1. 获取MIME类型

* MIME类型:在互联网通信过程中定义的一种文件数据类型，有利于网络识别数据的类型* 格式： 大类型/小类型   text/html        image/jpeg
* 获取：String getMimeType(String file)

代码

package com.bao.web.servletcontext;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/servletContextDemo2")
public class ServletContextDemo2 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//2. 通过HttpServlet获取ServletContext context = this.getServletContext();//3. 定义文件名称String filename = "a.jpg";//image/jpeg//4.获取MIME类型String mimeType = context.getMimeType(filename);System.out.println(mimeType);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

2. 域对象：共享数据

1. setAttribute(String name,Object value)
2. getAttribute(String name)
3. removeAttribute(String name)* ServletContext对象范围：所有用户所有请求的数据

代码演示：查看两个servlet是否能够共享数据

package com.bao.web.servletcontext;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/servletContextDemo3")
public class ServletContextDemo3 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//2. 通过HttpServlet获取ServletContext context = this.getServletContext();//设置数据context.setAttribute("msg","haha");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

package com.bao.web.servletcontext;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;@WebServlet("/servletContextDemo4")
public class ServletContextDemo4 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//2. 通过HttpServlet获取ServletContext context = this.getServletContext();//获取数据Object msg = context.getAttribute("msg");System.out.println(msg);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

3. 获取文件的真实路径

真实路径：获取文件在服务器中的路径
方法：String getRealPath(String path)

package com.bao.web.servletcontext;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;@WebServlet("/servletContextDemo5")
public class ServletContextDemo5 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 通过HttpServlet获取ServletContext context = this.getServletContext();// 获取文件的服务器路径String b = context.getRealPath("/b.txt");//web目录下资源访问System.out.println(b);File file = new File(b);//获取了路径就可以加载并读取文件内容String c = context.getRealPath("/WEB-INF/c.txt");//WEB-INF目录下的资源访问System.out.println(c);String a = context.getRealPath("/WEB-INF/classes/a.txt");//src目录下的资源访问System.out.println(a);}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

文件下载案例

需求

1. 页面显示超链接
2. 点击超链接后弹出下载提示框
3. 完成图片、视频文件下载

分析

1. 超链接指向的资源如果能够被浏览器解析，则在浏览器中展示，如果不能解析，则弹出下载提示框。不满足需求
2. 任何资源都必须弹出下载提示框
3. 使用响应头设置资源的打开方式：* content-disposition:attachment;filename=xxx

步骤

1. 定义页面，编辑超链接href属性，指向Servlet，传递资源名称filename
2. 定义Servlet1. 获取文件名称2. 使用字节输入流加载文件进内存3. 指定response的响应头： content-disposition:attachment;filename=xxx4. 将数据写出到response输出流

有可能遇到的问题

解决中文文件问题1. 获取客户端使用的浏览器版本信息2. 根据不同的版本信息，设置filename的编码方式不同

代码演示

download.html

<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><title>Title</title>
</head>
<body><a href="/ResFileDownloadCase/img/九尾.jpg">图片1</a><a href="/ResFileDownloadCase/img/java.wmv">视频</a><hr><a href="/ResFileDownloadCase/downloadServlet?filename=九尾.jpg">图片九尾</a><a href="/ResFileDownloadCase/downloadServlet?filename=jiuwei.jpg">图片jiuwei</a><a href="/ResFileDownloadCase/downloadServlet?filename=java.wmv">视频</a></body>
</html>

DownloadServlet

package com.bao.web.download;import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;@WebServlet("/downloadServlet")
public class DownloadServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//1.获取请求参数，文件名称String filename = request.getParameter("filename");//2.使用字节输入流加载文件进内存//2.1找到文件服务器路径ServletContext servletContext = this.getServletContext();String realPath = servletContext.getRealPath("/img/" + filename);//2.2用字节流关联FileInputStream fis = new FileInputStream(realPath);//3.设置response的响应头
/*//解决中文文件名问题//1.获取user-agent请求头、String agent = request.getHeader("user-agent");//2.使用工具类方法编码文件名即可filename = DownLoadUtils.getFileName(agent, filename);
*///3.1设置响应头类型：content-typeString mimeType = servletContext.getMimeType(filename);//获取文件的mime类型response.setHeader("content-type",mimeType);//3.2设置响应头打开方式:content-dispositionresponse.setHeader("content-disposition","attachment;filename="+filename);//4.将输入流的数据写出到输出流中ServletOutputStream sos = response.getOutputStream();byte[] buff = new byte[1024 * 8];int len = 0;while((len = fis.read(buff)) != -1){sos.write(buff,0,len);}sos.close();fis.close();}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}
}

DownloadUtils

浏览器文件下载中文乱码工具类

不需要记住代码，可在网上查找即可，直接使用

package com.bao.web.utils;import sun.misc.BASE64Encoder;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;public class DownLoadUtils {public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {if (agent.contains("MSIE")) {// IE浏览器filename = URLEncoder.encode(filename, "utf-8");filename = filename.replace("+", " ");} else if (agent.contains("Firefox")) {// 火狐浏览器BASE64Encoder base64Encoder = new BASE64Encoder();filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";} else {// 其它浏览器filename = URLEncoder.encode(filename, "utf-8");}return filename;}
}

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