redis-使用Java代码操作

Redis-安装和命令操作

(https://blog.csdn.net/qq_45174759/article/details/102525843)上，演示Redis使用Java代码操作，以及在项目中的实际应用。

使用Java代码操作Redis

Demo1.java
代码如下:

package com.hc;import redis.clients.jedis.Jedis;/*** @author胡聪* @site www.hc.com* @company xxx公司* @create  2019-10-13 10:29*/
public class Demo1 {public static void main(String[] args) {Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");System.out.println(jedis.ping());/*String(字符串)*///存值
//        jedis.set("name","hc");
//        jedis.set("sex","男");//取值
//        System.out.println(jedis.get("name"));/*哈希(Hash)*/
//        jedis.hset("user","name","hc");
//        jedis.hset("user","sex","男");
//        jedis.hset("user","age","20");
//        jedis.hset("user","pwd","375199");
//        System.out.println(jedis.hget("user","naem"));
//        Map<String, String> user = jedis.hgetAll("user");
//        for (Map.Entry<String, String> e : user.entrySet()) {
//            System.out.println("key:"+e.getKey()+",value:"+e.getValue());
//        }/*列表(List)*/jedis.lpush("hobby","a","b","c","d");System.out.println(jedis.lpop("hobby"));System.out.println(jedis.rpop("hobby"));}
}

项目中的应用演示例子
查询中使用redis的逻辑
如图所示：

redis在增删改中的使用
如图所示：

Demoservlet.java
代码如下：

package com.hc;import redis.clients.jedis.Jedis;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;/*** @author胡聪* @site www.hc.com* @company xxx公司* @create  2019-10-14 01:13*/
@WebServlet("/demo1")
public class Demoservlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doPost(req,resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");String booklist = jedis.get("booklist");if(booklist==null || "".equals(booklist)){//模拟实际项目开发需求，在项目中运用redis//查询数据库String mysqldata="data";//将mysqldata数据源转成json数组串jedis.set("booklist",mysqldata);booklist = jedis.get("booklist");req.setAttribute("mag","走了数据库数据");req.setAttribute("booklist",booklist);req.getRequestDispatcher("/booklist.jsp").forward(req,resp);}else{req.setAttribute("mag","直接从redis里面拿了数据");req.setAttribute("booklist",booklist);req.getRequestDispatcher("/booklist.jsp").forward(req,resp);}}
}

booklist.jsp

<%--Created by IntelliJ IDEA.User: machenikeDate: 2019/10/13Time: 11:53To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page isELIgnored="false" %>
<html>
<head><title>Title</title>
</head>
<body>
${mag}:${booklist}
</body>
</html>

效果如图所示：
第一次访问

第二次访问

项目实战演示（利用的是原生mvc框架演示）

实现来看一下我们的项目层理结构
如图所示：

web.xml
初次使用idea建立web项目时，你可能会遇到不能使用el表达式
解决办法一 : 修改web.xml的头文件,可以修改为：

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

解决办法二 : 在jsp中修改
但是这个方法不推荐，因为我们需要在每一个用到el表达式的页面进行代码的添加：

  <%@ page isELIgnored="false"%>

第一种方法
代码如下：

<!DOCTYPE web-app PUBLIC"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN""http://java.sun.com/dtd/web-app_2_3.dtd" ><web-app version="2.5"xmlns="http://java.sun.com/xml/ns/javaee"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"><display-name>Archetype Created Web Application</display-name><filter><filter-name>encodingFiter</filter-name><filter-class>com.hc.util.EncodingFiter</filter-class></filter><filter-mapping><filter-name>encodingFiter</filter-name><!-- /* 代表应用目录下的所有请求 --><url-pattern>/*</url-pattern></filter-mapping><servlet><servlet-name>dispatcherServlet</servlet-name><servlet-class>com.hc.framework.DispatcherServlet</servlet-class><init-param><param-name>xmlPath</param-name><param-value>/mvc.xml</param-value></init-param></servlet><servlet-mapping><servlet-name>dispatcherServlet</servlet-name><url-pattern>*.action</url-pattern></servlet-mapping>
</web-app>

由于是在maven项目中使用mvc框架，所以我们要导入相应的架包，在idea中使用mvc框架，它的层级关系和eclipse不同，所以会出现找不到.xml文件的问题，我们需要在pom.xml依赖中定义读取.xml文件的根目录
如图所示：

这样我们就可以读取到java文件下的.xml文件了，也就是可以解析它了
pom.xml
代码如下：

<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.hc</groupId><artifactId>mavendemo</artifactId><version>1.0-SNAPSHOT</version><packaging>war</packaging><name>mavendemo Maven Webapp</name><!-- FIXME change it to the project's website --><url>http://www.example.com</url><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.7</maven.compiler.source><maven.compiler.target>1.7</maven.compiler.target><servlet.version>4.0.0</servlet.version><mysql.version>5.1.44</mysql.version><jstl.version>1.2</jstl.version><standard.version>1.1.2</standard.version><tomcat-jsp.version>8.0.47</tomcat-jsp.version></properties><dependencies><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>${servlet.version}</version><scope>provided</scope></dependency><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId><version>2.9.0</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>${mysql.version}</version></dependency><dependency><groupId>com.alibaba</groupId><artifactId>fastjson</artifactId><version>1.2.28</version></dependency><dependency><groupId>jstl</groupId><artifactId>jstl</artifactId><version>${jstl.version}</version></dependency><dependency><groupId>taglibs</groupId><artifactId>standard</artifactId><version>${standard.version}</version></dependency><dependency><groupId>org.apache.tomcat</groupId><artifactId>tomcat-jsp-api</artifactId><version>${tomcat-jsp.version}</version></dependency><dependency><groupId>dom4j</groupId><artifactId>dom4j</artifactId><version>1.6.1</version></dependency><dependency><groupId>commons-beanutils</groupId><artifactId>commons-beanutils</artifactId><version>1.8.0</version></dependency><dependency><groupId>commons-logging</groupId><artifactId>commons-logging</artifactId><version>1.2</version></dependency><dependency><groupId>jaxen</groupId><artifactId>jaxen</artifactId><version>1.2.0</version></dependency></dependencies><build><finalName>mavendemo</finalName><resources><resource><directory>src/main/java</directory><includes><include>**/*.xml</include></includes></resource></resources><pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) --><plugins><plugin><artifactId>maven-clean-plugin</artifactId><version>3.1.0</version></plugin><!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging --><plugin><artifactId>maven-resources-plugin</artifactId><version>3.0.2</version></plugin><plugin><artifactId>maven-compiler-plugin</artifactId><version>3.8.0</version></plugin><plugin><artifactId>maven-surefire-plugin</artifactId><version>2.22.1</version></plugin><plugin><artifactId>maven-war-plugin</artifactId><version>3.2.2</version></plugin><plugin><artifactId>maven-install-plugin</artifactId><version>2.5.2</version></plugin><plugin><artifactId>maven-deploy-plugin</artifactId><version>2.8.2</version></plugin></plugins></pluginManagement></build>
</project>

然后就是我们redis实际运用了，修改我们的 BookAction.java
BookAction.java
代码如下：

package com.hc.web;import com.alibaba.fastjson.JSON;
import com.hc.dao.BookDao;
import com..entity.Book;
import com.hc.framework.ActionSupport;
import com.hc.framework.ModelDrivern;
import com.hc.util.PageBean;
import redis.clients.jedis.Jedis;import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.SQLException;
import java.util.List;public class BookAction extends ActionSupport implements ModelDrivern<Book> {private Book book = new Book();private BookDao bookDao = new BookDao();/*** 分页查询* @param req* @param resp* @return*/public String list(HttpServletRequest req,HttpServletResponse resp) {PageBean pageBean = new PageBean();pageBean.setRequest(req);try {List<Book> list = this.bookDao.list(book, pageBean);Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");String booklist = jedis.get("booklist");if(booklist==null || "".equals(booklist)){System.out.println("先从mysql数据库拿数据，很慢");String mysqldata= JSON.toJSONString(list);jedis.set("booklist",mysqldata);booklist = jedis.get("booklist");req.setAttribute("bookList",list);req.setAttribute("pageBean", pageBean);}else{System.out.println("直接从redis拿数据，很快");req.setAttribute("bookList", JSON.parse(booklist));req.setAttribute("pageBean", pageBean);jedis.del("booklist");System.out.println("查询方法更新缓存");}} catch (InstantiationException | IllegalAccessException | SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return "list";}/*** 跳转到增加或者修改页面* @param req* @param resp* @return*/public String preSave(HttpServletRequest req,HttpServletResponse resp) {
//      bid的类型是int类型，而int类型的默认值是0，如果jsp未传递bid的参数值，那么bid=0if(book.getBid() == 0) {System.out.println("增加逻辑.....");}else {
//          修改数据回显逻辑        try {
//              查单个Book b = this.bookDao.list(book, null).get(0);req.setAttribute("book", b);} catch (InstantiationException | IllegalAccessException | SQLException e) {e.printStackTrace();}}
//      新增页面与修改页面是同一个jspreturn "edit";}/*** 新增* @param req* @param resp* @return*/public String add(HttpServletRequest req,HttpServletResponse resp) {try {int add = this.bookDao.add(book);if(add>0){//           更新缓存Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");jedis.del("booklist");System.out.println("增加方法更新缓存");}} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException| SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}
//      新增完了后需要刷新页面return "toList";}/*** 修改* @param req* @param resp* @return*/public String edit(HttpServletRequest req,HttpServletResponse resp) {try {int edit = this.bookDao.edit(book);if(edit>0){//          更新缓存Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");jedis.del("booklist");System.out.println("修改方法更新缓存");}} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException| SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}
//      修改完了后需要刷新页面return "toList";}/*** 删除* @param req* @param resp* @return*/public String del(HttpServletRequest req,HttpServletResponse resp) {try {int del = this.bookDao.del(book);if(del>0){//          更新缓存Jedis jedis=new Jedis("192.168.149.129",6379);jedis.auth("123456");jedis.del("booklist");System.out.println("删除方法更新缓存");}} catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException| SQLException e) {e.printStackTrace();}
//      新增完了后需要刷新页面return "toList";}@Overridepublic Book getModel() {return book;}
}

查询方法运行结果如图所示：

时间对比图。如图所示：

增删改方法运行结果如图所示：