案例1. 利用Servlet的过滤器Filter进行完成脏话过滤

package cn.javabs.filter;

import java.io.IOException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

import javax.servlet.http.HttpServletResponse;

public class DirtyWordsFilterDemo implements Filter {

public void init(FilterConfig filterConfig) throws ServletException {

}

public void doFilter(ServletRequest req, ServletResponse resp,

FilterChain chain) throws IOException, ServletException {

HttpServletRequest request;

HttpServletResponse response;

try{

request = (HttpServletRequest)req;

response = (HttpServletResponse)resp;

}catch(Exception e){

throw new RuntimeException("non-http request");

}

DirtyWordHttpServletRequest dwrequest = new DirtyWordHttpServletRequest(request);

chain.doFilter(dwrequest, response);

}

public void destroy() {

}

}

class DirtyWordHttpServletRequest extends HttpServletRequestWrapper{

private String strs[] = {"傻逼","畜生","我去年买了个包"};

private HttpServletRequest request;

public DirtyWordHttpServletRequest(HttpServletRequest request){

super(request);

this.request = request;

}

@Override

public String getParameter(String name) {

String value = request.getParameter(name);

if(value==null)

return null;

for(String s:strs){

if(value.contains(s)){

value = value.replace(s, "**");

}

}

return value;

}

}

案例2. 利用Servlet的过滤器Filter进行完成Html编码过滤

package cn.javabs.filter;

import java.io.IOException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

import javax.servlet.http.HttpServletResponse;

public class HtmlFilterDemo implements Filter {

public void init(FilterConfig filterConfig) throws ServletException {

}

public void doFilter(ServletRequest req, ServletResponse resp,

FilterChain chain) throws IOException, ServletException {

HttpServletRequest request;

HttpServletResponse response;

try{

request = (HttpServletRequest)req;

response = (HttpServletResponse)resp;

}catch(Exception e){

throw new RuntimeException("non-http request");

}

HtmlHttpServletRequest hrequest = new HtmlHttpServletRequest(request);

chain.doFilter(hrequest, response);

}

public void destroy() {

}

}

class HtmlHttpServletRequest extends HttpServletRequestWrapper{

private HttpServletRequest request;

public HtmlHttpServletRequest(HttpServletRequest request){

super(request);

this.request = request;

}

@Override

public String getParameter(String name) {

String value = request.getParameter(name);

if(value==null)

return null;

value = htmlFilter(value);

return value;

}

private String htmlFilter(String message) {

if (message == null)

return (null);

char content[] = new char[message.length()];

message.getChars(0, message.length(), content, 0);

StringBuffer result = new StringBuffer(content.length + 50);

for (int i = 0; i < content.length; i++) {

switch (content[i]) {

case '

result.append("<");

break;

case '>':

result.append(">");

break;

case '&':

result.append("&");

break;

case '"':

result.append(""");

break;

default:

result.append(content[i]);

}

}

return (result.toString());

}

}

案例3. 利用Servlet的过滤器Filter进行完成字符编码过滤(Get及Post方式)

package cn.javabs.filter;

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import javax.servlet.Filter;

import javax.servlet.FilterChain;

import javax.servlet.FilterConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletRequestWrapper;

import javax.servlet.http.HttpServletResponse;

/**

* 同时解决GET及POST请求参数和响应输出的编码过滤器

*/

public class SetAllEncodingFilterDemo implements Filter {

private FilterConfig filterConfig;

public void init(FilterConfig filterConfig) throws ServletException {

this.filterConfig = filterConfig;

}

public void doFilter(ServletRequest req, ServletResponse resp,

FilterChain chain) throws IOException, ServletException {

HttpServletRequest request;

HttpServletResponse response;

try{

request = (HttpServletRequest)req;

response = (HttpServletResponse)resp;

}catch(Exception e){

throw new RuntimeException("non-http request");

}

String encoding = "UTF-8";

String value = filterConfig.getInitParameter("encoding");

if(value!=null){

encoding = value;

}

request.setCharacterEncoding(encoding);//POST请求方式

response.setContentType("text/html;charset="+encoding);

MyHttpServletRequest mrequest = new MyHttpServletRequest(request);

chain.doFilter(mrequest, response);

}

public void destroy() {

}

}

class MyHttpServletRequest extends HttpServletRequestWrapper{

private HttpServletRequest request;

public MyHttpServletRequest(HttpServletRequest request){

super(request);

this.request = request;

}

public String getParameter(String name) {

String value = request.getParameter(name);

if(value==null)

return value;

try {

if("get".equalsIgnoreCase(request.getMethod()))

value = new String(value.getBytes("ISO-8859-1"),request.getCharacterEncoding());

} catch (UnsupportedEncodingException e) {

e.printStackTrace();

}

return value;

}

}