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后台(26)——Filter（3）

2017-02-24 21:39 316 查看

版权声明

本文原创作者：谷哥的小弟

作者博客地址：http://blog.csdn.net/lfdfhl

在这篇博客中我们利用Filter一并解决POST和GET请求的中文乱码。

测试表单

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Welcome</title>
</head>
<body>
<form action="${pageContext.request.contextPath}/loginServlet" method="post">
<br/>
用  户：<input type="text" name="username"/><br/><br/>
密  码：<input type="password" name="password"/><br/><br/>
<input type="submit" value=" 登  录 " /><br/>
</form>
</body>
</html>

该页面非常简单，在点击”登录”之后跳转到loginServlet

测试Servlet

/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*/
package cn.com;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGetAndPost(req, resp);
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
doGetAndPost(req, resp);
}

private void doGetAndPost(HttpServletRequest req, HttpServletResponse resp){
String username=req.getParameter("username");
System.out.println("---> username="+username);
}
}

在该页面中利用getParameter( )测试是否乱码

利用Filter过滤乱码

嗯哼，终于轮到今天的主角上场了

/**
* 本文作者：谷哥的小弟
* 博客地址：http://blog.csdn.net/lfdfhl
*/
package cn.com;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
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 TestFilter implements Filter {

@Override
public void init(FilterConfig filterConfig) throws ServletException {

}

@Override
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest request=(HttpServletRequest) req;
HttpServletResponse response=(HttpServletResponse) res;
request=new MyHttpServletRequest(request);
chain.doFilter(request, response);
}

@Override
public void destroy() {

}

}

class MyHttpServletRequest extends HttpServletRequestWrapper{
HttpServletRequest request;
boolean isFirst=true;

public MyHttpServletRequest(HttpServletRequest request) {
super(request);
this.request=request;
}

@Override
public String getParameter(String name) {
Map<String, String[]> parameterMap=getParameterMap();
String[] values=parameterMap.get(name);
String value=values[0];
return value;
}

@Override
public String[] getParameterValues(String name) {
Map<String, String[]> parameterMap=getParameterMap();
String[] values=parameterMap.get(name);
return values;
}

@Override
public Map<String, String[]> getParameterMap() {
Map<String, String[]> parameterMap = request.getParameterMap();
if(isFirst){
Set<Entry<String, String[]>> entrySet = parameterMap.entrySet();
for(Entry<String, String[]> entry:entrySet){
String[] values = entry.getValue();
for(int i=0;i<values.length;i++){
String value=values[i];
try {
value=new String(value.getBytes("iso8859-1"),"UTF-8");
values[i]=value;
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
}
isFirst=false;
}
return parameterMap;
}
}

在该类中通过继承HttpServletRequestWrapper实现自己的HttpServletRequest，即文中的MyHttpServletRequest。

覆写getParameter( )使其最终调用getParameterMap( )

覆写getParameterValues( )使其最终调用getParameterMap( )

在getParameterMap( )中将每个请求参数用UTF-8重新编码

配置文件

<?xml version="1.0" encoding="UTF-8"?>
<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"> 
<filter>
<filter-name>TestFilter</filter-name>
<filter-class>cn.com.TestFilter</filter-class>
</filter>

<filter-mapping>
<filter-name>TestFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

<servlet>
<servlet-name>loginServlet</servlet-name>
<servlet-class>cn.com.LoginServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>loginServlet</servlet-name>
<url-pattern>/loginServlet</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

</web-app>

嗯哼，至此利用Filter同时解决了Post和Get请求时带来的中文乱码问题。

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