04_过滤器Filter_02_Filter解决中文乱码问题

【过滤器解决中文乱码问题实例】

【工程截图】

04_过滤器Filter_02_Filter解决中文乱码问题

【web.xml】

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>FilterDemo01</display-name>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<filter>
<filter-name>FilterTest01</filter-name>
<filter-class>com.Higgin.web.filter.FilterTest01</filter-class>
</filter>
<filter-mapping>
<filter-name>FilterTest01</filter-name>
<url-pattern>/*</url-pattern> <!-- 过滤所有 -->
</filter-mapping> </web-app>

【servletTest01.java】

package com.Higgin.web.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; /**
* Servlet implementation class ServletTest01
*/
@WebServlet("/ServletTest01")
public class ServletTest01 extends HttpServlet {
private static final long serialVersionUID = 1L; public ServletTest01() {
super();
} protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().write("中国 加油!China Come on!"); //将"中国 加油!China Come on!"显示在客户端界面上
} protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request,response);
} }

【情况一:未添加中文乱码过滤

【FilterTest01.java】

package com.Higgin.web.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; public class FilterTest01 implements Filter{ @Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException { System.out.println("I'm Filter!!!!");
//直接放行
chain.doFilter(request, response);
//让目标资源执行,即:放行
} @Override
public void init(FilterConfig arg0) throws ServletException { } @Override
public void destroy() { }
}

【运行结果】

浏览器端

04_过滤器Filter_02_Filter解决中文乱码问题

控制台

04_过滤器Filter_02_Filter解决中文乱码问题

【情况二:在Filter的都doFilter()方法中添加中文乱码过滤处理

【FilterTest01.java】

package com.Higgin.web.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; public class FilterTest01 implements Filter{ @Override
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException { System.out.println("I'm Filter!!!!"); //对request和response进行一些预处理
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("text/html;character=UTF-8"
); chain.doFilter(request, response);//让目标资源执行,即:放行
} @Override
public void init(FilterConfig arg0) throws ServletException { } @Override
public void destroy() { }
}

【运行结果】

浏览器端

04_过滤器Filter_02_Filter解决中文乱码问题

控制台

04_过滤器Filter_02_Filter解决中文乱码问题

【三种典型应用概述】

1.可以在Filter中根据条件决定是否调用chain.doFilter(request,response)方法,即是否放行让目标资源执行。

2.在目标资源执行之前,可以对request/response做预处理,再让目标资源执行。(如:为request和reponse设置编码为utf-8,以解决中文乱码问题)

3.让目标资源执行之后,可以捕获目标资源的执行结果,从而实现一些特殊的功能。

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