JavaEE Filter解决中文乱码问题

描述

使用 JavaEE Filter 解决 POST 方法提交汉字乱码的问题。

题目

编写过滤器，解决所有 Servlet 中使用 POST 方法提交汉字乱码的问题。

题目解决思路

分别创建登录和注册两个页面。
分别创建登录和注册两个 Servlet。
注册和登录两个页面使用 POST 的方式，提交中文数据给对应的 Servlet。
创建 CharacterEncodingFilter，处理中文乱码问题。

源代码

百度云

链接：https://pan.baidu.com/s/1CrCm15py7wEsIXcvCbwIIw 
提取码：sr6c

项目结构

09_Java Filter解决中文乱码问题.png

代码具体实现

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>用户注册</title>
</head>
<body>
<h2>用户注册(www.haicoder.net)</h2>
<form action="register" method="post">
    注册名：<input type="text" name="name">
    <input type="submit" value="注册">
</form>
</body>
</html>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>登录</title>
</head>
<body>
<h2>用户登录(www.haicoder.net)</h2>
<form action="login" method="post">
    登录名：<input type="text" name="user">
    <input type="submit" value="登录">
</form>
</body>
</html>

RegisterServlet 代码：

package net.haicoder.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("/register")
public class RegisterServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        PrintWriter pw = response.getWriter();
        pw.print("嗨客网(www.haicoder.net)<br/>");
        String name = request.getParameter("name");
        pw.print("注册成功，您的注册名字是：" + name);
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

LoginServlet 代码：

package net.haicoder.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("/login")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        PrintWriter pw = response.getWriter();
        pw.print("嗨客网(www.haicoder.net)<br/>");
        //获取提交的用户名，显示在页面上
        String user = request.getParameter("user");
        pw.print("登录成功，欢迎您：" + user);
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

CharacterEncodingFilter 代码：

package net.haicoder.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
@WebFilter(filterName = "CharacterEncodingFilter", urlPatterns = "/*")
public class CharacterEncodingFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        // 向下转型转成子接口
        HttpServletRequest request = (HttpServletRequest) req;
        // 获取请求的方式
        String method = request.getMethod();
        // 判断请求的方式是否是POST方法，注：POST是大写
        if ("POST".equals(method)) {
            // 设置请求的编码是utf-8
            req.setCharacterEncoding("utf-8");
        }
        // 放行
        chain.doFilter(req, resp);
    }
    public void destroy() {
    }
}