过滤器及请求封装器实现字符编码

1、Html代码

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <form method="post" action="hello">
        名称：<input type="text" name="name"><br>
        年龄：<input type="text" name="age"><br>
        <input type="submit" value="post提交">
    </form>
    <hr>
    <form method="get" action="hello">
        名称：<input type="text" name="name" value=""><br>
        年龄：<input type="text" name="age" value=""><br>
        <input type="submit" value="get提交" name="submit">
    </form>
</body>
</html>

html Code

2、Servlet代码

package com.test;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(urlPatterns = "/hello")
public class MyServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        // 读取参数
        String name = request.getParameter("name");
        String age = request.getParameter("age");
        // 响应客户端
        response.setContentType("text/html");
        PrintWriter writer = response.getWriter();
        writer.print(name + "|" + age);
        writer.close();
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
        doGet(request, response);
    }
}

Java Code

3、请求封装器

package com.test;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.UnsupportedEncodingException;

public class MyRequestWrapper extends HttpServletRequestWrapper {
    // 构造方法不可少，且在方法内部必须调用父类的构造方法
    public MyRequestWrapper(HttpServletRequest request) {
        super(request);
    }
    @Override
    public String getParameter(String name) {
        HttpServletRequest request = (HttpServletRequest)getRequest();
        String parameter = request.getParameter(name);
        try {
            return new String(parameter.getBytes("ISO-8859-1"), "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return null;
    }
}

Java Code

4、过滤器

package com.test;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter("/*")
public class EncodeDecodeFilter implements Filter {
    private FilterConfig filterConfig;
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        // 首先解决响应乱码
        response.setCharacterEncoding("UTF-8");
        // 解决请求乱码
        // 如果是post请求，把原始请求对象传递进去
        MyRequestWrapper myRequestWrapper = new MyRequestWrapper(request);
        if ("POST".equals(request.getMethod())) {
            request.setCharacterEncoding("UTF-8");
            chain.doFilter(request, response);
            return;
        }
        // 如果是get请求，包装请求对象传递进去
        chain.doFilter(myRequestWrapper, response);
    }
    public void destroy() { }
}

Java Code

6、测试方式

（1）浏览器输入地址：http://127.0.0.1/index.html

（2）填写表单时写入中文字符，提交，查看响应