如何使用过滤器处理中文乱码

如果浏览器提交数据给Servlet的时候含中文参数，那么在Servlet中就要处理中文乱码。如果有多个Servlet都要同时接收中文参数，那么在Servlet中处理中文乱码就比较麻烦。

解决办法：使用过滤器处理中文乱码。

处理post请求的乱码

index.jsp代码

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
  <form action="${pageContext.request.contextPath }/AddUserServlet" method="post">
    用户名:<input type="text" name="userName" /><br>
    <input type="submit" value="提交" />
  </form>
  <hr>
  <form action="${pageContext.request.contextPath }/AddProductServlet" method="post">
    产品名:<input type="text" name="productName" /><br>
    <input type="submit" value="提交" />
  </form>

</body>
</html>

AddUserServlet.java类代码（Servlet 业务处理）

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 AddUserServlet
 */
@WebServlet("/AddUserServlet")
public class AddUserServlet extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取文本框输入参数
        String userName=request.getParameter("userName");
        System.out.println("userName="+userName);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

AddProductServlet.java类代码（Servlet 业务处理）

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 AddProductServlet
 */
@WebServlet("/AddProductServlet")
public class AddProductServlet extends HttpServlet {
    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //获取文本框输入参数
        String productName=request.getParameter("productName");
        System.out.println("productName="+productName);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

创建一个CharacterEncodingFilter类来实现Filter接口，并实现Filter所有方法

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 CharacterEncodingFilter implements Filter {

    @Override
    public void destroy() {
        // TODO Auto-generated method stub

    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");
        chain.doFilter(request, response);

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub

    }

}

web.xml配置:

结果:

如果要处理Get请求的中文乱码，这时候需要对request对象进行增强处理。