JavaWeb项目自定义过滤器（字符集过滤器）

一个简单的字符集过滤器

此内容旨在记录JavaWeb项目中扩展过滤器的过程，并不能完全解决项目中的乱码问题

1、 自定义一个过滤器类

package com.jiuqi.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;

/**
 1. Title：CharacterFilter

 2. Description： 字符集过滤器
 3. 
 4. @author QiuChangjin
 5. @version 2018年4月13日
 */
public class CharacterFilter implements Filter {

    private String character; // 字符集编码类型

    /**
     * Filter的初始化
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // 读取web.xml中Filter配置的初始化参数
        character = filterConfig.getInitParameter("character");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
            throws IOException, ServletException {
        // 读取初始化的参数character
        servletRequest.setCharacterEncoding(character);
        servletResponse.setCharacterEncoding(character);
        servletResponse.setContentType("text/html; charset=UTF-8");
        filterChain.doFilter(servletRequest, servletResponse); // 放行，转到下一个过滤器
    }

    /**
     * 在Filter销毁前，完毕某些资源的回收
     */
    @Override
    public void destroy() {
    }
}

2、WEB-INF目录下的web.xml中增加filter，过滤器加载是有顺序的

<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_2_5.xsd" id="WebApp_ID"
    version="2.5">
    <display-name>MyTestdisplay-name>
    
    <filter>
        
        <filter-name>CharacterFilterfilter-name>
        
        <filter-class>com.jiuqi.filter.CharacterFilterfilter-class>
        
        <init-param>
            
            <param-name>characterparam-name>
            
            <param-value>utf-8param-value>
        init-param>
    filter>
    
    <filter-mapping>
        
        <filter-name>CharacterFilterfilter-name>
        
        <url-pattern>/*url-pattern>
    filter-mapping>
    <welcome-file-list>
        <welcome-file>index.jspwelcome-file>
    welcome-file-list>
web-app>

3、项目代码结构