经常在讨论区看到有人问我的JSP显示中文有乱码怎么办，我用request得到的用户输入的中文怎么是乱码，我把汉字写到数据库怎么是乱码，等等一些关于汉字乱码的问题。其实这个问题很简单，管它汉字不汉字，还是日文，还是其他的什么双字节的语言，我们一律把它当作UTF-8看待。（一）request中的双字节文字好下面我们就来实现在整个应用程序中使用UTF-8编码工作，之所以选择UTF-8不仅仅之于上述原因，我们知道java的就是基于在UTF-8之上的，所以我们选择UTF-8应该没错^_^我们首先把我们的.java, .jsp文件都用UTF-8编码来保存，如果以前的没有用UTF-8保存也无所谓，但是建议以后写的都用UTF-8来保存。并在.jsp里面写:<%@page contentType="text/html; charset=UTF-8"%>而不是<%@page contentType="text/html; charset=UTF-8"%>然后在web.xml添加下面一段：<web-app>...  <filter>    <filter-name>Set Character Encoding</filter-name>    <filter-class>com.redv.projects.eduadmin.util.filters.SetCharacterEncodingFilter</filter-class>    <init-param>      <param-name>encoding</param-name>      <param-value>UTF-8</param-value>    </init-param>  </filter>  <filter-mapping>    <filter-name>Set Character Encoding</filter-name>    <url-pattern>/*</url-pattern>  </filter-mapping>...</web-app>

其中com.redv.projects.eduadmin.util.filters.SetCharacterEncodingFilter的代码如下：

package com.redv.projects.eduadmin.util.filters;

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;import javax.servlet.UnavailableException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;

public class SetCharacterEncodingFilter    implements Filter {

  protected String encoding = null;

  protected FilterConfig filterConfig = null;

  protected boolean ignore = true;

  public void destroy() {

    this.encoding = null;    this.filterConfig = null;

  }

  public void doFilter(ServletRequest request, ServletResponse response,                       FilterChain chain) throws IOException, ServletException {

    // Conditionally select and set the character encoding to be used    if (ignore || (request.getCharacterEncoding() == null)) {      String encoding = selectEncoding(request);      if (encoding != null) {        request.setCharacterEncoding(encoding);           //就是这句话在工作的啦，哈哈，它：Overrides the name of the character encoding used in the body of this request. This method must be called prior to reading request parameters or reading input using getReader().      }    }