Filter的使用（解决中文乱码问题）

一、过滤器配置web.xml

<filter>
<filter-name>SetCharacterEncodingFilter</filter-name>
<filter-class>test.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GBK</param-value>
</init-param>
<init-param>
<param-name>ignore</param-name>
<param-value>true</param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>SetCharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

二、过滤器编写SetCharacterEncodingFilter.java

package test;

import java.io.IOException;
import javax.servlet.*;

public class SetCharacterEncodingFilter implements Filter{
protected String encoding = null; //设置请求正文使用的编码
protected FilterConfig filterConfig = null;
protected boolean ignore = true; //是否忽略客户端使用的编码

public void init(FilterConfig filterConfig) throws ServletException{
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
String value = filterConfig.getInitParameter("ignore");
if (value == null)
this.ignore = true;
else if (value.equalsIgnoreCase("true"))
this.ignore = true;
else if (value.equalsIgnoreCase("yes"))
this.ignore = true;
else
this.ignore = false;
}
public void doFilter(ServletRequest request,ServletResponse response,FilterChain chain)
throws IOException, ServletException{
if (ignore || (request.getCharacterEncoding() == null)){
String encoding = selectEncoding(request);
if (encoding != null)
request.setCharacterEncoding(encoding); //设置请求正文的编码方式
}
response.setContentType("text/html; charset="+encoding); //设置响应正文的编码方式，一般不设置响应编码方式
chain.doFilter(request, response);
}
protected String selectEncoding(ServletRequest request){
return (this.encoding);
}

public void destroy(){
this.encoding = null;
this.filterConfig = null;
}
}