filter元素和filter-mapping元素
<filter>过滤器元素将一个名字和实现javax.servlet.Filter的接口的类相关联。
1 新建一个类 Encoding Filter
package cn.bupt.duming.util;
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 EncodingFilter implements Filter{
private FilterConfig config = null ;
private String targetEncoding = "ASCLL" ;
public void destroy() {
// TODO Auto-generated method stub
config = null ;
this.targetEncoding = null ;
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
System.out.println("targetEncoding " + this.targetEncoding +"\n");
//执行代码
request.setCharacterEncoding(this.targetEncoding) ;
chain.doFilter(request, response) ;
}
public void init(FilterConfig config) throws ServletException {
// TODO Auto-generated method stub
this.config = config ;
//从配置文件中读取初始化参数（目标编码）
this.targetEncoding = config.getInitParameter("encoding") ;
}
}
2 配置Filter类。在web.xml中配置该filter
<filter>
<filter-name>EncodingFilter</filter-name>
<filter-class>cn.bupt.duming.util.EncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GB2312</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>EncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
3 重新运行该应用
会在控制台打印 targetEncoding GB2312 ， 说明配置成功。
