filter顾名思义,过滤器的意思,在javaweb中的Struts就利用了这种机制去实现视图和业务分离。
这里来配置下自己的Filter来理解下Struts的内在。
在web.xml 中添加下面:
myfilter sun.fifter.MyFifter myfilter *
这里意思是只要url的类型是* ,就会调 myfilter,
然后定义myfilter这个类:
package sun.fifter;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.tools.JavaCompiler;public class MyFifter implements javax.servlet.Filter{ public MyFifter() { // TODO Auto-generated constructor stub } @Override public void destroy() { // TODO Auto-generated method stub System.out.println("destroy"); } @Override public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException { // TODO Auto-generated method stub System.out.println("doFilter"); } @Override public void init(FilterConfig arg0) throws ServletException { // TODO Auto-generated method stub System.out.println("init"); }}
这样在调用的时候:http://localhost:8080/WebProject1/index.html
控制台就会输出;