Filter执行过程是什么
Filter执行的顺序
马克- to-win:马克 java社区:防盗版实名手机尾号: 73203。
马克-to-win:根据上面的说明“Filter的拦截的工作过程”的图,我们对Filter的Helloworld例子做一个小小的扩展(增加了一个 MarkToWinFilter2,代码和MarkToWinFilter几乎一样),来说明Filter的顺序,结论:filter-mapping在Web.xml中的顺序决定了Filter执行的顺序。
例 1.2.3
Web.xml中增加下一段:
<filter>
<filter-name>MarkToWinFilter2</filter-name>
<filter-class>com.MarkToWinFilter2</filter-class>
</filter>
<filter>
<filter-name>MarkToWinFilter</filter-name>
<filter-class>com.MarkToWinFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>MarkToWinFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>MarkToWinFilter2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
package com;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
public class MarkToWinFilter2 implements Filter {
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
response.setCharacterEncoding("GBK");
PrintWriter out = response.getWriter();
out.println("之前 filterChain.doFilter2");
System.out.println("之前 filterChain.doFilter2");
chain.doFilter(request, response);
System.out.println("之后 filterChain.doFilter2");
out.println("之后 filterChain.doFilter2");
}
public void init(FilterConfig fConfig) throws ServletException {
}
}
在浏览器中,当运行home.jsp时,浏览器中输出的结果是:
之前 filterChain.doFilter 之前 filterChain.doFilter2
这是在home.jsp
之后 filterChain.doFilter2 之后 filterChain.doFilter
同时Console中输出的结果是:
之前 filterChain.doFilter
之前 filterChain.doFilter2
inside jsp
之后 filterChain.doFilter2
之后 filterChain.doFilter