【filter】示例-优快云博客

本文链接：https://blog.youkuaiyun.com/jeep_ouc/article/details/21410643

本文展示了如何在Web应用中使用Java的Filter和Servlet进行整合，具体介绍了TestFilter类实现过滤逻辑，并通过web.xml配置将其应用于指定的Servlet（TestFilterServlet）。详细解释了Filter的生命周期方法和Servlet的基本请求响应流程。

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TestFilter.java

public class TestFilter implements Filter {

	public void destroy() {
	}

	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("aaa");
		chain.doFilter(request,response);
		System.out.println("bbb");
	}

	public void init(FilterConfig arg0) throws ServletException {
		System.out.println("init初始化");
	}
}

TestFilterServlet.java

public class TestFilterServlet extends HttpServlet {
  
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("testFilterServlet执行了 !!");
	}
}

web.xml

  <filter>
  		<filter-name>test</filter-name>
  		<filter-class>cn.edu.softrc.test.TestFilter</filter-class>
  </filter>
  <filter-mapping>
  		<filter-name>test</filter-name>
  		<url-pattern>/testFilterServlet</url-pattern>  <!-- 对testFilterServlet过滤 -->
  </filter-mapping>
  
  <servlet>
  		<servlet-name>TestFilterServlet</servlet-name>
  		<servlet-class>cn.edu.softrc.test.TestFilterServlet</servlet-class>
  </servlet>
  <servlet-mapping>
  		<servlet-name>TestFilterServlet</servlet-name>
  		<url-pattern>/testFilterServlet</url-pattern>
  </servlet-mapping>

result