JAVA WEB新特性之注解

注解主要代替在web.xml进行配的信息的
主要含有 @WebServlet
@WebListner
@WebFilter
@Resource
其中WebServlet初始化值配置的为

//@WebServlet("/fragment")//就等于在.xml文件中的配置应用内访问的名称和浏览器访问的名称
@WebServlet(
        initParams= {@WebInitParam(name="name", value = "小明11111111"),@WebInitParam(name="name2", value = "小黄")},
        //配置的初始值
        loadOnStartup=0,
        urlPatterns= {"/fragment","/text/fragment"}
        )
public class FragmentGG extends HttpServlet {

代替了<param-name>test</param-name>
<param-value>123456</param-value>进行初始化值

<servlet>
  <servlet-name>MySevlet2</servlet-name>
  <servlet-class>com.iotek.jee.servler.MySevler2</servlet-class>
  <init-param>
  <param-name>test</param-name>
  <param-value>123456</param-value>
  </init-param>
  <load-on-startup>0</load-on-startup>
  </servlet>
  

implements Filter 的监听@WebFilter

package com.ieek.ew;

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;
import javax.servlet.annotation.WebFilter;
@WebFilter("/*")//代表所有的应用都会走这个监听(也可以写单独的页面地址)
public class TestFilter implements Filter{

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        System.out.println("TestFilter destroy");
    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        System.out.println("TestFilter doFilter");
        arg2.doFilter(arg0, arg1);//运行的内容
        System.out.println("TestFilter end");
    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("TestFilter init");
    }

}

implements ServletContextListener
@WebListener的监听

package com.ieek.ew;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class ContextListener implements ServletContextListener {

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("contextDestroyed   ContextListener");
    }

    @Override
    public void contextInitialized(ServletContextEvent sce) {
        // TODO Auto-generated method stub
        System.out.println("contextInitialized   ContextListener");
    }

}

@Resource资源注解
首先需要从web.xml中添加

 <env-entry>
  <env-entry-name>test</env-entry-name>
  <env-entry-type>java.lang.String</env-entry-type>
  <env-entry-value>holle word</env-entry-value>
  </env-entry>

再从Servlet中引用

    private @Resource(name="test") String str;
        System.out.println(str);

结果打印holle word