JAVA-EE监听器BindingListener的使用------计算机网络经典

冷不防 2024-02-21 12:22 14阅读 0赞

>     Listener监听器
>     监听器是servlet规范的一员,和filter一样
>     它是给予我们java程序员的特殊时机,如果要执行这段代码,你需要想到使用对应的监听器
>     有servletContext,ContextAttribute,request,requestAttribute等
>     session和sessionAttribute
>     监听器都需要webListener注解
>     attribute监听的是域中数据的变化,只要数据变化,就会执行对应的方法
>     sessionBinding监听器不需要webListener进行注解,它是给我们的类用于实现的
>     假设一个类实现了该监听器,那么这个对象在被放入或是取出域的时候都会执行方法
>     bind绑定和unbind解绑
> 
>     Listener监听器
>     监听器是servlet规范的一员,和filter一样
>     它是给予我们java程序员的特殊时机,如果要执行这段代码,你需要想到使用对应的监听器
>     有servletContext,ContextAttribute,request,requestAttribute等
>     session和sessionAttribute
>     监听器都需要webListener注解
>     attribute监听的是域中数据的变化,只要数据变化,就会执行对应的方法
>     sessionBinding监听器不需要webListener进行注解,它是给我们的类用于实现的
>     假设一个类实现了该监听器,那么这个对象在被放入或是取出域的时候都会执行方法
>     bind绑定和unbind解绑

>     package com.bjpowernode.oa.listener;
>     
>     import com.bjpowernode.oa.Pojo.User;
>     import com.bjpowernode.oa.Pojo.User1;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/session/bind")
>     public class HttpSessionBindingListener extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             //获取session对象
>             HttpSession session = request.getSession();
>             //准备个对象
>             User user = new User("1","jack","123");
>             User1 user1 = new User1("2","rose","123");
>             session.setAttribute("user",user);
>             session.setAttribute("user1",user1);
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import com.bjpowernode.oa.Pojo.User;
>     import com.bjpowernode.oa.Pojo.User1;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/session/bind")
>     public class HttpSessionBindingListener extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             //获取session对象
>             HttpSession session = request.getSession();
>             //准备个对象
>             User user = new User("1","jack","123");
>             User1 user1 = new User1("2","rose","123");
>             session.setAttribute("user",user);
>             session.setAttribute("user1",user1);
>         }
>     }

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.annotation.WebListener;
>     import jakarta.servlet.http.HttpSessionAttributeListener;
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     
>     @WebListener
>     public class MyHttpAttListener implements HttpSessionAttributeListener
>     {
>         @Override
>         public void attributeAdded(HttpSessionBindingEvent se) {
>             System.out.println("session存档");
>         }
>     
>         @Override
>         public void attributeRemoved(HttpSessionBindingEvent se) {
>             System.out.println("session移除");
>         }
>     
>         @Override
>         public void attributeReplaced(HttpSessionBindingEvent se) {
>             System.out.println("session替换");
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.annotation.WebListener;
>     import jakarta.servlet.http.HttpSessionAttributeListener;
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     
>     @WebListener
>     public class MyHttpAttListener implements HttpSessionAttributeListener
>     {
>         @Override
>         public void attributeAdded(HttpSessionBindingEvent se) {
>             System.out.println("session存档");
>         }
>     
>         @Override
>         public void attributeRemoved(HttpSessionBindingEvent se) {
>             System.out.println("session移除");
>         }
>     
>         @Override
>         public void attributeReplaced(HttpSessionBindingEvent se) {
>             System.out.println("session替换");
>         }
>     }

>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/L/L")
>     public class SessionC extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             HttpSession session = request.getSession(false);
>             session.setAttribute("123","123");
>             session.setAttribute("123","123");
>             session.removeAttribute("123");
>         }
>     }
> 
>     package com.bjpowernode.oa.listener;
>     
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     import jakarta.servlet.http.HttpSession;
>     
>     import java.io.IOException;
>     
>     @WebServlet("/L/L")
>     public class SessionC extends HttpServlet
>     {
>         @Override
>         protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
>             HttpSession session = request.getSession(false);
>             session.setAttribute("123","123");
>             session.setAttribute("123","123");
>             session.removeAttribute("123");
>         }
>     }

>     package com.bjpowernode.oa.Pojo;
>     
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     import jakarta.servlet.http.HttpSessionBindingListener;
>     
>     public class User implements HttpSessionBindingListener
>     {
>         private String usercode;
>         private String username;
>         private String password;
>     
>         @Override
>         public void valueBound(HttpSessionBindingEvent event) {
>             System.out.println("数据绑定");
>         }
>     
>         @Override
>         public void valueUnbound(HttpSessionBindingEvent event) {
>             System.out.println("数据解绑");
>         }
>     
>         public String getUsercode() {
>             return usercode;
>         }
>     
>         public void setUsercode(String usercode) {
>             this.usercode = usercode;
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User() {
>         }
>     
>         public User(String usercode, String username, String password) {
>             this.usercode = usercode;
>             this.username = username;
>             this.password = password;
>         }
>     }
> 
>     package com.bjpowernode.oa.Pojo;
>     
>     import jakarta.servlet.http.HttpSessionBindingEvent;
>     import jakarta.servlet.http.HttpSessionBindingListener;
>     
>     public class User implements HttpSessionBindingListener
>     {
>         private String usercode;
>         private String username;
>         private String password;
>     
>         @Override
>         public void valueBound(HttpSessionBindingEvent event) {
>             System.out.println("数据绑定");
>         }
>     
>         @Override
>         public void valueUnbound(HttpSessionBindingEvent event) {
>             System.out.println("数据解绑");
>         }
>     
>         public String getUsercode() {
>             return usercode;
>         }
>     
>         public void setUsercode(String usercode) {
>             this.usercode = usercode;
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User() {
>         }
>     
>         public User(String usercode, String username, String password) {
>             this.usercode = usercode;
>             this.username = username;
>             this.password = password;
>         }
>     }

>     package com.bjpowernode.oa.Pojo;
>     
>     public class User1
>     {
>         private String usercode;
>         private String username;
>         private String password;
>     
>         public String getUsercode() {
>             return usercode;
>         }
>     
>         public void setUsercode(String usercode) {
>             this.usercode = usercode;
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User1() {
>         }
>     
>         public User1(String usercode, String username, String password) {
>             this.usercode = usercode;
>             this.username = username;
>             this.password = password;
>         }
>     }
> 
>     package com.bjpowernode.oa.Pojo;
>     
>     public class User1
>     {
>         private String usercode;
>         private String username;
>         private String password;
>     
>         public String getUsercode() {
>             return usercode;
>         }
>     
>         public void setUsercode(String usercode) {
>             this.usercode = usercode;
>         }
>     
>         public String getUsername() {
>             return username;
>         }
>     
>         public void setUsername(String username) {
>             this.username = username;
>         }
>     
>         public String getPassword() {
>             return password;
>         }
>     
>         public void setPassword(String password) {
>             this.password = password;
>         }
>     
>         public User1() {
>         }
>     
>         public User1(String usercode, String username, String password) {
>             this.usercode = usercode;
>             this.username = username;
>             this.password = password;
>         }
>     }