这个类即实现了进行数据库操作的Servlet类,又实现了Websocket的功能
package action; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.websocket.*; import javax.websocket.server.ServerEndpoint; import java.io.IOException; import java.sql.PreparedStatement; import java.sql.SQLException; import java.util.concurrent.CopyOnWriteArraySet; /** * 这个类即实现了进行数据库操作的Servlet类,又实现了Websocket的功能. */ //该注解用来指定一个URI,客户端可以通过这个URI来连接到WebSocket,类似Servlet的注解mapping; // servlet的注册放在了web.xml中。 @ServerEndpoint(value = "/websocket") public class ManagerServlet extends HttpServlet { //concurrent包的线程安全Set,用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话,可以使用Map来存放,其中Key可以为用户标识 private static CopyOnWriteArraySet<ManagerServlet> webSocketSet = new CopyOnWriteArraySet<ManagerServlet>(); //这个session不是Httpsession,相当于用户的唯一标识,用它进行与指定用户通讯 private javax.websocket.Session session=null; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException { System.out.println("进入doget方法>>>>>>>>>>>>>"); String msg; String name=request.getParameter("name"); //这里submit是数据库操作的方法,如果插入数据成功,则发送更新信号 if(submit("1",name)){ //发送更新信号 sendMessage(); msg="ok!"; }else { msg="error!"; } response.sendRedirect("manager.jsp?msg="+msg); } public void doPost(HttpServletRequest request,HttpServletResponse reponse) throws ServletException, IOException { doGet(request,reponse); } /** * 向数据库插入一个name * @param name * @return */ public boolean submit(String id,String name){ System.out.println("进入写入sql》》》》》》》》》》》》》》》》"); DB db=new DB(); String sql="insert into users(id,name) values(?,?)"; try{ PreparedStatement pstmt=db.getConnection().prepareStatement(sql); pstmt.setString(1,id); pstmt.setString(2, name); pstmt.executeUpdate(); return true; }catch (Exception e){ e.printStackTrace(); return false; }finally { try { db.getConnection().close(); } catch (SQLException e) { e.printStackTrace(); } } } /** * @OnOpen allows us to intercept the creation of a new session. * The session class allows us to send data to the user. * In the method onOpen, we'll let the user know that the handshake was * successful. * 建立websocket连接时调用 */ @OnOpen public void onOpen(Session session){ int i=1; submit(String.valueOf(i),"name"); System.out.println("建立websocket连接时调用>>>>>>>>>>>>>>>>"); System.out.println("Session " + session.getId() + " has opened a connection"); try { this.session=session; webSocketSet.add(this); //加入set中 session.getBasicRemote().sendText("Connection Established"); } catch (IOException ex) { ex.printStackTrace(); } } /** * When a user sends a message to the server, this method will intercept the message * and allow us to react to it. For now the message is read as a String. * 接收到客户端消息时使用,这个例子里没用 */ @OnMessage public void onMessage(String message, Session session){ System.out.println("Message from " + session.getId() + ": " + message); } /** * The user closes the connection. * * Note: you can't send messages to the client from this method * 关闭连接时调用 */ @OnClose public void onClose(Session session){ webSocketSet.remove(this); //从set中删除 System.out.println("Session " +session.getId()+" has closed!"); } /** * 注意: OnError() 只能出现一次. 其中的参数都是可选的。 * @param session * @param t */ @OnError public void onError(Session session, Throwable t) { t.printStackTrace(); } /** * 这个方法与上面几个方法不一样。没有用注解,是根据自己需要添加的方法。 * @throws IOException * 发送自定义信号,“1”表示告诉前台,数据库发生改变了,需要刷新 */ public void sendMessage() throws IOException{ //群发消息 for(ManagerServlet item: webSocketSet){ try { item.session.getBasicRemote().sendText("1"); } catch (IOException e) { e.printStackTrace(); continue; } } } }
//数据库连接方法类
package action; import java.sql.Connection; import java.sql.DriverManager; import constant.ConsumptionConstant; public class DB { //一开始必须填一个已经存在的数据库 private Connection conn=null; public Connection getConnection() { try{ System.out.println("进入》》》》》》》》》》》》》"); Class.forName(ConsumptionConstant.drivers); String url = ConsumptionConstant.url; conn = DriverManager.getConnection(url, ConsumptionConstant.userName, ConsumptionConstant.password);// 连接数据库 System.out.println("conn============"+conn); }catch(Exception e){ e.printStackTrace(); } return conn; } }
//常量类
package constant; /** * */ public interface ConsumptionConstant { String url="jdbc:mysql://localhost:3306/pei_test?serverTimezone=UTC&characterEncoding=utf-8"; String userName="root"; String password="123456"; String drivers ="com.mysql.jdbc.Driver"; }
//Client类信息查询
package fun; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import action.DB; import model.UserBean; public class Client { public List<UserBean> list(){ String sql = "select * from users"; //3.ResultSet类,用来存放获取的结果集!! List<UserBean> list = new ArrayList<UserBean>(); try { DB db =new DB(); ResultSet rs = db.getConnection().createStatement().executeQuery(sql); System.out.println("rs==========="+rs); ResultSetMetaData md = rs.getMetaData(); int columnCount = md.getColumnCount(); //Map rowData; while (rs.next()) { //rowData = new HashMap(columnCount); UserBean bean=new UserBean(); for (int i = 1; i <= columnCount; i++) { if(md.getColumnName(i).equals("id")) { bean.setId(String.valueOf(rs.getObject(i))); } if(md.getColumnName(i).equals("name")) { bean.setName(String.valueOf(rs.getObject(i))); } } list.add(bean); } System.out.println("list==========="+list); } catch (SQLException e) { e.printStackTrace(); } return list; } }
//实体类
package model; public class UserBean { private String id; private String name; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "UserBean [id=" + id + ", name=" + name + "]"; } public UserBean(String id, String name) { super(); this.id = id; this.name = name; } public UserBean() { super(); } }
//pom.xml文件
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com</groupId> <artifactId>websocktAndSql</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>javax.websocket</groupId> <artifactId>javax.websocket-api</artifactId> <version>1.1</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>3.0.1</version> <scope>provided</scope> </dependency> <!-- 数据库--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.38</version> </dependency> <dependency> <groupId>c3p0</groupId> <artifactId>c3p0</artifactId> <version>0.9.1.2</version> </dependency> </dependencies> </project>
//jsp文件
<%@ page import="model.UserBean" %> <%@ page import="java.util.List" %> <%@ page import="fun.Client" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <table id="table" border="1"> <tr> <th >id</th> <th >name</th> </tr> <% //的到数据库信息,放在list中 Client client=new Client(); List<UserBean> list= client.list(); if(list != null){ for(UserBean user : list){ %> <tr > <td ><%=user.getId()%></td> <td ><%=user.getName()%></td> </tr> <% } } %> </table> <div id="message"></div> <script> var websocket = null; //判断当前浏览器是否支持WebSocket if ('WebSocket' in window) { //建立连接,这里的/websocket ,是ManagerServlet中开头注解中的那个值 websocket = new WebSocket("ws://localhost:8080/websocktAndSql/websocket"); } else { alert('当前浏览器 Not support websocket') } //连接发生错误的回调方法 websocket.onerror = function () { setMessageInnerHTML("WebSocket连接发生错误"); }; //连接成功建立的回调方法 websocket.onopen = function () { setMessageInnerHTML("WebSocket连接成功"); } //接收到消息的回调方法 websocket.onmessage = function (event) { setMessageInnerHTML(event.data); if(event.data=="1"){ location.reload(); } } //连接关闭的回调方法 websocket.onclose = function () { setMessageInnerHTML("WebSocket连接关闭"); } //监听窗口关闭事件,当窗口关闭时,主动去关闭websocket连接,防止连接还没断开就关闭窗口,server端会抛异常。 window.onbeforeunload = function () { closeWebSocket(); } //将消息显示在网页上 function setMessageInnerHTML(innerHTML) { document.getElementById('message').innerHTML += innerHTML + '<br/>'; } //关闭WebSocket连接 function closeWebSocket() { websocket.close(); } </script> </body> </html>
//数据库
//项目结构
//tomcat启动后访问路径
http://localhost:8080/websocktAndSql/user.jsp