1、前提：在Mysql数据库下建立数据库web13，在web13下创建一张表user，插入几条数据如下：
2、创建HTML文件，命名为login，作为登录界面（以post方式提交）
1 <!DOCTYPE html> 2 <html> 3 <head> 4 <meta charset="UTF-8"> 5 <title>Insert title here</title> 6 </head> 7 <body> 8 <form action="/WEB13_sevrlet/login" method="post"> 9 用户名：<input type="text" name="username"><br/> 10 密码：<input type="password" name="password"><br/> 11 <input type="submit" value="登录"><br/> 12 </form> 13 </body> 14 </html>
3、创建连接池
c3p0-config.xml文件如下：
1 <?xml version="1.0" encoding="UTF-8"?> 2 <c3p0-config> 3 4 <default-config> 5 <property name="driverClass">com.mysql.jdbc.Driver</property> 6 <property name="jdbcUrl">jdbc:mysql:///web13</property> 7 <property name="user">root</property> 8 <property name="password">12345</property> 9 </default-config> 10 11 </c3p0-config>
DataSourceUtils.java文件如下：（可作为套用模板）
1 package com.itheima.utils; 2 3 import java.sql.Connection; 4 import java.sql.ResultSet; 5 import java.sql.SQLException; 6 import java.sql.Statement; 7 8 import javax.sql.DataSource; 9 10 import com.mchange.v2.c3p0.ComboPooledDataSource; 11 12 public class DataSourceUtils { 13 private static DataSource dataSource = new ComboPooledDataSource(); 14 private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>(); 15 16 // 直接可以获取一个连接池 17 public static DataSource getDataSource() { 18 return dataSource; 19 } 20 21 // 获取连接对象 22 public static Connection getConnection() throws SQLException { 23 Connection con = tl.get(); 24 if (con == null) { 25 con = dataSource.getConnection(); 26 tl.set(con); 27 } 28 return con; 29 } 30 31 // 开启事务 32 public static void startTransaction() throws SQLException { 33 Connection con = getConnection(); 34 if (con != null) { 35 con.setAutoCommit(false); 36 } 37 } 38 39 // 事务回滚 40 public static void rollback() throws SQLException { 41 Connection con = getConnection(); 42 if (con != null) { 43 con.rollback(); 44 } 45 } 46 47 // 提交并且 关闭资源及从ThreadLocall中释放 48 public static void commitAndRelease() throws SQLException { 49 Connection con = getConnection(); 50 if (con != null) { 51 con.commit(); // 事务提交 52 con.close();// 关闭资源 53 tl.remove();// 从线程绑定中移除 54 } 55 } 56 57 // 关闭资源方法 58 public static void closeConnection() throws SQLException { 59 Connection con = getConnection(); 60 if (con != null) { 61 con.close(); 62 } 63 } 64 65 public static void closeStatement(Statement st) throws SQLException { 66 if (st != null) { 67 st.close(); 68 } 69 } 70 71 public static void closeResultSet(ResultSet rs) throws SQLException { 72 if (rs != null) { 73 rs.close(); 74 } 75 } 76 }
4、编写Servlet实现类
User类代码如下：
1 package com.itheima.domain; 2 3 public class User { 4 private int id; 5 private String name; 6 private String password; 7 8 public User(){ 9 10 } 11 12 public int getId() { 13 return id; 14 } 15 16 public void setId(int id) { 17 this.id = id; 18 } 19 20 public String getName() { 21 return name; 22 } 23 24 public void setName(String name) { 25 this.name = name; 26 } 27 28 public String getPassword() { 29 return password; 30 } 31 32 public void setPassword(String password) { 33 this.password = password; 34 } 35 }
LoginServlet.java代码如下：
1 package com.itheima.login; 2 3 import java.io.IOException; 4 import java.sql.SQLException; 5 6 import javax.servlet.ServletContext; 7 import javax.servlet.ServletException; 8 import javax.servlet.http.HttpServlet; 9 import javax.servlet.http.HttpServletRequest; 10 import javax.servlet.http.HttpServletResponse; 11 12 import org.apache.commons.dbutils.QueryRunner; 13 import org.apache.commons.dbutils.handlers.BeanHandler; 14 15 import com.itheima.domain.User; 16 import com.itheima.utils.DataSourceUtils; 17 18 public class LoginServlet extends HttpServlet { 19 20 @Override 21 public void init() throws ServletException{ 22 //在Servletcontext域中存一个数据count 23 int count=0; 24 this.getServletContext().setAttribute("count", count); 25 } 26 27 public void doGet(HttpServletRequest request, HttpServletResponse response) 28 throws ServletException, IOException { 29 30 //1.获得用户名和密码 31 String username=request.getParameter("username"); 32 String password=request.getParameter("password"); 33 34 //2.从数据库中验证该用户名和密码是否正确 35 QueryRunner runner=new QueryRunner(DataSourceUtils.getDataSource()); 36 String sql="select * from user where username=? and password=?"; 37 User user=null; 38 try { 39 user=runner.query(sql, new BeanHandler<User>(User.class),username,password); 40 } catch (SQLException e) { 41 e.printStackTrace(); 42 } 43 //3.根据返回的结果给用户不同显示信息 44 if(user!=null){ 45 //从Servletcontext中取出count进行++运算 46 ServletContext context=this.getServletContext(); 47 Integer count=(Integer)context.getAttribute("count"); 48 count++; 49 //用户登录成功 50 response.getWriter().write(user.toString()+"--you are success login person"+count); 51 context.setAttribute("count", count); 52 }else{ 53 //用户登录失败 54 response.getWriter().write("Sorry,your username or password is wrong!"); 55 } 56 } 57 58 public void doPost(HttpServletRequest request, HttpServletResponse response) 59 throws ServletException, IOException { 60 doGet(request, response); 61 } 62 }
5、编写Servlet配置文件，代码如下：
1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"> 3 <display-name>WEB13_sevrlet</display-name> 4 <context-param> 5 <param-name>driver</param-name> 6 <param-value>com.mysql.jdbc.Driver</param-value> 7 </context-param> 8 9 <welcome-file-list> 10 <welcome-file>index.html</welcome-file> 11 <welcome-file>index.htm</welcome-file> 12 <welcome-file>index.jsp</welcome-file> 13 <welcome-file>default.html</welcome-file> 14 <welcome-file>default.htm</welcome-file> 15 <welcome-file>default.jsp</welcome-file> 16 </welcome-file-list> 17 18 <servlet> 19 <description></description> 20 <display-name>LoginServlet</display-name> 21 <servlet-name>LoginServlet</servlet-name> 22 <servlet-class>com.itheima.login.LoginServlet</servlet-class> 23 </servlet> 24 <servlet-mapping> 25 <servlet-name>LoginServlet</servlet-name> 26 <url-pattern>/login</url-pattern> 27 </servlet-mapping> 28 29 <servlet> 30 <description></description> 31 <display-name>ContextServlet</display-name> 32 <servlet-name>ContextServlet</servlet-name> 33 <servlet-class>com.itheima.context.ContextServlet</servlet-class> 34 </servlet> 35 <servlet-mapping> 36 <servlet-name>ContextServlet</servlet-name> 37 <url-pattern>/context</url-pattern> 38 </servlet-mapping> 39 40 </web-app>
6、测试，访问“http://localhost:8080/WEB13_sevrlet/login.html”
分别输入“Tom”，“123”，登录结果如下：
分别输入“Lucy”，“1234”，登录结果如下：
分别输入“Jack”，“123”，登录结果如下：
