Java HttpServlet模拟用户登录

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使用c3p0,dbutils

创建javaweb项目Web13

1.引入jar c3p0-0.9.1.2.jar,commons-dbutils-1.4.jar,mysql-connector-java-5.0.4-bin.jar

2.创建数据库web13和和user表

3.引入c3p0-config.xml，放在src目录下

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
    <default-config>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql:///web13</property>
    </default-config> 
</c3p0-config> 

4.添加工具类DataSourceUtils.java

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DataSourceUtils {

    private static DataSource dataSource = new ComboPooledDataSource();

    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();

    // 直接可以获取一个连接池
    public static DataSource getDataSource() {
        return dataSource;
    }

    // 获取连接对象
    public static Connection getConnection() throws SQLException {

        Connection con = tl.get();
        if (con == null) {
            con = dataSource.getConnection();
            tl.set(con);
        }
        return con;
    }

    // 开启事务
    public static void startTransaction() throws SQLException {
        Connection con = getConnection();
        if (con != null) {
            con.setAutoCommit(false);
        }
    }

    // 事务回滚
    public static void rollback() throws SQLException {
        Connection con = getConnection();
        if (con != null) {
            con.rollback();
        }
    }

    // 提交并且 关闭资源及从ThreadLocall中释放
    public static void commitAndRelease() throws SQLException {
        Connection con = getConnection();
        if (con != null) {
            con.commit(); // 事务提交
            con.close();// 关闭资源
            tl.remove();// 从线程绑定中移除
        }
    }

    // 关闭资源方法
    public static void closeConnection() throws SQLException {
        Connection con = getConnection();
        if (con != null) {
            con.close();
        }
    }

    public static void closeStatement(Statement st) throws SQLException {
        if (st != null) {
            st.close();
        }
    }

    public static void closeResultSet(ResultSet rs) throws SQLException {
        if (rs != null) {
            rs.close();
        }
    }

}

5.创建实体类User，用于接收查询用户信息的返回

    public class User {

    private int id;
    private String username;
    private String password;
    private String email;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    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 String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", password=" + password + ", email=" + email + "]";
    }



}

创建LoginServlet

public class LoginServlet extends HttpServlet {

    @Override
    public void init() throws ServletException {
        //在Seveltcontext域中存一个数据count
        int count = 0;
        this.getServletContext().setAttribute("count", count);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {



        //username=zhangsan&password=123

        //1、获得用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        //2、从数据库中验证该用户名和密码是否正确
        QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
        String sql = "select * from user where username=? and password=?";
        User user = null;
        try {
            user = runner.query(sql, new BeanHandler<User>(User.class), username,password);
        } catch (SQLException e) {
            e.printStackTrace();
        }

        //3、根据返回的结果给用户不同显示信息
        if(user!=null){
            //从servletcontext中取出count进行++运算
            ServletContext context = this.getServletContext();
            Integer count = (Integer) context.getAttribute("count");
            count++;
            //用户登录成功
            response.getWriter().write(user.toString()+"---you are success login person ："+count);
            context.setAttribute("count", count);
        }else{
            //用户登录失败
            response.getWriter().write("sorry your username or password is wrong");
        }

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

在web.xml中配置信息

<servlet>
    <servlet-name>LoginServlet</servlet-name>
    <servlet-class>xxxxxxx类全名.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>LoginServlet</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>

登录页面的表单login.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>  
    <form action="/WEB13/login" method="post">
        用户名：<input type="text" name="username"><br/>
        密码：<input type="password" name="password"><br/>
        <input type="submit" value="登录"><br/>
    </form>
</body>
</html>

开启Tomcat服务器，访问

http://localhost:8080/Web13/login