##  案例：用户登录

准备工作：

准备Maven  配置pom.xml

<?xml version="1.0" encoding="UTF-8"?>

<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>org.example</groupId>

  <artifactId>Login</artifactId>

  <version>1.0-SNAPSHOT</version>

  <packaging>war</packaging>

  <name>Login Maven Webapp</name>

  <!-- FIXME change it to the project's website -->

  <url>http://www.example.com</url>

  <properties>

    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <maven.compiler.source>1.7</maven.compiler.source>

    <maven.compiler.target>1.7</maven.compiler.target>

  </properties>

  <dependencies>

    <dependency>

      <groupId>junit</groupId>

      <artifactId>junit</artifactId>

      <version>4.11</version>

      <scope>test</scope>

    </dependency>

    <dependency>

      <groupId>mysql</groupId>

      <artifactId>mysql-connector-java</artifactId>

      <version>8.0.15</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->

    <dependency>

      <groupId>commons-logging</groupId>

      <artifactId>commons-logging</artifactId>

      <version>1.2</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->

    <dependency>

      <groupId>com.alibaba</groupId>

      <artifactId>druid</artifactId>

      <version>1.0.9</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/com.mchange/mchange-commons-java -->

    <dependency>

      <groupId>com.mchange</groupId>

      <artifactId>mchange-commons-java</artifactId>

      <version>0.2.12</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->

    <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-beans</artifactId>

      <version>5.0.0.RELEASE</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->

    <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-core</artifactId>

      <version>5.0.0.RELEASE</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-jdbc -->

    <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-jdbc</artifactId>

      <version>5.0.0.RELEASE</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->

    <dependency>

      <groupId>org.springframework</groupId>

      <artifactId>spring-tx</artifactId>

      <version>5.0.0.RELEASE</version>

    </dependency>

    <dependency>

      <groupId>org.junit.jupiter</groupId>

      <artifactId>junit-jupiter</artifactId>

      <version>RELEASE</version>

      <scope>compile</scope>

    </dependency>

    <dependency>

      <groupId>org.junit.jupiter</groupId>

      <artifactId>junit-jupiter</artifactId>

      <version>RELEASE</version>

      <scope>compile</scope>

    </dependency>

    <dependency>

      <groupId>org.testng</groupId>

      <artifactId>testng</artifactId>

      <version>RELEASE</version>

      <scope>compile</scope>

    </dependency>

    <dependency>

      <groupId>junit</groupId>

      <artifactId>junit</artifactId>

      <version>4.12</version>

      <scope>compile</scope>

    </dependency>

    <dependency>

      <groupId>javax.servlet</groupId>

      <artifactId>javax.servlet-api</artifactId>

      <version>4.0.1</version>

      <scope>provided</scope>

    </dependency>

    <dependency>

      <groupId>javax.servlet.jsp</groupId>

      <artifactId>jsp-api</artifactId>

      <version>2.2</version>

    </dependency>

    <!-- https://mvnrepository.com/artifact/commons-beanutils/commons-beanutils -->

    <dependency>

      <groupId>commons-beanutils</groupId>

      <artifactId>commons-beanutils</artifactId>

      <version>1.8.0</version>

    </dependency>

  </dependencies>

  <build>

    <finalName>Login</finalName>

    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->

      <plugins>

        <plugin>

          <artifactId>maven-clean-plugin</artifactId>

          <version>3.1.0</version>

        </plugin>

        <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_war_packaging -->

        <plugin>

          <artifactId>maven-resources-plugin</artifactId>

          <version>3.0.2</version>

        </plugin>

        <plugin>

          <artifactId>maven-compiler-plugin</artifactId>

          <version>3.8.0</version>

        </plugin>

        <plugin>

          <artifactId>maven-surefire-plugin</artifactId>

          <version>2.22.1</version>

        </plugin>

        <plugin>

          <artifactId>maven-war-plugin</artifactId>

          <version>3.2.2</version>

        </plugin>

        <plugin>

          <artifactId>maven-install-plugin</artifactId>

          <version>2.5.2</version>

        </plugin>

        <plugin>

          <artifactId>maven-deploy-plugin</artifactId>

          <version>2.8.2</version>

        </plugin>

      </plugins>

    </pluginManagement>

  </build>

</project>

User实体类：

package com.ftj.domain;

/**

 * 用户实体类javaBean

 */

public class User {

    private int id;

    private String username;

    private String password;

    private String gender;

    public User() {

    }

    public User(int id, String username, String password, String gender) {

        this.id = id;

        this.username = username;

        this.password = password;

        this.gender = gender;

    }

    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 getHehe() {

        return gender;

    }

    public void setHehe(String gender) {

        this.gender = gender;

    }

    @Override

    public String toString() {

        return "User{" +

                "id=" + id +

                ", username='" + username + '\'' +

                ", password='" + password + '\'' +

                ", gender='" + gender + '\'' +

                '}';

    }

}

UserDao

package com.ftj.dao;

/**

 * 操作数据中，user表的类

 */

import com.ftj.domain.User;

import com.ftj.util.JDBCUtil;

import org.springframework.jdbc.core.BeanPropertyRowMapper;

import org.springframework.jdbc.core.JdbcTemplate;

public class UserDao {

    //声明JDBCTemplate对象共用

    private JdbcTemplate template = new JdbcTemplate(JDBCUtil.getDataSource());

    /**

     * 登录方法

     *

     * @param loginUser 只有用户名和密码

     * @return 包含用户全部数据

     */

    public User login(User loginUser) {

        try {

            //1、编写sql

            String sql = "select * from user where username = ? and password = ?";

            //2、调用Query

            User user = template.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), loginUser.getUsername(), loginUser.getPassword());

            return user;

        } catch (Exception e) {

            e.printStackTrace();//记录日志

            return null;

        }

    }

}

登录验证

package com.ftj.servlet;

import com.ftj.dao.UserDao;

import com.ftj.domain.User;

import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.IOException;

import java.lang.reflect.InvocationTargetException;

import java.util.Map;

/**

 * JavaBean：标准的Java类

 * 1、要求：

 *      1、类必须被public修饰

 *      2、必须提供空参的构造器

 *      3、成员变量必须使用private修饰

 *      4、提供公共setter和getter方法

 * 2、功能：封装数据

 *

 * 概念：

 *      成员变量：

 *      属性：setter和getter方法截取后的产物

 *          例如：getUsername()-->Username-->username

 *

 * 方法:

 *      1、setProperty()

 *      2、getProperty()

 *      3、populate()

 */

@WebServlet("/loginServlet")

public class LoginServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //1、设置编码

        req.setCharacterEncoding("utf-8");

        /*//2、获取请求参数

        String username = req.getParameter("username");

        String password = req.getParameter("password");

        //3、封装user对象

        User loginUser = new User();

        loginUser.setUsername(username);

        loginUser.setPassword(password);

        //4、调用UserDao的login方法*/

        Map<String, String[]> map = req.getParameterMap();

        User loginUser = new User();

        try {

            BeanUtils.populate(loginUser,map);

        } catch (IllegalAccessException e) {

            e.printStackTrace();

        } catch (InvocationTargetException e) {

            e.printStackTrace();

        }

        UserDao dao = new UserDao();

        User user = dao.login(loginUser);

        //5、判断user

        if (user == null){

            //登录失败

            req.getRequestDispatcher("/failServlet").forward(req,resp);

        }else {

            //登录成功

            //存储数据

            req.setAttribute("user",user);

            //转发

            req.getRequestDispatcher("/successServlet").forward(req,resp);

        }

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        this.doGet(req, resp);

    }

}

Druid方式的JDBC

package com.ftj.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;

import java.io.IOException;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.Properties;

/**

 * JDBC工具类，使用Durid连接池

 */

public class JDBCUtil {

    private static DataSource ds;

    static {

        try {

            //1、加载配置文件

            Properties pro = new Properties();

            //使用ClassLoader加载配置文件，获取字节输入流

            String path = "jdbc.properties";

            InputStream is = JDBCUtil.class.getClassLoader().getResourceAsStream(path);

            pro.load(is);

            //2、初始化连接池对象

            ds = DruidDataSourceFactory.createDataSource(pro);

        } catch (IOException e) {

            e.printStackTrace();

        }catch (Exception e){

            e.printStackTrace();

        }

    }

    //获取连接池对象

    public static DataSource getDataSource(){

        return ds;

    }

    //获取连接Connection对象

    public static Connection getConnection() throws SQLException {

        return ds.getConnection();

    }

}

Druid配置文件

driverClassName=com.mysql.cj.jdbc.Driver

url=jdbc:mysql://localhost:3306/ftj?serverTimezone=UTC&characterEncoding=utf-8&useSSL=false

username=root

password=password

# 初始化连接数

initialSize=5

#最大连接数

maxActive=10

#超时时间

maxWait=3000

#报错信息意思是说：校验没有设置,将testWhileIdle修改为false不再报错，工程正常运行。

validationQuery:SELECT 1

testWhileIdle:true

testOnBorrow:false

testOnReturn:false

登录界面

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<form action="/loginServlet" 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">

</form>

</body>

</html>

JavaBean测试类

package com.ftj.test;

import com.ftj.domain.User;

import org.apache.commons.beanutils.BeanUtils;

import org.junit.Test;

import java.lang.reflect.InvocationTargetException;

public class BeanUtilTest {

    @Test

    public void test(){

        User user = new User();

        try {

            //BeanUtils.setProperty(user, "username", "ftj");

            BeanUtils.setProperty(user,"hehe","male");  //操作的不是成员变量

            String hehe = BeanUtils.getProperty(user, "hehe");

            System.out.println(hehe);

        } catch (IllegalAccessException | NoSuchMethodException e) {

            e.printStackTrace();

        } catch (InvocationTargetException e) {

            e.printStackTrace();

        }

        System.out.println(user);

    }

}

Druid测试类

package com.ftj.test;

import com.ftj.dao.UserDao;

import com.ftj.domain.User;

import org.junit.Test;

public class UserDaoTest {

    @Test

    public void testLogin(){

        User loginuser = new User();

        loginuser.setUsername("superbaby");

        loginuser.setPassword("123");

        UserDao dao = new UserDao();

        User user = dao.login(loginuser);

        System.out.println(user);

    }

}

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