[大数据]JDBC&DataSoure配置文件

jdbc.properties

url=jdbc:mysql://localhost:3306/db4?serverTimezone=Asia/Shanghai
user=root
password=0000
driver=com.mysql.cj.jdbc.Driver

工具类

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {
    private static String url;
    private static String user;
    private static String password;
    private static String driver;

    /**
     * 文件的读取，只需要读取即可拿到这些值。使用静态代码块
     */
    static {
        //读取资源文件
        try {
            //1.创建Properties集合类。
            Properties pro = new Properties();

            //2.加载文件(动态获取文件路径)
            //获取src路径下的文件的方式--> ClassLoader类加载器
            ClassLoader classLoader = JDBCUtils.class.getClassLoader();
            URL res = classLoader.getResource("jdbc.properties");
            String path = res.getPath();
            pro.load(new FileReader(path));

            //3.获取数据，赋值
            url = pro.getProperty("url");
            user = pro.getProperty("user");
            password = pro.getProperty("password");
            driver = pro.getProperty("driver");

            //4.注册驱动
            Class.forName(driver);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接
     *
     * @return 连接对象
     */
    public static Connection getConnection () throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    /**
     * 释放资源
     *
     * @param stmt
     * @param conn
     */
    public static void close (Statement stmt, Connection conn) {
        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }

    public static void close (Statement stmt1, Statement stmt2, Connection conn) {
        if (stmt1 != null) {
            try {
                stmt1.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (stmt2 != null) {
            try {
                stmt2.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }

    public static void close (ResultSet rs, Statement stmt, Connection conn) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }

        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }
}

通过一个简单的练习，了解Jdbc工具类

import cn.itcast.util.JDBCUtils;

import java.sql.*;
import java.util.Scanner;

public class JdbcDemo4 {
    /**
     * 练习：
     * 		* 需求：
     * 			1. 通过键盘录入用户名和密码
     * 			2. 判断用户是否登录成功
     */
    public static void main (String[] args) {
        //1.键盘录入，接受用户名和密码
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入用户名：");
        String name = sc.next();
        System.out.println("请输入密码：");
        String password = sc.next();

        //2.调用方法
        boolean flag = new JdbcDemo4().login(name, password);
        //3.判断
        if (flag){
            System.out.println("登录成功");
        }else{
            System.out.println("用户名或密码错误");
        }


    }

    //登录方法
    public boolean login(String username,String password){
        if (username==null||password==null){
            return false;
        }
        //连接数据库判断是否登录成
        Connection conn =null;
        ResultSet rs =null;
        PreparedStatement pstmt =null;
        try {
            //1.调用getConnection获取连接
             conn = JDBCUtils.getConnection();

            //2.定义sql语句
            String sql = "select * from user where username = ? and  password=?";

            //3.获取执行sql的对象
             pstmt = conn.prepareStatement(sql);

             //给?赋值
            pstmt.setString(1,username);
            pstmt.setString(2,password);

            //4.执行查询,不需要传递sql
             rs = pstmt.executeQuery();

            //5.判断
            return rs.next();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            JDBCUtils.close(rs,pstmt,conn);
        }
        return false;
    }
}

简单的事务回滚

import cn.itcast.util.JDBCUtils;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class JdbcDemo5 {
    public static void main (String[] args) {
        Connection conn = null;
        PreparedStatement prep1 = null;
        PreparedStatement prep2 = null;
        try {
            //1.调用getConnection方法实现连接
            conn = JDBCUtils.getConnection();

            //开启事务
            conn.setAutoCommit(false);

            //2.定义sql语句
            String sql1 = "update user set balance=balance+? where id=?";
            String sql2 = "update user set balance=balance-? where id=?";

            //3.获取执行sql对象
            prep1 = conn.prepareStatement(sql1);
            prep2 = conn.prepareStatement(sql2);

            //4.给?赋值
            prep1.setDouble(1, 500);
            prep1.setDouble(2, 1);

            prep2.setDouble(1, 500);
            prep2.setDouble(2, 2);


            //5.执行sql
            prep1.executeUpdate();

            //手动制造异常
            int i=3/0;

            prep2.executeUpdate();

            //提交事务
            conn.commit();
        } catch (Exception throwables) {
            try {
                //事务的回滚
                if (conn!=null){
                    conn.rollback();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            throwables.printStackTrace();
        } finally {
            JDBCUtils.close(prep1, prep2, conn);
        }
    }
}

?druid.properties

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/db3?serverTimezone=GMT
username=root
password=0000
# 初始化连接数量
initialSize=5
# 最大连接数
maxActive=10
# 超时时间
maxWait=3000

Druid工具类

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.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

/**
 * Druid连接池的工具类
 */
public class JDBCUtils {
    //1.定义成员变量
    private static DataSource ds;

    static {
        try {
            //1.加载配置文件
            Properties pro = new Properties();
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);

            //2.获取连接池对象
            ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接
     * @return
     * @throws SQLException
     */
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    /**
     * 释放资源
     * @param stmt
     * @param conn
     */
    public static void close(Statement stmt,Connection conn){
       close(null,stmt,conn);
    }
    public static void close(ResultSet rs, Statement stmt, Connection conn){
        if (rs!=null){
            try {
                rs.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (stmt!=null){
            try {
                stmt.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        if (conn!=null){
            try {
                //归还连接
                conn.close();
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
    }

    /**
     * 获取连接池方法
     * @return
     */
    public static DataSource getDataSource(){
        return ds;
    }
}

import cn.itcat.domain.Emp;
import cn.itcat.utils.JDBCUtils;
import org.junit.jupiter.api.Test;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import java.sql.Date;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

/**
 * 修改
 * 添加
 * 删除
 * 查询id为1001的记录，将其封装为Map集合
 * 查询所有记录，将其封装为List
 * 查询所有记录，将其封装为Emp对象的List集合
 * 查询总记录数
 */
public class JdbcTemplateDemo2 {

    //1.导入jar包
    //2.创建JdbcTemplate对象 获取连接
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    @Test
    public void getUpdate () {
        //3.定义sql语句
        String sql="update emp set salary=? where id=?";

        //4.执行sql
        int count = template.update(sql, 10000,1001);
        System.out.println(count);
    }
    @Test
    public void getInsert(){
        //3.定义sql语句
        String sql = "insert into emp(id,ename,dept_id) values(?,?,?)";

        //4.执行sql
        int count = template.update(sql, 1015,"郭靖", 10);
        System.out.println(count);
    }
    @Test
    public void getDelete(){
        //3.定义sql语句
        String sql="delete from emp where id=?";

        //4.执行sql
        int count = template.update(sql, 1015);
        System.out.println(count);
    }

    //查询id为1001的记录，将其封装为Map集合
    //注意：查询的结果集长度只能是1
    @Test
    public void getMap(){
        //3.定义sql语句
        String sql="select * from emp where id=?";

        //4.执行sql
        Map<String, Object> map = template.queryForMap(sql, 1001);
        System.out.println(map);
    }

    //查询所有记录，将其封装为List
    @Test
    public void getList(){
        //3.定义sql语句
        String sql="select * from emp ";

        //4.执行sql
        List<Map<String, Object>> list = template.queryForList(sql);
        System.out.println(list);
    }

    //查询所有记录，将其封装为Emp对象的List集合
    //自己实现
    @Test
    public void getEmpList(){
        //3.定义sql语句
        String sql="select * from emp ";

        //4.执行sql
        List<Emp> list = template.query(sql, new RowMapper<Emp>() {

            @Override
            public Emp mapRow (ResultSet rs, int i) throws SQLException {
                Emp emp = new Emp();
                int id = rs.getInt("id");
                String ename = rs.getString("ename");
                int job_id = rs.getInt("job_id");
                int mgr = rs.getInt("mgr");
                Date joindate = rs.getDate("joindate");
                double salary = rs.getDouble("salary");
                double bonus = rs.getDouble("bonus");
                int dept_id = rs.getInt("dept_id");

                emp.setId(id);
                emp.setEname(ename);
                emp.setJob_id(job_id);
                emp.setMgr(mgr);
                emp.setJoindate(joindate);
                emp.setSalary(salary);
                emp.setBonus(bonus);
                emp.setDept_id(dept_id);

                return emp;
            }
        });
        for (Emp emp : list) {
            System.out.println(emp);
        }
    }

    //查询所有记录，将其封装为Emp对象的List集合
    //别人提供的
    @Test
    public void getEmpList_2(){
        //3.定义sql语句
        String sql="select * from emp ";

        //4.执行sql
        List<Emp> list = template.query(sql,new BeanPropertyRowMapper<Emp>(Emp.class));

        //5.遍历打印输出
        for (Emp emp : list) {
            System.out.println(emp);
        }
    }

        //查询总记录数 queryForObject一般用来完成聚合函数
        @Test
        public void getCount(){
            //3.定义sql语句
            String sql="select count(id) from emp ";

            //4.执行sql
            Long total = template.queryForObject(sql, Long.class);
            System.out.println(total);
        }
}