学习JDBC这一篇就够了

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第一章 概述

JDBC（Java Database Connectivity）是SUN公司提供的一种数据库访问规则、规范，由于数据库种类较多且Java语言使用比较广泛，SUN公司就提供了一种规范，让其它的数据库提供商去实现底层的访问规则，我们的Java程序只要使用SUN公司提供的jdbc驱动就可以连接不同厂商的数据库了

第二章 数据库连接

1、工具类

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

public class JDBCUtil {
	private static String driverClass = "com.mysql.jdbc.Driver";
	private static String url = "jdbc:mysql://127.0.0.1:3306/mytest";
	private static String user = "root";
	private static String password = "root";

	static {
		try {
			Class.forName(driverClass);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}

	public static Connection getConnection() {
		try {
			return DriverManager.getConnection(url, user, password);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return null;
	}

	public static void release(Connection connection, PreparedStatement preparedStatement, ResultSet resultSet) {
		closeConnection(connection);
		closePreparedStatement(preparedStatement);
		closeResultSet(resultSet);
	}

	public static void release(Connection connection, PreparedStatement preparedStatement) {
		closeConnection(connection);
		closePreparedStatement(preparedStatement);
	}

	public static void closeConnection(Connection connection) {
		if (connection != null) {
			try {
				connection.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				connection = null;
			}
		}
	}

	public static void closePreparedStatement(PreparedStatement preparedStatement) {
		if (preparedStatement != null) {
			try {
				preparedStatement.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				preparedStatement = null;
			}
		}
	}

	public static void closeResultSet(ResultSet resultSet) {
		if (resultSet != null) {
			try {
				resultSet.close();
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				resultSet = null;
			}
		}
	}

}

2、测试类

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

import org.junit.Test;

public class JDBCTest {

	@Test
	public void testQuery() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		ResultSet resultSet = null;
		try {
			connection = JDBCUtil.getConnection();
			String sql = "select * from admin";
			preparedStatement = connection.prepareStatement(sql);
			resultSet = preparedStatement.executeQuery();
			while (resultSet.next()) {
				Object id = resultSet.getObject(1);
				Object username = resultSet.getObject(2);
				Object password = resultSet.getObject(3);

				System.out.println(id + ":" + username + ":" + password);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement, resultSet);
		}
	}

	@Test
	public void testInsert() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		try {
			connection = JDBCUtil.getConnection();
			String sql = "insert into admin values(NULL,'xiaowu','123456')";
			preparedStatement = connection.prepareStatement(sql);
			int rows = preparedStatement.executeUpdate(sql);
			if (rows > 0) {
				System.out.println("插入成功");
			} else {
				System.out.println("插入失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement);
		}
	}
	
	@Test
	public void testUpdate() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		try {
			connection = JDBCUtil.getConnection();
			String sql = "update admin set username = 'xiaoqi' where id = 5";
			preparedStatement = connection.prepareStatement(sql);
			int rows = preparedStatement.executeUpdate(sql);
			if (rows > 0) {
				System.out.println("修改成功");
			} else {
				System.out.println("修改失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement);
		}
	}
	
	@Test
	public void testDelete() {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		try {
			connection = JDBCUtil.getConnection();
			String sql = "delete from admin where id = 5";
			preparedStatement = connection.prepareStatement(sql);
			int rows = preparedStatement.executeUpdate(sql);
			if (rows > 0) {
				System.out.println("删除成功");
			} else {
				System.out.println("删除失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement);
		}
	}

}

第三章 数据库事务

@Test
public void testTransaction() {
	Connection connection = null;
	PreparedStatement preparedStatement = null;
	try {
		connection = JDBCUtil.getConnection();

		// 前提：关闭事务
		connection.setAutoCommit(false);

		String sql = "update account set money = money - ? where id = ?";
		preparedStatement = connection.prepareStatement(sql);

		// 扣钱， 扣ID为 1 的100块钱
		preparedStatement.setInt(1, 100);
		preparedStatement.setInt(2, 1);
		preparedStatement.executeUpdate();

        // 模拟异常
		int a = 10 / 0;

		// 加钱， 给ID为 2 加100块钱
		preparedStatement.setInt(1, -100);
		preparedStatement.setInt(2, 2);
		preparedStatement.executeUpdate();

		// 成功：提交事务
		connection.commit();
	} catch (SQLException e) {
		try {
			// 失败：回滚事务
			connection.rollback();
		} catch (SQLException e1) {
			e1.printStackTrace();
		}
		e.printStackTrace();
	} finally {
		JDBCUtil.release(connection, preparedStatement);
	}
}

第四章 数据库连接池

4.1、DBCP

1、基本使用

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

import org.apache.commons.dbcp2.BasicDataSource;

public class DBCPTest {

	public static void main(String[] args) throws SQLException {
		BasicDataSource dataSource = new BasicDataSource();
		dataSource.setUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUsername("root");
		dataSource.setPassword("root");

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
		dataSource.close();
	}

}

2、高级使用

dbcp-config.properties

#基本设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/mytest
username=root
password=root
#数据库连接池初始化数量
initialSize=10
#数据库连接池中的最大的数据库连接数
maxActive=50
#数据库连接池中的最小的数据库连接数
minIdle=5

DBCPWithConfig.java

import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSourceFactory;

public class DBCPWithConfig {

	@SuppressWarnings("static-access")
	public static void main(String[] args) throws Exception {
		BasicDataSourceFactory dataSourceFactory = new BasicDataSourceFactory();
		Properties properties = new Properties();
		InputStream is = DBCPWithConfig.class.getClassLoader().getResourceAsStream("dbcp-config.properties");
		properties.load(is);
		DataSource dataSource = dataSourceFactory.createDataSource(properties);

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
	}

}

4.2、Druid

1、基本使用

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

import com.alibaba.druid.pool.DruidDataSource;

public class DruidTest {

	public static void main(String[] args) throws SQLException {
		DruidDataSource dataSource = new DruidDataSource();
		dataSource.setUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUsername("root");
		dataSource.setPassword("root");

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
		dataSource.close();
	}

}

2、高级使用

druid-config.properties

#基本设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/mytest
username=root
password=root
#数据库连接池初始化数量
initialSize=10
#数据库连接池中的最大的数据库连接数
maxActive=50
#数据库连接池中的最小的数据库连接数
minIdle=5

DruidWithConfig.java

import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;

import javax.sql.DataSource;

import com.alibaba.druid.pool.DruidDataSourceFactory;

public class DruidWithConfig {

	@SuppressWarnings("static-access")
	public static void main(String[] args) throws Exception {
		DruidDataSourceFactory dataSourceFactory = new DruidDataSourceFactory();
		Properties properties = new Properties();
		InputStream is = DruidWithConfig.class.getClassLoader().getResourceAsStream("druid-config.properties");
		properties.load(is);
		DataSource dataSource = dataSourceFactory.createDataSource(properties);

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
	}

}

4.3、C3P0

1、基本使用

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

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Test {

	public static void main(String[] args) throws SQLException {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
		dataSource.close();
	}

}

2、高级使用

c3p0-config.xml

<c3p0-config>
	<default-config>
		
		<property name="driverClass">com.mysql.jdbc.Driverproperty>
		<property name="jdbcUrl">jdbc:mysql://127.0.0.1/mytestproperty>
		<property name="user">rootproperty>
		<property name="password">rootproperty>
		
		<property name="initialPoolSize">10property>
		
		<property name="maxPoolSize">100property>
		
		<property name="minPoolSize">10property>
	default-config>
c3p0-config>

C3P0WithConfig.java

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

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0WithConfig {

	public static void main(String[] args) throws SQLException {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();

		Connection connection = dataSource.getConnection();
		String sql = "select * from admin";
		PreparedStatement prepareStatement = connection.prepareStatement(sql);
		ResultSet resultSet = prepareStatement.executeQuery();
		while (resultSet.next()) {
			Object id = resultSet.getObject(1);
			Object username = resultSet.getObject(2);
			Object password = resultSet.getObject(3);
			System.out.println(id + ":" + username + ":" + password);
		}
		resultSet.close();
		connection.close();
		dataSource.close();
	}

}

第五章 DButils

1、基本的使用

Admin.java

public class Admin {
	private Integer id;
	private String username;
	private String password;

	public Integer getId() {
		return id;
	}

	public void setId(Integer 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;
	}

	@Override
	public String toString() {
		return "Admin [id=" + id + ", username=" + username + ", password=" + password + "]";
	}
}

DBUtilsTest.java

import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DBUtilsTest {

	@Test
	public void testQueryOne() {
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			QueryRunner queryRunner = new QueryRunner(dataSource);
			String sql = "select * from admin where id = ?";
			Admin admin = queryRunner.query(sql, new BeanHandler<Admin>(Admin.class), 1);
			System.out.println(admin);
			dataSource.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void testQueryAll() {
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			QueryRunner queryRunner = new QueryRunner(dataSource);
			String sql = "select * from admin";
			List<Admin> admins = queryRunner.query(sql, new BeanListHandler<Admin>(Admin.class));
			for (Admin admin : admins) {
				System.out.println(admin);
			}
			dataSource.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void testInsert() {
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			QueryRunner queryRunner = new QueryRunner(dataSource);
			String sql = "insert into admin values(NULL,?,?)";
			int rows = queryRunner.update(sql, "xiaojiu", "123456");
			if (rows > 0) {
				System.out.println("插入成功");
			} else {
				System.out.println("插入失败");
			}
			dataSource.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void testUpdate() {
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			QueryRunner queryRunner = new QueryRunner(dataSource);
			String sql = "update admin set username = 'xiaoqi' where id = ?";
			int rows = queryRunner.update(sql, 4);
			if (rows > 0) {
				System.out.println("修改成功");
			} else {
				System.out.println("修改失败");
			}
			dataSource.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	@Test
	public void testDelete() {
		try {
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
			dataSource.setUser("root");
			dataSource.setPassword("root");
			QueryRunner queryRunner = new QueryRunner(dataSource);
			String sql = "delete from admin where id = ?";
			int rows = queryRunner.update(sql, 6);
			if (rows > 0) {
				System.out.println("删除成功");
			} else {
				System.out.println("删除失败");
			}
			dataSource.close();
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

}

注意问题：

BeanHandler，查询到的单个数据封装成一个对象
BeanListHandler，查询到的多个数据封装成一个List<对象>
    
ArrayHandler，查询到的单个数据封装成一个数组
ArrayListHandler，查询到的多个数据封装成一个集合，集合里面的元素是数组
    
MapHandler，查询到的单个数据封装成一个map
MapListHandler，查询到的多个数据封装成一个集合，集合里面的元素是Map
    
ColumnListHandler
KeyedHandler
ScalarHandler    

2、自定义实现

ResultSetHandler.java

import java.sql.ResultSet;
import java.sql.SQLException;

public interface ResultSetHandler<T> {

	/**
	 * 定义数据封装的规则
	 * 
	 * @param 
	 * @param rs
	 */
	T handle(ResultSet rs) throws SQLException;

}

MyQueryRunner.java

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

import javax.sql.DataSource;

public class MyQueryRunner {

	private DataSource dataSource = null;

	public MyQueryRunner() {
		super();
	}

	public MyQueryRunner(DataSource dataSource) {
		super();
		this.dataSource = dataSource;
	}

	public <T> T query(String sql, ResultSetHandler<T> handler, Object... args) {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		try {
			connection = dataSource.getConnection();
			preparedStatement = connection.prepareStatement(sql);
			ParameterMetaData parameterMetaData = preparedStatement.getParameterMetaData();
			for (int i = 0; i < parameterMetaData.getParameterCount(); i++) {
				preparedStatement.setObject(i + 1, args[i]);
			}
			ResultSet resultSet = preparedStatement.executeQuery();
			return (T) handler.handle(resultSet);
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement);
		}
		return null;
	}

	public int update(String sql, Object... args) {
		Connection connection = null;
		PreparedStatement preparedStatement = null;
		try {
			connection = dataSource.getConnection();
			preparedStatement = connection.prepareStatement(sql);
			ParameterMetaData parameterMetaData = preparedStatement.getParameterMetaData();
			for (int i = 0; i < parameterMetaData.getParameterCount(); i++) {
				preparedStatement.setObject(i + 1, args[i]);
			}
			return preparedStatement.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			JDBCUtil.release(connection, preparedStatement);
		}
		return 0;
	}

}

Admin.java

public class Admin {
	private Integer id;
	private String username;
	private String password;

	public Integer getId() {
		return id;
	}

	public void setId(Integer 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;
	}

	@Override
	public String toString() {
		return "Admin [id=" + id + ", username=" + username + ", password=" + password + "]";
	}
}

MyQueryRunnerTest.java

import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class MyQueryRunnerTest {

	@Test
	public void testQueryOne() {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");
		MyQueryRunner queryRunner = new MyQueryRunner(dataSource);
		String sql = "select * from admin where id = ?";
		Admin admin = queryRunner.query(sql, new ResultSetHandler<Admin>() {
			@Override
			public Admin handle(ResultSet rs) throws SQLException {
				while (rs.next()) {
					Admin admin = new Admin();
					int id = rs.getInt("id");
					String username = rs.getString("username");
					String password = rs.getString("password");
					admin.setId(id);
					admin.setUsername(username);
					admin.setPassword(password);
					return admin;
				}
				return null;
			}
		}, 1);
		System.out.println(admin);
		dataSource.close();
	}

	@Test
	public void testQueryAll() {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");
		MyQueryRunner queryRunner = new MyQueryRunner(dataSource);
		String sql = "select * from admin";
		List<Admin> admins = queryRunner.query(sql, new ResultSetHandler<List<Admin>>() {
			@Override
			public List<Admin> handle(ResultSet rs) throws SQLException {
				List<Admin> admins = new ArrayList<Admin>();
				while (rs.next()) {
					Admin admin = new Admin();
					int id = rs.getInt("id");
					String username = rs.getString("username");
					String password = rs.getString("password");
					admin.setId(id);
					admin.setUsername(username);
					admin.setPassword(password);
					admins.add(admin);
				}
				return admins;
			}
		});
		for (Admin admin : admins) {
			System.out.println(admin);
		}
		dataSource.close();
	}

	@Test
	public void testInsert() {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");
		MyQueryRunner queryRunner = new MyQueryRunner(dataSource);
		String sql = "insert into admin values(NULL,?,?)";
		int rows = queryRunner.update(sql, "xiaoqiang", "123456");
		if (rows > 0) {
			System.out.println("插入成功");
		} else {
			System.out.println("插入失败");
		}
		dataSource.close();
	}

	@Test
	public void testUpdate() {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");
		MyQueryRunner queryRunner = new MyQueryRunner(dataSource);
		String sql = "update admin set username = 'mingming' where id = ?";
		int rows = queryRunner.update(sql, 4);
		if (rows > 0) {
			System.out.println("修改成功");
		} else {
			System.out.println("修改失败");
		}
		dataSource.close();
	}

	@Test
	public void testDelete() {
		ComboPooledDataSource dataSource = new ComboPooledDataSource();
		dataSource.setJdbcUrl("jdbc:mysql://127.0.0.1:3306/mytest");
		dataSource.setUser("root");
		dataSource.setPassword("root");
		MyQueryRunner queryRunner = new MyQueryRunner(dataSource);
		String sql = "delete from admin where id = ?";
		int rows = queryRunner.update(sql, 7);
		if (rows > 0) {
			System.out.println("删除成功");
		} else {
			System.out.println("删除失败");
		}
		dataSource.close();
	}

}