文章目录
1.JDBC基本介绍
1.概述
2.JDBC原理图
2.JDBC快速入门
1.JDBC API
2.JDBC程序编写步骤
3.环境配置
1.创建src/lib文件夹，放入jar包
2.加入到项目中
3.配置代码提示
4.代码实例
java
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package jdbc_;
import com.mysql.cj.jdbc.Driver; //注意sql8是这个驱动
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
* 完成简单的jdbc操作
*/
public class Jdbc01 {
public static void main(String[] args) throws SQLException {
//1.注册mysql驱动类
Driver driver = new Driver();
//2.得到连接
//（1）jdbc:mysql：//表示jdbc连接mysql的协议
//（2）localhost：主机，这个是数据库的ip地址
//（3）3306：mysql：监听的端口号
//（4）hsp_db02：是数据库的名字
//（5）mysql的本质就是socket连接
String url= "jdbc:mysql://localhost:3306/hsp_db02";
//将用户名和密码封装到properties对象
//这里的user和password是固定的
Properties properties = new Properties();
properties.setProperty("user", "root");
properties.setProperty("password", "root");
//获取连接
Connection connect = driver.connect(url, properties);
//3.执行sql
String sql = "insert into actor values(null, '刘德华', '男', '1970-1-1', '110')";
//statement用于执行静态sql并返回其生成对的结果的对象
Statement statement = connect.createStatement();
//执行
int i = statement.executeUpdate(sql);
System.out.println(i > 0 ? "成功" : "失败");
//4.关闭连接源
statement.close();
connect.close();
}
} 3.数据库五种连接方式（推荐使用4、5）
1.代码实例
java
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package jdbc_;
import com.mysql.cj.jdbc.Driver;
import org.junit.jupiter.api.Test;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
*/
public class JdbcConnect {
public static void main(String[] args) throws SQLException {
//方式一
//1.注册mysql驱动类
Driver driver = new Driver();
//2.得到连接
//（1）jdbc:mysql：//表示jdbc连接mysql的协议
//（2）localhost：主机，这个是数据库的ip地址
//（3）3306：mysql：监听的端口号
//（4）hsp_db02：是数据库的名字
//（5）mysql的本质就是socket连接
String url= "jdbc:mysql://localhost:3306/hsp_db02";
//将用户名和密码封装到properties对象
//这里的user和password是固定的
Properties properties = new Properties();
properties.setProperty("user", "root");
properties.setProperty("password", "root");
//获取连接
Connection connect = driver.connect(url, properties);
System.out.println("方式一：" + connect);
connect.close();
}
@Test
public void method02() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {
//方式二
Class<?> aClass = Class.forName("com.mysql.cj.jdbc.Driver");
Driver driver = (Driver) aClass.newInstance();
String url= "jdbc:mysql://localhost:3306/hsp_db02";
//将用户名和密码封装到properties对象
//这里的user和password是固定的
Properties properties = new Properties();
properties.setProperty("user", "root");
properties.setProperty("password", "root");
//获取连接
Connection connect = driver.connect(url, properties);
System.out.println("方式二：" + connect);
connect.close();
}
@Test
public void method03() throws ClassNotFoundException, InstantiationException, IllegalAccessException, SQLException {
//方式三，使用DriverManager来替代driver进行统一管理
Class<?> aClass = Class.forName("com.mysql.cj.jdbc.Driver");
Driver driver = (Driver) aClass.newInstance();
//创建url、user和password
String url= "jdbc:mysql://localhost:3306/hsp_db02";
String user= "root";
String password= "root";
DriverManager.registerDriver(driver); //注册driver驱动
Connection connection = DriverManager.getConnection(url, user, password); //获取连接
System.out.println("方式三：" + connection);
connection.close();
}
@Test
public void method04() throws ClassNotFoundException, SQLException {
//方式四，在加载驱动时使用静态代码块自动注册驱动
Class<?> aClass = Class.forName("com.mysql.cj.jdbc.Driver");
//创建url、user和password
String url= "jdbc:mysql://localhost:3306/hsp_db02";
String user= "root";
String password= "root";
//使用DriverManager获取连接
Connection connection = DriverManager.getConnection(url, user, password); //获取连接
System.out.println("方式四：" + connection);
connection.close();
}
@Test
public void method05() throws IOException, ClassNotFoundException, SQLException {
//获取properties文件的信息
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties")); //加载到properties文件中
String driver = properties.getProperty("driver");
String url = properties.getProperty("url");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//使用DriverManager获取连接
Connection connection = DriverManager.getConnection(url, user, password);
System.out.println("方式五：" + connection);
connection.close();
}
} 2.细节说明
1.第四种方式是自动加载驱动原因
Driver类加载的时候有个静态代码块
这个静态代码块会自动创建一个驱动实例并且注册
2.可不可以不写类加载语句？
答案是可以的
原因是在mysql的驱动4以后是自动加载的
mysql4以后自带配置文件会自动加载驱动并注册
3.方式五的连接方式（建议使用）
1.src下（或者任意位置）创建配置文件（自定义名字）
src\mysql.properties
properties
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user=root
password=root
url=jdbc:mysql://localhost:3306/hsp_db02
driver=com.mysql.cj.jdbc.Driver 注意这个文件不能加空格
2.获取连接
java
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//获取properties文件的信息
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties")); //加载到properties文件中
String driver = properties.getProperty("driver");
String url = properties.getProperty("url");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//使用DriverManager获取连接
Connection connection = DriverManager.getConnection(url, user, password); 4.课堂练习
题目
答案
java
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package jdbc_;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
*/
public class ConnectExercise {
public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
//加载配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//获取内容
String driver = properties.getProperty("driver");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
//编写sql
//1.插入五条语句
// String sql = "insert into actor values(null, '孙显圣', '男', '2002-12-8', '123456'), " +
// "(null, '孙显圣2', '男', '2005-2-8', '123456'), " +
// "(null, '孙显圣3', '男', '2001-12-8', '123456'), " +
// "(null, '孙显圣4', '男', '2004-12-8', '123456'), " +
// "(null, '孙显圣5', '男', '2006-12-8', '123456')";
//2.修改id=1的数据，将名字改成自己的
// String sql = "update actor set name = '孙显圣' where id = 1";
//3.删除id = 1的记录
String sql = "delete from actor where id = 1";
//创建statement
Statement statement = connection.createStatement();
//执行sql
int i = statement.executeUpdate(sql);
System.out.println(i > 0 ? "成功" : "失败");
//关闭连接
statement.close();
connection.close();
}
} 4.ResultSet查询
1.基本介绍
2.ResultSet查询表中所有数据
java
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package jdbc_;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
*/
public class ResultSet_ {
public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
//加载配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//获取内容
String driver = properties.getProperty("driver");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
//编写sql
//查询所有记录
String sql = "select * from actor ";
//创建statement
Statement statement = connection.createStatement();
//执行查询
ResultSet resultSet = statement.executeQuery(sql); //结果保存在resultSet中
while (resultSet.next()) { //初始的resultSet指向的是ArrayList的表头，如果下一条记录不为空，则将光标移动到下一条记录
//取出所有列的元素
int anInt = resultSet.getInt(1);
String string = resultSet.getString(2);
String string1 = resultSet.getString(3);
Date date = resultSet.getDate(4);
String string2 = resultSet.getString(5);
System.out.println(anInt + " " + string + " " + string1 + " " + date + " " + string2);
}
//关闭连接
resultSet.close();
statement.close();
connection.close();
}
} 3.SQL注入
5.预处理
1.基本介绍
2.预处理查询
java
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package jdbc_;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
*/
public class PreparedStatement_ {
public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
//加载配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//获取内容
String driver = properties.getProperty("driver");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
//编写sql
//查询记录
String sql = "select id, name from actor where id = ? and name = ?";
//创建Prestatement
PreparedStatement preparedStatement = connection.prepareStatement(sql);
//进行预处理
preparedStatement.setInt(1, 4);
preparedStatement.setString(2, "孙显圣");
//执行查询
ResultSet resultSet = preparedStatement.executeQuery(); //结果保存在resultSet中，这里是不带sql的
while (resultSet.next()) { //初始的resultSet指向的是ArrayList的表头，如果下一条记录不为空，则将光标移动到下一条记录
//取出所有列的元素
int anInt = resultSet.getInt(1);
String string = resultSet.getString(2);
System.out.println(anInt + " " + string);
}
//关闭连接
resultSet.close();
preparedStatement.close();
connection.close();
}
} 3.预处理DML
java
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package jdbc_;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
*/
public class PreparedStatement_01 {
public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
//加载配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//获取内容
String driver = properties.getProperty("driver");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
//加载驱动类
Class<?> aClass = Class.forName(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
//编写sql
//修改
String sql = "update actor set name = ? where id = ?";
//创建Prestatement
PreparedStatement preparedStatement = connection.prepareStatement(sql);
//进行预处理
preparedStatement.setString(1, "孙显圣");
preparedStatement.setInt(2, 2);
//执行更新
int i = preparedStatement.executeUpdate();//结果保存在resultSet中，这里是不带sql的
System.out.println(i > 0 ? "成功" : "失败");
//关闭连接
preparedStatement.close();
connection.close();
}
} 4.课堂练习
java
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package jdbc_;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
* 预处理课堂练习
*/
public class PreStatementExercise {
public static void main(String[] args) throws IOException, ClassNotFoundException, SQLException {
//读取配置文件
Properties properties = new Properties();
properties.load(new FileInputStream("src\\mysql.properties"));
//获取信息
String driver = properties.getProperty("driver");
String user = properties.getProperty("user");
String password = properties.getProperty("password");
String url = properties.getProperty("url");
//类加载
Class.forName(driver);
//获取连接
Connection connection = DriverManager.getConnection(url, user, password);
// //编写sql语句
// String sql = "insert into actor values(null, ?, ?, ?, ?)";
// //对sql进行预处理
// PreparedStatement preparedStatement = connection.prepareStatement(sql);
// preparedStatement.setString(1, "李华");
// preparedStatement.setString(2, "男");
// preparedStatement.setDate(3, Date.valueOf("2021-3-9")); //这里注意把日期变成string类型
// preparedStatement.setString(4, "123456");
// //修改tom的记录，将name改成king
// String sql = "update actor set name = ? where name = ?";
// //对sql进行预处理
// PreparedStatement preparedStatement = connection.prepareStatement(sql);
// preparedStatement.setString(1, "king");
// preparedStatement.setString(2, "tom");
// //删除一条记录
// String sql = "delete from actor where id = ?";
// //对sql进行预处理
// PreparedStatement preparedStatement = connection.prepareStatement(sql);
// preparedStatement.setInt(1, 3);
//查询全部记录并显示在控制台上
String sql = "select * from actor";
//预处理
PreparedStatement preparedStatement = connection.prepareStatement(sql);
//执行sql
ResultSet resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
//取出全部数据，并显示
int anInt = resultSet.getInt(1);
String string = resultSet.getString(2);
String string1 = resultSet.getString(3);
Date date = resultSet.getDate(4);
String string2 = resultSet.getString(5);
System.out.println(anInt + " " + string + " " + string1 + " " + date + " " + string2);
}
// //执行sql
// int i = preparedStatement.executeUpdate();
// System.out.println(i > 0 ? "成功" : "失败");
//关闭连接
resultSet.close();
preparedStatement.close();
connection.close();
}
} 6.JDBC_API
7.JDBCUtils
1.JDBCUtils工具类代码
java
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package utils;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;
/**
* @author 孙显圣
* @version 1.0
* 这是一个工具类，完成mysql的连接和关闭资源
*/
public class JDBCUtils {
//四个静态属性，因为每次程序运行的时候只需要一份
private static String user;
private static String password;
private static String url;
private static String driver;
static { //静态代码块为四个静态属性初始化
//读取配置文件
Properties properties = new Properties();
try {
properties.load(new FileInputStream("src\\mysql.properties")); //读取的配置文件的位置
} catch (IOException e) {
throw new RuntimeException(e);
}
//将信息给静态属性
user = properties.getProperty("user");
password = properties.getProperty("password");
url = properties.getProperty("url");
driver = properties.getProperty("driver");
}
//连接数据库
public static Connection getConnection() {
try {
return DriverManager.getConnection(url, user, password);
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
//关闭数据库
//1.ResultSet
//2.Statement,PrepareStatement,由于后一个是前一个的子接口，所以只传前面的就可以
//3.Connection
public static void close(ResultSet resultSet, Statement statement, Connection connection) {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}
} 2.JDBCUtils_DML演示
java
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package jdbc_;
import org.junit.jupiter.api.Test;
import utils.JDBCUtils;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* @author 孙显圣
* @version 1.0
*/
public class JDBCUtils_Use {
@Test
public void testDML() {
//建立连接
Connection connection = JDBCUtils.getConnection();
//编写sql语句进行修改
String sql = "update actor set name = ? where id = ?";
PreparedStatement preparedStatement = null;
try {
//进行预处理
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setString(1, "刘德华");
preparedStatement.setInt(2, 6);
//执行sql
int i = preparedStatement.executeUpdate();
System.out.println(i > 0 ? "成功" : "失败");
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
//关闭资源
JDBCUtils.close(null, preparedStatement, connection);
}
}
} 3.JDBCUtils_select演示
java
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package jdbc_;
import org.junit.jupiter.api.Test;
import utils.JDBCUtils;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* @author 孙显圣
* @version 1.0
*/
public class JDBCUtils_Use {
@Test
public void testSelect() {
//建立连接
Connection connection = JDBCUtils.getConnection();
//编写sql语句进行查询
String sql = "select name, phone from actor where id = ?";
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
//进行预处理
preparedStatement = connection.prepareStatement(sql);
preparedStatement.setInt(1, 8);
//执行查询
resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
String string = resultSet.getString("name");
String string1 = resultSet.getString("phone");
System.out.println(string + " " + string1);
}
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
//关闭资源
JDBCUtils.close(resultSet, preparedStatement, connection);
}
}
} 8.事务
1.基本介绍
2.案例------使用事务处理银行转账
1.创建表account
sql
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CREATE TABLE account(
id INT PRIMARY key auto_increment,
name VARCHAR(32) NOT NULL DEFAULT'',
blance DOUBLE NOT NULL DEFAULT 0
)
INSERT INTO account VALUES(null, '马云', 3000);
INSERT INTO account VALUES(null, '马化腾', 10000);
SELECT * FROM account 2.编写代码
java
复制代码
package jdbc_;
import utils.JDBCUtils;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
/**
* @author 孙显圣
* @version 1.0
*/
public class Transaciton {
public static void main(String[] args) {
Connection connection = null;
PreparedStatement preparedStatement = null;
PreparedStatement preparedStatement1 = null;
try {
//连接数据库
connection = JDBCUtils.getConnection();
//1.设置不自动提交事务
connection.setAutoCommit(false);
//编写sql进行模拟转账
String sql1 = "update account set blance = blance - 100 where name = ?";
//编写sql进行模拟接受
String sql2 = "update account set blance = blance + 100 where name = ?";
//预处理
preparedStatement = connection.prepareStatement(sql1);
preparedStatement.setString(1, "马云");
preparedStatement1 = connection.prepareStatement(sql2);
preparedStatement1.setString(1, "马化腾");
//执行1
preparedStatement.executeUpdate();
// //假设有个错误，则会回滚
// System.out.println(10/0);
//执行2
preparedStatement1.executeUpdate();
//3.如果都顺利执行完了也没有错误则提交事务
connection.commit();
} catch (SQLException e) {
try {
//2.如果中间出错了则回滚
connection.rollback();
} catch (SQLException ex) {
throw new RuntimeException(ex);
}
throw new RuntimeException(e);
} finally {
//关闭连接
JDBCUtils.close(null, preparedStatement, connection);
JDBCUtils.close(null, preparedStatement1, null);
}
}
} 
