Class.forName("com.mysql.jdbc.Driver");

static {
try {
DriverManager.registerDriver(new Driver());
}catch (SQLException var1) {
throw new RuntimeException( "can 't register driver! ");
}
}

Statement createStatement()

PreparedStatement prepareStatement(sql)

CallableStatement prepareCall(sql)

package com.bby;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class JdbcTransaction {
    public static void main(String[] args) throws Exception {
        String url = "jdbc:mysql:///jdbc?useSSL=false";
        String username = "root";
        String password = "1234";
        String sql = "update acount set money = 1002 where id = 1";
        String sql2 = "update acount set money = 1002 whe id = 1"; //注意這里SQL語(yǔ)句故意將where寫(xiě)錯(cuò)
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection(url, username, password);
        Statement statement = connection.createStatement();
        try {
            connection.setAutoCommit(false); // 開(kāi)啟手動(dòng)事務(wù)
            //執(zhí)行SQL語(yǔ)句并處理結(jié)果
            int count = statement.executeUpdate(sql);
            System.out.println(count);
            int count2 = statement.executeUpdate(sql2);
            System.out.println(count2);
            //提交事務(wù)
            connection.commit();
        } catch (Exception e) {
            //程序出現(xiàn)異常，回滾事務(wù)
            connection.rollback();
            e.printStackTrace();
        }        
    }
}

String sql2 = "update acount set money = 1002 wher id = 2";

// 定義sql
String sql = "update account set money = 3000 where id = 1";
// 獲取執(zhí)行sql的對(duì)象 Statement
Statement stmt = conn.createStatement();
// 執(zhí)行sql
int count = stmt.executeUpdate(sql);  //執(zhí)行完DML語(yǔ)句，受影響的行數(shù) 

// 定義sql
String sql = "drop database db2";
// 獲取執(zhí)行sql的對(duì)象 Statement
Statement stmt = conn.createStatement();
// 執(zhí)行sql
int count = stmt.executeUpdate(sql); //執(zhí)行完DDL語(yǔ)句，可能是0

package com.bby;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class JdbcResultSet {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        String url = "jdbc:mysql://localhost:3306/jdbc?useSSL=false";
        String username = "root";
        String password = "1234";
        Connection connection = DriverManager.getConnection(url, username, password);
        Statement statement = connection.createStatement();
        //定義查詢(xún)的SQL語(yǔ)句
        String sql = "select * from acount";
        //執(zhí)行查詢(xún)語(yǔ)句，獲取結(jié)果集
        ResultSet resultSet = statement.executeQuery(sql);
        //遍歷結(jié)果集
        while(resultSet.next()){
            int id = resultSet.getInt("id");
            String name = resultSet.getString("name");
            String money = resultSet.getString("money");
            System.out.println("id:" + id);
            System.out.println("name:" + name);
            System.out.println("money:" + money);
            System.out.println("-----------------");
        }
        resultSet.close();
        statement.close();
        connection.close();
    }
}

package com.bby;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class JdbcSqlInjection {
    public static void main(String[] args) throws Exception {
        Class.forName("com.mysql.jdbc.Driver");
        String url = "jdbc:mysql://localhost:3306/jdbc?useSSL=false";
        String username = "root";
        String password = "1234";
        Connection connection = DriverManager.getConnection(url, username, password);
        // 接收用戶(hù)輸入 用戶(hù)名和密碼
        String name = "abcdefg";
        String pwd = "' or '1' = '1";
        String sql = "select * from users where name = '" + name + "' and password = '" + pwd + "'";
        Statement statement = connection.createStatement();
        ResultSet resultSet = statement.executeQuery(sql);
        // 判斷登錄是否成功
        if (resultSet.next()) {
            System.out.println("登錄成功~");
        } else {
            System.out.println("登錄失敗~");
        }
        resultSet.close();
        statement.close();
        connection.close();
    }
}

// SQL語(yǔ)句中的參數(shù)值，使用？占位符替代
String sql = "select * from users where name = ? and password = ?";
// 通過(guò)Connection對(duì)象獲取，并傳入對(duì)應(yīng)的sql語(yǔ)句
PreparedStatement ps = connection.prepareStatement(sql);

setXxx(參數(shù)1，參數(shù)2);//給 ? 賦值， 參數(shù)1是編號(hào)（從1開(kāi)始） 參數(shù)2是值

executeUpdate(); // 執(zhí)行DDL語(yǔ)句和DML語(yǔ)句

executeQuery(); // 執(zhí)行DQL語(yǔ)句

package com.bby;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class JdbcPreparedStatement {
    public static void main(String[] args) throws Exception {
        String url = "jdbc:mysql:///jdbc?useSSL=false";
        String username = "root";
        String password = "1234";
        String name = "abcdefg";
        String pwd = "' or '1' = '1";
        Class.forName("com.mysql.jdbc.Driver");
        Connection connection = DriverManager.getConnection(url, username, password);
        //定義SQL語(yǔ)句
        String sql = "select * from users where name = ? and password = ?";
        //預(yù)編譯SQL語(yǔ)句
        PreparedStatement ps = connection.prepareStatement(sql);
        //填充占位符
        ps.setString(1, name);
        ps.setString(2, pwd);
        //執(zhí)行SQL語(yǔ)句
        ResultSet resultSet = ps.executeQuery();
        //判斷登錄是否成功
        if(resultSet.next()) {
            System.out.println("登陸成功！");
        } else {
            System.out.println("登錄失敗");
        }
        resultSet.close();
        ps.close();
        connection.close();
    }
}

Connection getConnection()

package com.bby;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.FileInputStream;
import java.sql.Connection;
import java.util.Properties;
public class JdbcDruid {
    public static void main(String[] args) throws Exception {
        // 加載配置文件
        Properties prop = new Properties();
        prop.load(new FileInputStream("jdbc-demo/src/druid.properties"));
        // 獲取連接池對(duì)象
        DataSource dataSource = DruidDataSourceFactory.createDataSource(prop);
        // 獲取數(shù)據(jù)庫(kù)連接 Connection
        Connection connection = dataSource.getConnection();
        System.out.println(connection); //獲取到了連接后就可以繼續(xù)做其他操作了
    }
}