JDBC

Posted 2021-02-12 chenpi

什么是JDBC

一种访问数据库的规范、标准；一组用JAVA语言编写的API；

例子

package jdbc;

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

import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

public class JDBCTest {
    /**
     * 数据库URL
     */
    static final String DB_URL = "jdbc:mysql://localhost/demo?user=root&password=root";

    public static void main(String[] args) {

        Connection conn = null;
        Statement stmt = null;
        PreparedStatement psmt = null;
        ResultSet rs = null;
        try {
            //获取数据库连接的三种方式
            //方式一,推荐该方式，首选方法，作为 DriverManager工具的替代
            MysqlDataSource mysqlDataSouurce = new MysqlDataSource();
            mysqlDataSouurce.setUrl(DB_URL);
            conn = mysqlDataSouurce.getConnection();
            
            //方式二
//            Class.forName("com.mysql.jdbc.Driver");
//            conn = DriverManager.getConnection(DB_URL);
            
            //方式三
//            Driver mysqlDriver = new com.mysql.jdbc.Driver();
//            DriverManager.registerDriver(mysqlDriver);
//            conn = DriverManager.getConnection(DB_URL);

            //事务相关
            conn.setAutoCommit(false);
            
            //插入数据，使用executeUpdate
            psmt = conn.prepareStatement("insert into user(name, address) values (?, ?)");
            psmt.setString(1, "user001");
            psmt.setString(2, "HangZhou");
            psmt.executeUpdate();
            
            // Statement,不接受参数
            stmt = conn.createStatement();
            //查询数据，使用executeQuery
            rs = stmt.executeQuery("SELECT id, name, address FROM user");
            

            // 获取SQL执行结果
            while (rs.next()) {
                long id = rs.getLong("id");
                String name = rs.getString("name");
                String address = rs.getString("address");

                System.out.print("ID: " + id + ", Name: " + name + ", Address: " + address + "
");
            }
            
            conn.commit();
            conn.setAutoCommit(true);
        } catch (SQLException se) {
            try {
                conn.rollback();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            se.printStackTrace();
        } catch (Exception e) {
            try {
                conn.rollback();
            } catch (SQLException e2) {
                e.printStackTrace();
            }
            e.printStackTrace();
        } finally {
            // 关闭资源
            try {
                if (rs != null) {
                    rs.close();
                }
            } catch (SQLException se1) {
            }

            try {
                if (stmt != null)
                    stmt.close();
            } catch (SQLException se2) {
            }

            try {
                if (psmt != null)
                    psmt.close();
            } catch (SQLException se3) {
            }
            
            try {
                if (conn != null)
                    conn.close();
            } catch (SQLException se4) {
                se4.printStackTrace();
            }
        }
    }
}