JavaJDBC连接数据库Connection

Java DataBase Connectivity
Java数据库连接

写在前面

• 注册驱动Class.forName()
• 获取连接DriverManager.getConnection()

详细过程

• mysql连接的url

String urlString = "jdbc:mysql://localhost:3306/数据库名";

• 方式一

//创建mysql驱动对象
Driver driver = new com.mysql.jdbc.Driver();
//设置访问数据库的用户名和密码
Properties properties = new Properties();
properties.setProperty("user", "用户名");
properties.setProperty("password", "密码");
//建立连接
Connection connection = driver.connect(urlString, properties);
//关闭连接
connection.close();

• 方式二

//创建mysql驱动对象
Driver driver = new com.mysql.jdbc.Driver();
//注册驱动
DriverManager.registerDriver(driver);
//通过DriverManager获取连接对象
Connection connection = DriverManager.getConnection(urlString, "用户名", "密码");
//关闭连接
connection.close();

• 方式三

//注册驱动
Class.forName("com.mysql.jdbc.Driver");
//获取连接
Connection connection = DriverManager.getConnection(urlString, "用户名", "密码");
//关闭连接
connection.close();

自定义的JdbcUtil类用来获取Connection对象

• properties文件

url=jdbc:mysql://localhost:3306/javawu
user=root
password=root
driver=com.mysql.jdbc.Driver

• JdbcUtil类

package com.javawu.util;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JdbcUtil {
    
    private static String driverString;
    private static String urlString;
    private static String userString;
    private static String passwordString;
    
    static {
        try {
            FileInputStream fileInputStream = new FileInputStream("./bin/db.properties");
            Properties properties = new Properties();
            properties.load(fileInputStream);
            urlString = properties.getProperty("url");
            driverString = properties.getProperty("driver");
            userString = properties.getProperty("user");
            passwordString = properties.getProperty("password");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
    //获取连接对象
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driverString);
            connection = DriverManager.getConnection(urlString, userString, passwordString);
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return connection;
    }
    
    //关闭相关对象、
    public static void close(Connection connection, Statement statement) {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
    public static void closeAll(Connection connection, Statement statement, ResultSet resultSet) {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}