JDBC的抽取和封装实例

工具类：

package com.zhangxin9727.jdbc_utils;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

//JDBC工具类
public class JDBCUtils {
    public static final String driverClass;
    public static final String url;
    public static final String username;
    public static final String password;

    static {
        //加载并解析属性文件
        Properties props = new Properties();
        //通过类加载器获取
        InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("jdbc.properties");
        try {
            props.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driverClass = props.getProperty("driverClass");
        url = props.getProperty("url");
        username = props.getProperty("username");
        password = props.getProperty("password");
    }

    //注册驱动
    public static void loadDriver() throws ClassNotFoundException {
        Class.forName(driverClass);
    }

    //获得连接方法
    public static Connection getConnection() throws Exception {
        loadDriver();
        Connection conn = DriverManager.getConnection(url, username, password);
        return conn;
    }

    //资源释放
    public static void release(Statement stmt, Connection conn) {
        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            stmt = null;
        }

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

    public static void release(ResultSet rs, Statement stmt, Connection conn) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            rs = null;
        }
        release(stmt, conn);
    }
}

测试类：

package com.zhangxin9727.jdbc_utils;

import org.junit.Test;

import java.sql.Connection;
import java.sql.Statement;

public class JDBCTest {
    @Test
    //保存记录
    public void test1() {
        Connection conn = null;
        Statement stmt = null;
        try {
            conn = JDBCUtils.getConnection();
            stmt = conn.createStatement();
            String sql = "INSERT user VALUES (null, 'dfg','987','张')";
            int num = stmt.executeUpdate(sql);
            if (num > 0) {
                System.out.println("保存成功");
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            JDBCUtils.release(stmt, conn);
        }
    }
}

资源文件：

driverClass = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/jdbctest?useSSL=false&useUnicode=true&characterEncoding=UTF8&serverTimezone=GMT%2B8
username = root
password = mypassword

数据库：

CREATE DATABASE jdbctest;
USE jdbctest;
CREATE TABLE user(
    uid INT PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(20),
    password VARCHAR(20),
    name VARCHAR(20)
);
INSERT user VALUES (NULL, 'aaa', '111', 'Alice'), (NULL, 'bbb', '222', 'Bob'), (NULL,'ccc', '333', 'Cidy');