Java连接数据库完整代码 查找和插入

package test;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;

import org.junit.Test;

public class Main {

    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    static {
        try {
            InputStream is = Main.class.getResourceAsStream("/jdbc.properties");
            Properties prop = new Properties();
            prop.load(is);

            driver = prop.getProperty("jdbc.driver");
            url = prop.getProperty("jdbc.url");
            username = prop.getProperty("jdbc.username");
            password = prop.getProperty("jdbc.password");

            // 将JDBC驱动加载到JVM中
            Class.forName(driver);

        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 演示JDBC
     * */
    @Test
    public void insert() throws Exception {
        String sql = "insert into tb_user values(null,?,?)";
        Connection conn = DriverManager.getConnection(url, username, password);
        PreparedStatement pst = conn.prepareStatement(sql);
        pst.setString(1, "李四");
        pst.setInt(2, 30);

        pst.executeUpdate();

        pst.close();
        conn.close();
    }

    /**
     * 查询
     * */
    @Test
    public void query() throws Exception {
        String sql = "select * from tb_user where id>=?";
        Connection conn = DriverManager.getConnection(url, username, password);
        PreparedStatement pst = conn.prepareStatement(sql);
        pst.setInt(1, 1);

        ResultSet rs = pst.executeQuery();
        while(rs.next()) {
            int id = rs.getInt("id");
            String name = rs.getString("name");
            int age = rs.getInt("age");
            System.out.printf("id:%d, name:%s, age:%d\n", id, name, age);
        }

        rs.close();
        pst.close();
        conn.close();
    }

    /**
     * 获得文件的路径
     * */
    @Test
    public void test1() throws Exception {
        // 从类路径根目标查找
        String path = this.getClass().getClassLoader().getResource("jdbc.properties").toURI().getPath();
        System.out.println(path);
    }
    @Test
    public void test2() throws Exception {
        // 从当前目标查找，/表示根目录
        String path = this.getClass().getResource("/jdbc.properties").toURI().getPath();
        System.out.println(path);
    }

}

完整项目：https://gitee.com/z1027195164/JavaLianJieShuJuKuWanZhengDaiMa-ChaZhaoHeChaRu/tree/master