JDBC底層代碼

jdbc底層代碼演示

標準格式代碼

package cn.gts.jdbc;

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

import org.junit.Test;

import cn.gts.entity.User;

public class Jdbc {
	@Test
    public void jdbcTest() {
        Connection conn = null;
        PreparedStatement psmt = null;
        ResultSet rs = null;
        
        try {
        	/*
    		 * jdbc四大配置參數
    		 * driverClassName：com.mysql.jdbc.Driver
    		 * url:jdbc:mysql://localhost:3306/test
    		 * username:root
    		 * password:123
    		 */
        	//加載驅動
    		Class.forName("com.mysql.jdbc.Driver");
    		String url = "jdbc:mysql://localhost:3306/test";
    		String username = "root";
    		String password = "123";
    		//獲得鏈接
    		conn = DriverManager.getConnection(url,username,password);
			
            //編寫sql語句
            String sql = "select * from user where username = ?";
            //預編譯sql語句
            psmt = conn.prepareStatement(sql);
            //設置參數值
            psmt.setString(1, "zhangSan");
            //執行sql語句獲得結果集
            rs = psmt.executeQuery();
            //遍歷結果集
            while(rs.next()) {
                //根據字段獲得數據
                String username = rs.getString("username");
                String password = rs.getString("password");
                //封裝
                User user = new User();
                user.setUsername(username);
                user.setPassword(password);
                
                System.out.println(user);
            }
            
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                rs.close();
                psmt.close();
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}