jdbc的dao层，和JDBCUtils

版权声明：JAVA https://blog.csdn.net/weixin_43190126/article/details/84868592

DAO层的实现：

package com.qyl.dao;

public class Dept {

	private Integer id;
	
	private String name;

	public Integer getId() {
		return id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	@Override
	public String toString() {
		return "Dept [id=" + id + ", name=" + name + "]";
	}
	
}

package com.qyl.dao;

import java.util.List;

public interface IDeptDao {
	
	/**
	 * 保存
	 * @param dept
	 */
	public void save(Dept dept);
	/**
	 * 删除
	 * @param id
	 */
	public void delete(Integer id);
	/**
	 * 修改
	 * @param dept
	 */
	public void update(Dept dept);
	/**
	 * 获取单个
	 * @param dept
	 */
	public Dept getOne(Integer id);
	/**
	 * 获取所有
	 * @param dept
	 */
	public List<Dept> getAll();

}

package com.qyl.dao.impl;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.qyl.dao.Dept;
import com.qyl.dao.IDeptDao;
import com.qyl.util.JDBCUtils;

public class DeptDaoImpl implements IDeptDao {

	@Override
	public void save(Dept dept) {
		Connection conn = null;
		Statement st = null;
		try {
			conn = JDBCUtils.getInstance().co();
			Statement st1 = conn.createStatement();
			// sql
			String sql = "insert into dept (name) value ('"+dept.getName()+"')";
			System.out.println(sql);
			// 执行语句
			st1.executeUpdate(sql);

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			// 释放资源
			JDBCUtils.getInstance().close(null, st, conn);
		}
	}

	@Override
	public void delete(Integer id) {

	}

	@Override
	public void update(Dept dept) {
		// TODO Auto-generated method stub

	}

	@Override
	public Dept getOne(Integer id) {
		
		return null;
	}

	@Override
	public List<Dept> getAll() {
		List<Dept> list = new ArrayList<>();
		Connection conn = null;
		Statement st = null;
		ResultSet result = null;
		// 加载驱动
		try {			
			conn = JDBCUtils.getInstance().co();
			//获取语句对象
			Statement st1 = conn.createStatement();
			//sql
			String sql = "select * from dept"; 
			//执行语句
			result = st1.executeQuery(sql);
			
			while (result.next()) {
				Dept dept = new Dept();
				dept.setId(result.getInt("id"));
				dept.setName(result.getString("name"));
				list.add(dept);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.getInstance().close(result, st, conn);
		}
		return list;
	}
}

package com.qyl.dao;

import java.util.List;

import org.junit.Test;

import com.qyl.dao.impl.DeptDaoImpl;

public class TestDaoImpl {

	private IDeptDao deptDao = new DeptDaoImpl();
	
	@Test
	public void testSave() throws Exception {
		Dept dept = new Dept();
		dept.setName("化学部");
		deptDao.save(dept);
	}
	
	
	@Test
	public void testGetAll() throws Exception {
		List<Dept> all = deptDao.getAll();
		System.out.println(all);
	}

JDBCUtils:

package com.qyl.dao.impl;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.qyl.dao.Dept;
import com.qyl.dao.IDeptDao;
import com.qyl.util.JDBCUtils;

public class DeptDaoImpl implements IDeptDao {

	@Override
	public void save(Dept dept) {
		Connection conn = null;
		Statement st = null;
		try {
			conn = JDBCUtils.getInstance().co();
			Statement st1 = conn.createStatement();
			// sql
			String sql = "insert into dept (name) value ('"+dept.getName()+"')";
			System.out.println(sql);
			// 执行语句
			st1.executeUpdate(sql);

		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			// 释放资源
			JDBCUtils.getInstance().close(null, st, conn);
		}
	}

	@Override
	public void delete(Integer id) {

	}

	@Override
	public void update(Dept dept) {
		// TODO Auto-generated method stub

	}

	@Override
	public Dept getOne(Integer id) {
		
		return null;
	}

	@Override
	public List<Dept> getAll() {
		List<Dept> list = new ArrayList<>();
		Connection conn = null;
		Statement st = null;
		ResultSet result = null;
		// 加载驱动
		try {			
			conn = JDBCUtils.getInstance().co();
			//获取语句对象
			Statement st1 = conn.createStatement();
			//sql
			String sql = "select * from dept"; 
			//执行语句
			result = st1.executeQuery(sql);
			
			while (result.next()) {
				Dept dept = new Dept();
				dept.setId(result.getInt("id"));
				dept.setName(result.getString("name"));
				list.add(dept);
			}
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			JDBCUtils.getInstance().close(result, st, conn);
		}
		return list;
	}
}

package com.qyl.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Properties;


public class JDBCUtils {
	
	//私有化构造器
	private JDBCUtils (){}
	//静态代码块
	
	private static Properties prop = null;
	private static JDBCUtils instance = null;
	
	static{
		try {
			prop = new Properties();		
			prop.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("db.properties"));		
			Class.forName(prop.getProperty("driver"));
			instance = new JDBCUtils();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	//获取实例化
	public static JDBCUtils getInstance(){
		return instance;
	}
	
	//获取链接
	public Connection co() throws Exception {
		return DriverManager.getConnection(prop.getProperty("url"),prop.getProperty("user"),prop.getProperty("password"));		
	}
	
	public void close(ResultSet result,Statement st,Connection conn) {
		try {
			try {
				if(result!=null)result.close();
			} catch (Exception e2) {
				e2.printStackTrace();
			}finally {
				try {
					if(st!=null)st.close();
				} catch (Exception e3) {
					e3.printStackTrace();
				}finally {
					try {
						if(conn!=null)conn.close();
					} catch (Exception e4) {
						e4.printStackTrace();
					}
				}
			}
		} catch (Exception e) {
			
		}
	}
}

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