JDBCUtils 类的创建及使用（增删改查）

拼搏现实的明天。 2022-02-04 04:01 218阅读 0赞

**JDBCUtils的创建：**

import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    
    public class JDBCUtils {
    	//这个工具类,主要为我们获取一个数据库连接
    	private static String driverName = "com.mysql.jdbc.Driver";
    	private static String url = "jdbc:mysql://localhost:3306/day04";
    	private static String username = "root";
    	private static String password = "123";
    	
    	//静态代码块,目的,让第一次使用到JDBCUtils中加载驱动,第二次以后不再加载了
    	static{
    		//1.加载驱动
    		try {
    			Class.forName(driverName);
    		} catch (ClassNotFoundException e) {
    			// TODO Auto-generated catch block
    			//System.out.println("驱动加载失败..请检查驱动包");
    			throw new RuntimeException("驱动加载失败..请检查驱动包");
    		}
    	}
    	
    	public static Connection getConnection() throws Exception{
    		//2.获取和数据库的连接
    		Connection conn =  DriverManager.getConnection(url, username, password);
    		//3.返回连接对象
    		return conn;
    		
    	}
    	//关闭所有资源的统一代码
    	public static void closeAll(Connection conn,Statement st,ResultSet rs){
    		//负责关闭
    		if(conn != null){
    			try {
    				conn.close();
    			} catch (SQLException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		if(st != null){
    			try {
    				st.close();
    			} catch (SQLException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		if(rs != null){
    			try {
    				rs.close();
    			} catch (SQLException e) {
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    	}
    
    }

**JDBCUtils 的使用：**

import java.sql.Connection;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    
    public class TestDemo {
    	public static void main(String[] args) {
    		// 1.获取到数据库连接
    		Connection conn = null;
    		// 2.通过连接对象, 获取SQL执行对象
    		Statement st = null;
    		// 3.st执行sql语句
    		ResultSet rs = null;
    		try {
    			conn = JDBCUtils.getConnection();
    			st = conn.createStatement();
    			rs = st.executeQuery("select * from category");
    			// 4.处理结果集
    			while (rs.next()) {
    				Object cid = rs.getObject("cid");
    				Object cname = rs.getObject("cname");
    				System.out.println(cid + "\t" + cname);
    			}
    		} catch (Exception e) {
    			// TODO Auto-generated catch block
    			e.printStackTrace();
    		}finally {
    			// 5.释放资源
    			JDBCUtils.closeAll(conn, st, rs);
    		}
    		
    
    	}
    }

**JDBCUtils 的 增删改查 操作： **

import java.sql.Connection;
    import java.sql.ResultSet;
    import java.sql.Statement;
    
    public class TestDemo {
    
    	public static void main(String[] args) {
    		// TODO Auto-generated method stub
    		//insert();
    //		delete();
    //		update();
    //		query();
    	}
    	//插入
    	public static void insert(){
    		//1.
    		Connection conn = null;
    		//2.
    		Statement st = null;
    		//4.
    		try{
    			conn = JDBCUtils.getConnection();
    			st = conn.createStatement();
    			int rows = st.executeUpdate("insert into category (cname) values ('饮料'),('灵饰'),('羽毛球')");
    			System.out.println("成功插入"+rows+"行!!!");
    		}catch(Exception e){
    			System.out.println(e);
    		}finally {
    			JDBCUtils.closeAll(conn, st,null);
    		}
    	}
    	//删除
    	public static void delete(){
    		//1.
    		Connection conn = null;
    		//2.
    		Statement st = null;
    		//3.
    		ResultSet rs = null;
    		//4.
    		try{
    			conn = JDBCUtils.getConnection();
    			st = conn.createStatement();
    			int rows = st.executeUpdate("delete from category where cname='饮料'");
    			System.out.println("成功删除"+rows+"行!!!");
    		}catch(Exception e){
    			System.out.println(e);
    		}finally {
    			JDBCUtils.closeAll(conn, st, rs);
    		}
    	}
    	//修改
    	public static void update(){
    		//1.
    		Connection conn = null;
    		//2.
    		Statement st = null;
    		//3.
    		ResultSet rs = null;
    		//4.
    		try{
    			conn = JDBCUtils.getConnection();
    			st = conn.createStatement();
    			int rows = st.executeUpdate("update category set cname='乒乓球类' where cid = 11");
    			System.out.println("成功修改"+rows+"行!!!");
    		}catch(Exception e){
    			System.out.println(e);
    		}finally {
    			JDBCUtils.closeAll(conn, st, rs);
    		}
    	}
    	//查询
    	public static void query(){
    		//1.
    		Connection conn = null;
    		//2.
    		Statement st = null;
    		//3.
    		ResultSet rs = null;
    		//4.
    		try{
    			conn = JDBCUtils.getConnection();
    			st = conn.createStatement();
    			rs = st.executeQuery("select * from category where cid= 14");
    			while(rs.next()){
    				Object cid = rs.getObject("cid");
    				Object cname = rs.getObject("cname");
    				System.out.println(cid+"\t"+cname);
    			}
    			
    		}catch(Exception e){
    			System.out.println(e);
    		}finally {
    			JDBCUtils.closeAll(conn, st, rs);
    		}
    	}
    }