java jdbc封装为DAO

╰半夏微凉° 2022-08-13 00:36 178阅读 0赞

package com.zhiru;
    
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
    
    class Student {
    	private String sno, sname, ssex;
    	private int sage;
    
    	public Student() {
    		super();
    	}
    
    	public Student(String no, String name, String sex, int age) {
    		this.sno = no;
    		this.sname = name;
    		this.ssex = sex;
    		this.sage = age;
    	}
    
    	public void setSno(String no) {
    		this.sno = no;
    	}
    
    	public void setSname(String name) {
    		this.sname = name;
    	}
    
    	public void setAge(int age) {
    		this.sage = age;
    	}
    
    	public String getSno() {
    		return sno;
    	}
    
    	public String getName() {
    		return sname;
    	}
    
    	public int getAge() {
    		return sage;
    	}
    
    	public String getSex() {
    		return ssex;
    	}
    }
    
    public class MyDao {
    	/*
    	 * dao:数据访问对象 将对数据库的操作封装为对一个类的操作。 它处于数据库之上，业务逻辑之下
    	 * 包括的功能：加载驱动，获取数据库连接，添加，查询，删除用户，查询所有用户。
    	 */
    	static {
    		try {
    			Class.forName("com.mysql.jdbc.Driver");
    		} catch (ClassNotFoundException e) {
    			e.printStackTrace();
    		}
    	}
    
    	// 获取数据库连接
    	public Connection getConnection() {
    		try {
    			return DriverManager.getConnection(
    					"jdbc:mysql://localhost:3306/test", "root", "root");
    		} catch (SQLException e) {
    			e.printStackTrace();
    		}
    		return null;
    
    	}
    
    	// 关闭数据库连接
    	public void release(ResultSet rs, Statement s, Connection con)
    			throws SQLException {
    		if (rs != null) {
    			rs.close();
    		}
    		if (s != null) {
    			s.close();
    		}
    		if (con != null) {
    			con.close();
    		}
    	}
    
    	public Student getStudentBySno(String mysno) throws SQLException {
    		ResultSet rs = null;
    		Connection con = null;
    		PreparedStatement ps = null;
    		String sql = "select * from student where sno=?";
    		try {
    			con = this.getConnection();
    			ps = con.prepareStatement(sql);
    			ps.setString(1, mysno);
    			rs = ps.executeQuery();
    			if (rs.next()) {
    				Student stu = new Student(rs.getString("sno"),
    						rs.getString("sname"), rs.getString("ssex"),
    						rs.getInt("sage"));
    				return stu;
    			}
    		} catch (SQLException e) {
    			e.printStackTrace();
    		} finally {
    			this.release(rs, ps, con);
    		}
    		return null;
    
    	}
    
    	public static void main(String[] args) throws SQLException {
    		// TODO Auto-generated method stub
    		MyDao md = new MyDao();
    		Student stu = md.getStudentBySno("001");
    		System.out.println(stu.getSno() + "---" + stu.getName() + "---"
    				+ stu.getAge() + "---" + stu.getSex());
    	}
    
    }