JAvaはmysqlをオブジェクトでより削除

まずドライバを登録し、登録を駆動すればいいので、コードを1つのクラスにカプセル化します.

/*               ，            ，                 ， 
 *             ，         ，       ，static{}            ，
 * static           ，
        */

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


public class Util {

	static String url="jdbc:mysql://127.0.0.1:3306/mydata";			//    
	static String user="root";										//       
	static String pass="1";
	
	
	static{														//         ，          
		try {
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	
	public static Connection getConn() throws SQLException		//    Connection  ，       
	{
		return DriverManager.getConnection(url, user, pass);  
	}
	
	
	public static void free(Statement st,Connection conn) 		// sql      ，    
	{
		 if(st!=null)
			try {
				st.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		   finally{							//       ，conn      
			   if(conn!=null)
				try {
					conn.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
		   }
		
		/*st.close();
		conn.close();*/
	}
	
	public static void free(ResultSet rs,Statement st,Connection conn)
	{
		if(rs!=null)
			try {
				rs.close();
			} catch (SQLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		free(st,conn);
	}
}

mysqlのstudentテーブルをオブジェクトにカプセル化

//              ，         get set  


public class Student {
 private int id;
 private String name;
 private int age;
 
 public Student(int id){
	 this.id=id;
 }
 
 public Student(int id,String name,int age)
 {
	 this.id=id;
	 this.name=name;
	 this.age=age;
 }
public int getId() {
	return id;
}
public void setId(int id) {
	this.id = id;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public int getAge() {
	return age;
}
public void setAge(int age) {
	this.age = age;
}
 
}

mysqlを書くためのクラスを作成する文

/*       sql  ，             ，     sql  ，
       sql    ，            */


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

import javax.naming.spi.DirStateFactory.Result;


public class StuDao {

	public void insert(Student s)			//    
	{
		try {
			Connection conn=Util.getConn();
			
			/*       preparedStatement Statement     ，  Statement     ， Statement execteUpdate
			   ，        sql  ，                                 
			  ：String sql="insert into student(id,name,age)values(1,zhangsan,11)";
			String sql="insert into student(id,name,age)values(2,lisi,12)";
			String sql="insert into student(id,name,age)values(3,wangwu,13)";
			  ，PreparedStatement        ，          ————?,  setInt        
			             ?,          */
			
			String sql="insert into student(id,name,age)values(?,?,?)";
			PreparedStatement st=conn.prepareStatement(sql);
			st.setInt(1, s.getId());
			st.setString(2, s.getName());
			st.setInt(3, s.getAge());
			int i=st.executeUpdate();
			
			Util.free(st, conn);
			
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	
	public void update(Student s)			//    
	{
		try {
			Connection conn=Util.getConn();
			
			String sql="update student set name=?,age=? where id=?";
			PreparedStatement st=conn.prepareStatement(sql);
			
			st.setString(1, s.getName());
			st.setInt(2, s.getAge());
			st.setInt(3, s.getId());
			int i=st.executeUpdate();
			
			Util.free(st, conn);
			
			
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
	}
	
	public void delete(Student s){			//    
		try {
			Connection conn = Util.getConn();
			
			String sql="delete from student where id =?";
			PreparedStatement st = conn.prepareStatement(sql);
			
			st.setInt(1, s.getId());
			
			int i=st.executeUpdate();
			
			Util.free(st, conn);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
	public void select1(Student s){			//    
		try {
			Connection conn = Util.getConn();
			
			String sql = "select * from student where id=?";
			
			PreparedStatement st = conn.prepareStatement(sql);
			st.setInt(1, s.getId());
			
			ResultSet rs = st.executeQuery();
			while(rs.next()){
				System.out.println(rs.getInt(1)+" "+rs.getString(2)+" "+rs.getInt(3));
			}
			Util.free(st, conn);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	
}

テストクラス

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


public class TestConnection {

	
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		Student s=new Student(4);
		StuDao dao=new StuDao();
		dao.select1(s);
	}

}