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-개발환경-

IDE : Eclipse IDE for Java Developers Version: 2020-03 (4.15.0)
language : java 8
DB GUI : SQLyog Community - MySQL GUI v12.2.1 ( 64 bit )
MySQL : MySQL Server 5.5

 

-Server-

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package networkTest3;
 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
 
import com.koreait.interfaceTest.interfaceTest;
 
public class Server3 extends JFrame implements ActionListener,Runnable{
    //JAVA UI
    JTextArea textArea; 
    JPanel panel; 
    JTextField textField;
    JButton button;
    //Network
    ServerSocket serverSocket;
    Socket socket;
    PrintWriter printWriter;
    Scanner scanner;
    String message="";
    
    
    public Server3() {
        setTitle("채팅창");
        setBounds(80, 50, 400, 500);
        addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                if(printWriter!=null) {
                    printWriter.write("나갈게요\n");
                    printWriter.write("bye\n");
                    printWriter.flush();
 
                    if(serverSocket!=null)try {serverSocket.close();} catch (IOException e1) {e1.printStackTrace();}
                    if(socket!=null)try {socket.close();} catch (IOException e1) {e1.printStackTrace();}
                    if(printWriter!=null)try {printWriter.close();} catch (Exception e1) {e1.printStackTrace();}
                    if(scanner!=null)try {scanner.close();} catch (Exception e1) {e1.printStackTrace();}
 
                    System.exit(0);
                }
            }
        });
        
        //Center
        textArea=new JTextArea();
        textArea.setBackground(Color.orange);
        textArea.setEditable(false);//편집 불가능
        
        //bottom
        panel=new JPanel(new BorderLayout());
        button=new JButton("입력");
        textField=new JTextField();
        
        //actionlistener
        button.addActionListener(this);
        textField.addActionListener(this);
        
        //subRegister
        panel.add(textField,BorderLayout.CENTER);
        panel.add(button,BorderLayout.EAST);
        
        //size
        panel.setPreferredSize(new Dimension(400, 40));
        
        //Register
        add(textArea,BorderLayout.CENTER);
        add(panel,BorderLayout.SOUTH);
        
        setVisible(true);
    }
    
    public static void main(String[] args) {
        Server3 server = new Server3();
        try {
            server.serverSocket=new ServerSocket(10004);
            server.message= "192.168.0.12 서버의 10004 번 포트로 서버 시작\n";
            server.message+="클라이언트가 접속하기를 기다립니다.\n";
            server.textArea.setText(server.message);
            
            server.textField.setEnabled(false);
            server.button.setEnabled(false);
            
            server.socket=server.serverSocket.accept();
            server.message= server.socket+ "접속 성공\n"+ server.message;
            server.textArea.setText(server.message);
            
            server.textField.setEnabled(true);
            server.button.setEnabled(true);
            server.textField.requestFocus();
            
            server.printWriter =new PrintWriter(server.socket.getOutputStream());
            server.scanner= new Scanner(server.socket.getInputStream());
            
            new Thread(server).start();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
 
    @Override
    public void actionPerformed(ActionEvent e) {
        String msg=textField.getText().trim();
        if(msg.length()>0) {
            message=  message + "server >> " + msg+ "\n";
            textArea.setText(message);
            
            if(printWriter!=null) {
                printWriter.write(msg+"\n");
                printWriter.flush();
            }
        }
        textField.setText("");
        textField.requestFocus();
    }
 
    @Override
    public void run() {
        while(socket!=null) {
            String msg="";
            try {
                msg=scanner.nextLine().trim();
            } catch (Exception e) {
                break;
            }
            if(msg.length()>0) {
                message= message+ "Client >> " +msg +"\n";
                textArea.setText(message);
                if(msg.toLowerCase().equals("bye")) 
                    break;
                try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}
            }
        }
        textField.setEnabled(false);
        button.setEnabled(false);
        if(serverSocket!=null)try {serverSocket.close();} catch (IOException e) {e.printStackTrace();}
        if(socket!=null)try {socket.close();} catch (IOException e) {e.printStackTrace();}
        if(printWriter!=null)try {printWriter.close();} catch (Exception e) {e.printStackTrace();}
        if(scanner!=null)try {scanner.close();} catch (Exception e) {e.printStackTrace();}
    
    }
}
 
 cs

 

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-Description-

Server3 생성자에는 UI 구성

 

72 : 채팅입력후 enter 누르면 actionlistener가 실행되도록  textField에도 actionlistener를 걸어줌

91 : 포트번호를 10004번 포트로한 ServerSocket 객체생성 (포트번호는 만번때 이후로는 자유로히 사용가능)

96~97 : 클라이언트와 연결전에 입력칸(textfield)와 버튼(button) 비활성화

99 : 클라이언트 연결 대기

103~104 : 입력칸(textfield)와 버튼(button) 활성화

105 : 초점을 textfield로 설정 

107~108 : 서버-클라이언트간 I/O를 위한 출력,입력 객체 생성

110 : 클라이언트로부터의 메세지를 주기적으로 받아들이는 Thread 실행

124 : 클라이언트로 메세지 전달  ( 메세지의 끝부분 에는 "\n"이 들어가야함 )

125 : 전달버퍼가 꽉차기 전에도 전달가능하게함 

137 : 들어온 메세지를 읽어들임

141~147 : 들어온 메세지를 가공해서 textArea에 출력 

151~154 : 통신객체들을 close() 해준다

-Client-

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package networkTest3;
 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
 
public class Client3 extends JFrame implements ActionListener,Runnable{
    //JAVA UI
        JTextArea textArea; 
        JPanel panel; 
        JTextField textField;
        JButton button;
        //Network
        Socket socket;
        PrintWriter printWriter;
        Scanner scanner;
        String message="";
        
        public Client3() {
            setTitle("채팅창");
            setBounds(500, 50, 400, 500);
            addWindowListener(new WindowAdapter() {
                @Override
                public void windowClosing(WindowEvent e) {
                    if(printWriter!=null) {
                        printWriter.write("나갈게요\n");
                        printWriter.write("bye\n");
                        printWriter.flush();
 
                        if(socket!=null)try {socket.close();} catch (IOException e1) {e1.printStackTrace();}
                        if(printWriter!=null)try {printWriter.close();} catch (Exception e1) {e1.printStackTrace();}
                        if(scanner!=null)try {scanner.close();} catch (Exception e1) {e1.printStackTrace();}
 
                        System.exit(0);
                    }
                }
            });
            
            //Center
            textArea=new JTextArea();
            textArea.setBackground(Color.orange);
            textArea.setEditable(false);//편집 불가능
            
            //bottom
            panel=new JPanel(new BorderLayout());
            button=new JButton("입력");
            textField=new JTextField();
            
            //actionlistener
            button.addActionListener(this);
            textField.addActionListener(this);
            
            //subRegister
            panel.add(textField,BorderLayout.CENTER);
            panel.add(button,BorderLayout.EAST);
            
            //size
            panel.setPreferredSize(new Dimension(400, 40));
            
            //Register
            add(textArea,BorderLayout.CENTER);
            add(panel,BorderLayout.SOUTH);
            
            setVisible(true);
        }
        public static void main(String[] args) {
            Client3 client = new Client3();
            try {
                client.socket=new Socket("192.168.0.12", 10004);
                client.message= "192.168.0.12 서버의 10004 번 포트로 서버 접속\n";
                client.message+="서버로 접속 성공\n";
                client.textArea.setText(client.message);
                
                client.textField.setEnabled(true);
                client.button.setEnabled(true);
                client.textField.requestFocus();
                
                client.printWriter =new PrintWriter(client.socket.getOutputStream());
                client.scanner= new Scanner(client.socket.getInputStream());
                
                new Thread(client).start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        @Override
        public void actionPerformed(ActionEvent e) {
            String msg=textField.getText().trim();
            if(msg.length()>0) {
                message=  message + "Client >> " + msg+ "\n";
                textArea.setText(message);
                
                if(printWriter!=null) {
                    printWriter.write(msg+"\n");
                    printWriter.flush();
                }
            }
            textField.setText("");
            textField.requestFocus();
        }
 
        @Override
        public void run() {
            while(socket!=null) {
                String msg="";
                try {
                    msg=scanner.nextLine().trim();
                } catch (Exception e) {
                    break;
                }
                if(msg.length()>0) {
                    message= message+ "Server >> " +msg +"\n";
                    textArea.setText(message);
                    if(msg.toLowerCase().equals("bye")) 
                        break;
                    try {Thread.sleep(100);} catch (InterruptedException e) {e.printStackTrace();}
                }
            }
            textField.setEnabled(false);
            button.setEnabled(false);
            if(socket!=null)try {socket.close();} catch (IOException e) {e.printStackTrace();}
            if(printWriter!=null)try {printWriter.close();} catch (Exception e) {e.printStackTrace();}
            if(scanner!=null)try {scanner.close();} catch (Exception e) {e.printStackTrace();}
        
        }
}
 
 cs
더보기

-Description

85 : client.socket=new Socket("192.168.0.12", 10004) 인자로 IP주소, 포트번호를 전달

 

 

-요약-

네트워크 통신을 위하여

Socket ,  PrintWriter(전달하는 입장) , Scanner (받는입장) 객체변수 생성, 

함수로는 socket.getOutputStream() , socket.getInputStream() 을 사용하여

PrintWriter 객체생성, Scanner 객체 생성이 필요함을 배웠다.

네트워크 통신종료후에는 해당 객체들의 close() 명령이 필요하다.

-마침글-

네트워크 통신을 이용한 채팅프로그램을 제작해 보았다.

'21년이전 > 국비-JAVA+SQL' 카테고리의 다른 글

Memo 기능구현  (0) 2021.02.23
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-개발환경-

IDE : Eclipse IDE for Java Developers Version: 2020-03 (4.15.0)
DB GUI : SQLyog Community - MySQL GUI v12.2.1 ( 64 bit )
MySQL : MySQL Server 5.5

추가 자료 : mysql-connector-java-5.1.27-bin.jar 드라이버 파일


-설정-

Eclipse -> Package Explorer -> 생성한 패키지의 오른쪽 마우스 클릭 -> Build Path

-> Configure Build Path.. ->Library 탭 click -> Add JARs.. ->  mysql-connector-java-5.1.27-bin.jar 선택

 

-구성-

Memo package composition

 

-DbUtil-

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package DbTest;
 
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 DbUtil {
    //mysql에 연결하는 connection을 리턴하는 메소드
    public static Connection getMySQLConnection() {
        Connection conn=null;//db와 연결함
        try {
            Class.forName("com.mysql.jdbc.Driver");
//            String url= "jdbc:mysql://localhost:3306/javaam";
            //위와 같이 url을 작성하면 한글이 "?"로 입력되는 문제가 발생된다.
            //유니코드(UTF-8)를 사용할 경우 아래와 같이 url에 유니코드를 사용하도록 코딩을 추가하면 한글이 정상적으로 입력된다.
            String url= "jdbc:mysql://localhost:3306/javaam?useUnicode=true&characterEncoding=UTF-8";
            conn= DriverManager.getConnection(url,"root","0000");
        } catch (ClassNotFoundException e) {
            System.out.println("드라이버 클래스가 없거나 읽어올수 없습니다.");
        } catch (SQLException e) {
            System.out.println("데이터베이스 접속 정보가 올바르지 않습니다.");
        }
        return conn;
    }
    
    //데이터베이스 작업에 사용한 객체를 닫는 메소드
    public static void close(Connection conn) {
        if(conn!=null) {
            try {conn.close();} catch (SQLException e) {e.printStackTrace();}
        }
    }
    public static void close(Statement conn) {
        if(conn!=null) {
            try {conn.close();} catch (SQLException e) {e.printStackTrace();}
        }
    }
    public static void close(PreparedStatement conn) {
        if(conn!=null) {
            try {conn.close();} catch (SQLException e) {e.printStackTrace();}
        }
    }
    public static void close(ResultSet conn) {
        if(conn!=null) {
            try {conn.close();} catch (SQLException e) {e.printStackTrace();}
        }
    }
}
 
 cs

-java와 sql 연동하는 DbUtil class

더보기

-Desciption-

15 : Class.forName("com.mysql.jdbc.Driver");    동적로딩 수행

동적로딩 : 어떠한 클래스가 로딩 될지 모르기 때문에 Class.forName()함수를 이용해서 해당 클래스를 메모리로 로딩함

 

-MemoProject-

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package DbTest;
 
import java.util.ArrayList;
import java.util.Scanner;
 
public class MemoProject {
 
    public static void main(String[] args) {
        int choosed=0;
        while (choosed!=5) {
            System.out.println("==================================================");
            System.out.println("1.입력 2.목록보기 3.수정 4.삭제 5.종료");
            System.out.println("==================================================");
            do {
                Scanner scanner =new Scanner(System.in);
                choosed=Integer.valueOf(scanner.nextLine());
            }while( !(1<=choosed && choosed<8));
            
            switch(choosed) {
            case 1: Insert(); break;
            case 2: select();break;
            case 3: update();break;
            case 4: delete();break;
            }
            
        }
        System.out.println("프로그램을 종료합니다");
    }
 
    private static void update() {
        System.out.println("수정할 글 번호를 입력하세요 : ");
        int idx=new Scanner(System.in).nextInt();
        
        if(MemoDAO.update(idx)) {
            System.out.println(idx+"번 글 수정완료!");
        }else {
            System.out.println(idx+ "해당 글이 존재하지 않거나 비밀번호가 올바르지 않습니다.");
        } 
}
 
 
    private static void delete() {
        System.out.println("삭제할 글 번호를 입력하세요 : ");
        int idx=new Scanner(System.in).nextInt();
        
        if(MemoDAO.delete(idx)) {
            System.out.println(idx+"번 글 삭제완료!");
        }else {
            System.out.println(idx+ "해당 글이 존재하지 않거나 비밀번호가 올바르지 않습니다.");
        }
        
    }
 
 
    private static void select() {
        ArrayList<MemoVO> list=MemoDAO.select();
        
        //반드시 null을 먼저 비교해야함. 이유 : null이면 , list.size()는 에러남.
        if(list==null || list.size()==0) {
            System.out.println("빈 ArrayList입니다.");
        }else {
            for(MemoVO vo: list) {
                System.out.println(vo);
            }
        }
    }
 
    private static void Insert() {
        Scanner scanner= new Scanner(System.in);
        System.out.println("이름 : ");
        String name= scanner.nextLine();
        System.out.println("비번 : ");
        String password= scanner.nextLine();
        System.out.println("메모 : ");
        String memo= scanner.nextLine();
        
        MemoVO vo=new MemoVO();
        vo.setName(name);
        vo.setPassword(password);
        vo.setMemo(memo);
        
        if(MemoDAO.insert(vo))
            System.out.println("저장완료!");
        else {
            System.out.println("저장실패!");
        }
        System.out.println("저장완료!!!");
    }
}
 
 cs

-UI를 구현한 MemoProject class-

더보기

-Desciption-

30 : update() 메소드는 사용자로 부터 받은 idx에 따른 MemoDAO.update(idx)을 수행

42 : delete() 메소드는 사용자로 부터 받은 idx 에 따른 MemoDAO.delete(idx) 을 수행

56 : select() 메소드는 MemoDAO.select()를 호출하여 결과를 ArrayList<MemoVO> 객체에 저장후, 내용출력

68 : Insert() 메소드는 사용자로부터 name,password,memo 를 입력받고 , MemoVO객체로 가공후,

MemoDAO.insert(vo)를 수행.

-MemoVO-

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package DbTest;
 
import java.util.Date;
 
//VO(Value Object): 게시글 한 건을 기억할 클래스
// 게시글 한 건을 기억할 클래스
public class MemoVO {
    private int idx;
    private String name;
    private String password;
    private String memo;
    private Date writeDate;
    
 
    public int getIdx() {
        return idx;
    }
 
    public void setIdx(int idx) {
        this.idx = idx;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getPassword() {
        return password;
    }
 
    public void setPassword(String password) {
        this.password = password;
    }
 
    public String getMemo() {
        return memo;
    }
 
    public void setMemo(String memo) {
        this.memo = memo;
    }
 
    public Date getWriteDate() {
        return writeDate;
    }
 
    public void setWriteDate(Date writeDate) {
        this.writeDate = writeDate;
    }
 
    @Override
    public String toString() {
        return "MemoVO [idx=" + idx + ", name=" + name + ", password=" + password + ", memo=" + memo + ", writeDate="
                + writeDate + "]";
    }
}
 
 cs

-데이터만을 처리하는 MemoVO class-

더보기

-Description-

8~10 : idx, name,password,memo, writeDate  인스턴스 변수들 선언
기타 : data input out 을 위한 set,get 함수 구현

-MemoDAO-

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package DbTest;
 
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Scanner;
 
import com.koreait.interfaceTest.interfaceTest;
 
//DAO(Data Access Object) : db에 접속해서  sql 명령을 실행하는 메소들만 모아 놓은 클래스 
public class MemoDAO {
    public static boolean insert(MemoVO vo) {
        boolean result = true;
 
        Connection conn= null;
        PreparedStatement pstmt=null;
        
        try {
            conn= DbUtil.getMySQLConnection();
            //SQL
            String sql= "insert into memo (name,password,memo) values (?,?,?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, vo.getName());
            pstmt.setString(2, vo.getPassword());
            pstmt.setString(3, vo.getMemo());
            pstmt.executeUpdate();
        } catch (SQLException e) {
            System.out.println("옳바른 sql 명령이 실행되지 않았다.");
            result=false;
        } finally {
        DbUtil.close(conn);
        DbUtil.close(pstmt);
        }
        return result;
    }
    
    public static ArrayList<MemoVO> select(){
        Connection conn=null;
        PreparedStatement pstmt=null;
        ResultSet rs = null;
        ArrayList<MemoVO> list= null;
        
        try {
            conn = DbUtil.getMySQLConnection();
            String sql="SELECT * FROM memo ORDER BY idx DESC";
            pstmt = conn.prepareStatement(sql);
            rs = pstmt.executeQuery();
            list=new ArrayList<MemoVO>();
            
            while(rs.next()) {    //ResultSet객체에 저장된 데이터가 있는 동안 반복한다.
                MemoVO vo = new MemoVO();
                vo.setIdx(rs.getInt("idx"));
                vo.setName(rs.getString("name"));
                vo.setPassword(rs.getString("password"));
                vo.setMemo(rs.getString("memo"));
                vo.setWriteDate(rs.getTimestamp("writeDate"));//getTimestamp 는 날짜,시간 다꺼내옴 , getTime은 시간만 꺼내옴, getDate는 날짜만 꺼내옴
                list.add(vo);
            }
            
        } catch (SQLException e) {
            System.out.println("옳바른 sql 명령이 실행되지 않았다.");
        } finally {
            DbUtil.close(conn);
            DbUtil.close(pstmt);
            DbUtil.close(rs);
        }
        
        return list;
    }
    
    public static boolean delete(int idx) {
        boolean result= true;
        Connection conn = null;
        PreparedStatement pstmt=null;
        ResultSet rs=null;
        
        try {
            conn= DbUtil.getMySQLConnection();
            String sql="Select * From memo where idx=?";
            pstmt=conn.prepareStatement(sql);
            pstmt.setInt(1, idx);
            rs=pstmt.executeQuery();
            
            if(rs.next()) {
                MemoVO vo = new MemoVO();
                vo.setIdx(rs.getInt("idx"));
                vo.setName(rs.getString("name"));
                vo.setPassword(rs.getString("password"));
                vo.setMemo(rs.getString("memo"));
                vo.setWriteDate(rs.getTimestamp("writeDate"));
                System.out.println("삭제할 글 확인하기");
                System.out.println(vo);
                
                System.out.println("해당 게시글 비밀번호를 입력하세요.");
                String password=new Scanner(System.in).nextLine().trim();
                
                //삭제할 글의 비밀번호와 삭제하기 위해 입력한 비밀번호를 비교
                if(vo.getPassword().equals(password))  {
                    sql="delete from memo where idx=?";//delete 와 from 사이에 * 넣으면 인식못함
                    pstmt=conn.prepareStatement(sql);
                    pstmt.setInt(1, idx);
                    pstmt.executeUpdate();
                }
                else {
                    return false;
                }
            }else {
                System.out.println("삭제할 글이 테이블에 존재하지 않습니다");
                DbUtil.close(conn);
                DbUtil.close(pstmt);
                DbUtil.close(rs);
                return false;
            }
        } catch (SQLException e) {
            System.out.println("옳바른 sql 명령이 실행되지 않았다.");
        } finally {
            DbUtil.close(conn);
            DbUtil.close(pstmt);
            DbUtil.close(rs);
        }
        return true;
    }
 
    public static boolean update(int idx) {
        Connection conn = null;
        PreparedStatement pstmt=null;
        ResultSet rs=null;
        
        try {
            conn= DbUtil.getMySQLConnection();
            String sql="Select * From memo where idx=?";
            pstmt=conn.prepareStatement(sql);
            pstmt.setInt(1, idx);
            rs=pstmt.executeQuery();
            
            if(rs.next()) {
                MemoVO vo = new MemoVO();
                vo.setIdx(rs.getInt("idx"));
                vo.setName(rs.getString("name"));
                vo.setPassword(rs.getString("password"));
                vo.setMemo(rs.getString("memo"));
                vo.setWriteDate(rs.getTimestamp("writeDate"));
                System.out.println("수정할 글 확인하기");
                System.out.println(vo);
                
                System.out.println("해당 게시글 비밀번호를 입력하세요.");
                String password=new Scanner(System.in).nextLine().trim();
                
                if(vo.getPassword().equals(password))  {
                    System.out.print("수정할 메모를 입력해주세요 : ");
                    String memo=new Scanner(System.in).nextLine().trim();
                    sql="update memo set memo=? where idx=?"; 
                    pstmt=conn.prepareStatement(sql);
                    pstmt.setString(1, memo);
                    pstmt.setInt(2, vo.getIdx());
                    pstmt.executeUpdate();
                }
                else {
                    return false;
                }
            }else {
                System.out.println("수정할 글이 테이블에 존재하지 않습니다");
                DbUtil.close(conn);
                DbUtil.close(pstmt);
                DbUtil.close(rs);
                return false;
            }
        } catch (SQLException e) {
            System.out.println("옳바른 sql 명령이 실행되지 않았다.");
        } finally {
            DbUtil.close(conn);
            DbUtil.close(pstmt);
            DbUtil.close(rs);
        }
        return true;
    }
}
 
 cs

- sql명령어를 처리하는 MemoDAO class-

-Description-

 14~37 : insert메소드
       21 : conn= DbUtil.getMySQLConnection() 을 통해 db 연결
 23~27  : sql명령어를 작성후 , setString을 이용해서 ? 채우기 
       28 : pstmt.executeUpdate() 을 통해 sql 명령 수행. 
  33~34 : Connection , PreparedStatement 등, sql 관련 객체변수를 닫아줌

  39~71 : select메소드
   42,49 : ResultSet 객체 변수를 선언 . 해당객체변수는 pstmt.executeQuery() 결과를 받음
( pstmt.executeUpdate()는 sql-table에 변동이 생길때 사용,
 pstmt.executeQuery()는 단순 table 변동없이 값을 읽어들일때 사용)

 73~124 : delete메소드

126~179 : update메소드

 

-요약-

JAVA와 SQL의 연동을 위해서,  자바 코드내 드라이버관련 코드를 작성할 필요가 있음

JAVA코드내 SQL명령어로는 PreparedStatement pstmt=conn.prepareStatement(sql)와 같은예비준비단계를 거치게됨

SQL관련 자바 객체를 생성했으면 , 닫아줘야함(의무는 아님)

 

-마침글-

Back 단에서 java를 이용해 미니게시판느낌의 메모를 구현해 보았다.

 

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