Java::활용 -Network

 

package p11_network;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;

//1. 입력후 글자 지워짐
//2. 외부메세지를 textArea 에 보이게하기
//3. 스롤내려가게 만들기
//4. 메세지 공백 안보내지게

public class Ex01TcpIpMultiChatClient extends JFrame {

  public static void main(String[] args) {
    new Ex01TcpIpMultiChatClient();
  }

  private JTextArea ta;
  private JScrollPane scp;
  private JTextField tf;
  private String nickname;
  private DataOutputStream out;

  public Ex01TcpIpMultiChatClient() throws HeadlessException {
    init();
    arrange();
    inflate();
  }

  private void init() {
    nickname = JOptionPane.showInputDialog("Input Nickname");
    //10.100.204.26
    String ip = JOptionPane.showInputDialog("Server IP", "10.100.204.26");

    ta = new JTextArea();
    ta.setEditable(false); //텍스트 수정 가능 여부
    scp = new JScrollPane(ta);
    tf = new JTextField();
    //폰트 관련
    ta.setFont(new Font("맑은 고딕", Font.PLAIN, 20));
    tf.setFont(new Font("맑은 고딕", Font.PLAIN, 20));

    //소켓 생성 , 입출력은 try catch 문이 따라옴
    try {
      Socket socket = new Socket(ip,7777);
      out = new DataOutputStream(socket.getOutputStream());
      out.writeUTF(nickname);
      new Thread(new Reciver(socket)).start(); //implements Runnable
//      new Reciver().start(); //extends Thread

    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    //메세지 보내기 기능
    tf.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        try {
          String sendMSG = tf.getText();
          if(!sendMSG.equals("")){
            System.out.println("입력됨!"+tf.getText());
            out.writeUTF(nickname+":"+tf.getText());
            tf.setText("");
            scp.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

            JScrollBar verticalBar = scp.getVerticalScrollBar();
            verticalBar.setValue(verticalBar.getMaximum());
          }
        } catch (IOException ex) {
          throw new RuntimeException(ex);
        }
      }
    });
  }
  private void arrange() {
    add(scp, "Center");
    add(tf, "South");
  }

  private void inflate() {
    setTitle("Chatting Room");
    setSize(450, 640);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(this);
    setVisible(true);
  }
  class Reciver implements Runnable{
//  class Reciver extends Thread{
    DataInputStream in;

    public Reciver(Socket socket) {
      try {
        in = new DataInputStream(socket.getInputStream());
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    }
    @Override
    public void run() {
      while (in != null){
        try {
          String msg = in.readUTF();
          //과제(수정) 프로그램안에서 띄우기
          ta.append(msg+"\n");
          ta.setCaretPosition(ta.getDocument().getLength());
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
    }
  }
}

 

package p11_network;

import java.net.*;
import java.io.*;
import java.util.*;

public class Ex02TcpIpMultichatServer {
  public static void main(String args[]) {
    new Ex02TcpIpMultichatServer().start();
  }

  HashMap clients;

  //동기화
  Ex02TcpIpMultichatServer() {
    clients = new HashMap();
    Collections.synchronizedMap(clients);
  }

  //서버는 서버 소켓이 있어야함, 클라이언트는 소켓만 있어도 가능
  public void start() {
    ServerSocket serverSocket = null;
    Socket socket = null;

    try {
      serverSocket = new ServerSocket(7777);
      System.out.println("Server started...");
      //서버는 무한적으로 돌아가야한다
      while (true) {
        socket = serverSocket.accept();
        System.out.println("Connected from [" + socket.getInetAddress() + ":" + socket.getPort() + "]");
        ServerReceiver thread = new ServerReceiver(socket);
        thread.start();
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  } // start()

  void sendToAll(String msg) {
    Iterator it = clients.keySet().iterator();

    while (it.hasNext()) {
      try {
        DataOutputStream out = (DataOutputStream) clients.get(it.next());
        out.writeUTF(msg);
      } catch (IOException e) {
      }
    } // while
  } // sendToAll


  class ServerReceiver extends Thread {
    Socket socket;
    DataInputStream in;
    DataOutputStream out;

    ServerReceiver(Socket socket) {
      this.socket = socket;
      try {
        in = new DataInputStream(socket.getInputStream());
        out = new DataOutputStream(socket.getOutputStream());
      } catch (IOException e) {
      }
    }

    public void run() {
      String name = "";
      try {
        name = in.readUTF();
        sendToAll("#" + name + " 님이 입장하셨습니다.");

        clients.put(name, out);
        System.out.println("현재 접속자 수: " + clients.size());
        while (in != null) {
          sendToAll(in.readUTF());
        }
      } catch (IOException e) {
        // ignore
      } finally {
        sendToAll("#" + name + " is disconnected");
        clients.remove(name);
        System.out.println("Terminated from [" + socket.getInetAddress() + ":" + socket.getPort() + "]");
        System.out.println("현재 접속자 수: " + clients.size());
      } // try
    } // run
  } // ReceiverThread
} // class

---

package p07_Collection;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.function.IntFunction;

public class Ex10Generics {
  public static void main(String[] args) {
    // Generics 사용목적
    //1) 형변환 코드를 생략하여 간결해짐.
    //2) 타입의 안정성을 도모.
//    ArrayList list = new ArrayList();  // 제네릭스 미사용
    ArrayList<Card> list = new ArrayList(); //제네릭스 사용
    list.add(new Card(7, "Spade", "rect"));
    list.add(new Card(2, "Spade", 2));
    list.add(new Card(3, "Spade", true));
    list.add(new Card(4, "Spade", new Object()));
    list.add(new Card(5, "Spade", "A"));
//    Card card = (Card) list.get(0); // 제네릭스 미사용
    Card card = list.get(0); // 제네릭스 사용

    // 배열을 List 타입으로 변경하는 3가지 방법
//    Card[] cards = list.toArray(new Card[list.size()]); //Java 8 이전
//    Card[] cards = list.stream().toArray(Card[]::new); //Java 8 이후
//    Card[] cards = list.toArray(Card[]::new); //Java 11 이후
    Card[] cards = list.toArray(new IntFunction<Card[]>() { //Java 11 이후
      @Override
      public Card[] apply(int value) {
        System.out.println(">>" + value); //0인 이유:
        //배열의 길이가 0인 이유는 배열을 참조하기 위함.(null로 초기화하기도 함.)
        return new Card[value];
      }
    });
    Deck<Card> deck = new Deck<>();
    deck.set(cards);
    deck.print();
  }
}
/*
class Card {
  private int num; private String type;
  public Card(int num, String type) {this.num = num;this.type=type;}
  public String toString(){return num + "/" + type;}
}
*/
class Card<K, V, G> {
  private K num;
  private V type;
  private G fig;

  public Card(K num, V type, G fig) {
    this.num = num;
    this.type = type;
    this.fig = fig;
  }

  public void setKVG(K num, V type, G fig) {
    this.num = num;
    this.type = type;
    this.fig = fig;
  }

  public String toString() {
    return num + "/" + type;
  }
}

class Deck<T> {
  T[] deck;  // Card[] deck;

  void set(T[] deck) {
    this.deck = deck;
  }

  void print() {
    for (int i = 0; i < deck.length; i++) {
      if (i != 0) System.out.print(", ");
      System.out.print(deck[i]);
    }
    System.out.println();
  }
}

package p07_Collection;

public class Ex11GenericsSuperExtends {
  public static void main(String[] args) {
    Gen1 gen1 = new Gen1();
    Gen2 gen2 = new Gen2();
    Gen3 gen3 = new Gen3();
    //<? super type>,<? extends type> //상속관계를 이용하여 타입을 제약

    //Gen2의 조상이 Gen1, Gen1을 조상으로하는 하위 모든 자손 gen1, gen2, gen3
    GenType<? super Gen2> genType = new GenType<>(gen3);
    GenType<? extends Gen2> genType1 = new GenType<>(gen2);
    // Gen2를 상속받는 하위 모든 자손 gen2, gen3
    GenType<? extends Gen2> genType2 = new GenType<>(gen3);
    //
    GenType<?> genType3 = new GenType<>(new Object());

  }
}

class Gen1 {
  String name = "Gen1";

  public String toString() {
    return name;
  }
}

class Gen2 extends Gen1 {
  String name = "Gen2";

  public String toString() {
    return name;
  }
}

class Gen3 extends Gen2 {
  String name = "Gen3";

  public String toString() {
    return name;
  }
}

class GenType<T>{
  T obj;
  public GenType(T obj){this.obj = obj;}
  public void set(T obj){ this.obj = obj;}
  public T get(){ return obj;}
}

---

package p10_Stream;

import java.util.ArrayList;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;

public class Ex06FunctionPackage {
  //일반적으로 자주 쓰이는 메서드 형식 4가지를
  //@FunctionalInterface 형태로 만듬

  public static void main(String[] args) {
    //1.매개변수 없고 리턴타입이 있을 때
    Supplier<Integer> supplier = new Supplier<Integer>() {
      @Override
      public Integer get() {
        return (int) (Math.random() * 100) + 1;
      }
    };
    supplier = () -> {
      return (int) (Math.random() * 100) + 1;
    };
    supplier = () -> (int) (Math.random() * 100) + 1;
    //2.매개변수 있고 리턴타입이 없을 때
    Consumer<Integer> consumer = new Consumer<Integer>() {
      @Override
      public void accept(Integer integer) {
        System.out.println(integer + " ");
      }
    };
    consumer = integer -> System.out.println(integer + " ");
    //3. 매개변수도 있고 리턴타입도 있을 때
    Function<Integer, Integer> function = new Function<Integer, Integer>() {
      @Override
      public Integer apply(Integer integer) {
        return integer * 10;
      }
    };
    function = integer -> integer * 10;

    //4. 매개변수도 있고 리턴타입도 있는데 리턴 타입이 boolean일 때
    Predicate<Integer> predicate = new Predicate<Integer>() {
      @Override
      public boolean test(Integer integer) {
        return integer % 2 == 0;
      }
    };
    predicate = integer -> integer % 2 == 0;

    //응용
    List<Integer> list = new ArrayList<>();
    makeRandomList(supplier, list);
    System.out.println(list);
    printEven(predicate, consumer, list);
    List<Integer> newList = doSomething(function, list);
    System.out.println(newList);
  }

  private static <T> void makeRandomList(Supplier<T> supplier, List<T> list) {
    for (int i = 0; i < 10; i++) list.add(supplier.get());
  }

  private static <T> List<T> doSomething(Function<T, T> function, List<T> list) {
    List<T> tempList = new ArrayList<T>(list.size());
    for (T item : list) tempList.add(function.apply(item));
    return tempList;
  }

  private static <T> void printEven(Predicate<T> predicate, Consumer<T> consumer, List<T> list) {
    for (T i : list) if (predicate.test(i)) consumer.accept(i);
    System.out.println();
  }
}

---

새로운 테이블 생성하기 

alter session set "_ORACLE_SCRIPT" = true;
create user db7 IDENTIFIED by 1234 default tablespace USERS;

 

--권한 부여
grant connect, resource to db7;

테스트해서 성공하면 됨

 

 

create table memo(memo varchar2(20));

테이블 생성

오라클 버전 확인

select *from v$version;

oracle 21c jdbc driver download

 

https://www.oracle.com/kr/database/technologies/appdev/jdbc-downloads.html

JDBC and UCP Downloads page | Oracle 대한민국

 

ojdbc11.jar

5.01MB

 

ucp.jar

1.72MB

 

인텔리J에서 오라클 연동하기

연동 파일에 넣고 git push 해줌

 

연동시 경로가 안맞는 버그가 생길수 있어서 프로젝트안에 넣어줌

 

다운받은 .jar 를 추가해준다

---

 

package p12_database;

import java.sql.*;

public class DAOSet {
  private Connection conn;
  private PreparedStatement pstmt;
  private Statement stmt;
  private ResultSet rs;

  public Connection connectDB() throws SQLException {
    //String driver ="jdbc:mariadb://127.0.0.1:3306/db7"; //maria db
    String driver = "jdbc:oracle:thin:@localhost:1521:xe"; //oracle
    String user = "db7", pass = "1234";
    conn = DriverManager.getConnection(driver, user, pass);
    return conn;
  }
  public void closeDB() {
    try {
      if (rs != null) rs.close();
      if (stmt != null) stmt.close();
      if (pstmt != null) pstmt.close();
      if (conn != null) conn.close();
      System.out.println(conn.isClosed()?"접속종료":"접속중");
    } catch (SQLException e) {
      throw new RuntimeException(e);
    }
  }
}

package p12_database;

import java.sql.Connection;
import java.sql.SQLException;

public class DAOSetTest {
  public static void main(String[] args) {
    DAOSet daoSet = new DAOSet();
    try {
      Class.forName("oracle.jdbc.driver.OracleDriver");
      Connection conn = daoSet.connectDB();
      System.out.println(conn.isClosed()?"접속종료":"접속중");
    } catch (ClassNotFoundException e) {
      System.out.println("드라이버로딩 오류: "+e.getMessage());
    } catch (SQLException e) {
      System.out.println("접속 오류: "+e.getMessage());
    }
    finally {
      daoSet.closeDB();
    }
  }
}