gistfile1.java

package socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ConnectException;
import java.net.Socket;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class AliveMonitor {

	private static final int PORT = 5550;
	private static final String HOST = "localhost";

	public AliveMonitor(){

		Process process = null;
		while(true){
			boolean isAlive = true;
			InputStream is = null;
			BufferedReader br = null;
			Socket socket = null;
			try {
				socket = new Socket(HOST, PORT);
				System.out.println("connect.");

				is = socket.getInputStream();
				br = new BufferedReader(new InputStreamReader(is));

				System.out.println("-");

				String line = null;
				while((line = br.readLine()) != null){
					System.out.println(".");
					System.out.println(line);
					if(!line.equals("ok"))
						isAlive = false;
				}

				System.out.println("*");

			} catch (ConnectException e) {
				e.printStackTrace();
				isAlive = false;
			} catch (UnknownHostException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} finally {
				try {
					if(is != null)
						is.close();
					if(br != null)
						br.close();
					if(socket != null)
						socket.close();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}

			SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
			String date = sdf.format(new Date());
			if(!isAlive){
				System.out.println(date + ": app is NOT alive.");
				Runtime rt = Runtime.getRuntime();
				try {
					if(process != null){
						process.destroy();
						System.out.println("kill process.");
					}
					process = rt.exec("java -jar c:/Users/cs/Desktop/test.jar");
					System.out.println("process is restarted.");
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			else{
				System.out.println(date + ": app is alive.");
			}

			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}

		}
	}

	public static void main(String[] args) {
		try {
			new AliveMonitor();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

gistfile2.java

package socket;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class ServerSocketThread extends Thread {

	private static final int PORT = 5550;
	public int INTERVAL = 100;

	public ServerSocketThread(){
	}

	@Override
	public void run(){
		try{
			ServerSocket serverSocket = new ServerSocket(PORT);

			boolean flag = true;
			while(flag){
				System.out.println("waiting.");
				Socket socket = serverSocket.accept();
				System.out.println(socket.getInetAddress() + ": connected.");

				OutputStreamWriter osw = new OutputStreamWriter(socket.getOutputStream());
				// BufferedWriter bw = new BufferedWriter(osw);
				// bw.write("ok");
				// bw.flush();

				osw.write("ok");
				osw.flush();

				System.out.println(socket.getInetAddress() + ": disconnect.");

				if(osw != null)
					osw.close();
//				if(bw != null)
//					bw.close();
				if(socket != null)
					socket.close();

				Thread.sleep(100);

			}
			serverSocket.close();

		} catch (InterruptedException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		// このプログラムはjarにしておいて、AliveMonitorから起動する
		ServerSocketThread st = new ServerSocketThread();
		st.start();
	}

}