寫了個android上測試socket的例子：

server側：

class ServerThread extends Thread {

	/**
	 * TCP.
	 */
	@Override
	public void run() {
		ServerSocket serSocket = null;
		try {
			serSocket = new ServerSocket(4567);
			// wait until accept request from client !
			System.out.println("== before ServerSocket.accept(TCP) ==");
			Socket socket = serSocket.accept();
			InputStream is = socket.getInputStream();
			byte[] bytes = new byte[1024];
			int temp = 0;
			while ((temp = is.read(bytes)) != -1) {
				System.out.println(new String(bytes, 0, temp));
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				serSocket.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
			System.out.println("== after ServerSocket.accept(TCP) ==");
		}
	}
}
 

client側：

	@Test
	public void startClientSocket() {
		Socket socket = null;
		InputStream is = null;
		try {
			// get socket object
			socket = new Socket("192.168.1.102", 4567);
			// get outputStream
			OutputStream os = socket.getOutputStream();

			is = new FileInputStream("C:/test.txt");
			byte[] bytes = new byte[1024];
			int temp = 0;
			while ((temp = is.read(bytes)) != -1) {
				os.write(bytes, 0, temp);
			}
			os.flush();
			is.close();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
 

執行後發現logcat中有SocketException：

10-03 17:19:16.225: W/System.err(16398): java.net.SocketException: Connection reset by peer
10-03 17:19:16.264: W/System.err(16398): 	at org.apache.harmony.luni.platform.OSNetworkSystem.read(Native Method)
10-03 17:19:16.264: W/System.err(16398): 	at dalvik.system.BlockGuard$WrappedNetworkSystem.read(BlockGuard.java:273)
10-03 17:19:16.264: W/System.err(16398): 	at org.apache.harmony.luni.net.PlainSocketImpl.read(PlainSocketImpl.java:458)
10-03 17:19:16.264: W/System.err(16398): 	at org.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:85)
10-03 17:19:16.264: W/System.err(16398): 	at org.apache.harmony.luni.net.SocketInputStream.read(SocketInputStream.java:65)
10-03 17:19:16.272: W/System.err(16398): 	at com.example.androidstudy.socket.ServerThread.run(SocketActivity.java:54)
 

上網查了些資料，發現原因如下：
java.net.SocketException: （Connection reset或者Connect reset by peer:Socket write error）。

該異常在客戶端和伺服器端均有可能發生，引起該異常的原因有兩個，第一個就是如果一端的Socket被關閉（或主動關閉或者因為異常退出而引起的關閉），另一端仍傳送資料，傳送的第一個資料包引發該異常(Connect reset by peer)。另一個是一端退出，但退出時並未關閉該連線，另一端如果在從連線中讀資料則丟擲該異常（Connection reset）。簡單的說就是在連線斷開後的讀和寫操作引起的。請參照：http://developer.51cto.com/art/201003/189724.htm

client側的socket使用後沒有關閉，所以在client側的測試程式碼後面追加了finally，異常就不再發生了。

...... 
		finally {
			try {
				socket.close();
			} catch (IOException e) {
				e.printStackTrace();
			}

		}