非堵塞socket实现android手机与PC的文件传输

      项目须要是通过WIFI建立手机和PC的通信，然后自己定义一个简单的协议对要传输的文件进行校验，传输的文件是2张3M的图片，要求考虑网络中断情况处理。

      我这里採用的是非堵塞socket来实现的，之前查过非常多资料，认为这样的比較方便，其有用传统的那种socket也是能够实现的，至于堵塞问题，能够开两个线程。这样保证读取不是同一个线程，也就能够解决。

      程序大致是这种流程，手机端发送一个“filename”字符串给PC，PC校验字符串后返回文件名称。然后手机端再把接收到的文件名称发送给PC端。进行校验，假设PC端校验成功，那么PC端就開始传输这个文件给手机端。手机端就接收这个文件。

至于网络中断的问题，后来发现，仅仅要在服务端发送文件的那一段程序加入try-catch，捕获这个异常，这样服务端的程序就不会死掉，进入等待。等到手机再次和PC端建立连接。那么就能够又一次发送文件。这里是重传，而不是续传，后来想过。也仅仅有6M，实际測试过。大概2-3秒就能够传完。重传和续传意义不大，所以就简单的重传了。

      程序例如以下：

PC端：

public class MyServer {
	private final static Logger logger = Logger.getLogger(MyServer.class.getName());
	
	public static void main(String[] args) {
		Selector selector = null;
		ServerSocketChannel serverSocketChannel = null;
		
		try {
			selector = Selector.open();
			serverSocketChannel = ServerSocketChannel.open();
			serverSocketChannel.configureBlocking(false);
			serverSocketChannel.socket().setReuseAddress(true);
			serverSocketChannel.socket().bind(new InetSocketAddress(1991));
			serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
			while (selector.select() > 0) {
				Iterator<SelectionKey> it = selector.selectedKeys().iterator();
				while (it.hasNext()) {
					SelectionKey readyKey = it.next();
					it.remove();

					SocketChannel socketChannel = null;
					String string = "";
					try {
						socketChannel = ((ServerSocketChannel) readyKey.channel()).accept();
						string = receiveData(socketChannel);
						logger.log(Level.INFO, string);
						if(string.equals("filename")){
							File f= new File("D:/chz.jpg");  
						    if (f.exists() && f.isFile()){  
						        sendData(socketChannel, "chz.jpg");
						    }else{  
						        logger.info("file doesn't exist or is not a file");  
						    }  
						}
						if(string.equals("chz.jpg")){
							sendFile(socketChannel, new File("D:/chz.jpg"));
						}
					}catch(Exception ex){
						logger.log(Level.SEVERE, "1", ex);
					} finally {
						try {
							socketChannel.close();
						} catch(Exception ex) {
							logger.log(Level.SEVERE, "2", ex);
						}
					}
				}
			}
		} catch (ClosedChannelException ex) {
			logger.log(Level.SEVERE, "3", ex);
		} catch (IOException ex) {
			logger.log(Level.SEVERE, "4", ex);
		} finally {
			try {
				selector.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "5", ex);
			}
			try {
				serverSocketChannel.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "6", ex);
			}
		}
	}

	private static String receiveData(SocketChannel socketChannel) throws IOException {
		String string = null;
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		ByteBuffer buffer = ByteBuffer.allocate(1024);
		
		try {
			byte[] bytes;
			int size = 0;
			while ((size = socketChannel.read(buffer)) >= 0) {
				buffer.flip();
				bytes = new byte[size];
				buffer.get(bytes);
				baos.write(bytes);
				buffer.clear();
			}
			bytes = baos.toByteArray();
			string = new String(bytes);
		}catch(Exception ex){
			logger.log(Level.SEVERE, "7", ex);
		}finally {
			try {
				baos.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "8", ex);
			}
		}
		return string;
	}

	private static void sendData(SocketChannel socketChannel, String string) throws IOException {
		byte[] bytes = string.getBytes();
		ByteBuffer buffer = ByteBuffer.wrap(bytes);
		socketChannel.write(buffer);
		socketChannel.socket().shutdownOutput();
	}
	
	private static void receiveFile(SocketChannel socketChannel, File file) throws IOException {
		FileOutputStream fos = null;
		FileChannel channel = null;
		
		try {
			fos = new FileOutputStream(file);
			channel = fos.getChannel();
			ByteBuffer buffer = ByteBuffer.allocateDirect(1024);

			int size = 0;
			while ((size = socketChannel.read(buffer)) != -1) {
				buffer.flip();
				if (size > 0) {
					buffer.limit(size);
					channel.write(buffer);
					buffer.clear();
				}
			}
		}catch(Exception ex){
			logger.log(Level.SEVERE, "9", ex);
		} finally {
			try {
				channel.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "10", ex);
			}
			try {
				fos.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "11", ex);
			}
		}
	}

	private static void sendFile(SocketChannel socketChannel, File file) throws IOException {
		FileInputStream fis = null;
		FileChannel channel = null;
		try {
			fis = new FileInputStream(file);
			channel = fis.getChannel();
			ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
			int size = 0;
			while ((size = channel.read(buffer)) != -1) {
				buffer.rewind();
				buffer.limit(size);
				socketChannel.write(buffer);
				buffer.clear();
			}
			socketChannel.socket().shutdownOutput();
		}catch(Exception ex){
			logger.log(Level.SEVERE, "12", ex);
		} finally {
			try {
				channel.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "13", ex);
			}
			try {
				fis.close();
			} catch(Exception ex) {
				logger.log(Level.SEVERE, "14", ex);
			}
		}
	}
}

ANDROID端：

public class MainActivity extends Activity {

	private Button mButton;
	private EditText et;
	private static String string;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
     
        et = (EditText)findViewById(R.id.edittext1);
        et.setText("192.168.1.214");
		mButton = (Button)findViewById(R.id.button1);
		mButton.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				string = et.getText().toString();
				new Thread(new Runnable() {
					
					@Override
					public void run() {
						// TODO Auto-generated method stub
						SocketChannel socketChannel = null;
						try {
							socketChannel = SocketChannel.open();
							SocketAddress socketAddress = new InetSocketAddress(string, 1991);
							socketChannel.connect(socketAddress);
							
							sendData(socketChannel, "filename");
							String string = "";
							string = receiveData(socketChannel);
							if(!string.isEmpty()){
								socketChannel = SocketChannel.open();
								socketChannel.connect(new InetSocketAddress("192.168.1.214", 1991));
								sendData(socketChannel, string);
								receiveFile(socketChannel, new File("sdcard/afile/"+string));
							}
						} catch (Exception ex) {
							Log.i("chz", null, ex);
						} finally {
							try {
								socketChannel.close();
							} catch(Exception ex) {}
						}
					}
				}).start();
			}
		});
	
   }

		private void sendData(SocketChannel socketChannel, String string) throws IOException {
			byte[] bytes = string.getBytes();
			ByteBuffer buffer = ByteBuffer.wrap(bytes);
			socketChannel.write(buffer);
			socketChannel.socket().shutdownOutput();
		}

		private String receiveData(SocketChannel socketChannel) throws IOException {
			String string = null;
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			
			try {
				ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
				byte[] bytes;
				int count = 0;
				while ((count = socketChannel.read(buffer)) >= 0) {
					buffer.flip();
					bytes = new byte[count];
					buffer.get(bytes);
					baos.write(bytes);
					buffer.clear();
				}
				bytes = baos.toByteArray();
				string = new String(bytes);
//				socketChannel.socket().shutdownInput();
			} finally {
				try {
					baos.close();
				} catch(Exception ex) {}
			}
			return string;
		}
		
		private static void sendFile(SocketChannel socketChannel, File file) throws IOException {
			FileInputStream fis = null;
			FileChannel channel = null;
			try {
				fis = new FileInputStream(file);
				channel = fis.getChannel();
				ByteBuffer buffer = ByteBuffer.allocateDirect(1024);
				int size = 0;
				while ((size = channel.read(buffer)) != -1) {
					buffer.rewind();
					buffer.limit(size);
					socketChannel.write(buffer);
					buffer.clear();
				}
				socketChannel.socket().shutdownOutput();
			} finally {
				try {
					channel.close();
				} catch(Exception ex) {}
				try {
					fis.close();
				} catch(Exception ex) {}
			}
		}

		private static void receiveFile(SocketChannel socketChannel, File file) throws IOException {
			FileOutputStream fos = null;
			FileChannel channel = null;
			
			try {
				fos = new FileOutputStream(file);
				channel = fos.getChannel();
				ByteBuffer buffer = ByteBuffer.allocateDirect(1024);

				int size = 0;
				while ((size = socketChannel.read(buffer)) != -1) {
					buffer.flip();
					if (size > 0) {
						buffer.limit(size);
						channel.write(buffer);
						buffer.clear();
					}
				}
			} finally {
				try {
					channel.close();
				} catch(Exception ex) {}
				try {
					fos.close();
				} catch(Exception ex) {}
			}
		}


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

      番外：事实上做这个文件传输遇到的最头痛的问题不是程序难不难写。而是wifi通信的建立。最初我是用自己win7的电脑连路由器。然后手机也连路由器做的測试，没有问题。但是后来项目需求是下位机是一台XP的电脑。并且要求点对点建立wifi，所以仅仅能有一端设成wifi热点。还有一端连接这个热点。设想非常完美，然后找了实验室唯一一台XP电脑測试了两天，都没有可以让我手机连上PC。后来各种问，才知道XP不支持为android创wifi热点，真心坑呀。然后我就想反过来做呗，手机建wifi热点，电脑连。耶果然连上了，但是。明明写好的程序，各种执行不了，最后手机巨热，（我心痛死我的小米。求不黑小米。真心一直用小米，仅仅是导师不给配开发手机，仅仅能用自己手机，哎）所以直接pass这个想法，最后百度了一下。貌似可以接外接硬件设备，例如说360随身wifi硬件，嗯导师最终答应淘宝买一个来測试下，今天买吧。

       哦，整个程序參考了两位大神博客：http://www.cnblogs.com/hongten/archive/2012/04/29/java_socket.html

 http://blog.csdn.net/kongxx/article/details/7288896尤其是后面这位大神的一个专栏专门讲java socket的。讲得非常好。

      这个文件传输的整个project地址：http://download.csdn.net/detail/u012321815/8047863