非阻塞socket实现android手机与PC的文件传输

      项目需要是通过WIFI建立手机和PC的通信，然后自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。

      我这里采用的是非阻塞socket来实现的，之前查过很多资料，觉得这种比较方便，其实用传统的那种socket也是可以实现的，至于阻塞问题，可以开两个线程，这样保证读取不是同一个线程，也就可以解决。

      程序大致是这样的流程，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，然后手机端再把接收到的文件名发送给PC端，进行校验，如果PC端校验成功，那么PC端就开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，只要在服务端发送文件的那一段程序添加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，那么就可以重新发送文件，这里是重传，而不是续传，后来想过，也只有6M，实际测试过，大概2-3秒就可以传完，重传和续传意义不大，所以就简单的重传了。

      程序如下：

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：其实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测试，没有问题，但是后来项目需求是下位机是一台XP的电脑，而且要求点对点建立wifi，所以只能有一端设成wifi热点，另一端连接这个热点。设想很完美，然后找了实验室唯一一台XP电脑测试了两天，都没有能够让我手机连上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，可是，明明写好的程序，各种运行不了，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，只是导师不给配开发手机，只能用自己手机，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，比方说360随身wifi硬件，嗯导师终于答应淘宝买一个来测试下，今天买吧。

       哦，整个程序参考了两位大神博客：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，讲得很好。

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