java学习小笔记（三.socket通信）【转】

java学习小笔记（三.socket通信）【转】
三，socket通信
1.http://blog.csdn.net/kongxx/article/details/7288896这个人写的关于socket通信不错，循序渐进式的讲解，用代码示例说明，运用流和socket进行远程通讯

2.最简单的socket是一个服务端对应一个客户端
server的写法
1. ServerSocket server = new ServerSocket(10000);
2. Socket socket = server.accept();
3. BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
4. PrintWriter out = new PrintWriter(socket.getOutputStream());
6. while (true) {
7. String msg = in.readLine();
8. System.out.println(msg);
9. out.println("Server received " + msg);
10. out.flush();
11. if (msg.equals("bye")) {
12. break;
13. }
14. }
15. socket.close();
client的写法
1. Socket socket = new Socket("localhost", 10000);
2. BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
3. PrintWriter out = new PrintWriter(socket.getOutputStream());
4. BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
6. while (true) {
7. String msg = reader.readLine();
8. out.println(msg);
9. out.flush();
10. if (msg.equals("bye")) {
11. break;
12. }
13. System.out.println(in.readLine());
14. }
15. socket.close();
3.复杂一点的就是多个客户端同时访问服务器。在客户端使用循环启动多个客户端访问同一服务端，在服务端只要server.accept()一接收到就新建线程，然后把把上面的读写操作放进线程内处理。

4.如果要利用socke传递对象，就要让对象实现Serializable 序列化接口，使用ObjectInputStream和ObjectOutputStream进行序列化和反序列化
server的写法
1. ObjectInputStream is = null;
2. ObjectOutputStream os = null;
3. try {
4. is = new ObjectInputStream(new BufferedInputStream(socket.getInputStream()));
5. os = new ObjectOutputStream(socket.getOutputStream());
7. Object obj = is.readObject();
8. User user = (User)obj;
9. System.out.println("user: " + user.getName() + "/" + user.getPassword());
11. user.setName(user.getName() + "_new");
12. user.setPassword(user.getPassword() + "_new");
14. os.writeObject(user);
15. os.flush();
16. } catch (IOException ex) {
client的写法
1. ObjectOutputStream os = null;
2. ObjectInputStream is = null;
4. try {
5. socket = new Socket("localhost", 10000);
7. os = new ObjectOutputStream(socket.getOutputStream());
8. User user = new User("user_" + i, "password_" + i);
9. os.writeObject(user);
10. os.flush();
12. is = new ObjectInputStream(new BufferedInputStream(socket.getInputStream()));
13. Object obj = is.readObject();
14. if (obj != null) {
15. user = (User)obj;
16. System.out.println("user: " + user.getName() + "/" + user.getPassword());
17. }
18. } catch(IOException ex) {
5.如果还需要传送时压缩流再传送，就要用到GZIPInputStream和GZIPOutputStream进行压缩和反压缩
server的写法
1. GZIPInputStream gzipis = null;
2. ObjectInputStream ois = null;
3. GZIPOutputStream gzipos = null;
4. ObjectOutputStream oos = null;
6. try {
7. gzipis = new GZIPInputStream(socket.getInputStream());
8. ois = new ObjectInputStream(gzipis);
9. gzipos = new GZIPOutputStream(socket.getOutputStream());
10. oos = new ObjectOutputStream(gzipos);
12. Object obj = ois.readObject();
13. User user = (User)obj;
14. System.out.println("user: " + user.getName() + "/" + user.getPassword());
16. user.setName(user.getName() + "_new");
17. user.setPassword(user.getPassword() + "_new");
19. oos.writeObject(user);
20. oos.flush();
21. gzipos.finish();
22. } catch (IOException ex) {
client的写法
1. Socket socket = null;
2. GZIPOutputStream gzipos = null;
3. ObjectOutputStream oos = null;
4. GZIPInputStream gzipis = null;
5. ObjectInputStream ois = null;
7. try {
8. socket = new Socket();
9. SocketAddress socketAddress = new InetSocketAddress("localhost", 10000);
10. socket.connect(socketAddress, 10 * 1000);
11. socket.setSoTimeout(10 * 1000);
13. gzipos = new GZIPOutputStream(socket.getOutputStream());
14. oos = new ObjectOutputStream(gzipos);
15. User user = new User("user_" + i, "password_" + i);
16. oos.writeObject(user);
17. oos.flush();
18. gzipos.finish();
20. gzipis = new GZIPInputStream(socket.getInputStream());
21. ois = new ObjectInputStream(gzipis);
22. Object obj = ois.readObject();
23. if (obj != null) {
24. user = (User)obj;
25. System.out.println("user: " + user.getName() + "/" + user.getPassword());
26. }
27. } catch(IOException ex) {
6.如果要加密传送，就要使用加密后的socket，而不是使用加密的流

server的写法，只需要对socket进行处理，流的处理不变
1. ServerSocketFactory factory = SSLServerSocketFactory.getDefault();
2. ServerSocket server = factory.createServerSocket(10000);
client的写法
1. SocketFactory factory = SSLSocketFactory.getDefault();
2. socket = factory.createSocket("localhost", 10000);
使用加密技术，需要用到keystore文件
keytool -genkey -alias mysocket -keyalg RSA -keystore mysocket.jks

7.使用nio实现socket通信
java.nio包是Java在1.4之后增加的，用来提高I/O操作的效率。在nio包中主要包括以下几个类或接口:
* Buffer：缓冲区，用来临时存放输入或输出数据。
* Charset：用来把Unicode字符编码和其它字符编码互转。
* Channel：数据传输通道，用来把Buffer中的数据写入到数据源，或者把数据源中的数据读入到Buffer。
* Selector：用来支持异步I/O操作，也叫非阻塞I/O操作。
把对象转为字节数组
1. public static byte[] toBytes(Object object) {
2. ByteArrayOutputStream baos = new ByteArrayOutputStream();
3. ObjectOutputStream oos = null;
4. try {
5. oos = new ObjectOutputStream(baos);
6. oos.writeObject(object);
7. byte[] bytes = baos.toByteArray();
8. return bytes;
吧字节数组转为对象
1. ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
2. ObjectInputStream ois = null;
3. try {
4. ois = new ObjectInputStream(bais);
5. Object object = ois.readObject();
6. return object;
server端的写法
1. Selector selector = null;
2. ServerSocketChannel serverSocketChannel = null;
3. try {
4. selector = Selector.open();
5. serverSocketChannel = ServerSocketChannel.open();
6. serverSocketChannel.configureBlocking(false);
7. serverSocketChannel.socket().setReuseAddress(true);
8. serverSocketChannel.socket().bind(new InetSocketAddress(10000));
9. serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
10. while (selector.select() > 0) {
11. Iterator<SelectionKey> it = selector.selectedKeys().iterator();
12. while (it.hasNext()) {
13. SelectionKey readyKey = it.next();
14. it.remove();
15.                     execute((ServerSocketChannel) readyKey.channel());
  
  private static void execute(ServerSocketChannel serverSocketChannel) throws IOException {
          SocketChannel socketChannel = null;
          try {
              socketChannel = serverSocketChannel.accept();
              MyRequestObject myRequestObject = receiveData(socketChannel);
              logger.log(Level.INFO, myRequestObject.toString());
  
              MyResponseObject myResponseObject = new MyResponseObject(
                      "response for " + myRequestObject.getName(),
                      "response for " + myRequestObject.getValue());
              sendData(socketChannel, myResponseObject);
  
  MyRequestObject myRequestObject = 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();
              Object obj = SerializableUtil.toObject(bytes);
              myRequestObject = (MyRequestObject)obj;
  
  sendData(SocketChannel socketChannel, MyResponseObject myResponseObject) throws IOException {
          byte[] bytes = SerializableUtil.toBytes(myResponseObject);
          ByteBuffer buffer = ByteBuffer.wrap(bytes);
          socketChannel.write(buffer);
client的写法
1. socketChannel = SocketChannel.open();
2. SocketAddress socketAddress = new InetSocketAddress("localhost", 10000);
3. socketChannel.connect(socketAddress);
5. MyRequestObject myRequestObject = new MyRequestObject("request_" + idx, "request_" + idx);
6. logger.log(Level.INFO, myRequestObject.toString());
7. sendData(socketChannel, myRequestObject);
9. MyResponseObject myResponseObject = receiveData(socketChannel);
10. logger.log(Level.INFO, myResponseObject.toString());
1. private void sendData(SocketChannel socketChannel, MyRequestObject myRequestObject) throws IOException {
2. byte[] bytes = SerializableUtil.toBytes(myRequestObject);
3. ByteBuffer buffer = ByteBuffer.wrap(bytes);
4. socketChannel.write(buffer);
5.             socketChannel.socket().shutdownOutput();
  
  private MyResponseObject receiveData(SocketChannel socketChannel) throws IOException {
              MyResponseObject myResponseObject = 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();
                  Object obj = SerializableUtil.toObject(bytes);
                  myResponseObject = (MyResponseObject) obj;
                  socketChannel.socket().shutdownInput();
  return myResponseObject;
上面的例子都需要先运行server再运行client。
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原文地址：https://www.cnblogs.com/wxmdevelop/p/4238517.html