Socket和DatagramSocket的区别
简而言之就是：
Socket使用的tcp连接，需要先连接之后才能发送数据。
DatagramSocket使用的UDP连接，客户端不需要先连接数据，可以直接发送给指定服务端。
DatagramSocket：
客户端发送（直接发送数据，没有连接的过程）：
protected void connectServerWithUDPSocket(Context context, String id) {
DatagramSocket socket;
try {
//创建DatagramSocket对象并指定一个端口号，注意，如果客户端需要接收服务器的返回数据,
//还需要使用这个端口号来receive，所以一定要记住
socket = new DatagramSocket(null);
//使用InetAddress(Inet4Address).getByName把IP地址转换为网络地址
InetAddress serverAddress = null;
mHost = Utils.getLocalIpStr(context);
Log.d(TAG, "connectServerWithUDPSocket mHost =" + mHost);
if (null == mHost) return;
try {
serverAddress = InetAddress.getByName(mHost);
} catch (UnknownHostException e) {
Log.d(TAG, "未找到服务器");
e.printStackTrace();
}
//Inet4Address serverAddress = (Inet4Address) Inet4Address.getByName("192.168.1.32");
String str = id;//设置要发送的报文
byte data[] = str.getBytes();//把字符串str字符串转换为字节数组
//创建一个DatagramPacket对象，用于发送数据。
//参数一：要发送的数据 参数二：数据的长度 参数三：服务端的网络地址 参数四：服务器端端口号
DatagramPacket packet = new DatagramPacket(data, data.length, serverAddress, PORT);
try {
socket.send(packet);//把数据发送到服务端。
} catch (IOException e) {
Log.d(TAG, "发送失败");
e.printStackTrace();
}
Log.d(TAG, "socket.send------------------------");
} catch (SocketException e) {
Log.i(TAG, "建立接收数据报失败");
e.printStackTrace();
}
}服务端接收：
public void serverReceviedByUdp() {
//创建一个DatagramSocket对象，并指定监听端口。（UDP使用DatagramSocket）
DatagramSocket socket;
try {
socket = new DatagramSocket(PORT);
//创建一个byte类型的数组，用于存放接收到得数据
byte data[] = new byte[4 * 1024];
//创建一个DatagramPacket对象，并指定DatagramPacket对象的大小
DatagramPacket packet = new DatagramPacket(data, data.length);
while (true) {
//读取接收到得数据
socket.receive(packet);
//把客户端发送的数据转换为字符串。
//使用三个参数的String方法。参数一：数据包 参数二：起始位置 参数三：数据包长
String result = new String(packet.getData(), packet.getOffset(), packet.getLength());
Log.d(TAG, "service result = " + result);
}
} catch (SocketException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}Socket：
服务端：
public class TcpServer {
private static ServerSocket serverSocket;
private static Socket socket;
public static void startServer(){
if (serverSocket == null){
new Thread(new Runnable() {
@Override
public void run() {
try {
serverSocket = new ServerSocket(8080);
Log.i("tcp" , "服务器等待连接中");
socket = serverSocket.accept();
Log.i("tcp" , "客户端连接上来了");
InputStream inputStream = socket.getInputStream();
byte[] buffer = new byte[1024];
int len = -1;
while ((len = inputStream.read(buffer)) != -1) {
String data = new String(buffer, 0, len);
Log.i("tcp" , "收到客户端的数据-----------------------------:" + data);
EventBus.getDefault().post(new MessageServer(data));
}
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
socket = null;
serverSocket = null;
}
}
}).start();
}
}
public static void sendTcpMessage(final String msg){
if (socket != null && socket.isConnected()) {
new Thread(new Runnable() {
@Override
public void run() {
try {
socket.getOutputStream().write(msg.getBytes());
socket.getOutputStream().flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
}客户端（这边需要先连接服务端之后，才能发送数据）：
public class TcpClient {
public static Socket socket;
public static void startClient(final String address ,final int port){
if (address == null){
return;
}
if (socket == null) {
new Thread(new Runnable() {
@Override
public void run() {
try {
Log.i("tcp", "启动客户端");
socket = new Socket(address, port);
Log.i("tcp", "客户端连接成功");
PrintWriter pw = new PrintWriter(socket.getOutputStream());
InputStream inputStream = socket.getInputStream();
byte[] buffer = new byte[1024];
int len = -1;
while ((len = inputStream.read(buffer)) != -1) {
String data = new String(buffer, 0, len);
Log.i("tcp", "收到服务器的数据---------------------------------------------:" + data);
EventBus.getDefault().post(new MessageClient(data));
}
Log.i("tcp", "客户端断开连接");
pw.close();
} catch (Exception EE) {
EE.printStackTrace();
Log.i("tcp", "客户端无法连接服务器");
}finally {
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
socket = null;
}
}
}).start();
}
}
public static void sendTcpMessage(final String msg){
if (socket != null && socket.isConnected()) {
new Thread(new Runnable() {
@Override
public void run() {
try {
socket.getOutputStream().write(msg.getBytes());
socket.getOutputStream().flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();
}
}
参考：
https://blog.csdn.net/qq_29634351/article/details/81458915