一、TCP
TCP建立连接后，通信双方都可以进行数据的传输；在保证可靠性上，采用超时重传和捎带确认机制；在流量控制上，采用滑动窗口协议，协议中规定，对于窗口内未经确认的分组需要重传；在拥塞控制上，采用慢启动算法。
TCP服务端工作代码
private static final int TCP_SERVER_PORT = 2321;
//创建一个ServerSocket对象
ServerSocket serverSocket = null;
private void initDataServer(){
try{
//TCP_SERVER_PORT为指定的绑定端口，为int类型
serverSocket = new ServerSocket(TCP_SERVER_PORT);
//监听连接请求
Socket socket = serverSocket.accept();
//写入读Buffer中、获取输入流
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//放入写buffer中、获取输出流
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
//读取接收信息转换为字符串
String ingoingMsg = in.readLine() + System.getProperty("line.separator");
//生成发送字符串
String outgoingMsg = "goodbye from port" + TCP_SERVER_PORT + System.getProperty("line.separator");
//将发送字符串写入上面定义的BufferWriter中
out.write(outgoingMsg);
//刷新，发送
out.flush();
//关闭
socket.close();
} catch (InterruptedIOException e) {
//超时错误
e.printStackTrace();
//IO异常
} catch (IOException e) {
e.printStackTrace();
} finally {
if(serverSocket != null){
try{
serverSocket.close();
}catch (IOException e) {
e.printStackTrace();
}
}
}
}
TCP客户端代码
public void initDataClient(){
try{
//初始化Socket，TCP_SERVER_PORT为指定端口，int类型
Socket socket = new Socket("localhost", TCP_SERVER_PORT);
//获取输入流
BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
//获取输出流
BufferedWriter out = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
//读取接收信息转换为字符串
String ingoingMsg = in.readLine() + System.getProperty("line.separator");
//生成输出内容
String outMsg = "TCP connecting to" + TCP_SERVER_PORT + System.getProperty("line.separator");
//写入
out.write(outMsg);
//刷新，发送
out.flush();
//获取输入流
String inMsg = in.readLine() + System.getProperty("line.separator");
//关闭连接
socket.close();
}catch (UnknownHostException e){
e.printStackTrace();
}catch (IOException e) {
e.printStackTrace();
}
}
二、UDP通信
UDP不提供数据报分组、组装和数据报排序的特点，当报文发送之后是无法得知其是否安全完整到达。
UDP服务端代码
//接收的字节的大小，客户端发送的数据不能超过MAX_UDP_DATAGRAM_LEN
byte[] IMsg = new byte[MAX_UDP_DATAGRAM_LEN];
//实例化一个DatagramPacket类
DatagramPacket dp = new DatagramPacket(IMsg, IMsg.length);
//新建一个DatagramPacket类
DatagramPacket ds = null;
try{
//UDP服务器监听的端口
ds = new DatagramPacket(UDP_SERVER_PORT);
//准备接收数据
ds.receive(dp);
} catch (SocketException e){
e.printStackTrace();
} catch (IOException e){
e.printStackTrace();
} finally {
//如果ds对象不为空，则关闭ds对象
if (da != null){
ds.close();
}
}
UDP客户端代码
//定义需要发送的信息
String udpMsg = "hello world from UDP client" + UDP_SERVER_PORT;
//新建一个DatagramPacket类
DatagramPacket ds = null;
try{
//初始化DatagramPacket对象
ds = new DatagramPacket();
InetAddress serverAddr = InetAddress.getByName("127.0.0.1");
DatagramPacket dp;
//初始化DatagramPacket对象
dp = new DatagramPacket(udpMsg.getBytes(), udpMsg.length(), serverAddr, UDP_SERVER_PORT);
//发送
ds.send(dp);
//Socket连接异常
} catch (SocketException e){
e.printStackTrace();
//不能连接到主机
} catch (UnknownHostException e){
e.printStackTrace();
//数据流异常
} catch (IOException e){
e.printStackTrace();
//其他异常
} catch (Exception e){
e.printStackTrace();
} finally {
//如果ds对象不为空，则关闭ds对象
if (ds != null){
ds.close();
}
}
