TCP UDP
这里简单的总结一下TCP和UDP编程的写法，另外涉及到HttpUrlConnection的用法 。
TCP套接字
一、项目的流程如下说明：
1、客户输入一行字符，通过其套接字发送到服务器。 2、服务器从其连接的套接字中选取一行字符。 3、服务器将该行字符转换成大写并通过连接的套接字返回给客户 4、客户机从套接字中读取修改后的行，将其打印。
二、客户端的代码如下：
public class TCPClient {
public static void main(String[] args) throws Exception {
String sentence;
String modifiedSentence;
BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
Socket clientSocket = new Socket("localhost", 9999);
DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());
BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
sentence = inFromUser.readLine();
outToServer.writeBytes(sentence + "\n");
modifiedSentence = inFromServer.readLine();
System.out.println("FROM SERVER: " + modifiedSentence);
clientSocket.close();
}
}
三、服务器的代码如下：
public class TCPServer {
public static void main(String[] args) throws Exception {
String clientSentence;
String capitalzedSentence;
ServerSocket serverSocket = new ServerSocket(9999);
while (true) {
Socket connectionSocket = serverSocket.accept();
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));
DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());
clientSentence = inFromClient.readLine();
capitalzedSentence = clientSentence.toUpperCase() + "\n";
outToClient.writeBytes(capitalzedSentence);
}
}
}
四、运行的效果如下：
UDP套接字
项目的流程和上述的一样，这里不再赘述。
一、UDP客户端的代码：
public class UDPClient {
public static void main(String[] args) throws Exception {
BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
DatagramSocket clientSocket = new DatagramSocket();
InetAddress IPAddress = InetAddress.getByName("localhost");
byte[] sendData = new byte[1024];
byte[] receiveData = new byte[1024];
String sentence = inFromUser.readLine();
sendData = sentence.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9999);
clientSocket.send(sendPacket);
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
clientSocket.receive(receivePacket);
String modifiedSentence = new String(receivePacket.getData());
System.out.println("FROM SERVER: " + modifiedSentence);
clientSocket.close();
}
}
二、UDP服务器的代码：
public class UDPServer {
public static void main(String[] args) throws Exception {
DatagramSocket serverSocket = new DatagramSocket(9999);
byte[] sendData = new byte[1024];
byte[] receiveData = new byte[1024];
while (true) {
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
String sentence = new String(receivePacket.getData());
InetAddress IPAddress = receivePacket.getAddress();
int port = receivePacket.getPort();
String capitalizedSentence = sentence.toLowerCase();
sendData = capitalizedSentence.getBytes();
DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
serverSocket.send(sendPacket);
}
}
}
和TCP不同的是，UDP可以先运行客户端，然后再运行服务器。这是因为当你执行客户端时，客户端进程并没有试图和服务器发起连接。
URLConnection的使用
一、从urlconnection中读取数据：
public class ReadFromUrlConn {
public static void main(String[] args) throws Exception {
URL url = new URL("https://www.baidu.com/");
URLConnection connection = url.openConnection();
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
System.out.println(inputLine);
in.close();
}
}
二、HttpURLConnection的post请求数据
public void login() {
HttpURLConnection httpURLConnection = null;
InputStream inputStream = null;
DataOutputStream out = null;
try {
URL url = new URL("http://localhost:9999/CsiiLearn/request/postTest.action");
httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST"); // 大小写是有区别的
httpURLConnection.setConnectTimeout(8000);
httpURLConnection.setReadTimeout(8000);
httpURLConnection.setDoOutput(true); // 这个需要在getOutputStream之前调用
out = new DataOutputStream(httpURLConnection.getOutputStream());
String params = "username=huxh&password=123456"; // post方法的请求参数
out.writeBytes(params);
inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder stringBuilder = new StringBuilder();
String line = "";
while ((line = bufferedReader.readLine()) != null) {
stringBuilder.append(line);
}
System.out.println("response: " + stringBuilder.toString());
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
inputStream.close();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
一个多线程的例子
一、客户端的代码，请求得到一个随机产生的字符串
public class MainClient {
public static void main(String[] args) {
try {
Socket socket = new Socket("localhost", 9999);
BufferedReader inFromServer = new BufferedReader(new InputStreamReader(socket.getInputStream()));
String line = inFromServer.readLine();
System.out.println(line);
} catch (IOException e) {
e.printStackTrace();
}
}
}
二、服务器的代码，服务于客户端的请求
public class MainServer {
public static void main(String[] args) {
try {
ServerSocket serverSocket = new ServerSocket(9999);
ExecutorService executorService = Executors.newFixedThreadPool(10);
while (true) {
Socket socket = serverSocket.accept();
System.out.println("request has accept");
executorService.execute(new MulitpleThread(socket));
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
三、服务器开启的服务线程
public class MulitpleThread implements Runnable {
private Socket socket;
MulitpleThread(Socket socket) {
this.socket = socket;
}
@Override
public void run() {
try {
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
out.writeBytes("L。 " + new Random().nextInt(10));
socket.close(); // 这个是需要的，要不然客户端没有得到数据。
} catch (Exception e) {
e.printStackTrace();
}
}
}
