NIO BIO AIO

BIO

IO The system of stream class

1、InputStream/OutputStream ：
 Abstract class of byte stream 
2、Reader/Writer ：
 Abstract class of character stream 
3、FileInputStream/FileOutputStream ：
 Node flow , Direct operation in bytes “ file ”
4、ByteArrayInputStream/ByteArrayOutputStream ：
 Node flow , Direct operation in bytes “ Byte array object ”
5、DataInputStream/DataOutputStream：
 Data flow , Steerable data types 
6、ObjectInputStream/ObjectOutputStream ：
 Processing flow , Direct operation in bytes “ object ”
7、DateInputStream/DateOutputStream ：
 Processing flow , Direct operation in bytes “ Basic data type and string type ”
8、FileReader/FileWriter ：
 Node flow ： Direct operation in characters “ text file ”, Be careful ： Can only read and write text files 
9、BufferedReader/BufferedWriter ：
 Processing flow ： take Reader/Writer Objects are packaged , Add cache function , Improve reading and writing efficiency 
10、BufferedInputStream/BufferedOutputStream ：（ Buffer byte stream ）
 Processing flow , take InputStream/OutputStream Objects are packaged ,, Add cache function , Improve reading and writing efficiency 
11、InputStreamReader/OutputStreamWriter ：
 Processing flow ： Convert byte stream object to character stream object 
12、PrintWriter ：
 Processing flow ： take OutputStream For packaging , Can easily output characters , More flexible 

File

--> Abstracting files into objects 
// Operate on files 
File file = new File("E:/bb.txt");

System.out.println(file.exists());
// Note that only files can be created -->at java.base/java.io.WinNTFileSystem.createFileExclusively(Native Method)
System.out.println(file.createNewFile());

System.out.println(file.getName());

System.out.println(file.getPath());
System.out.println(file);--> And getPath() The method has the same effect 

System.out.println(file.isHidden());

System.out.println(file.isDirectory());

System.out.println(file.isFile());

System.out.println(file.delete());

// Returns the last modified time of the file -->long type , Construct time instances , The output shows the specific time 
System.out.println(new Date(file.lastModified()));

// Returns the number of bytes in the file . The folder can be calculated , Go straight back to 0
System.out.println(file.length());

// Returns a collection of all file and folder names under the file object path 
String[] list = file.list();

// Returns the of all files and folders under this file object path File A collection of objects 
File[] files = file.listFiles();

// Rename the file , You need to create a new file in advance File example , And then put the new File Instance incoming method 
File file1 = new File("E:/aa.txt");
boolean b = file.renameTo(file1);

// Operate on the directory 
File file1 = new File("E:/a/b");

file1.mkdirs();

System.out.println(file1.exists());
System.out.println(file1.isDirectory());

File file2 = new File("E:");
String[] arr = file2.list();
for (String tru : arr) {
     
System.out.println(tru);
}
File[] arr1 = file2.listFiles();
for (File temp : arr1) {
     
System.out.println(temp);
}

// Get the parent file class object --> Generated by the parent for the upper path of the current file File Class instance 
--> Get the parent class instance directly 
File file = new File("E:/a/aa.txt");
File parentFile = file.getParentFile();
System.out.println(parentFile.getPath());
System.out.println(parentFile.getName());
--> Get the parent file path , To create a File class 
String parent = file.getParent();
File file1 = new File(parent);
System.out.println(file1.getPath());
System.out.println(file1.getName());

FileInputStream

--> File byte stream --> Read data to disk --> No buffer 
FileInputStream file=null;
try {
     
 file=new FileInputStream("E:/ test IO flow .txt");
 StringBuilder aa = new StringBuilder();
 int temp = 0;
 try {
     
     //file.read()--> Bytes read 
     while ((temp = file.read()) != -1) {
     
         System.out.println(temp);
         System.out.println(aa.append((char) temp));
     }
 } catch (IOException e) {
     
     e.printStackTrace();
 }
} catch (FileNotFoundException e) {
     
 e.printStackTrace();
} finally {
     
 try {
     
     if (file != null) {
     
         file.close();
     }
 } catch (IOException e) {
     
     e.printStackTrace();
 }
}

buffer

//--> Mode one 
FileInputStream file = null;
FileOutputStream bb = null;
try {
     
 file = new FileInputStream("E:/ Screen capture .png");
 bb=new FileOutputStream("E:/cc.png");
 // Create a cache to store data 
 byte[] f = new byte[1024];
 int temp = 0;       
 /** *  Every time you store data in an array , Except for the last transmission , The array is filled  */
 while ((temp = file.read(f)) != -1) {
     
     bb.write(f,0,temp);     //  Write data to memory 
 }
 // Save the data in memory to disk 
 bb.flush();
} catch (FileNotFoundException e) {
     
 e.printStackTrace();
} finally {
     
 try {
     
     if (file==null){
     
         file.close();
     }
     if (bb != null) {
     
         bb.close();
     }
 } catch (IOException e) {
     
     e.printStackTrace();
 }
}

//--> Mode two 
FileInputStream file = null;
FileOutputStream bb = null;
try {
     
 file = new FileInputStream("E:/ Screen capture .png");
 bb=new FileOutputStream("E:/cc.png");
 // Create a cache to store data 
 // You can specify the length or the length of the calling file 
 // When using a given length , Need to use while loop 
 // When using the call file length , No need to use while loop 
 byte[] f = new byte[file.available()];
 // take file Read to cache , Then output the data in the cache to the memory 
 file.read(f);
 // Save the data in memory to disk 
 bb.write(f);
 bb.flush();
} catch (FileNotFoundException e) {
     
 e.printStackTrace();
} finally {
     
 try {
     
     if (file==null){
     
         file.close();
     }
     if (bb != null) {
     
         bb.close();
     }
 } catch (IOException e) {
     
     e.printStackTrace();
 }
}

Buffer byte stream

FileInputStream aa = null;
BufferedInputStream bb = null;
BufferedOutputStream cc = null;
FileOutputStream dd = null;
try {
     
 aa = new FileInputStream("E:/ Screen capture .png");
 bb = new BufferedInputStream(aa);
 dd = new FileOutputStream("E:/bb.png");
 cc = new BufferedOutputStream(dd);
 int temp = 0;
 // In buffer stream byte The default array length is 8192
 // There is memory space between input stream and output stream 
 // After using the buffer stream, you can directly use the buffer stream object to put data into memory 
 while ((temp = bb.read()) != -1) {
     
     // After using the buffer stream, you can directly put the data in memory into the buffer stream 
     cc.write(temp);
 }
 cc.flush();
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 // The order of closing the flow ： Turn it on and off （ It is related to the order in which the flow object is created , The input stream part comes first , The output stream part is later ）
 try {
     
     if (bb != null) {
     
         bb.close();
     }
     if (aa != null) {
     
         aa.close();
     }
     if (cc != null) {
     
         bb.close();
     }
     if (dd != null) {
     
         bb.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

DataOutputStream

//--> Data output stream （ Processing flow ）
DataOutputStream aa = null;
try {
     
 aa = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("e:/ Data flow .txt")));
 aa.writeChar('a');
 aa.writeDouble(10.2);
 aa.writeBoolean(false);
 aa.writeUTF("yang");
 aa.flush();
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

DataInputStream

//--> Data input stream 
DataInputStream aa = null;
try {
     
 aa = new DataInputStream(new BufferedInputStream(new FileInputStream("E:/ Data flow .txt")));
 // The type is read in the same order as it is stored , Otherwise, it cannot be read 
 System.out.println(aa.readChar());
	System.out.println(aa.readDouble());
	System.out.println(aa.readBoolean());
	System.out.println(aa.readUTF());
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

ObjectOutputStream

//--> Object flow （ Processing flow ）-- Object node output stream -- Write operations to basic data types 
ObjectOutputStream aa = null;
try {
     
 aa = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream("e:/ Object flow .txt")));
 aa.writeChar('a');
 aa.writeDouble(Math.random());
 aa.writeBoolean(true);
 aa.writeUTF("jing");
 aa.flush();
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

ObjectInputStream

//--> Object node input stream --> Read basic data types and serialize and deserialize class objects 
ObjectInputStream aa = null;
try {
     
 aa = new ObjectInputStream(new BufferedInputStream(new FileInputStream("E:/ Object flow .txt")));
 System.out.println(aa.readChar());
 System.out.println(aa.readDouble());
 System.out.println(aa.readBoolean());
 System.out.println(aa.readUTF());
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

InputStreamReader–>OutputStreamWriter

// Used to convert byte stream into character stream 
BufferedReader aa = null;
BufferedWriter bb = null;
try {
     
 aa = new BufferedReader(new InputStreamReader(System.in));
 bb = new BufferedWriter(new OutputStreamWriter(System.out));
 while (true) {
     
     bb.write(" Please enter by keyboard ：");
     bb.flush();
     // Put keyboard input into variables in memory , Call... When output is convenient 
     String temp = aa.readLine();
     if ("exit".equals(temp)) {
     
         return;
     }
     bb.write(" What you input is ："+temp);
     bb.newLine();
     bb.flush();
 }
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
     if (bb != null) {
     
         bb.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

PrintWriter

//--> Character output stream 
BufferedReader aa = null;
PrintWriter bb = null;
try {
     
 aa = new BufferedReader(new InputStreamReader(new FileInputStream("e:/ test IO flow .txt")));
 bb = new PrintWriter("e:/PrintWriter Line break .txt");
 String temp = "";
 int i = 1;
 while ((temp = aa.readLine()) != null) {
     
     bb.println(i + temp);       // Use PrintWriter Streams do not need to be refreshed , The stream has its own refresh and line feed function 
     i++;
 }
} catch (Exception e) {
     
 e.printStackTrace();
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
     if (bb != null) {
     
         bb.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

ByteArrayInputStream

//--> Byte array input stream 
// establish byte Array , Use String call getBytes() Method creation 
byte[] aa = "abcdefgh".getBytes();
ByteArrayInputStream bb = null;
StringBuilder cc = new StringBuilder();
try {
     
 // The construction method of byte array input stream requires a byte Array ,byte Arrays act as data sources 
 bb = new ByteArrayInputStream(aa);
 int temp = 0;
 while ((temp = bb.read()) != -1) {
     
     //System.out.println((char)temp);
     cc.append((char) temp);        // Read all at once 
 }
 System.out.println(cc.toString());      // No need to use StringBuilder Object connection , Direct output is best 
}finally {
     
 try {
     
     if (bb != null) {
     
         bb.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

ByteArrayOutputStream

//--> Byte array output stream 
ByteArrayOutputStream aa = null;
try {
     
 aa = new ByteArrayOutputStream();
 aa.write('a');
 aa.write('b');
 aa.write('c');
 byte[] arr = aa.toByteArray();
 for (int i = 0; i < arr.length; i++) {
     
     System.out.print((char) arr[i]);
 }
}finally {
     
 try {
     
     if (aa != null) {
     
         aa.close();
     }
 } catch (Exception e) {
     
     e.printStackTrace();
 }
}

NIO

Manipulating byte arrays

// Create byte cache , The initial length is 10, Initially, write type array 
ByteBuffer buffer = ByteBuffer.allocate(10);
System.out.println(buffer.position());
System.out.println(buffer.limit());
System.out.println(buffer.capacity());
System.out.println("----------------");
String s = "yang";
// In the data 
buffer.put(s.getBytes());
System.out.println(buffer.position());
System.out.println(buffer.limit());
System.out.println(buffer.capacity());
// Cache inversion 
buffer.flip();
// Single read 
byte b = buffer.get();
System.out.println((char)b);
System.out.println(buffer.position());
System.out.println(buffer.limit());
System.out.println(buffer.capacity());
// Since a data has been read , Cannot use array to read , You can use the repeat read method , Reset position To read the status 
buffer.rewind();
System.out.println(buffer.position());
System.out.println(buffer.limit());
System.out.println(buffer.capacity());
// Create a new array to receive the value of the cache 
byte[] bytes = new byte[buffer.limit()];
buffer.get(bytes);
System.out.println(new String(bytes, 0, bytes.length));
//
buffer.clear();
System.out.println(buffer.position());
System.out.println(buffer.limit());
System.out.println(buffer.capacity());
//buffer.put(s.getBytes());
buffer.get(bytes);
System.out.println(new String(bytes, 0, bytes.length));

Local Channel passageway

@Test
public void liu() throws IOException {
     
// The first way 
FileInputStream fileInputStream = new FileInputStream("E:/1.png");
FileOutputStream fileOutputStream = new FileOutputStream("E:/2.png");

// Create cache 
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
FileChannel inChannel = fileInputStream.getChannel();
FileChannel outChannel = fileOutputStream.getChannel();
int read = inChannel.read(byteBuffer);
while (read != -1) {
     
  byteBuffer.flip();
  outChannel.write(byteBuffer);
  byteBuffer.clear();
  read = inChannel.read(byteBuffer);
}
outChannel.close();
inChannel.close();

// The second way 
FileChannel input = FileChannel.open(Paths.get("E:/1.png"), StandardOpenOption.READ);
FileChannel output = FileChannel.open(Paths.get("E:/4.png"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
// Pass in 1
input.transferTo(0, input.size(), output);
// Pass in 2
output.transferFrom(input, 0, input.size());
}

Decentralized write aggregate read

@Test
public void fenJu() throws IOException {
     
FileInputStream fileInputStream = new FileInputStream("E:/aa.txt");
FileChannel channel1 = fileInputStream.getChannel();

ByteBuffer allocate1 = ByteBuffer.allocate(10);
ByteBuffer allocate2 = ByteBuffer.allocate(1024);
ByteBuffer[] byteBuffers = {
     allocate1, allocate2};
long read = channel1.read(byteBuffers);

System.out.println(new String(allocate1.array(), 0, allocate1.limit()));
System.out.println(new String(allocate2.array(), 0, allocate2.limit()));
allocate1.flip();
allocate2.flip();
FileOutputStream fileOutputStream = new FileOutputStream("E:/cc.txt");
FileChannel channel2 = fileOutputStream.getChannel();
channel2.write(byteBuffers);
}

Encoding and decoding

@Test
public void bianJie() throws CharacterCodingException {
     
// Output all encoding methods , return Map aggregate 
SortedMap<String, Charset> stringCharsetSortedMap = Charset.availableCharsets();
Set<Map.Entry<String, Charset>> entries = stringCharsetSortedMap.entrySet();
/*for (Map.Entry en : entries) { System.out.println(en.getKey() + " " + en.getValue()); }*/
// get GBK Encoding mode 
Charset gbk = Charset.forName("GBK");
// Get encoder 
CharsetEncoder charsetEncoder = gbk.newEncoder();
// Get decoder 
CharsetDecoder charsetDecoder = gbk.newDecoder();
// get CharBuffer buffer 
CharBuffer allocate = CharBuffer.allocate(1024);
String string = " Invincible ";
allocate.put(string);
// With GBK Method to encode buffer data , The output needs to reverse the buffer 
allocate.flip();
ByteBuffer encode = charsetEncoder.encode(allocate);
System.out.println(encode.limit());
/*for (int i = 0; i < 4; i++) { System.out.println(encode.get()); }*/
// With GBK Mode to decode encoded data 
allocate.flip();
CharBuffer decode = charsetDecoder.decode(encode);
System.out.println(decode.toString());
}

NIO Realize data transmission between client and server （ Blocked state ）

public class ClientServiceBlocking {
     

@Test
public void client() throws IOException {
     
  // Get the communication channel between the client and the server 
  SocketChannel socketChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9999));
  // Get the communication channel between the client and the disk 
  FileChannel open = FileChannel.open(Paths.get("E:/1.png"), StandardOpenOption.READ);
  // Test the second way 
  //open.transferTo(0, open.size(), socketChannel);
  //NIO Create cache 
  ByteBuffer allocate = ByteBuffer.allocate(1024);
  int read = open.read(allocate);
  while (read != -1) {
     
      allocate.flip();
      socketChannel.write(allocate);
      allocate.clear();
      read = open.read(allocate);
  }
  // Close channel 
  open.close();
  socketChannel.close();
}

@Test
public void service() throws IOException {
     

  // Create a server-side channel 
  ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
  // The server side specifies the port accessed by the client , Binding required 
  serverSocketChannel.bind(new InetSocketAddress(9999));
  // The server listens to the client information 
  SocketChannel accept = serverSocketChannel.accept();

  // Create a server-side and local disk channel 
  FileChannel open = FileChannel.open(Paths.get("E:/2.png"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
  // Create a cache to receive client data 
  ByteBuffer allocate = ByteBuffer.allocate(1024);
  // The server reads the client data 
  int read = accept.read(allocate);
  // Infinite loop read 
  while (read != -1) {
     
      allocate.flip();
      open.write(allocate);
      allocate.clear();
      read = accept.read(allocate);
  }

  // Close channel 
  open.close();
  accept.close();
  serverSocketChannel.close();

}
}

NIO Realize data transmission between client and server （ Non blocking state ）

public class ClientServiceNonBlocking {
     

@Test
public void client() throws IOException {
     

  // Create client-side and server-side channels 
  SocketChannel open = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9998));
  // Set the client channel to non blocking state ***
  open.configureBlocking(false);
  // Create client and disk channels 
  FileChannel open1 = FileChannel.open(Paths.get("E:/1.png"), StandardOpenOption.READ);
  // Create cache 
  ByteBuffer allocate = ByteBuffer.allocate(1024);
  int read = open1.read(allocate);
  while (read != -1) {
     
      allocate.flip();
      open.write(allocate);
      allocate.clear();
      read = open1.read(allocate);
  }
  // Close channel 
  open1.close();
  open.close();
}

@Test
public void service() throws IOException {
     

  // Create a server-side channel 
  ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
  // Set the server non blocking state 
  serverSocketChannel.configureBlocking(false);
  // Server side binding listening port number 
  serverSocketChannel.bind(new InetSocketAddress(9998));
  // Create selector / multiplexer 
  Selector selector = Selector.open();
  // Selector agent listens 
  serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
  // Create server and disk channels 
  //FileChannel open = FileChannel.open(Paths.get("E:/3.png"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
  // Polling for listening information 
  while (selector.select() > 0) {
     
      // Traverse the selector listening information set 
      Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
      while (iterator.hasNext()) {
     
          SelectionKey next = iterator.next();
          // Make sure that the crying protector is in the ready state 
          if (next.isAcceptable()) {
     
              // The server is connected to the client 
              SocketChannel accept = serverSocketChannel.accept();
              // Switch non blocking state 
              accept.configureBlocking(false);
              // Put the read operation in the selector 
              accept.register(selector, SelectionKey.OP_READ);
          } else if (next.isReadable()) {
     
              // Create read channel 
              SocketChannel channel = (SocketChannel) next.channel();
              // Create server and disk channels 
              FileChannel open = FileChannel.open(Paths.get("E:/3.png"), StandardOpenOption.WRITE, StandardOpenOption.CREATE);
              // Create cache 
              ByteBuffer allocate = ByteBuffer.allocate(1024);
              // Read client channel information 
              int read = channel.read(allocate);
              System.out.println(read);
              while (read != -1) {
     
                  allocate.flip();
                  open.write(allocate);
                  allocate.clear();
                  read = channel.read(allocate);
              }
          }
      }
      // Turn off the iterator 
      iterator.remove();
  }
}
}

Network programming

InetAddress–InetSocketAddress

System.out.println("===============InetAddress Class simple to use =============================");
// according to InetAddress Class to get the native directly InetAddress object 
InetAddress aa = InetAddress.getLocalHost();
// Access to the host IP Address 
System.out.println(" Access to the host IP Address "+aa.getHostAddress());
// Get the hostname 
System.out.println(" Get the host name "+aa.getHostName());
// Get... According to the domain name InetAddress object 
InetAddress bb = InetAddress.getByName("www.jd.com");
// obtain IP Address 
System.out.println("www.jd.com Of IP Address " + bb.getHostAddress());
// Get the hostname 
System.out.println("www.jd.com The host name "+bb.getHostName());
// according to IP The address for InetAddress object 
InetAddress cc = InetAddress.getByName("163.23.142.67");
System.out.println(" according to 163.23.142.67 To obtain the IP Address " + cc.getHostAddress());
// When you type IP Address 163.23.142.67 Nonexistence or DNS（ Domain name resolution system ） It is not allowed to IP Address and domain name mapping , Unable to get host address （ And IP The address has the same name ）
//System.out.println(" according to 163.23.142.67 Obtained hostname " + cc.getHostName());
System.out.println("==============InetSocketAddress Class simple to use =============================");
// according to localhost establish InetSocketAddress Class object 
InetSocketAddress a = new InetSocketAddress("localhost", 8888);
System.out.println(a.getAddress());
System.out.println(a.getHostName());
System.out.println(a.getPort());
// according to 127.0.0.1 establish InetSocketAddress object 
InetSocketAddress c = new InetSocketAddress("127.0.0.1", 7777);
System.out.println(c.getAddress());
System.out.println(c.getHostName());
System.out.println(c.getPort());
// according to IP The address for InetSocketAddress object 
InetSocketAddress b = new InetSocketAddress("192.168.1.5", 9999);
System.out.println(b.getAddress());
System.out.println(b.getHostName());
// Get the port number 
System.out.println(b.getPort());
// according to InetAddress Object to obtain InetSocketAddress object 
InetAddress f = InetAddress.getByName("192.168.1.40");
InetSocketAddress d = new InetSocketAddress(f, 6666);
System.out.println(d.getAddress());
System.out.println(d.getHostName());
System.out.println(d.getPort());

Reptiles

//URL The method is simple to use 
// establish URL object 
URL aa = new URL("https://www.baidu.com");
// Get agreement name 
System.out.println(" Get agreement name ："+aa.getProtocol());
// Get the hostname 
System.out.println(" Get the hostname ："+aa.getHost());
// Access to domain name 
System.out.println(" Access to domain name ："+aa.getPort());
// Get the file name 
System.out.println(" Get the file name ："+aa.getFile());
// Get the default port number 
System.out.println(" Get the default port number ："+aa.getDefaultPort());
// Get path 
System.out.println(" Get path ："+aa.getPath());
// Web crawler 
// establish URL object 
URL bb = new URL("https://www.csdn.net/");      //CSDN Website home page 
// Get byte input stream 
InputStream cc = bb.openStream();
// Use buffer streams 
BufferedReader dd = new BufferedReader(new InputStreamReader(cc, "utf-8"));
// Store to local disk 
BufferedWriter ff = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("index.html"), "utf-8"));
// Reading while writing 
String temp = null;
while ((temp = dd.readLine()) != null) {
     
 ff.write(temp);
 ff.newLine();
 ff.flush();
}
dd.close();
ff.close();
cc.close();

The chat room TCP

--  Client multithreading 
public class Text7{
     

 public static void main(String[] args) throws IOException {
     

     System.out.println("==== The client starts ！！====");

     // establish Socket object 
     Socket aa = new Socket("192.168.1.40", 9999);

     // Create a thread class object that the client sends information to the server 
     sendMessage bb = new sendMessage(aa);
     new Thread(bb).start();

     // Create a thread class object for the client to receive server information 
     getMessage cc = new getMessage(aa);
     new Thread(cc).start();

 }
}

// The client sends information to the thread 
class sendMessage implements Runnable{
     

 DataOutputStream bb = null;

 BufferedReader cc = null;

 private Socket aa;

 private boolean flag = true;

 // Initialize the incoming through the thread class Socket Endpoint 
 public sendMessage(Socket aa){
     
     this.aa = aa;
 }

 // Get keyboard input data 
 private String getMessage(){
     
     // by str initialization , When something goes wrong with the program , You can also return the initialization value 
     String str = "";
     try {
     
         System.out.println(" Please enter the information sent ：");
         cc = new BufferedReader(new InputStreamReader(System.in));
         str = cc.readLine();
     } catch (Exception e) {
     
         flag = false;
         Text9.closeAll(cc);
     }
     return str;
 }

 // Send data to the server 
 private void sendMessage(String string) {
     
     try {
     
         bb = new DataOutputStream(aa.getOutputStream());
         bb.writeUTF(string);
         bb.flush();
     } catch (IOException e) {
     
         flag = false;
         Text9.closeAll(bb);
     }
 }

 @Override
 public void run() {
     

     while (flag) {
     
         this.sendMessage(this.getMessage());
         // Sleep is not added here , There is a problem with printing , Because it's dual threaded 
         try {
     
             Thread.sleep(500);
         } catch (InterruptedException e) {
     
             e.printStackTrace();
         }
     }

 }
}

// The client receives the information thread 

class getMessage implements Runnable {
     

 DataInputStream oo = null;

 private Socket bb;

 private boolean flag = true;

 public getMessage(Socket socket) {
     
     this.bb = socket;
 }

 // Get server information 
 private void receiveServerMessage() {
     
     try {
     
         oo = new DataInputStream(bb.getInputStream());
         System.out.println(oo.readUTF());
     } catch (Exception e) {
     
         flag = false;
         Text9.closeAll(oo);
     }
 }

 @Override
 public void run() {
     

     while (flag) {
     
         this.receiveServerMessage();
     }

 }
}

--  Server side 
public class Text8{
     

 public static void main(String[] args) throws IOException {
     

     System.out.println("==== Server startup ====");

     // establish ServerSocket object 
     ServerSocket aa = new ServerSocket(9999);
     // Listen for requests from clients 
     Socket bb = aa.accept();

     // Data streams get input and output 
     // Data stream get input 
     while (true) {
     
         DataInputStream q = new DataInputStream(bb.getInputStream());
         //***q.readUTF() When used many times , It is necessary to define variable reception ！！
         String str = q.readUTF();
         System.out.println(" The client sends information ："+str);
         // Data stream get output 
         DataOutputStream w = new DataOutputStream(bb.getOutputStream());
         w.writeUTF(" The server has received the message ："+str);
         w.flush();
     }
 }
}

Customer consultation UDP

--  Server side 
public static void main(String[] args) throws IOException {
     
 System.out.println("======= Customer service starts ！！==============");
 Scanner h = new Scanner(System.in);
 DatagramSocket aa = new DatagramSocket(9999);
 while (true) {
     
     byte[] arr = new byte[1024];
     DatagramPacket bb = new DatagramPacket(arr, arr.length);
     // Start receiving 
     aa.receive(bb);
     // View the received data 
     // Don't understand,  // I understand 
     String str = new String(bb.getData(), 0, bb.getLength());
     System.out.println(" Customer said ：" + str);
     String p = h.next();
     byte[] arr2 = p.getBytes();
     DatagramPacket cc = new DatagramPacket(arr2, arr2.length, bb.getAddress(), bb.getPort());
     aa.send(cc);
     if ("bye".equals(p)) {
     
         break;
     }
 }
 
}

--  client 
public static void main(String[] args) throws IOException {
     
 Scanner h = new Scanner(System.in);
 System.out.println("======= The consultant starts ！！=========");
 // Datagram packets for sending and receiving 
 // This application will send data , Use the port unique to this application 
 DatagramSocket aa = new DatagramSocket(8888);
 while (true) {
     
     String p = h.next();
     // Ready to send packets 
     byte[] arr = p.getBytes();
     // Data sent , Data length , Address sent to the host , Port sent to the host 
     DatagramPacket bb = new DatagramPacket(arr, arr.length, InetAddress.getByName("localhost"), 9999);
     // Start sending 
     aa.send(bb);
     // Store received datagram packets 
     byte[] arr2 = new byte[1024];
     DatagramPacket cc = new DatagramPacket(arr2, arr2.length);
     // Receive datagram packets 
     aa.receive(cc);
     String str = new String(cc.getData(), 0, cc.getLength());
     System.out.println(" Customer service said ：" + str);
     if ("bye".equals(p)) {
     
         break;
     }
 }
 // Close data 
 //aa.close();
}