Network programming1
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This document discusses network programming in Java. It shows how to get the local host address and address of google.com. It defines a server as a program that listens on a TCP port for connections and a client as a program that initiates connections. It demonstrates how to create a server socket to listen on a port and how a client socket can connect to an IP address and port. It also discusses Java I/O streams for input and output and how to handle files in Java including checking if a directory exists, creating it if not, opening output streams to write to files, and approaches for reading from files.
![public static void main(String[] args) throws
UnknownHostException {
InetAddress localAddress = InetAddress.getLocalHost();
System.out.println(localAddress.getHostAddress());
}
public static void main(String[] args) throws
UnknownHostException {
InetAddress googleAddress =
InetAddress.getByName("www.google.com");
System.out.println(googleAddress.getHostAddress());
}](https://image.slidesharecdn.com/networkprogramming1-141013060139-conversion-gate01/85/Network-programming1-2-320.jpg)
![Write to a File : Second approach
DataOutputStream provides a wrapper over an OutputStream to
write primitive data types, not just byte[]](https://image.slidesharecdn.com/networkprogramming1-141013060139-conversion-gate01/85/Network-programming1-9-320.jpg)
Network programming1
- 1. Network Programming with Java
- 2. public static void main(String[] args) throws UnknownHostException { InetAddress localAddress = InetAddress.getLocalHost(); System.out.println(localAddress.getHostAddress()); } public static void main(String[] args) throws UnknownHostException { InetAddress googleAddress = InetAddress.getByName("www.google.com"); System.out.println(googleAddress.getHostAddress()); }
- 3. TCP/IP Server: That(a program or a process) listens to a TCP port. Client: What (a program or a process) initiates the connection Server is represented by java.net.ServerSocket Client is represented by java.net.Socket int portNumber = 7896; // TCP port Number ServerSocket server = new ServerSocket(portNumber);// listen on port Socket socket = server.accept(); // Blocks until connection made String destIP = "172.17.20.123"; // Target Host IPv4 Address int portNumber = 7896; // TCP port Number Socket socket = new Socket(destIP, portNumber);// connect
- 4. Stay & while connected… Server Client Wait for connection Server’s Output/ Client’s Input Client’s Output/ Server’s Input
- 5. Java I/O Some important OutputStream child: DataOutputStream FileOutputStream ByteArrayOutputStream
- 6. Java I/O Some important InputStream child: DataInputStream FileInputStream ByteArrayInputStream Read an input integer Example
- 7. File Handling if(false==dir.exists() || false==dir.isDirectory()){ dir.mkdirs(); }
- 8. File Handling 5. Open an OutputStream to the file: 6. Write the raw bytes to the OutputStream, flush and close it
- 9. Write to a File : Second approach DataOutputStream provides a wrapper over an OutputStream to write primitive data types, not just byte[]
- 10. Read from a File Read byte-by-byte Read Bytes chunk-wise : Faster approach