NETWORKING - Introduction to Java Programming: Comprehensive Version - page 1151

72 /** Run a thread */
73 public void run() {
74 try {
75 // Create data input and output streams
76 DataInputStream inputFromClient = new DataInputStream(
77 socket.getInputStream());
78 DataOutputStream outputToClient = new DataOutputStream(
79 socket.getOutputStream());
80
81

I/O

// Continuously serve the client

82 while ( true ) {

83 // Receive radius from the client

84 double radius = inputFromClient.readDouble();

85
86 // Compute area

87 double area = radius * radius * Math.PI;

88
89 // Send area back to the client

90 outputToClient.writeDouble(area);

91
92 Platform.runLater(() -> {
93 ta.appendText( "radius received from client: " +
94 radius + '\n' );
95 ta.appendText( "Area found: " + area + '\n' );
96 });
97 }
98 }
99 catch (IOException e) {
100 ex.printStackTrace();
101 }
102 }
103 }
104 }

update GUI

The server creates a server socket at port 8000 (line 29) and waits for a connection (line 35).
When a connection with a client is established, the server creates a new thread to handle
the communication (line 54). It then waits for another connection in an infinite while loop
(lines 33-55).
The threads, which run independently of one another, communicate with designated
clients. Each thread creates data input and output streams that receive and send data to a
client.

31.8

✓ ✓

How do you make a server serve multiple clients?

Check

Point

31.5 Sending and Receiving Objects
A program can send and receive objects from another program.

Key
Point

In the preceding examples, you learned how to send and receive data of primitive types. You
can also send and receive objects using ObjectOutputStream and ObjectInputStream
on socket streams. To enable passing, the objects must be serializable. The following example
demonstrates how to send and receive objects.
The example consists of three classes: StudentAddress.java (Listing 31.5), StudentClient.
java (Listing 31.6), and StudentServer.java (Listing 31.7). The client program collects student
information from the client and sends it to a server, as shown in Figure 31.10.
The StudentAddress class contains the student information: name, street, city, state,
and zip. The StudentAddress class implements the Serializable interface. Therefore, a
StudentAddress object can be sent and received using the object output and input streams.