import java.applet.*;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.rmi.*;
import java.rmi.registry.*;
import java.util.*;
import com.oreilly.servlet.HttpMessage;
public class DaytimeApplet extends Applet {
static final int DEFAULT_PORT = 1313;
TextField httpText, httpObject, socketText, socketObject, RMIObject;
Button refresh;
public void init() {
// Construct the user interface
setLayout(new BorderLayout());
// On the left create labels for the various communication
// mechanisms
Panel west = new Panel();
west.setLayout(new GridLayout(5, 1));
west.add(new Label("HTTP text: ", Label.RIGHT));
west.add(new Label("HTTP object: ", Label.RIGHT));
west.add(new Label("Socket text: ", Label.RIGHT));
west.add(new Label("Socket object: ", Label.RIGHT));
west.add(new Label("RMI object: ", Label.RIGHT));
add("West", west);
// On the right create text fields to display the retrieved time values
Panel center = new Panel();
center.setLayout(new GridLayout(5, 1));
httpText = new TextField();
httpText.setEditable(false);
center.add(httpText);
httpObject = new TextField();
httpObject.setEditable(false);
center.add(httpObject);
socketText = new TextField();
socketText.setEditable(false);
center.add(socketText);
socketObject = new TextField();
socketObject.setEditable(false);
center.add(socketObject);
RMIObject = new TextField();
RMIObject.setEditable(false);
center.add(RMIObject);
add("Center", center);
// On the bottom create a button to update the times
Panel south = new Panel();
refresh = new Button("Refresh");
south.add(refresh);
add("South", south);
}
public void start() {
refresh();
}
private void refresh() {
// Fetch and display the time values
httpText.setText(getDateUsingHttpText());
httpObject.setText(getDateUsingHttpObject());
socketText.setText(getDateUsingSocketText());
socketObject.setText(getDateUsingSocketObject());
RMIObject.setText(getDateUsingRMIObject());
}
private String getDateUsingHttpText() {
try {
// Construct a URL referring to the servlet
URL url = new URL(getCodeBase(), "/servlet/DaytimeServlet");
// Create a com.oreilly.servlet.HttpMessage to communicate with that URL
HttpMessage msg = new HttpMessage(url);
// Send a GET message to the servlet, with no query string
// Get the response as an InputStream
InputStream in = msg.sendGetMessage();
// Wrap the InputStream with a DataInputStream
DataInputStream result =
new DataInputStream(new BufferedInputStream(in));
// Read the first line of the response, which should be
// a string representation of the current time
String date = result.readLine();
// Close the InputStream
in.close();
// Return the retrieved time
return date;
}
catch (Exception e) {
// If there was a problem, print to System.out
// (typically the Java console) and return null
e.printStackTrace();
return null;
}
}
private String getDateUsingHttpObject() {
try {
// Construct a URL referring to the servlet
URL url = new URL(getCodeBase(), "/servlet/DaytimeServlet");
// Create a com.oreilly.servlet.HttpMessage to communicate with that URL
HttpMessage msg = new HttpMessage(url);
// Construct a Properties list to say format=object
Properties props = new Properties();
props.put("format", "object");
// Send a GET message to the servlet, passing "props" as a query string
// Get the response as an ObjectInputStream
InputStream in = msg.sendGetMessage(props);
ObjectInputStream result = new ObjectInputStream(in);
// Read the Date object from the stream
Object obj = result.readObject();
Date date = (Date)obj;
// Return the string representation of the Date
return date.toString();
}
catch (Exception e) {
// If there was a problem, print to System.out
// (typically the Java console) and return null
e.printStackTrace();
return null;
}
}
private int getSocketPort() {
try { return Integer.parseInt(getParameter("socketPort")); }
catch (NumberFormatException e) { return DEFAULT_PORT; }
}
private String getDateUsingSocketText() {
InputStream in = null;
try {
// Establish a socket connection with the servlet
Socket socket = new Socket(getCodeBase().getHost(), getSocketPort());
// Print an empty line, indicating we want the time as plain text
PrintStream out = new PrintStream(socket.getOutputStream());
out.println();
out.flush();
// Read the first line of the response
// It should contain the current time
in = socket.getInputStream();
DataInputStream result =
new DataInputStream(new BufferedInputStream(in));
String date = result.readLine();
// Return the retrieved string
return date;
}
catch (Exception e) {
// If there was a problem, print to System.out
// (typically the Java console) and return null
e.printStackTrace();
return null;
}
finally {
// Always close the connection
// This code executes no matter how the try block completes
if (in != null) {
try { in.close(); }
catch (IOException ignored) { }
}
}
}
private String getDateUsingSocketObject() {
InputStream in = null;
try {
// Establish a socket connection with the servlet
Socket socket = new Socket(getCodeBase().getHost(), getSocketPort());
// Print a line saying "object", indicating we want the time as
// a serialized Date object
PrintStream out = new PrintStream(socket.getOutputStream());
out.println("object");
out.flush();
// Create an ObjectInputStream to read the response
in = socket.getInputStream();
ObjectInputStream result =
new ObjectInputStream(new BufferedInputStream(in));
// Read an object, and cast it to be a Date
Object obj = result.readObject();
Date date = (Date)obj;
// Return a string representation of the retrieved Date
return date.toString();
}
catch (Exception e) {
// If there was a problem, print to System.out
// (typically the Java console) and return null
e.printStackTrace();
return null;
}
finally {
// Always close the connection
// This code executes no matter how the try block completes
if (in != null) {
try { in.close(); }
catch (IOException ignored) { }
}
}
}
private String getRegistryHost() {
return getCodeBase().getHost();
}
private int getRegistryPort() {
try { return Integer.parseInt(getParameter("registryPort")); }
catch (NumberFormatException e) { return Registry.REGISTRY_PORT; }
}
private String getRegistryName() {
String name = getParameter("registryName");
if (name == null) {
name = "DaytimeServlet"; // default
}
return name;
}
private String getDateUsingRMIObject() {
try {
Registry registry =
LocateRegistry.getRegistry(getRegistryHost(), getRegistryPort());
DaytimeServer daytime =
(DaytimeServer)registry.lookup(getRegistryName());
return daytime.getDate().toString();
}
catch (ClassCastException e) {
System.out.println("Retrieved object was not a DaytimeServer: " +
e.getMessage());
}
catch (NotBoundException e) {
System.out.println(getRegistryName() + " not bound: " + e.getMessage());
}
catch (RemoteException e) {
System.out.println("Hit remote exception: " + e.getMessage());
}
catch (Exception e) {
System.out.println("Problem getting DaytimeServer reference: " +
e.getClass().getName() + ": " + e.getMessage());
}
return null;
}
public boolean handleEvent(Event event) {
// When the refresh button is pushed, refresh the display
// Use JDK 1.0 events for maximum portability
switch (event.id) {
case Event.ACTION_EVENT:
if (event.target == refresh) {
refresh();
return true;
}
}
return false;
}
}
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