httplogger.java

《精通JAVA手机游戏与应用程序设计》随书光盘

package HttpThread;

import java.io.*;

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.io.*;

public class HttpLogger extends MIDlet {

	private Display display;

	private Command exitCommand = new Command("Exit", Command.EXIT, 1);

	private Command okCommand = new Command("OK", Command.OK, 1);

	private Command cancelCommand = new Command("Cancel", Command.CANCEL, 1);

	private URLEntry mainForm;

	public HttpLogger() {
	}

	protected void destroyApp(boolean unconditional)
			throws MIDletStateChangeException {
		exitMIDlet();
	}

	protected void pauseApp() {
	}

	protected void startApp() throws MIDletStateChangeException {
		if (display == null) {
			initMIDlet();
		}
	}

	private void initMIDlet() {
		display = Display.getDisplay(this);
		mainForm = new URLEntry();
		display.setCurrent(mainForm);
	}

	public void exitMIDlet() {
		notifyDestroyed();
	}

	// 显示错误信息

	void displayError(Throwable e, Displayable next) {
		Alert a = new Alert("Exception");
		a.setString(e.toString());
		a.setTimeout(Alert.FOREVER);
		display.setCurrent(a, next);
	}

	// 输入URL

	class URLEntry extends TextBox implements CommandListener {

		URLEntry() {
			super("Enter URL:", "http://127.0.0.1:8080/HelloWorld.html", 100, 0);
			addCommand(exitCommand);
			addCommand(okCommand);
			setCommandListener(this);
		}

		public void commandAction(Command c, Displayable d) {
			if (c == exitCommand) {
				exitMIDlet();
			} else if (c == okCommand) {

				Logger f = new Logger(this, getString());
				Thread t = new Thread(f);
				t.start();
				display.setCurrent(f);

			}
		}
	}

	// 连接网络的新线程

	class Logger extends Form implements Runnable, CommandListener {
		private Displayable next;

		private HttpConnection conn;

		private String url;

		private StringItem text = new StringItem(null, "");

		Logger(Displayable next, String url) {
			super("HTTP 信息");

			this.url = url;
			this.next = next;

			addCommand(cancelCommand);
			setCommandListener(this);
			append(text);

		}

		public void commandAction(Command c, Displayable d) {
			display.setCurrent(next);

			try {
				conn.close();
			} catch (IOException e) {
				displayError(e, next);
			}
		}

		public void run() {
			//创建一个连接不要放在构造函数中
			try {
				conn = (HttpConnection) Connector.open(url);
			} catch (IOException e) {
				e.printStackTrace();
			}

			update("连接到" + conn.getURL());

			try {
				int rc = conn.getResponseCode();
				update("Response code: " + rc);
				update("Response message: " + conn.getResponseMessage());

				String key;

				for (int i = 0; (key = conn.getHeaderFieldKey(i)) != null; ++i) {
					update(key + ": " + conn.getHeaderField(i));
				}
			} catch (IOException e) {
				update("获得的异常: " + e.toString());
			}

			removeCommand(cancelCommand);
			addCommand(okCommand);
		}

		// 使用string item显示获得的信息

		void update(String line) {
			if (display.getCurrent() != this)
				return;

			String old = text.getText();
			StringBuffer buf = new StringBuffer();

			buf.append(old);
			if (old.length() > 0) {
				buf.append('\n');
			}

			buf.append(line);
			text.setText(buf.toString());
		}
	}
}