alertdemo.java

来自「j2me学习 简单例子」· Java 代码 · 共 188 行

package example.demoseniorui.alert;

import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
import javax.microedition.lcdui.ChoiceGroup;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Gauge;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

/**
 * <p>J2ME Alert Demo</p>
 * 
 * @author 刘光辉
 * @version 2009.01.23
 */
public class AlertDemo extends MIDlet {

	private static final int SECOND = 1000;
	private static final Command CMD_EXIT = new Command("Exit", Command.EXIT, 1);
	private static final Command CMD_SHOW = new Command("Show", Command.SCREEN,
			1);
	private static final String[] typeStrings = { "Alarm", "Confirmation",
			"Error", "Info", "Warning" };
	private static final String[] timeoutStrings = { "2 Seconds", "4 Seconds",
			"8 Seconds", "Forever" };
	private Display display;
	private boolean firstTime;
	private Form mainForm;

	/**
	 * <p>AlertDemo的构造函数</p>
	 */
	public AlertDemo() {
		firstTime = true;
		mainForm = new Form("Alert Options");
	}

	/**
	 * <p>启动程序,使MIDlet处于active状态</p>
	 * @see javax.microedition.midlet.MIDlet#startApp()
	 */
	protected void startApp() throws MIDletStateChangeException {
		display = Display.getDisplay(this);
		showOption();
	}

	/**
	 * <p>创建这个MIDlet的基本显示</p>
	 * <p>在这个方法里可以选择Alert的类型和特性</p>
	 */
	private void showOption() {
		if (firstTime) {
			ChoiceGroup types = new ChoiceGroup("Types", ChoiceGroup.POPUP,
					typeStrings, null);
			mainForm.append(types);

			ChoiceGroup timeouts = new ChoiceGroup("Timeouts",
					ChoiceGroup.POPUP, timeoutStrings, null);
			mainForm.append(timeouts);

			String[] optionStrings = { "Show Indicator" };
			ChoiceGroup options = new ChoiceGroup("Options", ChoiceGroup.POPUP,
					optionStrings, null);
			mainForm.append(options);

			mainForm.addCommand(CMD_SHOW);
			mainForm.addCommand(CMD_EXIT);
			mainForm.setCommandListener(new AlertListener(types, timeouts,
					options));

			firstTime = false;
		}
		display.setCurrent(mainForm);
	}

	/**
	 * <p>暂停程序,使MIDlet处于pause状态</p>
	 * @see javax.microedition.midlet.MIDlet#pauseApp()
	 */
	protected void pauseApp() {

	}

	/**
	 * <p>销毁程序,使MIDlet处于destroyed状态</p>
	 * 
	 * @param boolean unconditional 
	 * <ul>true 释放资源保存数据进入destroyed状态,false 抛出异常保持当前状态</ul>
	 * @see javax.microedition.midlet.MIDlet#destroyApp(boolean)
	 */
	protected void destroyApp(boolean arg0) throws MIDletStateChangeException {

	}

    private Gauge createIndicator(int maxValue) {
        if (maxValue == Alert.FOREVER) {
            return new Gauge(null, false, Gauge.INDEFINITE, Gauge.CONTINUOUS_RUNNING);
        }

        final int max = maxValue / SECOND;
        final Gauge indicator = new Gauge(null, false, max, 0);

        //        if (maxValue != Gauge.INDEFINITE) {
        new Thread() {
                public void run() {
                    int value = 0;

                    while (value < max) {
                        indicator.setValue(value);
                        ++value;

                        try {
                            Thread.sleep(1000);
                        } catch (InterruptedException ie) {
                            // ignore
                        }
                    }
                }
            }.start();

        //        }
        return indicator;
    }
    
	class AlertListener implements CommandListener {

		AlertType[] alertTypes = { AlertType.ALARM, AlertType.CONFIRMATION,
				AlertType.ERROR, AlertType.INFO, AlertType.WARNING };
		ChoiceGroup typesCG;
		int[] timeouts = { 2 * SECOND, 4 * SECOND, 8 * SECOND, Alert.FOREVER };
		ChoiceGroup timeoutsCG;
		ChoiceGroup indicatorCG;

		/**
		 * <p>AlertListener的构造函数</p>
		 * @param ChoiceGroup types 类型
		 * @param ChoiceGroup timeouts 时间间隔
		 * @param ChoiceGroup indicator 跳转指向
		 */
		public AlertListener(ChoiceGroup types, ChoiceGroup timeouts,
				ChoiceGroup indicator) {
			typesCG = types;
			timeoutsCG = timeouts;
			indicatorCG = indicator;
		}

		/**
		 * <p>命令处理函数,实现commandListener接口</p>
		 * @param Command c 命令对象
		 * @param Displayable d 被放置到显示屏显示的对象
		 */
		public void commandAction(Command c, Displayable d) {
			if (c == CMD_SHOW) {
				int typeIndex = typesCG.getSelectedIndex();
				Alert alert = new Alert("Alert");
				alert.setType(alertTypes[typeIndex]);

				int timeoutIndex = timeoutsCG.getSelectedIndex();
				alert.setTimeout(timeouts[timeoutIndex]);
				alert.setString(typeStrings[typeIndex] + " Alert, Running "
						+ timeoutStrings[timeoutIndex]);

				boolean[] SelectedFlags = new boolean[1];
				indicatorCG.getSelectedFlags(SelectedFlags);

				if (SelectedFlags[0]) {
					Gauge indicator = createIndicator(timeouts[timeoutIndex]);
					alert.setIndicator(indicator);
				}

				display.setCurrent(alert);
			} else if (c == CMD_EXIT) {
				try {
					destroyApp(false);
				} catch (MIDletStateChangeException e) {
					e.printStackTrace();
				}
				notifyDestroyed();
			}
		}

	}
}