maindisplayable.java

《Java程序设计实践教程》代码

/***************************************************
*  程序文件名称：　mainDisplayable.java
*  功能：用户操作界面显示模块
***************************************************/
import javax.microedition.lcdui.*;

		//窗口初始化
  public class mainDisplayable extends Form implements CommandListener {
  	//设置滚动消息窗口
  	Ticker t; 								
  	//定义退出按纽
  	private Command exitCommand;        
  	//定义查询菜单项
  	private Command newSearchCommand;   
  	//定义前一次查询菜单项
  	private Command preSearchCommand;    
  	//定义关于的帮助菜单项
  	private Command aboutCommand;       
  	//定义提示对话框
  	private Alert alert;                  
  	//定义图片对象
  	private Image img;                 
	//定义图片列表
	private ImageItem imgItem;			


  public mainDisplayable() {
    super("地区天气信息");
    t = new Ticker("您好，欢迎使用天气信息系统，请从菜单选择：");
    this.setTicker(t);
    //设置退出按纽
    exitCommand = new Command("退出",Command.EXIT,2);
    //设置菜单项
    newSearchCommand = new Command("新的查询",Command.SCREEN,1);
    preSearchCommand = new Command("上次查询",Command.SCREEN,1);
    aboutCommand = new Command("关于",Command.HELP,1);
    this.addCommand(exitCommand);
    this.addCommand(newSearchCommand);
    this.addCommand(preSearchCommand);
    this.addCommand(aboutCommand);
    try {
      imgInit();
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }

    this.setCommandListener(this);
    String about = "地区天气信息系统\n"+
                   "联系方式：   \n"+
                   " QQ：42987826";
    //设置提示对话框
    alert = new Alert("关于",about,img,AlertType.INFO);
    alert.setTimeout(Alert.FOREVER);
  }
  public void commandAction(Command command, Displayable displayable) {
    if(command==exitCommand){
        //退出查询系统
      Info_client.quitApp();
    }
    else if(command==newSearchCommand){
        //调用查询界面模块
      Info_client.instance.newDisplay = new newDisplayable();
      Info_client.instance.display.setCurrent(Info_client.instance.newDisplay);
    }
    else if (command==preSearchCommand){
      //显示前一次查询的结果
      Info_client.instance.display.setCurrent(Info_client.instance.preDisplay);
    }
    else if (command==aboutCommand){
      //调用Alert对话框显示帮助
      Info_client.instance.display.setCurrent(alert);
    }
  }

  	//显示主界面图片
  private void imgInit() throws Exception {
    img = img.createImage("/dlpopinco.png");
    imgItem=new ImageItem("", img,ImageItem.LAYOUT_CENTER,"Image Cannot be shown");
    this.append(imgItem);

  }
}