MIDP高级UI的使用（三）TextBox

MIDP高级UI的使用（三）TextBox2009-10-10 博客园农民学编程当我们需要再移动设备上输入数据时，TextBox 就派上用场了，我们使用的TextBox 构造函数参数共有四个，TextBox textbox = new TextBox（string title, string content, string maxLength, string limitType），第一个是标题，第二个是TextBox 的初始内容，第三个是允许输入字符的最大长度，第四个是限制内型。值得注意的是：一个TextBox 必须附加一个命令，否则用户将不能激发任何行为，而陷入这个TextBox 中。

下面是一个常见的TextBox 的例子。

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/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package com.thinkrace.TextBox;
import javax.microedition.lcdui.Choice;
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.TextBox;
import javax.microedition.lcdui.TextField;
import javax.microedition.lcdui.Ticker;
import javax.microedition.midlet.*;
/**
 * @author pengjw
 */
public class TextBoxDemo extends MIDlet implements CommandListener{
  private Display display;
  private ChoiceGroup types;
  private ChoiceGroup options;
  private Form mainForm;
  private static final Command CMD_EXIT = new Command（"Exit", Command.EXIT, 1）;
  private static final Command CMD_BACK = new Command（"Back", Command.BACK, 1）;
  private static final Command CMD_SHOW = new Command（"Show", Command.SCREEN ,1）;
  private static final String[] textBoxLabels ={
    "Any Character", "Email", "Number", "Decimal", "Phone", "URL"
  };
  private static final int[] textBoxTypes ={
    TextField.ANY, TextField.EMAILADDR, TextField.NUMERIC,
    TextField.DECIMAL, TextField.PHONENUMBER, TextField.URL
  };
  //firstTime用来判断TextBoxDemo是否被实例化 
  private boolean firstTime;
  public TextBoxDemo（）{
    /**
     * 来自文档的说明 
     * Display represents the manager of the display and input devices of the system. 
     * It includes methods for retrieving properties of the device and for requesting that objects be displayed on the device. 
     * There is exactly one instance of Display per MIDlet and the application can get 
     * a reference to that instance by calling the getDisplay（） method. 
     */
    display = Display.getDisplay（this）;
    firstTime = true;
  }
  public void startApp（） {
    if（firstTime）{
      mainForm = new Form（"Select a Text Box Type"）;
      mainForm.append（"select a textbox type"）;
      types = new ChoiceGroup（"Choice Type", Choice.EXCLUSIVE, textBoxLabels, null）;
      mainForm.append（types）;
      String[] optionStrings = {"As Password", "Show Ticker"};
      options = new ChoiceGroup（"Options", Choice.MULTIPLE, optionStrings, null）;
      mainForm.append（options）;
      mainForm.addCommand（CMD_EXIT）;
      mainForm.addCommand（CMD_SHOW）;
      mainForm.setCommandListener（this）;
      firstTime = false;
    }
    //设置当前显示的窗体
    display.setCurrent（mainForm）;
  }
  public void pauseApp（） {
  }
  public void destroyApp（boolean unconditional） {
  }
  /**
   * 实现CommandListener接口的抽象方法
   * 根据不同的Command做不同的事情
   */
  public void commandAction（Command c, Displayable d） {
    if（c == CMD_EXIT）{
      destroyApp（false）;
      notifyDestroyed（）;
    }
    else if（c == CMD_SHOW）{
      int Index = types.getSelectedIndex（）;
      String title = textBoxLabels[Index];
      int choiceType = textBoxTypes[Index];
      boolean[] flags = new boolean[2];
      /** 
       * 来自文档的说明，这个方法可以给一个bool数组赋值 
       * Query the state of a choicegroup and renturns the state of all elements in the boolean array. 
       */
      options.getSelectedFlags（flags）;
      if（flags[0]）{
        choiceType = TextField.PASSWORD;
      }
      TextBox textBox = new TextBox（title,"",50,choiceType）;
      if（flags[1]）{
        textBox.setTicker（new Ticker（"TextBox:" + title））;
      }
      textBox.addCommand（CMD_BACK）;
      textBox.setCommandListener（this）;
      display.setCurrent（textBox）;
    }
    else if（c == CMD_BACK）{
      display.setCurrent（mainForm）;
    }
  }
}