Android UI设计系列之自定义EditText实现带清除功能的输入框(3)

public class ClearEditText extends EditText implements TextWatcher, 
    OnFocusChangeListener { 
 
  /** 
   * 左右两侧图片资源 
   */ 
  private Drawable left, right; 
  /** 
   * 是否获取焦点，默认没有焦点 
   */ 
  private boolean hasFocus = false; 
  /** 
   * 手指抬起时的X坐标 
   */ 
  private int xUp = 0; 
   
  public ClearEditText(Context context) { 
    this(context, null); 
  } 
 
  public ClearEditText(Context context, AttributeSet attrs) { 
    this(context, attrs, android.R.attr.editTextStyle); 
  } 
 
  public ClearEditText(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    initWedgits(); 
  } 
 
  /** 
   * 初始化各组件 
   * @param attrs 
   *      属性集 
   */ 
  private void initWedgits() { 
    try { 
      // 获取drawableLeft图片，如果在布局文件中没有定义drawableLeft属性，则此值为空 
      left = getCompoundDrawables()[0]; 
      // 获取drawableRight图片，如果在布局文件中没有定义drawableRight属性，则此值为空 
      right = getCompoundDrawables()[2]; 
      initDatas(); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
 
  /** 
   * 初始化数据 
   */ 
  private void initDatas() { 
    try { 
      // 第一次显示，隐藏删除图标 
      setCompoundDrawablesWithIntrinsicBounds(left, null, null, null); 
      addListeners(); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
 
  /** 
   * 添加事件监听 
   */ 
  private void addListeners() { 
    try { 
      setOnFocusChangeListener(this); 
      addTextChangedListener(this); 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
 
  @Override 
  public void beforeTextChanged(CharSequence s, int start, int count, 
      int after) { 
  } 
 
  @Override 
  public void onTextChanged(CharSequence s, int start, int before, int after) { 
    if (hasFocus) { 
      if (TextUtils.isEmpty(s)) { 
        // 如果为空，则不显示删除图标 
        setCompoundDrawablesWithIntrinsicBounds(left, null, null, null); 
      } else { 
        // 如果非空，则要显示删除图标 
        if (null == right) { 
          right = getCompoundDrawables()[2]; 
        } 
        setCompoundDrawablesWithIntrinsicBounds(left, null, right, null); 
      } 
    } 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent event) { 
    try { 
      switch (event.getAction()) { 
      case MotionEvent.ACTION_UP: 
        // 获取点击时手指抬起的X坐标 
        xUp = (int) event.getX(); 
        // 当点击的坐标到当前输入框右侧的距离小于等于getCompoundPaddingRight()的距离时，则认为是点击了删除图标 
        // getCompoundPaddingRight()的说明：Returns the right padding of the view, plus space for the right Drawable if any. 
        if ((getWidth() - xUp) <= getCompoundPaddingRight()) { 
          if (!TextUtils.isEmpty(getText().toString())) { 
            setText(""); 
          } 
        } 
        break; 
      default: 
        break; 
      } 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
    return super.onTouchEvent(event); 
  } 
 
  @Override 
  public void afterTextChanged(Editable s) { 
  } 
 
  @Override 
  public void onFocusChange(View v, boolean hasFocus) { 
    try { 
      this.hasFocus = hasFocus; 
    } catch (Exception e) { 
      e.printStackTrace(); 
    } 
  } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android" 
  android:orientation="vertical" 
  android:layout_width="fill_parent" 
  android:layout_height="fill_parent" 
  android:background="#ffffff"> 
  <TextView 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:layout_margin="10dip" 
    android:text="@string/hello" 
    android:gravity="center" 
    android:textSize="20sp" 
    android:textColor="#000000" /> 
   
  <com.llew.e.clear.view.wedgit.ClearEditText 
    android:id="@+id/clearEditText" 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:layout_margin="10dip" 
    android:paddingRight="8dip" 
    android:paddingTop="5dip" 
    android:paddingBottom="5dip" 
    android:hint="请输入QQ号码" 
    android:background="@drawable/pay_widget_input" 
    android:drawableLeft="@drawable/super_qq" 
    android:drawableRight="@drawable/clear_normal_list" /> 
 
</LinearLayout> 

public class MainActivity extends Activity { 
  /** Called when the activity is first created. */ 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
  } 
}