目的：
有时候在做搜索功能时，如果EditText有内容，则在右侧显示一个删除图标，点击删除图标删除内容；

当EditText内容为空时，则隐藏删除图标。
效果图：

edittext.gif

p.s. 这是我正在做的一个毕业设计，Android + JavaWeb。前端app，后台都会有。我每天会往Github上提交代码，这个上面会有完整的项目。欢迎star，fork。GitHub：https://github.com/uweii/SHShop

/*
* 自定义EditText，有文字时，右边显示删除按钮
* 没有文字时，隐藏删除按钮
* */
public class ClearTextEditText extends AppCompatEditText implements View.OnFocusChangeListener, TextWatcher {
  private Drawable mClearDrawable;
  private boolean hasFocus; //控件是否有焦点
  public ClearTextEditText(Context context) {
      super(context);
      init(context, null);
  }

  public ClearTextEditText(Context context, AttributeSet attrs) {
      super(context, attrs);
      init(context, attrs);
  }

  public ClearTextEditText(Context context, AttributeSet attrs, int defStyleAttr) {
      super(context, attrs, defStyleAttr);
      init(context, attrs);
  }
  private void init(Context context, AttributeSet attr){
      mClearDrawable = getCompoundDrawables()[2];
      if(mClearDrawable == null){
          mClearDrawable = getResources().getDrawable(R.drawable.del_icon);
      }
      //drawable.setBounds ：设置Drawable的边界，必须要有
      mClearDrawable.setBounds(0,0, mClearDrawable.getIntrinsicWidth(), mClearDrawable.getIntrinsicHeight());
      setOnFocusChangeListener(this);
      addTextChangedListener(this);
  }

  @Override
  public void onFocusChange(View view, boolean b) {
      this.hasFocus = b;
      LogUtil.d("hasFocus: " + b);
      if (hasFocus){
          //焦点存在，而且有输入值，显示右侧删除图标
          setDrawableRightVisible(getText().length() > 0);
      }else {
          //没有焦点，隐藏删除图标
          setDrawableRightVisible(false);
          clearFocus();
      }
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
      if(event.getAction() == MotionEvent.ACTION_UP){
          if(getCompoundDrawables()[2] != null){
              //根据触摸的位置判断是否点击 右侧图标
              boolean isTouchRight = (event.getX() > (getWidth() - getTotalPaddingRight())) &&
                      (event.getX() < (getWidth() - getPaddingRight()));
              //LogUtil.d("isTouchRight： " + isTouchRight);
              if(isTouchRight){
                  setText("");
              }
          }
      }
      return super.onTouchEvent(event);
  }

  private void setDrawableRightVisible(boolean visible){
      Drawable drawableRight = visible ? mClearDrawable : null;
      //getCompoundDrawables()可以获得一个{DrawableLeft, DrawableTop, DrawableRiht, DrawableBottom}的数组。
      //getCompoundDrawables()[2]表示获取EditText的DrawableRight
      setCompoundDrawables(getCompoundDrawables()[0],getCompoundDrawables()[1], drawableRight, getCompoundDrawables()[3]);
  }

  @Override
  public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
      if(mOnTextChangedListener != null){
          mOnTextChangedListener.beforeTextChanged(charSequence, i, i1, i2);
      }
  }

  @Override
  public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
      if(hasFocus){
          setDrawableRightVisible(charSequence.length() > 0);
      }
      if(mOnTextChangedListener != null){
          mOnTextChangedListener.onTextChanged(charSequence, i, i1, i2);
      }
  }

  @Override
  public void afterTextChanged(Editable editable) {
      if(mOnTextChangedListener != null){
          mOnTextChangedListener.afterTextChanged(editable);
      }
  }
  //文本改变接口监听
  public interface OnTextChangedListener{
      void beforeTextChanged(CharSequence s, int start, int count, int after);

      void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter);

      void afterTextChanged(Editable s);
  }
  private OnTextChangedListener mOnTextChangedListener;
  public void setOnTextChangedListener(OnTextChangedListener onTextChangedListener){
      this.mOnTextChangedListener = onTextChangedListener;
  }

}

现在我们就使用这个自定义控件：

 <com.up.uwei.shshop.view.ClearTextEditText
                android:id="@+id/et_search"
                android:layout_width="0dp"
                android:layout_height="40dp"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="5dp"
                android:layout_weight="5"
                android:background="@drawable/bg_input"
                android:drawableLeft="@drawable/ic_search"
                android:gravity="center_vertical"
                android:hint="输入搜索"
                android:textColor="@color/search_hint"
                android:textSize="15sp" />

就可以咯、