Android开发实现带清空按钮的EditText示例

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.support.v4.content.ContextCompat;
import android.support.v4.graphics.drawable.DrawableCompat;
import android.support.v7.widget.AppCompatEditText;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import com.gdc.control.R;
public class ClearableEditText extends AppCompatEditText implements View.OnTouchListener, View.OnFocusChangeListener, TextWatcher {
  private Drawable       clearTextIcon;
  private OnFocusChangeListener mOnFocusChangeListener;
  private OnTouchListener    mOnTouchListener;
  private boolean canClear = false;
  public ClearableEditText(final Context context) {
    super(context);
    init(context);
  }
  public ClearableEditText(final Context context, final AttributeSet attrs) {
    super(context, attrs);
    init(context);
  }
  public ClearableEditText(final Context context, final AttributeSet attrs,
      final int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context);
  }
  @Override
  public void setOnFocusChangeListener(final OnFocusChangeListener
      onFocusChangeListener) {
    mOnFocusChangeListener = onFocusChangeListener;
  }
  @Override
  public void setOnTouchListener(final OnTouchListener onTouchListener) {
    mOnTouchListener = onTouchListener;
  }
  private void init(final Context context) {
    final Drawable drawable = ContextCompat.getDrawable(context, R.drawable.ic_clear_edittext);
    final Drawable wrappedDrawable = DrawableCompat.wrap(drawable);
    DrawableCompat.setTint(wrappedDrawable, getCurrentHintTextColor());
    clearTextIcon = wrappedDrawable;
    clearTextIcon.setBounds(0, 0, clearTextIcon.getIntrinsicWidth(),
        clearTextIcon.getIntrinsicHeight());
    setClearIconVisible(false);
    super.setOnTouchListener(this);
    super.setOnFocusChangeListener(this);
    addTextChangedListener(this);
  }
  @Override
  public void onFocusChange(final View view, final boolean hasFocus) {
    if (hasFocus) {
      setClearIconVisible(getText().length() > 0);
    } else {
      setClearIconVisible(false);
      setCanClear(true);
    }
    if (mOnFocusChangeListener != null) {
      mOnFocusChangeListener.onFocusChange(view, hasFocus);
    }
  }
  @Override
  public boolean onTouch(final View view, final MotionEvent motionEvent) {
    final int x = (int) motionEvent.getX();
    if (x > getWidth() - getPaddingRight() - clearTextIcon.getIntrinsicWidth()) {
      if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
        if (clearTextIcon.isVisible()) {
          setError(null);
          setText("");
        } else if (isCanClear()) {
          setCanClear(false);
          setError(null);
          setText("");
        }
      }
      return true;
    } else {
      return mOnTouchListener != null && mOnTouchListener.onTouch(view,
          motionEvent);
    }
  }
  @Override
  public final void onTextChanged(final CharSequence s, final int start, final
  int before, final int count) {
    if (isFocused()) {
      setClearIconVisible(s.length() > 0);
    }
  }
  @Override
  public void beforeTextChanged(CharSequence s, int start, int count, int after) {
  }
  @Override
  public void afterTextChanged(Editable s) {
  }
  private void setClearIconVisible(final boolean visible) {
    clearTextIcon.setVisible(visible, false);
    final Drawable[] compoundDrawables = getCompoundDrawables();
    setCompoundDrawables(compoundDrawables[0], compoundDrawables[1], visible ?
        clearTextIcon :
        null, compoundDrawables[3]);
  }
  public synchronized boolean isCanClear() {
    return canClear;
  }
  public synchronized void setCanClear(boolean canClear) {
    this.canClear = canClear;
  }
}