android 帶清除按鈕的EditText

Android自帶的EditText沒有清除按鈕，爲了開發需求，需要重寫EditText

public class ClearEditText extends AppCompatEditText implements View.OnFocusChangeListener, TextWatcher {
    /**
     * 刪除按鈕的引用
     */
    private Drawable mClearDrawable;
    private boolean isHideDeleteBtn;
    /**
     * 控件是否有焦點
     */
    private boolean hasFoucs;

    public ClearEditText(Context context) {
        this(context, null);
    }

    public ClearEditText(Context context, AttributeSet attrs) {
        //這裏構造方法也很重要，不加這個很多屬性不能再XML裏面定義
        this(context, attrs, android.R.attr.editTextStyle);
    }

    public ClearEditText(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }


    private void init() {
        if (mClearDrawable == null) {
//          throw new NullPointerException("You can add drawableRight attribute in XML");
            mClearDrawable = getResources().getDrawable(R.drawable.input_delete, null);
        }
        setLongClickable(false);
        setTextIsSelectable(false);
        setCustomSelectionActionModeCallback(new ActionMode.Callback() {
            @Override
            public boolean onCreateActionMode(ActionMode mode, Menu menu) {
                return false;
            }

            @Override
            public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
                return false;
            }

            @Override
            public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
                return false;
            }

            @Override
            public void onDestroyActionMode(ActionMode mode) {

            }
        });

        mClearDrawable.setBounds(0, 0, mClearDrawable.getIntrinsicWidth(), mClearDrawable.getIntrinsicHeight());
        setLongClickable(false);
        setTextIsSelectable(false);
        //默認設置隱藏圖標
        setClearIconVisible(false);
        //設置焦點改變的監聽
        setOnFocusChangeListener(this);
        //設置輸入框裏面內容發生改變的監聽
        addTextChangedListener(this);
    }


    /**
     * 由於不能直接給EditText設置點擊事件，所以用記住我們按下的位置來模擬點擊事件
     * 當我們按下的位置在 EditText的寬度 - 圖標到控件右邊的間距 - 圖標的寬度  和
     * EditText的寬度 - 圖標到控件右邊的間距之間我們就算點擊了圖標，豎直方向就沒有考慮
     */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_UP) {
            if (getCompoundDrawables()[2] != null) {
                boolean touchable = event.getX() > (getWidth() - getTotalPaddingRight())
                        && (event.getX() < ((getWidth() - getPaddingRight())))
                        && event.getY() > getPaddingRight()
                        && event.getY() < (getHeight() - getPaddingRight());
                if (touchable) {
                    this.setText("");
                }
            }
        }
        return super.onTouchEvent(event);
    }

    /**
     * 當ClearEditText焦點發生變化的時候，判斷裏面字符串長度設置清除圖標的顯示與隱藏
     */
    @Override
    public void onFocusChange(View v, boolean hasFocus) {
        this.hasFoucs = hasFocus;
        if (hasFocus) {
            setClearIconVisible(getText().length() > 0);
        } else {
            setClearIconVisible(false);
        }
    }

    /**
     * 設置清除圖標的顯示與隱藏，調用setCompoundDrawables爲EditText繪製上去
     *
     * @param visible
     */
    public void setClearIconVisible(boolean visible) {
        if (isHideDeleteBtn) {
            return;
        }
        Drawable right = visible ? mClearDrawable : null;
        setCompoundDrawables(getCompoundDrawables()[0],
                getCompoundDrawables()[1], right, getCompoundDrawables()[3]);
    }

    public void setHideDeleteBtn(boolean isHide) {
        isHideDeleteBtn = isHide;
    }
    
    /**
     * 當輸入框裏面內容發生變化的時候回調的方法
     */
    @Override
    public void onTextChanged(CharSequence s, int start, int count, int after) {
        if (null == getText()) {
            return;
        }
        if (hasFoucs) {
            setClearIconVisible(getText().length() > 0);
        }
    }

    @Override
    public void beforeTextChanged(CharSequence s, int start, int count, int after) {
    }

    @Override
    public void afterTextChanged(Editable s) {

    }

    @Override
    public boolean onTextContextMenuItem(int id) {
        return true;
    }
}