Android学习笔记——自定义EditText增加清除功能

运算效果：

实现代码：

import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.text.Editable;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.EditText;

public class CustomEditText extends EditText {
    private Drawable mRight;
    private Rect mBounds;

    public CustomEditText(Context context) {
        super(context);
        init();
    }

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

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

    private void init() {
        setDrawable();
        // 增加文本监听器
        addTextChangedListener(new TextWatcher() {

            @Override
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {

            }

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

            }

            @Override
            public void afterTextChanged(Editable s) {
                setDrawable();
            }
        });
    }

    // 输入框右边的图标显示控制
    private void setDrawable() {
        if (length() == 0) {
            setCompoundDrawables(null, null, null, null);
        } else {
            setCompoundDrawables(null, null, mRight, null);
        }
    }

    @Override
    public void setCompoundDrawables(Drawable left, Drawable top,
            Drawable right, Drawable bottom) {
        if (mRight == null) {
            this.mRight = right;
        }
        super.setCompoundDrawables(left, top, right, bottom);
    }

    // 输入事件处理
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (mRight != null && event.getAction() == MotionEvent.ACTION_UP) {
            this.mBounds = mRight.getBounds();
            int eventX = (int) event.getX();
            int width = mBounds.width();
            int right = getRight();
            if (eventX > (right - 2 * width)) {
                setText("");
                event.setAction(MotionEvent.ACTION_CANCEL);
            }
        }
        return super.onTouchEvent(event);
    }

    @Override
    protected void finalize() throws Throwable {
        super.finalize();
        this.mRight = null;
        this.mBounds = null;
    }

}