Android 自定义属性（点击生成随机数）

布局文件

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"    xmlns:openxu="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent" android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.bwie.test.myview.MainActivity">    <com.bwie.test.myview.MyView        android:layout_width="200dip"        android:layout_height="100dip"        openxu:mTextSize="25sp"        openxu:mText="自定义属性"        openxu:mTextColor="#0000ff"        android:background="#f00"        /></RelativeLayout>
  别忘了写这句，否则不可以调用自定义的属性值
  xmlns:openxu="http://schemas.android.com/apk/res-auto"

在Values文件夹下创建attrs.xml文件
<?xml version="1.0" encoding="utf-8"?><resources>    <attr name="mText" format="string"/>    <attr name="mTextColor" format="color" />    <attr name="mTextSize" format="dimension" />    <declare-styleable name="MyView">        <attr name="mText"/>        <attr name="mTextColor"/>        <attr name="mTextSize"/>    </declare-styleable></resources>
自定义Class类继承View，实现的代码：
public class MyView extends View{    /*文字*/    private String mText;    private int mTextColor;    private int mTextSize;//    绘制文本范围    private Rect mbound;    private Paint mPaint;    public MyView(Context context) {        this(context,null);    }    public MyView(Context context, AttributeSet attrs) {        this(context, attrs,0);    }    /*构造方法里边实例化画笔*/    public MyView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);    /*  //  自定义布局        mText="文字";        mTextColor= Color.BLACK;        mTextSize=100;        mPaint = new Paint();        mPaint.setTextSize(mTextSize);        mPaint.setColor(mTextColor);        *//* 获得绘制文本的宽s和高*//*        mbound = new Rect();        mPaint.getTextBounds(mText,0,mText.length(),mbound);*/        //获取自定义属性的值        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.MyView, defStyleAttr, 0);        mText=a.getString(R.styleable.MyView_mText);        mTextColor=a.getColor(R.styleable.MyView_mTextColor,Color.BLACK);//        mTextSize=(int) a.getDimension(R.styleable.MyView_mTextSize,100); // int,float----可以强转为int        mTextSize=a.getDimensionPixelSize(R.styleable.MyView_mTextSize,100);  //int ,int        a.recycle();//回收        mPaint = new Paint();        mPaint.setTextSize(mTextSize);        mPaint.setColor(mTextColor);//        获得绘制文本的宽和高        mbound = new Rect();        mPaint.getTextBounds(mText,0,mText.length(),mbound);    }    public MyView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {        super(context, attrs, defStyleAttr, defStyleRes);    }    /*测量*/    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);    }    /*绘制*/    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        /* 绘制文字*/        canvas.drawText(mText,getWidth()/2-mbound.width()/2,getHeight()/2-mbound.height()/2,mPaint);    }    //定位    @Override    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {        super.onLayout(changed, left, top, right, bottom);    }    /*点击*/    @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()){            case MotionEvent.ACTION_MOVE:                break;            case MotionEvent.ACTION_DOWN:                /*随机数*/                float a=(float) (Math.random()*10000);                mText=""+a;                invalidate(); //更新视图                break;            case MotionEvent.ACTION_UP:                Log.d("main","抬起");                break;        }        return super.onTouchEvent(event);    }
最后的效果图