<?xml version="1.0" encoding="utf-8"?>
<resources><declare-styleable name="MyTextView"><attr name="titleText" format="string"/><attr name="titleTextColor" format="color"/><attr name="titleTextSize" format="dimension"/></declare-styleable>
</resources>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:custom="http://schemas.android.com/apk/res/com.qianmo.VerificationCode"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"><com.qianmo.VerificationCode.view.MyTextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:padding="100dp"custom:titleText="3712"custom:titleTextColor="#ff0000"android:layout_centerInParent="true"custom:titleTextSize="40sp"/></RelativeLayout>

package com.qianmo.VerificationCode.view;import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.util.TypedValue;
import android.view.View;import com.qianmo.VerificationCode.R;import java.util.HashSet;
import java.util.Random;
import java.util.Set;/*** Created by wangjitao on 2016/10/13 0013.* 用于实现获取随机码*/
public class MyTextView extends View {/*** 由于是自定义的View，首先我们要确定那些属性是用户可以自己定义的* 1，View里面显示的字* 2，显示字的大小* 3，显示字的颜色*/private String mTitleText;private int mTitleTextColor;private int mTitleTextSize;/*** 画笔*/private Paint mPaint;/*** view的矩形背景*/private Rect mBound;public MyTextView(Context context) {this(context, null);}public MyTextView(Context context, AttributeSet attrs) {this(context, attrs, 0);}/*** 获得自定义的属性** @param context* @param attrs* @param defStyleAttr*/public MyTextView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);/*** 获得我们自定义的一些属性*/TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.MyTextView, defStyleAttr, 0);mTitleText = randomText(); //初始化显示的数字for (int i = 0; i < a.getIndexCount(); i++) {int attr = a.getIndex(i);switch (attr) {case R.styleable.MyTextView_titleText:mTitleText = a.getString(attr);break;case R.styleable.MyTextView_titleTextColor:mTitleTextColor = a.getColor(attr, Color.BLACK);break;case R.styleable.MyTextView_titleTextSize://设置默认大小为16mTitleTextSize = a.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));break;}}//将TypedArray对象回收a.recycle();/*** 初始化画笔*/mPaint = new Paint();mPaint.setAntiAlias(true);mPaint.setTextSize(mTitleTextSize);mPaint.setColor(mTitleTextColor);mBound = new Rect();mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);/*** 模仿点击换验证码*/this.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View view) {mTitleText = randomText();postInvalidate();}});}/*** 获取四位随机数验证码** @return*/private String randomText() {Random random = new Random();Set<Integer> set = new HashSet<Integer>();while (set.size() < 4) {int randomInt = random.nextInt(10);set.add(randomInt);}StringBuffer sb = new StringBuffer();for (Integer i : set) {sb.append("" + i);}return sb.toString();}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {/*** 处理当宽高都是wrap_content的情况*/int widthMode = MeasureSpec.getMode(widthMeasureSpec);int widthSize = MeasureSpec.getSize(widthMeasureSpec);int heightMode = MeasureSpec.getMode(heightMeasureSpec);int heightSize = MeasureSpec.getSize(heightMeasureSpec);int width = 0;int height = 0;if (widthMode == MeasureSpec.EXACTLY) {width = widthSize;} else {mPaint.setTextSize(mTitleTextSize);mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);float textWidth = mBound.width();int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight());width = desired;}if (heightMode == MeasureSpec.EXACTLY) {height = heightSize;} else {mPaint.setTextSize(mTitleTextSize);mPaint.getTextBounds(mTitleText, 0, mTitleText.length(), mBound);float textWidth = mBound.height();int desired = (int) (getPaddingTop() + textWidth + getPaddingBottom());height = desired;}setMeasuredDimension(width, height);}@Overrideprotected void onDraw(Canvas canvas) {/*** 绘制文字和矩形*/mPaint.setColor(Color.YELLOW);canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);mPaint.setColor(mTitleTextColor);canvas.drawText(mTitleText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint);}
}