Android本地验证码的简易实现方法（防止暴力登录）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:myattribute="http://schemas.android.com/apk/res-auto" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" > 
 <com.calvin.verification_code.MyView 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_centerInParent="true" 
  android:padding="10dp" 
  myattribute:text="0 0 0 0 " 
  myattribute:textcolor="#000" 
  myattribute:textsize="40sp" 
  android:id="@+id/myView" /> 
 <EditText 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:inputType="number" 
  android:hint="刷新后输入" 
  android:layout_below="@+id/myView" 
  android:layout_centerHorizontal="true" 
  android:layout_marginTop="20dp" 
  android:id="@+id/editText" /> 
 <Button 
  android:text="确认" 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_alignBottom="@+id/editText" 
  android:layout_alignParentEnd="true" 
  android:layout_marginEnd="10dp" 
  android:id="@+id/button" /> 
</RelativeLayout> 

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
 <declare-styleable name="MyView"> 
  <attr name="text" format="string"/> 
  <attr name="textcolor" format="color"/> 
  <attr name="textsize" format="dimension"/> 
 </declare-styleable> 
</resources> 

public MyView(Context context, AttributeSet attrs, int defStyle) { 
  super(context, attrs, defStyle); 
  TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.MyView); 
  for (int i = 0; i < a.getIndexCount(); i++) { 
   int attr = a.getIndex(i); 
   switch (attr) { 
    case R.styleable.MyView_text: 
     mText = a.getString(attr); 
     break; 
    case R.styleable.MyView_textcolor: 
     //二参为默认颜色 
     mTextColor = a.getColor(attr, Color.BLACK); 
     break; 
    case R.styleable.MyView_textsize: 
     // 默认字体大小为16sp，TypeValue把sp转化为px 
     mTextSize = a.getDimensionPixelSize(attr, 
       (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 
         16, getResources().getDisplayMetrics())); 
     break; 
   } 
  } 
  a.recycle(); 
  mPaint = new Paint(); 
  mPaint.setTextSize(mTextSize); 
  mBound = new Rect(); 
  //获得绘制文本的宽和高 
  mPaint.getTextBounds(mText, 0, mText.length(), mBound); 
  this.setOnClickListener(new OnClickListener() { 
   @Override 
   public void onClick(View v) { 
    //生成一个随机的四位数字，并发送一个自定义广播 
    mText = randomText(); 
    postInvalidate(); 
   } 
  }); 
 } 

@Override  
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
  int width = 0; 
  int height = 0; 
  int specMode = MeasureSpec.getMode(widthMeasureSpec); 
  int specSize = MeasureSpec.getSize(widthMeasureSpec); 
  switch (specMode) { 
   case MeasureSpec.EXACTLY: 
    width = getPaddingLeft() + getPaddingRight() + specSize; 
    break; 
   case MeasureSpec.AT_MOST: 
    width = getPaddingLeft() + getPaddingRight() + mBound.width(); 
    break; 
  } 
  //同样逻辑处理高 
  setMeasuredDimension(width, height); 
} 
 @Override 
 protected void onDraw(Canvas canvas) { 
  mPaint.setColor(Color.YELLOW); 
  canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint); 
  mPaint.setColor(mTextColor); 
  canvas.drawText(mText, getWidth() / 2 - mBound.width() / 2, getHeight() / 2 + mBound.height() / 2, mPaint); 
  Random random = new Random(); 
  for(int i = 0; i <= 3; i++){ 
   int temp = random.nextInt(colors.length); 
   mPaint.setColor(colors[temp]); 
   mPaint.setStrokeWidth(3); 
   canvas.drawLine(randomStartWidth(),randomStartHeight(),randomEndWidth(),randomEndHeight(),mPaint); 
  } 
 } 

Intent intent = new Intent(); 
intent.setAction("com.seu_calvin.update"); 
intent.putExtra("data", sb.toString()); 
getContext().sendBroadcast(intent);