<declare-styleable name="CustomTitleView">
 <attr name="titleColor" format="color" />
 <attr name="titleSize" format="dimension" />
 <attr name="titleBackground" format="color" />
 <attr name="titleLenth" format="integer" />
 </declare-styleable>

 //文本
 private StringBuffer mTitleText;
 //文本的顏色
 private int mTitleColor;
 //文本的大小
 private int mTitleSize;
 //背景顏色
 private int mBackground;
 //控制生成的隨機(jī)字符串長(zhǎng)度
 private int mLenth;
 //繪制時(shí)控制文本繪制的范圍
 private Rect mBound;
 //畫筆
 private Paint mPaint;
 //隨機(jī)數(shù)對(duì)象
 private Random random = new Random();
 //字符串邊距
 private int padding_left;
 //隨機(jī)的值
 String[] data = {"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
  "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
  "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"};

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

 public CustomTitleView(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
 }

 public CustomTitleView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 setOnClickListener(this);
 TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CustomTitleView);
 int n = typedArray.getIndexCount();
 for (int i = 0; i < n; i++) {
  int attr = typedArray.getIndex(i);
  switch (attr) {
  case R.styleable.CustomTitleView_titleColor:
   mTitleColor = typedArray.getColor(attr, Color.BLACK);
   break;
  case R.styleable.CustomTitleView_titleSize:
   mTitleSize = typedArray.getDimensionPixelSize(attr, (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
   break;
  case R.styleable.CustomTitleView_titleBackground:
   mBackground = typedArray.getColor(attr, Color.BLACK);
   break;
  case R.styleable.CustomTitleView_titleLenth:
   mLenth = typedArray.getInteger(attr, 4);
   break;
  }
 }
 //回收
 typedArray.recycle();
 mPaint = new Paint();
 randomText();
 mPaint.setTextSize(mTitleSize);
 //創(chuàng)建一個(gè)矩形
 mBound = new Rect();
 //第一個(gè)參數(shù)為要測(cè)量的文字，第二個(gè)參數(shù)為測(cè)量起始位置，第三個(gè)參數(shù)為測(cè)量的最后一個(gè)字符串的位置，第四個(gè)參數(shù)為rect對(duì)象
 mPaint.getTextBounds(mTitleText.toString(), 0, mTitleText.length(), mBound);
 }

/**
 * 計(jì)算寬高
 *
 * @param lenth widthMeasureSpec或heightMeasureSpec
 * @param isWidth true為計(jì)算寬度,false為計(jì)算高度
 */
 private int getMeasuredLength(int lenth, boolean isWidth) {
 if (isWidth) {
  if (MeasureSpec.getMode(lenth) == MeasureSpec.EXACTLY) {
  //設(shè)置了精確尺寸,通過(guò)MeasureSpec.getSize()獲得尺寸返回寬度
  return MeasureSpec.getSize(lenth);
  } else {
  //設(shè)置了warp_content，則需要我們自己計(jì)算
  /**
   * 首先給畫筆設(shè)置文字大小
   * 通過(guò)getTextBounds方法獲得繪制的Text的寬度
   * 然后因?yàn)槲覀兊淖远xView只有一個(gè)text所以我們只需要getPaddingLeft()+getPaddingRight()+textwidth即可計(jì)算出顯示出view所需要最小的寬度
   * 一般計(jì)算寬度為getPaddingLeft()+getPaddingRight()+自己繪畫的文字或者圖片的寬度，因?yàn)橛?jì)算的是所需寬度，假設(shè)我們繪制了圖片+文字，那么就需要判斷圖片的寬度跟文字的寬度那個(gè)更大比如getPaddingLeft()+getPaddingRight()+Math.max(圖片的寬度，文字的寬度)即得出所需寬度
   */
  if (MeasureSpec.getMode(lenth) == MeasureSpec.AT_MOST) {
   mPaint.setTextSize(mTitleSize);
   mPaint.getTextBounds(mTitleText.toString(), 0, mTitleText.length(), mBound);
   float textwidth = mBound.width();
   int desired = (int) (getPaddingLeft() + textwidth + getPaddingRight());
   return Math.min(desired,MeasureSpec.getSize(lenth));
  }

  }
 } else {
  if (MeasureSpec.getMode(lenth) == MeasureSpec.EXACTLY) {
  //用戶設(shè)置了精確尺寸,通過(guò)MeasureSpec.getSize()獲得尺寸返回高度
  return MeasureSpec.getSize(lenth);
  } else {
  if (MeasureSpec.getMode(lenth) == MeasureSpec.AT_MOST) {
   //設(shè)置了warp_content，則需要我們自己計(jì)算
   mPaint.setTextSize(mTitleSize);
   mPaint.getTextBounds(mTitleText.toString(), 0, mTitleText.length(), mBound);
   float texthgeight = mBound.height();
   int desired = (int) (getPaddingTop() + texthgeight + getPaddingBottom());
   return Math.min(desired,MeasureSpec.getSize(lenth));
  }
  }
 }
 return 0;
 }

@Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 setMeasuredDimension(getMeasuredLength(widthMeasureSpec, true), getMeasuredLength(heightMeasureSpec, false));
 }

//xx表示widthMeasureSpec或者h(yuǎn)eightMeasureSpec

if(MeasureSpec.getMode(xx)==MeasureSpec.EXACTLY){
 //進(jìn)入這里則代表設(shè)置了match_parent或者將控件的layout_width或layout_height指定為具體數(shù)值時(shí)如andorid:layout_width="100dp"，這樣我們就可以直接通過(guò)MeasureSpec.getSize(xx)方法獲得寬或高 
}else if(MeasureSpec.getMode(xx)==MeasureSpec.EXACTLY){
 //進(jìn)入這里代表設(shè)置了wrap_content，那么則需要我們自己計(jì)算寬或高
}else{
 //進(jìn)入這個(gè)則代表代表是未指定尺寸，這種情況不多，一般都是父控件是AdapterView，通過(guò)measure方法傳入的模式
}

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 padding_left = 0;
 mPaint.setColor(mBackground);
 canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), mPaint);
 mPaint.setColor(mTitleColor);
 for (int i = 0; i < mTitleText.length(); i++) {
  randomTextStyle(mPaint);
  padding_left += mPaint.measureText(String.valueOf(mTitleText.charAt(i)))+10;
  canvas.drawText(String.valueOf(mTitleText.charAt(i)), padding_left, getHeight() / 2 + mBound.height() / 2, mPaint);
 }
 }
private void randomTextStyle(Paint paint) {
 paint.setFakeBoldText(random.nextBoolean()); //true為粗體，false為非粗體
 float skewX = random.nextInt(11) / 10;
 skewX = random.nextBoolean() ? skewX : -skewX;
 paint.setTextSkewX(skewX); //float類型參數(shù)，負(fù)數(shù)表示右斜，整數(shù)左斜
 paint.setUnderlineText(true); //true為下劃線，false為非下劃線
 paint.setStrikeThruText(false); //true為刪除線，false為非刪除線
 }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:cq="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="horizontal">

 <chapter.com.rxjavachapter.CustomTitleView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerInParent="true"
 android:padding="10dp"
 cq:titleBackground="@android:color/black"
 cq:titleColor="#ff0000"
 cq:titleLenth="4"
 cq:titleSize="10sp" />

</RelativeLayout>

 @Override
 public void onClick(View v) {
 randomText();
 postInvalidate();
 }
/**
 * 獲得隨機(jī)的字符串
 *
 * @return
 */
 private void randomText() {
 mTitleText = new StringBuffer();
 for (int i = 0; i < mLenth; i++) {
  mTitleText.append(data[(int) (Math.random() * data.length)]);
 }
 }

 /**
 * 獲得到隨機(jī)的值
 *
 * @return
 */
 public String getCode() {
 return mTitleText.toString();
 }

 /**
 * 判斷是否相同
 *
 * @return
 */
 public boolean isEqual(String code) {
 if (code != null) {
  return code.toUpperCase().equals(getCode().toUpperCase()) ? true : false;
 } else {
  return false;
 }
 }