android实现图片验证码方法解析(自绘控件)

 <declare-styleable name="VerifyCode">
 <attr name="codeTextSize" format="dimension"/>
 <attr name="codeBackground" format="color"/>
 <attr name="codeLength" format="integer"/>
 <attr name="isContainChar" format="boolean"/>
 <attr name="pointNum" format="integer"/>
 <attr name="linNum" format="integer"/>
 </declare-styleable>

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.MotionEvent;
import android.view.View;
import java.util.Random;
/**
 * 类描述:自定义验证码
 * 创建者：lb
 */
public class VerifyCode extends View {
 private String mCodeText;//文本内容
 private int mCodeTextSize;//文本大小
 private int mCodeLength;//验证码长度
 private int mCodeBackground;//背景色
 private boolean isContainChar;//验证码是否包含字母
 private int mPointNum;//干扰点数
 private int mLineNum;//干扰线数
 private Paint mPaint;//画笔
 private Rect mBound;//绘制范围
 private Bitmap bitmap;//验证码图片
 private static Random mRandom = new Random();
 private static int mWidth;//控件的宽度
 private static int mHeight;//控件的高度
 public VerifyCode(Context context) {
 super(context);
 }
 public VerifyCode(Context context, AttributeSet attrs) {
 super(context, attrs);
 initAttrValues(context,attrs);
 initData();
 }
 /**
 * 初始化属性集合
 * @param context
 * @param attrs
 */
 private void initAttrValues(Context context, AttributeSet attrs){
 // //获取在AttributeSet中定义的 VerifyCode 中声明的属性的集合
 TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.VerifyCode);
 //获取TypeArray的长度
 int count=typedArray.getIndexCount();
 for (int i=0;i<count;i++){
  //获取此项属性的ID
  int index=typedArray.getIndex(i);
  switch (index){
  case R.styleable.VerifyCode_codeTextSize:
   // 默认设置为16sp，TypeValue类 px转sp 一个转换类
   mCodeTextSize =typedArray.getDimensionPixelSize(index,(int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_SP, 16, getResources().getDisplayMetrics()));
   break;
  case R.styleable.VerifyCode_codeBackground:
mCodeBackground=typedArray.getColor(index,Color.WHITE);
   break;
  case R.styleable.VerifyCode_codeLength:
   mCodeLength=typedArray.getInteger(index,4);
   break;
  case R.styleable.VerifyCode_isContainChar:
   isContainChar=typedArray.getBoolean(index,false);
   break;
  case R.styleable.VerifyCode_pointNum:
   mPointNum=typedArray.getInteger(index,100);
   break;
  case R.styleable.VerifyCode_linNum:
   mLineNum=typedArray.getInteger(index,3);
   break;
  }
 }
 //Recycles the TypedArray, to be re-used by a later caller
 //官方解释：回收TypedArray 以便后面的使用者重用
 typedArray.recycle();
 }
 /**
 * 初始化数据
 */
 private void initData(){
 mCodeText=getValidationCode(mCodeLength,isContainChar);
 mPaint=new Paint();
 mPaint.setAntiAlias(true);
 mBound=new Rect();
 //计算文字所在矩形，可以得到宽高
 mPaint.getTextBounds(mCodeText,0, mCodeText.length(),mBound);
 }
 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 //获取控件宽高的显示模式
 int widthMode=MeasureSpec.getMode(widthMeasureSpec);
 int heightMode=MeasureSpec.getMode(heightMeasureSpec);
 //获取宽高的尺寸值 固定值的宽度
 int widthSize=MeasureSpec.getSize(widthMeasureSpec);
 int heightSize=MeasureSpec.getSize(heightMeasureSpec);
 //设置宽高默认为建议的最小宽高
 int width= getDefaultSize(getSuggestedMinimumWidth(),widthMeasureSpec) ;
 int height=getDefaultSize(getSuggestedMinimumHeight(),heightMeasureSpec);

// MeasureSpec父布局传递给后代的布局要求 包含 确定大小和三种模式
// EXACTLY：一般是设置了明确的值或者是MATCH_PARENT
// AT_MOST：表示子布局限制在一个最大值内，一般为WARP_CONTENT
// UNSPECIFIED：表示子布局想要多大就多大，很少使用
 if (widthMode==MeasureSpec.EXACTLY){
  width=widthSize;
 }else{
  mPaint.setTextSize(mCodeTextSize);
  mPaint.getTextBounds(mCodeText,0,mCodeText.length(),mBound);
  float textWidth=mBound.width();
  int tempWidth=(int)(getPaddingLeft()+textWidth+getPaddingRight());
  width=tempWidth;
 }
 if (heightMode == MeasureSpec.EXACTLY)
 {
  height = heightSize;
 } else
 {
  mPaint.setTextSize(mCodeTextSize);
  mPaint.getTextBounds(mCodeText, 0, mCodeText.length(), mBound);
  float textHeight = mBound.height();
  int tempHeight = (int) (getPaddingTop() + textHeight + getPaddingBottom());
  height = tempHeight;
 }
 //设置测量的宽高
 setMeasuredDimension(width,height);
 }
 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 mWidth=getWidth();
 mHeight=getHeight();

 if (bitmap==null){
  bitmap=createBitmapValidate();
 }
 canvas.drawBitmap(bitmap,0,0,mPaint);
 }
 @Override
 public boolean onTouchEvent(MotionEvent event) {
 switch (event.getAction()){
  case MotionEvent.ACTION_DOWN:
  refresh();
  break;
 }
 return super.onTouchEvent(event);
 }
 /**
 * 创建图片验证码
 * @return
 */
 private Bitmap createBitmapValidate(){
 if(bitmap != null && !bitmap.isRecycled()){
  //回收并且置为null
  bitmap.recycle();
  bitmap = null;
 }
 //创建图片
 Bitmap sourceBitmap=Bitmap.createBitmap(mWidth,mHeight, Bitmap.Config.ARGB_8888);
 //创建画布
 Canvas canvas=new Canvas(sourceBitmap);
 //画上背景颜色
 canvas.drawColor(mCodeBackground);
 //初始化文字画笔
 mPaint.setStrokeWidth(3f);
 mPaint.setTextSize(mCodeTextSize);
 //测量验证码字符串显示的宽度值
 float textWidth=mPaint.measureText(mCodeText);
 //画上验证码
 int length = mCodeText.length();
 //计算一个字符的所占位置
 float charLength = textWidth / length;
 for (int i = 1; i <= length; i++) {
  int offsetDegree = mRandom.nextInt(15);
  //这里只会产生0和1，如果是1那么正旋转正角度，否则旋转负角度
  offsetDegree = mRandom.nextInt(2) == 1 ? offsetDegree : -offsetDegree;
  //用来保存Canvas的状态。save之后，可以调用Canvas的平移、放缩、旋转、错切、裁剪等操作。
  canvas.save();
  //设置旋转
  canvas.rotate(offsetDegree, mWidth / 2, mHeight / 2);
  //给画笔设置随机颜色
  mPaint.setARGB(255, mRandom.nextInt(200) + 20, mRandom.nextInt(200) + 20,
   mRandom.nextInt(200) + 20);
  //设置字体的绘制位置
  canvas.drawText(String.valueOf(mCodeText.charAt(i - 1)), (i - 1) * charLength+5,
   mHeight * 4 / 5f, mPaint);
  //用来恢复Canvas之前保存的状态。防止save后对Canvas执行的操作对后续的绘制有影响。
  canvas.restore();
 }
 //重新设置画笔
 mPaint.setARGB(255, mRandom.nextInt(200) + 20, mRandom.nextInt(200) + 20,
  mRandom.nextInt(200) + 20);
 mPaint.setStrokeWidth(1);
 //产生干扰效果1 －－ 干扰点
 for (int i = 0; i < mPointNum; i++) {
  drawPoint(canvas, mPaint);
 }
 //生成干扰效果2 －－ 干扰线
 for (int i = 0; i < mLineNum; i++) {
  drawLine(canvas, mPaint);
 }
 return sourceBitmap;
 }
 /**
 * 生成干扰点
 */
 private static void drawPoint(Canvas canvas, Paint paint) {
 PointF pointF = new PointF(mRandom.nextInt(mWidth) + 10, mRandom.nextInt(mHeight) + 10);
 canvas.drawPoint(pointF.x, pointF.y, paint);
 }
 /**
 * 生成干扰线
 */
 private static void drawLine(Canvas canvas, Paint paint) {
 int startX = mRandom.nextInt(mWidth);
 int startY = mRandom.nextInt(mHeight);
 int endX = mRandom.nextInt(mWidth);
 int endY = mRandom.nextInt(mHeight);
 canvas.drawLine(startX, startY, endX, endY, paint);
 }
 /**
 * 获取验证码
 *
 * @param length 生成随机数的长度
 * @param contains 是否包含字符串
 * @return
 */
 public String getValidationCode(int length,boolean contains) {
 String val = "";
 Random random = new Random();
 for (int i = 0; i < length; i++) {
  if (contains){
  //字母或数字
  String code = random.nextInt(2) % 2 == 0 ? "char" : "num";
  //字符串
  if ("char".equalsIgnoreCase(code)) {
   //大写或小写字母
   int choice = random.nextInt(2) % 2 == 0 ? 65 : 97;
   val += (char) (choice + random.nextInt(26));
  } else if ("num".equalsIgnoreCase(code)) {
   val += String.valueOf(random.nextInt(10));
  }
  }else{
  val += String.valueOf(random.nextInt(10));
  }
 }
 return val;
 }
 /**
 *判断验证码是否一致 忽略大小写
 */
 public Boolean isEqualsIgnoreCase(String CodeString) {
 return mCodeText.equalsIgnoreCase(CodeString);
 }
 /**
 * 判断验证码是否一致 不忽略大小写
 */
 public Boolean isEquals(String CodeString) {
 return mCodeText.equals(CodeString);
 }
 /**
 * 提供外部调用的刷新方法
 */
 public void refresh(){
 mCodeText= getValidationCode(mCodeLength,isContainChar);
 bitmap = createBitmapValidate();
 invalidate();
 }
}