Android本地验证码的生成代码

android客户端生成本地验证码主要用来限制用户随意按请求按钮，其实该示例也是来对自定义view的练练手而已，先给出效果图吧

其中可定制：

＊干扰线数目
＊干扰点数目
＊背景颜色
＊验证码字体大小及字数

相信以上可以满足一般的需要了吧，不够的话可自行添加，下面就来讲实现的步骤了

继承view，重写构造方法，并初始化所需参数

public class ValidationCode extends View {

private Paint mTextPaint;//文字画笔
private Paint mPointPaint;//干扰点画笔
private Paint mPathPaint;//干扰线画笔
private Paint mBitmapPaint;//Bitmap图画笔
private String mCodeString;//随机验证码
private int mCodeCount;//验证码位数
private float mTextSize;//验证码字符大小
private int mPointNumber;//干扰点数目
private int mLineNumber;//干扰线数目
private int mBackGround;//背景颜色
private float mTextWidth;//验证码字符串的显示宽度
private static int mWidth;//控件的宽度
private static int mHeight;//控件的高度
private static Random mRandom = new Random();
private Bitmap bitmap = null;//生成验证码图片

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

public ValidationCode(Context context, AttributeSet attrs) {
 super(context, attrs);
 getAttrValues(context, attrs);
 init();
}

/**
 * 获取布局文件中的值
 */
private void getAttrValues(Context context, AttributeSet attrs) {
 TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ValidationCode);
 mCodeCount = typedArray.getInteger(R.styleable.ValidationCode_CodeCount, 4);
 mPointNumber = typedArray.getInteger(R.styleable.ValidationCode_PointNumber, 100);
 mLineNumber = typedArray.getInteger(R.styleable.ValidationCode_LineNumber, 2);
 mTextSize = typedArray.getDimension(R.styleable.ValidationCode_CodeTextSize, 20);
 mBackGround = typedArray.getColor(R.styleable.ValidationCode_BackGround,Color.WHITE);
 typedArray.recycle();
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 setMeasuredDimension(measureWidth(widthMeasureSpec), measureHeight(heightMeasureSpec));

}

/**
 * 初始化画笔
 */
private void init() {
 //生成随机数字和字母组合
 mCodeString = getValidationCode(mCodeCount);
 //初始化文字画笔
 mTextPaint = new Paint();
 mTextPaint.setStrokeWidth(3);
 mTextPaint.setTextSize(mTextSize);
 //初始化干扰点画笔
 mPointPaint = new Paint();
 mPointPaint.setStrokeWidth(4);
 mPointPaint.setStrokeCap(Paint.Cap.ROUND);//设置断点处为圆形
 //初始化干扰线画笔
 mPathPaint = new Paint();
 mPathPaint.setStrokeWidth(5);
 mPathPaint.setColor(Color.GRAY);
 mPathPaint.setStyle(Paint.Style.STROKE);//设置画笔为空心
 mPathPaint.setStrokeCap(Paint.Cap.ROUND);//设置断点处为圆形
 //初始化Bitmap画笔
 mBitmapPaint = new Paint();
 mBitmapPaint.setColor(Color.RED);
 //取得验证码字符串显示的宽度值
 mTextWidth = mTextPaint.measureText(mCodeString);

}
}

getAttrValues方法是用来配置自定义的属性，需要在 values 中新建 * attrs.xml * 文件，并加上自定义的属性，如下：

<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="ValidationCode">
 <attr name="CodeCount" format="integer"/>
 <attr name="PointNumber" format="integer"/>
 <attr name="LineNumber" format="integer"/>
 <attr name="CodeTextSize" format="dimension"/>
 <attr name="BackGround" format="color"/>
</declare-styleable>
</resources>

onMeasure方法则是在你需要对自定义的view的大小做出处理时，通过setMeasuredDimension设置该控件大小，下面给出重新定义的宽高代码块

/**
* 对view的宽高进行重新定义
*/
private int measureWidth(int measureSpec) {
int result = 0;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);

if (specMode == MeasureSpec.EXACTLY) {
 result = specSize;
} else {
 result = (int) (mTextWidth * 2.0f);
 if (specMode == MeasureSpec.AT_MOST) {
  result = Math.min(result, specSize);
 }
}
return result;
}

private int measureHeight(int measureSpec) {
int result = 0;

int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);

if (specMode == MeasureSpec.EXACTLY) {
 result = specSize;
} else {
 result = (int) (mTextWidth / 1.5f);
 if (specMode == MeasureSpec.AT_MOST) {
  result = Math.min(result, specSize);
 }
}
return result;
}

重写onDraw()，绘制图形

1、绘制验证码文本字符串，干扰点，干扰线，生成验证码的bitmap图

/**
* 获取验证码
*
* @param length 生成随机数的长度
* @return
*/
public static String getValidationCode(int length) {
String val = "";
Random random = new Random();
for (int i = 0; i < length; i++) {
 //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));
 }
}
return val;
}

/**
* 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);
}

/**
1. 绘制验证码并返回
*/
private Bitmap generateValidate(){
if(bitmap != null && !bitmap.isRecycled()){
 //回收并且置为null
 bitmap.recycle();
 bitmap = null;
}
//创建图片和画布
Bitmap sourceBitmap = Bitmap.createBitmap(mWidth,mHeight, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(sourceBitmap);

//画背景颜色
canvas.drawColor(mBackGround);

//画上验证码
int length = mCodeString.length();
float charLength = mTextWidth / 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;
 canvas.save();
 canvas.rotate(offsetDegree, mWidth / 2, mHeight / 2);
 //给画笔设置随机颜色
 mTextPaint.setARGB(255, mRandom.nextInt(200) + 20, mRandom.nextInt(200) + 20,
   mRandom.nextInt(200) + 20);
 canvas.drawText(String.valueOf(mCodeString.charAt(i - 1)), (i - 1) * charLength * 1.6f + 30,
   mHeight * 2 / 3f, mTextPaint);
 canvas.restore();
}

//产生干扰效果1 －－ 干扰点
for (int i = 0; i < mPointNumber; i++) {
 mPointPaint.setARGB(255, mRandom.nextInt(200) + 20, mRandom.nextInt(200) + 20,
   mRandom.nextInt(200) + 20);
 drawPoint(canvas, mPointPaint);
}

//生成干扰效果2 －－ 干扰线
for (int i = 0; i < mLineNumber; i++) {
 mPathPaint.setARGB(255, mRandom.nextInt(200) + 20, mRandom.nextInt(200) + 20,
   mRandom.nextInt(200) + 20);
 drawLine(canvas, mPathPaint);
}

canvas.save();
return sourceBitmap;
}

2、实现onDraw()方法，绘画出验证码

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);

//获取控件的宽和高
mHeight = getHeight();
mWidth = getWidth();

if(bitmap == null){
 bitmap = generateValidate();
}
canvas.drawBitmap(bitmap,0,0,mBitmapPaint);
}

添加触摸事件，点击切换验证码

@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
 case MotionEvent.ACTION_DOWN:
  mCodeString = getValidationCode(mCodeCount);
  bitmap = generateValidate();
  invalidate();
  break;
 default:
  break;
}
return super.onTouchEvent(event);
}

添加公开使用方法

我们总是需要提供给用户调用的方法，判断验证码是否一致之类的，方便用户进一步的操作，这里提供个几个方法

/**
* 判断验证码是否一致
*
* @String CodeString
* 这里忽略大小写
*/
public Boolean isEqualsIgnoreCase(String CodeString) {
return mCodeString.equalsIgnoreCase(CodeString);
}

/**
* 判断验证码是否一致
* 不忽略大小写
*/
public Boolean isEquals(String CodeString) {
return mCodeString.equals(CodeString);
}

/**
* 外界控件调用刷新验证码图片
*/
public void refresh(){
mCodeString = getValidationCode(mCodeCount);
bitmap = generateValidate();
invalidate();
}

来源：https://blog.csdn.net/Loften_93663469/article/details/51367979