Android本地验证码的生成

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;
}

1. 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();
}

以上就是生成本地验证码的一个简单的自定义view步骤，这里就给出源码地址，有需要的就去看看https://github.com/myloften/VerificationCodeSample