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怎么在Android中生成一个本地验证码？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。
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();
}看完上述内容，你们掌握怎么在Android中生成一个本地验证码的方法了吗？如果还想学到更多技能或想了解更多相关内容，欢迎关注亿速云行业资讯频道，感谢各位的阅读！
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