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Android图形验证码

时间：2020-03-11 20:58:45

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Android图形验证码

1. 前言

图形验证码可以让服务器以图片的形式传给客户端，也可以让客户端自己实现。那客户端要怎么做呢？其实很简单，可以使用Android的Canvas、Paint和Random来实现。用Random来随机生成数字、字母、颜色、画笔原点等等，设置Paint的颜色和样式，然后再Canvas上面绘制，这样一个图形验证码就生成好了。

2. 具体实现

根据上面所说的，我们可以封装一个工具类来使用，详细功能有：

自定义验证码类型：数字、字母、数字字母组合自定义验证码大小自定义验证码背景颜色自定义干扰线数量自定义字体大小、数量、间距

具体代码如下：

package com.fantasy.blogdemo.captcha;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import java.util.Random;/*** 图形验证码工具* <pre>*author : Fantasy*version : 1.0, -06-27*since : 1.0, -06-27* </pre>*/public class Captcha {private static final char[] CHARS_NUMBER = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9'};private static final char[] CHARS_LETTER = {'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'};private static final char[] CHARS_ALL = {'0', '1', '2', '3', '4', '5', '6','7', '8', '9', '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'};/*** 验证码图片的宽度*/private int mWidth;/*** 验证码图片的高度*/private int mHeight;private int mBackgroundColor;/*** 验证码的长度*/private int mLength;/*** 干扰线的数量*/private int mLineNumber;private int mFontSize;/*** 字体左边距*/private int mFontPaddingLeft;/*** 字体左边距范围值*/private int mFontPaddingLeftRang;/*** 字体上边距*/private int mFontPaddingTop;/*** 字体上边距范围值*/private int mFontPaddingTopRang;private TYPE mType;private Random mRandom;private static Captcha mInstance;/*** 生成的验证码*/private String mCode;public enum TYPE {NUMBER, LETTER, CHARS}private Captcha() {mType = TYPE.CHARS;mWidth = 200;mHeight = 80;mBackgroundColor = Color.WHITE;mLength = 4;mLineNumber = 2;mFontSize = 50;mFontPaddingLeft = 20;mFontPaddingLeftRang = 20;mFontPaddingTop = 45;mFontPaddingTopRang = 15;mRandom = new Random();}public static Captcha getInstance() {if (mInstance == null) {synchronized (Captcha.class) {mInstance = new Captcha();}}return mInstance;}/*** 设置验证码类型，有：数字、英文字母、数字加英文字母** @param type 类型* @return CaptchaUtils实例*/public Captcha setType(TYPE type) {mType = type;return mInstance;}/*** 设置验证码图片大小** @param width 宽度* @param height 高度* @return CaptchaUtils实例*/public Captcha setSize(int width, int height) {mWidth = width;mHeight = height;return mInstance;}/*** 设置背景颜色** @param color 颜色* @return CaptchaUtils实例*/public Captcha setBackgroundColor(int color) {mBackgroundColor = color;return mInstance;}/*** 设置验证码的长度** @param length 长度* @return CaptchaUtils实例*/public Captcha setLength(int length) {mLength = length;return mInstance;}/*** 设置干扰性数量** @param number 数量* @return CaptchaUtils实例*/public Captcha setLineNumber(int number) {mLineNumber = number;return mInstance;}/*** 设置字体大小** @param size 字体大小* @return CaptchaUtils实例*/public Captcha setFontSize(int size) {mFontSize = size;return mInstance;}/*** 设置字体间距** @param paddingLeft 左边距* @param paddingTop 上边距* @return CaptchaUtils实例*/public Captcha setFontPadding(int paddingLeft, int paddingTop) {mFontPaddingLeft = paddingLeft;mFontPaddingTop = paddingTop;return mInstance;}/*** 设置字体间距** @param paddingLeft左边距* @param paddingLeftRang 左边距范围值* @param paddingTop上边距* @param paddingTopRang 上边距范围值* @return CaptchaUtils实例*/public Captcha setFontPadding(int paddingLeft, int paddingLeftRang, int paddingTop,int paddingTopRang) {mFontPaddingLeft = paddingLeft;mFontPaddingLeftRang = paddingLeftRang;mFontPaddingTop = paddingTop;mFontPaddingTopRang = paddingTopRang;return mInstance;}/*** 获取生成的图形验证码** @return 图形验证码的字符串*/public String getCode() {return mCode;}/*** 生成图形验证码** @return 图形验证码的图片*/public Bitmap create() {mCode = createCode();Bitmap bitmap = Bitmap.createBitmap(mWidth, mHeight, Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(bitmap);canvas.drawColor(mBackgroundColor);Paint paint = new Paint();paint.setTextSize(mFontSize);int fontPaddingLeft = 0;for (int i = 0; i < mCode.length(); i++) {getRandomTextStyle(paint);fontPaddingLeft += getRandomFontPaddingLeft();canvas.drawText(String.valueOf(mCode.charAt(i)), fontPaddingLeft, getRandomFontPaddingTop(), paint);}for (int i = 0; i < mLineNumber; i++) {drawLine(canvas, paint);}canvas.save();canvas.restore();return bitmap;}/*** 生成图形验证码** @return 图形验证码的字符串*/private String createCode() {StringBuilder buffer = new StringBuilder();switch (mType) {case NUMBER:for (int i = 0; i < mLength; i++) {buffer.append(CHARS_NUMBER[mRandom.nextInt(CHARS_NUMBER.length)]);}break;case LETTER:for (int i = 0; i < mLength; i++) {buffer.append(CHARS_LETTER[mRandom.nextInt(CHARS_LETTER.length)]);}break;case CHARS:for (int i = 0; i < mLength; i++) {buffer.append(CHARS_ALL[mRandom.nextInt(CHARS_ALL.length)]);}break;default:for (int i = 0; i < mLength; i++) {buffer.append(CHARS_ALL[mRandom.nextInt(CHARS_ALL.length)]);}break;}return buffer.toString();}/*** 获取随机颜色** @return 颜色*/private int getRandomColor() {int red = mRandom.nextInt(256);int green = mRandom.nextInt(256);int blue = mRandom.nextInt(256);return Color.rgb(red, green, blue);}/*** 获取随机文本样式** @param paint 涂料*/private void getRandomTextStyle(Paint paint) {int color = getRandomColor();paint.setColor(color);paint.setFakeBoldText(mRandom.nextBoolean()); // true为粗体，false为非粗体int skewX = mRandom.nextInt(11) / 10;skewX = mRandom.nextBoolean() ? skewX : -skewX;paint.setTextSkewX(skewX); // 负数表示右斜，整数左斜// paint.setUnderlineText(true); // true为下划线，false为非下划线// paint.setStrikeThruText(true); // true为删除线，false为非删除线}/*** 获取随机字体左边距** @return 左边距*/private int getRandomFontPaddingLeft() {return mFontPaddingLeft + mRandom.nextInt(mFontPaddingLeftRang);}/*** 获取随机字体上边距** @return 上边距*/private int getRandomFontPaddingTop() {return mFontPaddingTop + mRandom.nextInt(mFontPaddingTopRang);}/*** 生成干扰性** @param canvas 画布* @param paint 涂料*/private void drawLine(Canvas canvas, Paint paint) {int color = getRandomColor();int startX = mRandom.nextInt(mWidth);int startY = mRandom.nextInt(mHeight);int stopX = mRandom.nextInt(mWidth);int stopY = mRandom.nextInt(mHeight);paint.setStrokeWidth(1);paint.setColor(color);canvas.drawLine(startX, startY, stopX, stopY, paint);}}

3. 使用方式

获取实例并设置

mCaptcha = Captcha.getInstance().setType(Captcha.TYPE.CHARS).setSize(200, 80).setBackgroundColor(Color.WHITE).setLength(4).setLineNumber(2).setFontSize(50).setFontPadding(20, 20, 45, 15);

生成图形验证码，并且在ImageView中显示

mIvCaptcha.setImageBitmap(mCaptcha.create());

获取验证码的字符串，可用于比对输入是否正确

if (result.equals(mCaptcha.getCode())) {showToast(R.string.captcha_correct);} else {showToast(R.string.captcha_wrong);}