（转）Android 之生成图形验证码

 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import java.util.Random;

 /**
  * Created by ekikousei易皇星 on 16/11/21.
  * E-mail:13764664731@163.com
  * Signature:缘分是本书,翻的不经意会错过,读的太认真会流泪!!
  * <p/>
  * TODO:类描述:  用于图形验证码的工具类
  */
 public class CodeUtils {

 //    private static final char[] CHARS = {
 //            '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'
 //    };

     private static final char[] CHARS = {

             '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 CodeUtils mCodeUtils;
     private int mPaddingLeft, mPaddingTop;
     private StringBuilder mBuilder = new StringBuilder();
     private Random mRandom = new Random();

     //Default Settings
 //    private static final int DEFAULT_CODE_LENGTH = 6;//验证码的长度  这里是6位
     private static final int DEFAULT_CODE_LENGTH = 4;//验证码的长度  这里是4位
     private static final int DEFAULT_FONT_SIZE = 60;//字体大小
     private static final int DEFAULT_LINE_NUMBER = 3;//多少条干扰线
     private static final int BASE_PADDING_LEFT = 40; //左边距
     private static final int RANGE_PADDING_LEFT = 30;//左边距范围值
     private static final int BASE_PADDING_TOP = 70;//上边距
     private static final int RANGE_PADDING_TOP = 15;//上边距范围值
     private static final int DEFAULT_WIDTH = 300;//默认宽度.图片的总宽
     private static final int DEFAULT_HEIGHT = 100;//默认高度.图片的总高
     private static final int DEFAULT_COLOR = 0xDF;//默认背景颜色值

     private String code;

     public static CodeUtils getInstance() {
         if (mCodeUtils == null) {
             mCodeUtils = new CodeUtils();
         }
         return mCodeUtils;
     }

     //生成验证码图片  返回类型为bitmap 直接用imageview.setbitmap()即可
     public Bitmap createBitmap() {
         mPaddingLeft = 0; //每次生成验证码图片时初始化
         mPaddingTop = 0;

         Bitmap bitmap = Bitmap.createBitmap(DEFAULT_WIDTH, DEFAULT_HEIGHT, Bitmap.Config.ARGB_8888);
         Canvas canvas = new Canvas(bitmap);

         code = createCode();

         canvas.drawColor(Color.rgb(DEFAULT_COLOR, DEFAULT_COLOR, DEFAULT_COLOR));
         Paint paint = new Paint();
         paint.setTextSize(DEFAULT_FONT_SIZE);

         for (int i = 0; i < code.length(); i++) {
             randomTextStyle(paint);
             randomPadding();
             canvas.drawText(code.charAt(i) + "", mPaddingLeft, mPaddingTop, paint);
         }

         //干扰线
         for (int i = 0; i < DEFAULT_LINE_NUMBER; i++) {
             drawLine(canvas, paint);
         }

         canvas.save(Canvas.ALL_SAVE_FLAG);//保存
         canvas.restore();
         return bitmap;
     }

     /**
      * 得到图片中的验证码字符串
      *
      * @return
      */
     public String getCode() {
         return code;
     }

     //生成验证码
     public String createCode() {
         mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容

         for (int i = 0; i < DEFAULT_CODE_LENGTH; i++) {
             mBuilder.append(CHARS[mRandom.nextInt(CHARS.length)]);
         }

         return mBuilder.toString();
     }

     //生成干扰线
     private void drawLine(Canvas canvas, Paint paint) {
         int color = randomColor();
         int startX = mRandom.nextInt(DEFAULT_WIDTH);
         int startY = mRandom.nextInt(DEFAULT_HEIGHT);
         int stopX = mRandom.nextInt(DEFAULT_WIDTH);
         int stopY = mRandom.nextInt(DEFAULT_HEIGHT);
         paint.setStrokeWidth(1);
         paint.setColor(color);
         canvas.drawLine(startX, startY, stopX, stopY, paint);
     }

     //随机颜色
     private int randomColor() {
         mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容

         String haxString;
         for (int i = 0; i < 3; i++) {
             haxString = Integer.toHexString(mRandom.nextInt(0xFF));
             if (haxString.length() == 1) {
                 haxString = "0" + haxString;
             }

             mBuilder.append(haxString);
         }

         return Color.parseColor("#" + mBuilder.toString());
     }

     //随机文本样式
     private void randomTextStyle(Paint paint) {
         int color = randomColor();
         paint.setColor(color);
         paint.setFakeBoldText(mRandom.nextBoolean());  //true为粗体，false为非粗体
         float skewX = mRandom.nextInt(11) / 10;
         skewX = mRandom.nextBoolean() ? skewX : -skewX;
         paint.setTextSkewX(skewX); //float类型参数，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
     }

     //随机间距
     private void randomPadding() {
         mPaddingLeft += BASE_PADDING_LEFT + mRandom.nextInt(RANGE_PADDING_LEFT);
         mPaddingTop = BASE_PADDING_TOP + mRandom.nextInt(RANGE_PADDING_TOP);
     }
 }

转载自:https://blog.csdn.net/jky_yihuangxing/article/details/53301834

很简单，直接上代码了。