Android编程生成验证码图片

利用该类，可生成用于提示验证码的bitmap

代码块

代码块：Code.java

import java.util.Random;  import android.graphics.Bitmap;  import android.graphics.Canvas;  import android.graphics.Color;  import android.graphics.Paint;  import android.graphics.Bitmap.Config;  public class Code {      private static final char[] CHARS = {          '2', '3', '4', '5', '6', '7', '8', '9',          'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'l', 'm',           'n', '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', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'      };      private static Code bmpCode;      public static Code getInstance() {          if(bmpCode == null)              bmpCode = new Code();          return bmpCode;      }      //default settings      private static final int DEFAULT_CODE_LENGTH = 4;      private static final int DEFAULT_FONT_SIZE = 25;      private static final int DEFAULT_LINE_NUMBER = 2;      private static final int BASE_PADDING_LEFT = 5, RANGE_PADDING_LEFT = 15, BASE_PADDING_TOP = 15, RANGE_PADDING_TOP = 20;      private static final int DEFAULT_WIDTH = 80, DEFAULT_HEIGHT = 40;      //settings decided by the layout xml      //canvas width and height      private int width = DEFAULT_WIDTH, height = DEFAULT_HEIGHT;       //random word space and pading_top      private int base_padding_left = BASE_PADDING_LEFT, range_padding_left = RANGE_PADDING_LEFT,               base_padding_top = BASE_PADDING_TOP, range_padding_top = RANGE_PADDING_TOP;      //number of chars, lines; font size      private int codeLength = DEFAULT_CODE_LENGTH, line_number = DEFAULT_LINE_NUMBER, font_size = DEFAULT_FONT_SIZE;      //variables      private String code;      private int padding_left, padding_top;      private Random random = new Random();      //验证码图片      public Bitmap createBitmap() {          padding_left = 0;          Bitmap bp = Bitmap.createBitmap(width, height, Config.ARGB_8888);           Canvas c = new Canvas(bp);          code = createCode();          c.drawColor(Color.WHITE);          Paint paint = new Paint();          paint.setTextSize(font_size);          for (int i = 0; i < code.length(); i++) {              randomTextStyle(paint);              randomPadding();              c.drawText(code.charAt(i) + "", padding_left, padding_top, paint);          }          for (int i = 0; i < line_number; i++) {              drawLine(c, paint);          }          c.save( Canvas.ALL_SAVE_FLAG );//保存            c.restore();//          return bp;      }      public String getCode() {          return code;      }      //验证码      private String createCode() {          StringBuilder buffer = new StringBuilder();          for (int i = 0; i < codeLength; i++) {              buffer.append(CHARS[random.nextInt(CHARS.length)]);          }          return buffer.toString();      }      private void drawLine(Canvas canvas, Paint paint) {          int color = randomColor();          int startX = random.nextInt(width);          int startY = random.nextInt(height);          int stopX = random.nextInt(width);          int stopY = random.nextInt(height);          paint.setStrokeWidth(1);          paint.setColor(color);          canvas.drawLine(startX, startY, stopX, stopY, paint);      }      private int randomColor() {          return randomColor(1);      }      private int randomColor(int rate) {          int red = random.nextInt(256) / rate;          int green = random.nextInt(256) / rate;          int blue = random.nextInt(256) / rate;          return Color.rgb(red, green, blue);      }      private void randomTextStyle(Paint paint) {          int color = randomColor();          paint.setColor(color);          paint.setFakeBoldText(random.nextBoolean());  //true为粗体，false为非粗体          float skewX = random.nextInt(11) / 10;          skewX = random.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      }      private void randomPadding() {          padding_left += base_padding_left + random.nextInt(range_padding_left);          padding_top = base_padding_top + random.nextInt(range_padding_top);      }  }