Android绘制验证码的实例代码

/**
 * Created by Iflytek_dsw on 2017/7/3.
 */
public class IdentifyCodeUtil {
  private static final int CODE_NUMBER = 4;
  private static final int LINE_NUMBER = 5;
  private static final int POINT_NUMBER = 10;
  private StringBuffer stringBuffer = null;
  private Random random = new Random();
  //随机数数组
  private static final char[] CHARS = {
      '2', '3', '4', '5', '6', '7', '8', '9',
      'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', '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 IdentifyCodeUtil instance;
  public static IdentifyCodeUtil getInstance(){
    if(instance == null){
      instance = new IdentifyCodeUtil();
    }
    return instance;
  }
  public Bitmap createBitmapCode(int width, int height){
    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    canvas.drawColor(Color.LTGRAY);
    drawCodeText(canvas, width, height);
    drawLines(canvas, width, height);
    drawPoint(canvas, width, height);
    return bitmap;
  }
  /**
   * 返回验证码
   * @return 验证码生成的字符串
   */
  public String getIdentifyCode(){
    if(stringBuffer == null){
      return "";
    }
    return stringBuffer.toString();
  }
  /**
   * 生成验证码
   * @return
   */
  private String buildIdentifyCode(){
    StringBuffer stringBuffer = new StringBuffer();
    for(int i=0; i