Android繪制驗證碼的實例代碼

更新時間：2017年07月04日 11:29:32 作者：andoter

這篇文章主要介紹了Android繪制驗證碼的實例代碼,需要的朋友可以參考下

在前面仿華為加載動畫、仿網(wǎng)易音樂聽歌識曲-麥克風動畫中，我們通過繪圖的基礎知識完成了簡單的繪制。在本例中，我們將繪制常見的驗證碼。

一、效果圖

identify

二、知識點與思路分析

通過上面的效果圖觀察，我們可以看到里面有繪制的隨機線條，隨機繪制的驗證碼。

繪制線條，直線或曲線

繪制文本，生成的驗證碼文本的繪制

繪制圓點。

三、代碼編寫

/**
 * 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();
  //隨機數(shù)數(shù)組
  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;
  }
  /**
   * 返回驗證碼
   * @return 驗證碼生成的字符串
   */
  public String getIdentifyCode(){
    if(stringBuffer == null){
      return "";
    }
    return stringBuffer.toString();
  }
  /**
   * 生成驗證碼
   * @return
   */
  private String buildIdentifyCode(){
    StringBuffer stringBuffer = new StringBuffer();
    for(int i=0; i < CODE_NUMBER;i++){
      stringBuffer.append(CHARS[random.nextInt(CHARS.length)]);
    }
    Log.d("Code",stringBuffer.toString());
    return stringBuffer.toString();
  }
  /**
   * 繪制文本
   * @param canvas  畫布
   * @param width   寬度
   * @param height  高度
   */
  private void drawCodeText(Canvas canvas,int width, int height){
    Paint paint = new Paint();
    paint.setTextSize(50);
    /**構建驗證碼code*/
    String text = buildIdentifyCode();
    float textLength = paint.measureText(text);
    int startMaxLength = (int) ((width - textLength) / 2);
    /**隨機計算驗證碼繪制每次開頭的位置*/
    int startPosition = random.nextInt(startMaxLength);
    //繪制文字
    for(int index = 0; index < text.length(); index++){
      /**生成旋轉的角度*/
      int offsetDegree = random.nextInt(15);
      /**這里只會產(chǎn)生0和1，如果是1那么正旋轉正角度，否則旋轉負角度*/
      offsetDegree = random.nextInt(2) == 1 ? offsetDegree : -offsetDegree;
      canvas.save();
      //設置旋轉
      canvas.rotate(offsetDegree, width / 2, height / 2);
      /**生成隨機的顏色*/
      paint.setARGB(255, random.nextInt(200) + 20, random.nextInt(200) + 20,
          random.nextInt(200) + 20);
      char tempChar = text.charAt(index);
      //給畫筆設置隨機顏色
      canvas.drawText(String.valueOf(tempChar), startPosition +index * textLength / text.length() +15,
          height * 3 / 5f,paint);
      canvas.restore();
    }
  }
  /**
   * 生成干擾線
   * @param canvas
   * @param width
   * @param height
   */
  private void drawLines(Canvas canvas,int width, int height){
    Paint paint = new Paint();
    paint.setStrokeWidth(3);
    for(int i = 0;i < LINE_NUMBER;i++){
      paint.setARGB(255, random.nextInt(200) + 30, random.nextInt(200) + 30, random.nextInt(200) + 30);
      int startX = random.nextInt(width);
      int startY = random.nextInt(height);
      int endX = random.nextInt(width);
      int endY = random.nextInt(height);
      canvas.drawLine(startX, startY, endX, endY, paint);
    }
  }
  /**
   * 生成干擾點
   */
  private void drawPoint(Canvas canvas, int width, int height) {
    Paint paint = new Paint();
    paint.setStrokeWidth(3);
    paint.setColor(Color.GRAY);
    for(int i=0; i< POINT_NUMBER; i++){
      PointF pointF = new PointF(random.nextInt(width) + 10, random.nextInt(height) + 10);
      canvas.drawPoint(pointF.x, pointF.y, paint);
    }
  }
}

identifycode