在前面仿华为加载动画、仿网易音乐听歌识曲-麦克风动画中，我们通过绘图的基础知识完成了简单的绘制。在本例中，我们将绘制常见的验证码。
一、效果图
二、知识点与思路分析
通过上面的效果图观察，我们可以看到里面有绘制的随机线条，随机绘制的验证码。
绘制线条，直线或曲线
绘制文本，生成的验证码文本的绘制
绘制圆点。
三、代码编写
/**
* 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 < CODE_NUMBER;i++){
stringBuffer.append(CHARS[random.nextInt(CHARS.length)]);
}
Log.d("Code",stringBuffer.toString());
return stringBuffer.toString();
}
/**
* 绘制文本
* @param canvas 画布
* @param width 宽度
* @param height 高度
*/
private void drawCodeText(Canvas canvas,int width, int height){
Paint paint = new Paint();
paint.setTextSize(50);
/**构建验证码code*/
String text = buildIdentifyCode();
float textLength = paint.measureText(text);
int startMaxLength = (int) ((width - textLength) / 2);
/**随机计算验证码绘制每次开头的位置*/
int startPosition = random.nextInt(startMaxLength);
//绘制文字
for(int index = 0; index < text.length(); index++){
/**生成旋转的角度*/
int offsetDegree = random.nextInt(15);
/**这里只会产生0和1，如果是1那么正旋转正角度，否则旋转负角度*/
offsetDegree = random.nextInt(2) == 1 ? offsetDegree : -offsetDegree;
canvas.save();
//设置旋转
canvas.rotate(offsetDegree, width / 2, height / 2);
/**生成随机的颜色*/
paint.setARGB(255, random.nextInt(200) + 20, random.nextInt(200) + 20,
random.nextInt(200) + 20);
char tempChar = text.charAt(index);
//给画笔设置随机颜色
canvas.drawText(String.valueOf(tempChar), startPosition +index * textLength / text.length() +15,
height * 3 / 5f,paint);
canvas.restore();
}
}
/**
* 生成干扰线
* @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);
}
}
/**
* 生成干扰点
*/
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);
}
}
}
以上所述是小编给大家介绍的Android绘制验证码的实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对脚本之家网站的支持！
