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
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/**
* 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
如对本文有疑问， 点击进行留言回复！！
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