这里介绍一种，数字英文随机生成的图片验证码，使用很简单，一行代码，调用一个工具类，就能完美的实现图片验证的显示了。

效果如下：

**具体思路如下：

理清思路，接下来看下代码吧！

public class CodeUtils {    //随机码集    private static final char[] CHARS = {            '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',            'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',            'n', 'o', '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', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'    };    private static CodeUtils mCodeUtils;    private int mPaddingLeft, mPaddingTop;    private StringBuilder mBuilder = new StringBuilder();    private Random mRandom = new Random();    //Default Settings    private static final int DEFAULT_CODE_LENGTH = 4;//验证码的长度  这里是4位    private static final int DEFAULT_FONT_SIZE = 60;//字体大小    private static final int DEFAULT_LINE_NUMBER = 3;//多少条干扰线    private static final int BASE_PADDING_LEFT = 20; //左边距    private static final int RANGE_PADDING_LEFT = 30;//左边距范围值    private static final int BASE_PADDING_TOP = 70;//上边距    private static final int RANGE_PADDING_TOP = 15;//上边距范围值    private static final int DEFAULT_WIDTH = 200;//默认宽度.图片的总宽    private static final int DEFAULT_HEIGHT = 100;//默认高度.图片的总高    private static final int DEFAULT_COLOR = Color.rgb(0xee, 0xee, 0xee);//默认背景颜色值    private String code;    public static CodeUtils getInstance() {        if (mCodeUtils == null) {            mCodeUtils = new CodeUtils();        }        return mCodeUtils;    }    //生成验证码图片    public Bitmap createBitmap() {        mPaddingLeft = 0; //每次生成验证码图片时初始化        mPaddingTop = 0;        Bitmap bitmap = Bitmap.createBitmap(DEFAULT_WIDTH, DEFAULT_HEIGHT, Bitmap.Config.ARGB_8888);        Canvas canvas = new Canvas(bitmap);        code = createCode();        canvas.drawARGB(0, 0, 0, 0);        canvas.drawColor(DEFAULT_COLOR);        Paint paint = new Paint();        paint.setTextSize(DEFAULT_FONT_SIZE);        for (int i = 0; i < code.length(); i++) {            randomTextStyle(paint);            randomPadding();            canvas.drawText(code.charAt(i) + "", mPaddingLeft, mPaddingTop, paint);        }        //干扰线        for (int i = 0; i < DEFAULT_LINE_NUMBER; i++) {            drawLine(canvas, paint);        }        canvas.save(Canvas.ALL_SAVE_FLAG);//保存        canvas.restore();        return bitmap;    }    /**     * 得到图片中的验证码字符串     *     * @return     */    public String getCode() {        return code;    }    //生成验证码    public String createCode() {        mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容        for (int i = 0; i < DEFAULT_CODE_LENGTH; i++) {            mBuilder.append(CHARS[mRandom.nextInt(CHARS.length)]);        }        return mBuilder.toString();    }    //生成干扰线    private void drawLine(Canvas canvas, Paint paint) {        int color = randomColor();        int startX = mRandom.nextInt(DEFAULT_WIDTH);        int startY = mRandom.nextInt(DEFAULT_HEIGHT);        int stopX = mRandom.nextInt(DEFAULT_WIDTH);        int stopY = mRandom.nextInt(DEFAULT_HEIGHT);        paint.setStrokeWidth(1);        paint.setColor(color);        canvas.drawLine(startX, startY, stopX, stopY, paint);    }    //随机颜色    private int randomColor() {        mBuilder.delete(0, mBuilder.length()); //使用之前首先清空内容        String haxString;        for (int i = 0; i < 3; i++) {            haxString = Integer.toHexString(mRandom.nextInt(0xEE));            if (haxString.length() == 1) {                haxString = "0" + haxString;            }            mBuilder.append(haxString);        }        return Color.parseColor("#" + mBuilder.toString());    }    //随机文本样式    private void randomTextStyle(Paint paint) {        int color = randomColor();        paint.setColor(color);        paint.setFakeBoldText(mRandom.nextBoolean());  //true为粗体，false为非粗体        float skewX = mRandom.nextInt(11) / 10;        skewX = mRandom.nextBoolean() ? skewX : -skewX;        paint.setTextSkewX(skewX); //float类型参数，负数表示右斜，整数左斜        paint.setUnderlineText(mRandom.nextBoolean()); //true为下划线，false为非下划线        paint.setStrikeThruText(mRandom.nextBoolean()); //true为删除线，false为非删除线    }    //随机间距    private void randomPadding() {        mPaddingLeft += BASE_PADDING_LEFT + mRandom.nextInt(RANGE_PADDING_LEFT);        mPaddingTop = BASE_PADDING_TOP + mRandom.nextInt(RANGE_PADDING_TOP);    }}

至此，我们的工具类就完成了，是不是很简单，那么怎么使用呢？

也很简单，我们可以看到通过CodeUtils.getInstance().createBitmap();方法，就可以获取生成的由工具类生成的图片验证码的bitmap，那么我们只需要将这个bitmap，设置到需要展示图片验证码的ImageView上即可。

以下是完整代码：

布局界面:

Activity界面:

public class MainActivity extends AppCompatActivity {    private Bitmap bitmap;    private String code;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //获取需要展示图片验证码的ImageView        final ImageView image = (ImageView) findViewById(R.id.image);        //获取工具类生成的图片验证码对象        bitmap = CodeUtils.getInstance().createBitmap();        //获取当前图片验证码的对应内容用于校验        code = CodeUtils.getInstance().getCode();        image.setImageBitmap(bitmap);        image.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                bitmap = CodeUtils.getInstance().createBitmap();                code = CodeUtils.getInstance().getCode();                image.setImageBitmap(bitmap);                Toast.makeText(MainActivity.this, code, Toast.LENGTH_SHORT).show();            }        });    }}

综上；我们就完成了一个常见的图片验证码工具的封装和使用

**当然一定还有更多方法和更优化的逻辑，还请大家提出，共同完善，

觉得还不够方便？还想要什么功能？告诉我！欢迎反馈，欢迎Star。