修复验证码位数的bug，优化代码

src/main/java/com/wf/captcha/SpecCaptcha.java

@@ -9,90 +9,93 @@ import java.io.IOException;
 import java.io.OutputStream;
 
 import javax.imageio.ImageIO;
+
 /**
- * <p>png格式验证码</p>
- *
- * @author: wuhongjun
- * @version:1.0
+ * png格式验证码
+ * Created by 王帆 on 2018-07-27 上午 10:08.
  */
-public class SpecCaptcha extends Captcha
-{
-    public SpecCaptcha()
-    {
+public class SpecCaptcha extends Captcha {
+
+    public SpecCaptcha() {
     }
-    public SpecCaptcha(int width, int height)
-    {
-        this.width = width;
-        this.height = height;
+
+    public SpecCaptcha(int width, int height) {
+        setWidth(width);
+        setHeight(height);
     }
-    public SpecCaptcha(int width, int height, int len){
-        this(width,height);
-        this.len = len;
+
+    public SpecCaptcha(int width, int height, int len) {
+        this(width, height);
+        setLen(len);
     }
-    public SpecCaptcha(int width, int height, int len, Font font){
-        this(width,height,len);
-        this.font = font;
-    }
-    /**
-     * 生成验证码
-     * @throws java.io.IOException IO异常
-     */
-    @Override
-    public void out(OutputStream out){
-        graphicsImage(alphas(), out);
+
+    public SpecCaptcha(int width, int height, int len, Font font) {
+        this(width, height, len);
+        setFont(font);
     }
 
     /**
-     * 画随机码图
-     * @param strs 文本
+     * 生成验证码
+     *
      * @param out 输出流
+     * @return 是否成功
      */
-    private boolean graphicsImage(char[] strs, OutputStream out){
-        boolean ok = false;
-        try
-        {
-            BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
-            Graphics2D g = (Graphics2D)bi.getGraphics();
+    @Override
+    public boolean out(OutputStream out) {
+        checkAlpha();
+        return graphicsImage(textChar(), out);
+    }
+
+    /**
+     * 生成验证码图形
+     *
+     * @param strs 验证码
+     * @param out  输出流
+     * @return boolean
+     */
+    private boolean graphicsImage(char[] strs, OutputStream out) {
+        boolean ok;
+        try {
+            BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
+            Graphics2D g = (Graphics2D) bi.getGraphics();
             AlphaComposite ac3;
-            Color color ;
+            Color color;
             int len = strs.length;
             g.setColor(Color.WHITE);
-            g.fillRect(0,0,width,height);
-            // 随机画干扰的蛋蛋
-            for(int i=0;i<15;i++){
+            g.fillRect(0, 0, width, height);
+            // 随机画干扰的圆圈
+            for (int i = 0; i < 15; i++) {
                 color = color(150, 250);
                 g.setColor(color);
-                g.drawOval(num(width), num(height), 5+num(10), 5+num(10));// 画蛋蛋，有蛋的生活才精彩
+                g.drawOval(num(width), num(height), 5 + num(10), 5 + num(10));
                 color = null;
             }
             g.setFont(font);
-            int h  = height - ((height - font.getSize()) >>1),
-                w = width/len,
-                size = w-font.getSize()+1;
-            /* 画字符串 */
-            for(int i=0;i<len;i++)
-            {
+            int h = height - ((height - font.getSize()) >> 1);
+            int w = width / len;
+            int size = w - font.getSize() + 1;
+            // 画字符串
+            for (int i = 0; i < len; i++) {
                 ac3 = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.7f);// 指定透明度
                 g.setComposite(ac3);
                 color = new Color(20 + num(110), 20 + num(110), 20 + num(110));// 对每个字符都用随机颜色
                 g.setColor(color);
-                g.drawString(strs[i]+"",(width-(len-i)*w)+size, h-4);
+                g.drawString(String.valueOf(strs[i]), (width - (len - i) * w) + size, h - 4);
                 color = null;
                 ac3 = null;
             }
             ImageIO.write(bi, "png", out);
             out.flush();
             ok = true;
-        }catch (IOException e){
+        } catch (IOException e) {
             ok = false;
-        }finally
-        {
-        	try {
-				out.close();
-			} catch (IOException e) {
-				// TODO Auto-generated catch block
-				e.printStackTrace();
-			}
+            e.printStackTrace();
+        } finally {
+            try {
+                out.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
         }
         return ok;
     }