更改没图片时缓存报错的bug

src/main/java/cloud/tianai/captcha/template/slider/CacheSliderCaptchaTemplate.java

@@ -34,13 +34,28 @@ public class CacheSliderCaptchaTemplate implements SliderCaptchaTemplate {
         queue = new LinkedList<>();
         // 初始化一个队列扫描
         scheduledExecutor.scheduleAtFixedRate(() -> {
+            try {
                 while (pos.get() < this.size) {
-                int count = pos.incrementAndGet();
+                    if (pos.get() >= size) {
-                if (count > size) {
                         return;
                     }
                     SliderCaptchaInfo slideImageInfo = target.getSlideImageInfo();
+                    if (slideImageInfo != null) {
                         queue.add(slideImageInfo);
+                        // 添加记录
+                        pos.incrementAndGet();
+                    }else {
+                        // 休眠500毫秒
+                        try {
+                            TimeUnit.MILLISECONDS.sleep(500);
+                        } catch (InterruptedException ignored) {
+                        }
+                    }
+
+                }
+            } catch (Exception e) {
+                // cache所有
+                log.error("缓存队列扫描时出错， ex", e);
             }
         }, 0, 100, TimeUnit.MILLISECONDS);
     }

src/main/java/cloud/tianai/captcha/template/slider/DefaultSliderCaptchaTemplate.java

@@ -1,6 +1,7 @@
 package cloud.tianai.captcha.template.slider;
 
 import lombok.SneakyThrows;
+import lombok.extern.slf4j.Slf4j;
 
 import javax.imageio.ImageIO;
 import java.awt.*;
@@ -21,6 +22,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
  * @Date 2020/5/29 8:06
  * @Description 滑块验证码模板
  */
+@Slf4j
 public class DefaultSliderCaptchaTemplate implements SliderCaptchaTemplate {
 
     /**
@@ -186,6 +188,11 @@ public class DefaultSliderCaptchaTemplate implements SliderCaptchaTemplate {
 
     @SneakyThrows
     public SliderCaptchaInfo getSlideImageInfo(String targetFormatName, String matrixFormatName) {
+        if (resourceImageFiles.isEmpty() ||  templateImageFiles.isEmpty()) {
+            log.warn("滑块验证码生成失败， 资源或模板为空，不能进行生成, 资源文件列表长度: {}, 模板文件列表长度: {}",
+                    resourceImageFiles.size(), templateImageFiles.size());
+            return null;
+        }
         URL resourceImage = getRandomResourceImage();
         Map<String, URL> templateImages = getRandomTemplateImages();