✨ #12398 随机图片工具类

src/main/java/org/b3log/solo/util/Images.java

+/*
+ * Copyright (c) 2010-2018, b3log.org & hacpai.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.b3log.solo.util;
+
+import org.apache.commons.lang.time.DateFormatUtils;
+import org.apache.commons.lang.time.DateUtils;
+import org.b3log.latke.logging.Level;
+import org.b3log.latke.logging.Logger;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * Image utilities.
+ *
+ * @author <a href="http://88250.b3log.org">Liang Ding</a>
+ * @version 1.0.0.0, Feb 14, 2018
+ * @since 2.7.0
+ */
+public final class Images {
+
+    /**
+     * Logger.
+     */
+    private static final Logger LOGGER = Logger.getLogger(Images.class);
+
+    /**
+     * Gets an image URL randomly. Sees https://github.com/b3log/bing for more details.
+     *
+     * @return an image URL
+     */
+    public static final String randImage() {
+        try {
+            final long min = DateUtils.parseDate("20171104", new String[]{"yyyyMMdd"}).getTime();
+            final long max = System.currentTimeMillis();
+            final long delta = max - min;
+            final long time = ThreadLocalRandom.current().nextLong(0, delta) + min;
+
+            return "https://img.hacpai.com/bing/" + DateFormatUtils.format(time, "yyyyMMdd") + ".jpg";
+        } catch (final Exception e) {
+            LOGGER.log(Level.ERROR, "Generates random image URL failed", e);
+
+            return "https://img.hacpai.com/bing/20171104.jpg";
+        }
+    }
+
+    /**
+     * Gets image URLs randomly.
+     *
+     * @param n the specified size
+     * @return image URLs
+     */
+    public static List<String> randomImages(final int n) {
+        final List<String> ret = new ArrayList<>();
+
+        int i = 0;
+        while (true) {
+            if (i >= n * 5) {
+                break;
+            }
+
+            final String url = randImage();
+            if (!ret.contains(url)) {
+                ret.add(url);
+            }
+
+            if (ret.size() >= n) {
+                return ret;
+            }
+
+            i++;
+        }
+
+        return ret;
+    }
+
+    /**
+     * Private constructor.
+     */
+    private Images() {
+    }
+}

src/test/java/org/b3log/solo/util/ImagesTestCase.java

+/*
+ * Copyright (c) 2010-2018, b3log.org & hacpai.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.b3log.solo.util;
+
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+import java.util.List;
+
+/**
+ * {@link org.b3log.solo.util.Images} test case.
+ *
+ * @author <a href="http://88250.b3log.org">Liang Ding</a>
+ * @version 1.0.0.0, Feb 14, 2018
+ * @since 2.7.0
+ */
+public final class ImagesTestCase {
+
+    /**
+     * Test method for {@linkplain Images#randImage()}.
+     */
+    @Test
+    public void randImage() {
+        final String url = Images.randImage();
+        Assert.assertEquals(url.length(), "https://img.hacpai.com/bing/20171104.jpg".length());
+    }
+
+    /**
+     * Test method for {@linkplain Images#randomImages(int)}.
+     */
+    @Test
+    public void randImages() {
+        final List<String> urls = Images.randomImages(10);
+        Assert.assertEquals(urls.size(), 10);
+    }
+}