[Add] BotCommandProcess 新增'色图'功能以随机从排行榜中获取一张图片;

[Add] BufferMessageEvent 增加用于获取Sender发送内容的Event实现;
[Change] BotEventHandler Handler现在允许命令处理方法不返回消息(返回'null');

src/main/java/net/lamgc/cgj/bot/BotCommandProcess.java

@@ -7,10 +7,14 @@
 import net.lamgc.cgj.Main;
 import net.lamgc.cgj.bot.cache.*;
 import net.lamgc.cgj.bot.event.BotEventHandler;
+import net.lamgc.cgj.bot.event.BufferMessageEvent;
 import net.lamgc.cgj.bot.sort.PreLoadDataComparator;
 import net.lamgc.cgj.pixiv.PixivDownload;
 import net.lamgc.cgj.pixiv.PixivSearchBuilder;
 import net.lamgc.cgj.pixiv.PixivURL;
+import net.lamgc.cgj.pixiv.PixivDownload.PageQuality;
+import net.lamgc.cgj.pixiv.PixivURL.RankingContentType;
+import net.lamgc.cgj.pixiv.PixivURL.RankingMode;
 import net.lamgc.cgj.util.URLs;
 import net.lamgc.utils.base.runner.Argument;
 import net.lamgc.utils.base.runner.Command;
@@ -295,6 +299,18 @@ public static String userArtworks() {
         return "功能未完成";
     }
 
+    @Command(commandName = "st")
+    public static String r18Image() {
+        BufferMessageEvent event = new BufferMessageEvent();
+        RandomRankingArtworksSender artworksSender = 
+            new RandomRankingArtworksSender(event, 1, 200, 
+            RankingMode.MODE_MALE, 
+            RankingContentType.TYPE_ALL, 
+            PageQuality.ORIGINAL);
+        artworksSender.send();
+        return event.getBufferMessage();
+    }
+
     /**
      * 搜索命令
      * @param fromGroup 来源群(系统提供)

src/main/java/net/lamgc/cgj/bot/event/BotEventHandler.java

@@ -224,7 +224,7 @@ public void processMessage(MessageEvent event) {
             }
         }
         long processTime = System.currentTimeMillis() - time;
-        if(Objects.requireNonNull(result) instanceof String && !isMute(event.getFromGroup())) {
+        if(!Objects.isNull(result) && result instanceof String && !isMute(event.getFromGroup())) {
             try {
                 event.sendMessage((String) result);
             } catch (Exception e) {

src/main/java/net/lamgc/cgj/bot/event/BufferMessageEvent.java

@@ -0,0 +1,59 @@
+package net.lamgc.cgj.bot.event;
+
+import java.util.Objects;
+
+public class BufferMessageEvent extends MessageEvent {
+
+    StringBuffer buffer = new StringBuffer();
+
+    public final MessageEvent parent;
+
+    /**
+     * 以空消息空Id生成BufferMessageEvent
+     */
+    public BufferMessageEvent() {
+        super(0, 0, "");
+        parent = null;
+    }
+
+    /**
+     * 提供消息内容构造BufferMessageEvent
+     * @param message 传入的消息内容
+     */
+    public BufferMessageEvent(String message) {
+        super(0, 0, message);
+        parent = null;
+    }
+
+    /**
+     * 使用事件构造BufferMessageEvent
+     * @param parentEvent 父级消息事件对象
+     */
+    public BufferMessageEvent(MessageEvent parentEvent) {
+        super(parentEvent.getFromGroup(), parentEvent.getFromQQ(), parentEvent.getMessage());
+        parent = parentEvent;
+    }
+
+    @Override
+    public int sendMessage(String message) {
+        buffer.append(message);
+        return 0;
+    }
+
+    /**
+     * 当提供了父级消息事件时, 本方法调用父级消息事件对象的{@code getImageUrl(String)}, 如果没有, 返回{@code null}
+     */
+    @Override
+    public String getImageUrl(String image) {
+        return Objects.isNull(this.parent) ? null : this.parent.getImageUrl(image);
+    }
+
+    /**
+     * 获取缓冲区消息内容
+     * @return 消息内容
+     */
+    public String getBufferMessage() {
+        return buffer.toString();
+    }
+
+}