[Add] MessageSenderBuilder, MessageSenderFactory 增加用于创建MessageSender而又与平台无关的Builder, 初步增加对应Factory;

src/main/java/net/lamgc/cgj/bot/message/MessageSenderBuilder.java

@@ -0,0 +1,43 @@
+package net.lamgc.cgj.bot.message;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+/**
+ * 消息发送器构造
+ */
+public final class MessageSenderBuilder {
+
+    private final static AtomicReference<MessageSenderFactory> currentFactory = new AtomicReference<>();
+
+    private MessageSenderBuilder() {}
+
+    /**
+     * 获取消息发送器
+     * @param source 消息源类型
+     * @param id 消息源Id
+     * @return 返回新建的发送器
+     */
+    public static MessageSender getMessageSender(MessageSource source, long id) {
+        MessageSenderFactory messageSenderFactory = currentFactory.get();
+        if(messageSenderFactory == null) {
+            throw new IllegalStateException("The factory is not ready");
+        }
+        try {
+            return messageSenderFactory.createMessageSender(source, id);
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    /**
+     * 设置消息发送器工厂
+     * @param factory 工厂对象
+     */
+    public static void setCurrentMessageSenderFactory(MessageSenderFactory factory) {
+        if(currentFactory.get() != null) {
+            throw new IllegalStateException("Factory already exists");
+        }
+        currentFactory.set(factory);
+    }
+
+}