#535 修复Tomcat 不能正常关闭的问题，增加线程池shutdown相关的操作

weixin-java-mp/src/main/java/me/chanjar/weixin/mp/api/WxMpMessageRouter.java

@@ -75,6 +75,29 @@ public class WxMpMessageRouter {
     this.exceptionHandler = new LogExceptionHandler();
   }
 
+  /**
+   * <pre>
+   * 使用自定义的 {@link ExecutorService}
+   * </pre>
+   */
+  public WxMpMessageRouter(WxMpService wxMpService, ExecutorService executorService) {
+    this.wxMpService = wxMpService;
+    this.executorService = executorService;
+    this.messageDuplicateChecker = new WxMessageInMemoryDuplicateChecker();
+    this.sessionManager = new StandardSessionManager();
+    this.exceptionHandler = new LogExceptionHandler();
+  }
+
+  /**
+   * <pre>
+   * 如果使用默认的 {@link ExecutorService}，则系统退出前，应该调用该方法。
+   * </pre>
+   */
+  public void shutDownExecutorService() {
+    this.executorService.shutdown();
+  }
+
+
   /**
    * <pre>
    * 设置自定义的 {@link ExecutorService}

weixin-java-mp/src/test/java/me/chanjar/weixin/mp/api/WxMpMessageRouterTest.java

@@ -8,6 +8,8 @@ import me.chanjar.weixin.mp.bean.message.WxMpXmlOutMessage;
 import org.testng.*;
 import org.testng.annotations.*;
 
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.Map;
 
 /**
@@ -67,9 +69,23 @@ public class WxMpMessageRouterTest {
     prepare(true, sb, router);
     router.route(message);
     Thread.sleep(500);
+    router.shutDownExecutorService();
     Assert.assertEquals(sb.toString(), expected);
   }
 
+  @Test(dataProvider = "messages-1")
+  public void testExternalExcutorService(WxMpXmlMessage message, String expected) throws InterruptedException {
+    StringBuffer sb = new StringBuffer();
+    ExecutorService executorService = Executors.newFixedThreadPool(100);
+    WxMpMessageRouter router = new WxMpMessageRouter(null, executorService);
+    prepare(true, sb, router);
+    router.route(message);
+    Thread.sleep(500);
+    executorService.shutdown();
+    Assert.assertEquals(sb.toString(), expected);
+  }
+
+
   public void testConcurrency() throws InterruptedException {
     final WxMpMessageRouter router = new WxMpMessageRouter(null);
     router.rule().handler(new WxMpMessageHandler() {