任务告警模块化，代码重构优化。

doc/XXL-JOB官方文档.md

@@ -1245,8 +1245,7 @@ API服务请求参考代码：com.xxl.job.executor.ExecutorBizTest
 - 2、提供基于HTTP的任务Handler（Bean任务，JobHandler="HttpJobHandler"）；业务方只需要提供HTTP链接即可，不限制语言、平台；
 
 ### 5.18 任务失败告警
-默认提供邮件失败告警，可扩展短信、钉钉等方式，扩展代码位置为 "com.xxl.job.admin.core.alarm.JobAlarmer"。
-如果需要新增一种告警方式，只需要新增一个实现 "com.xxl.job.admin.core.alarm.JobAlarm" 接口的告警实现即可
+默认提供邮件失败告警，可扩展短信、钉钉等方式。如果需要新增一种告警方式，只需要新增一个实现 "com.xxl.job.admin.core.alarm.JobAlarm" 接口的告警实现即可。可以参考默认提供邮箱告警实现 "EmailJobAlarm"。
 
 ### 5.19 调度中心Docker镜像构建
 可以通过以下命令快速构建调度中心，并启动运行；

xxl-job-admin/src/main/java/com/xxl/job/admin/core/alarm/JobAlarmer.java

@@ -1,17 +1,38 @@
 package com.xxl.job.admin.core.alarm;
 
-import com.xxl.job.admin.core.alarm.impl.EmailJobAlarm;
 import com.xxl.job.admin.core.model.XxlJobInfo;
 import com.xxl.job.admin.core.model.XxlJobLog;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
 import org.springframework.stereotype.Component;
 
-import javax.annotation.Resource;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
 
 @Component
-public class JobAlarmer {
+public class JobAlarmer implements ApplicationContextAware, InitializingBean {
+    private static Logger logger = LoggerFactory.getLogger(JobAlarmer.class);
 
-    @Resource
-    private EmailJobAlarm emailJobAlarm;
+    private ApplicationContext applicationContext;
+    private List<JobAlarm> jobAlarmList;
+
+    @Override
+    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
+        this.applicationContext = applicationContext;
+    }
+
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        Map<String, JobAlarm> serviceBeanMap = applicationContext.getBeansOfType(JobAlarm.class);
+        if (serviceBeanMap != null && serviceBeanMap.size() > 0) {
+            jobAlarmList = new ArrayList<JobAlarm>(serviceBeanMap.values());
+        }
+    }
 
     /**
      * job alarm
@@ -22,15 +43,23 @@ public class JobAlarmer {
      */
     public boolean alarm(XxlJobInfo info, XxlJobLog jobLog) {
 
-        // alarm by email
-        boolean emailResult = emailJobAlarm.doAlarm(info, jobLog);
-
-        // do something, custom alarm strategy, such as sms
-        // ...
-
-        return emailResult;
+        boolean result = false;
+        if (jobAlarmList!=null && jobAlarmList.size()>0) {
+            result = true;  // success means all-success
+            for (JobAlarm alarm: jobAlarmList) {
+                boolean resultItem = false;
+                try {
+                    resultItem = alarm.doAlarm(info, jobLog);
+                } catch (Exception e) {
+                    logger.error(e.getMessage(), e);
+                }
+                if (!resultItem) {
+                    result = false;
+                }
+            }
         }
 
-
+        return result;
+    }
 
 }

xxl-job-admin/src/main/java/com/xxl/job/admin/core/thread/JobFailMonitorHelper.java

@@ -61,13 +61,7 @@ public class JobFailMonitorHelper {
 								// 2、fail alarm monitor
 								int newAlarmStatus = 0;		// 告警状态：0-默认、-1=锁定状态、1-无需告警、2-告警成功、3-告警失败
 								if (info!=null && info.getAlarmEmail()!=null && info.getAlarmEmail().trim().length()>0) {
-									boolean alarmResult = true;
-									try {
-										alarmResult = XxlJobAdminConfig.getAdminConfig().getJobAlarmer().alarm(info, log);
-									} catch (Exception e) {
-										alarmResult = false;
-										logger.error(e.getMessage(), e);
-									}
+									boolean alarmResult = XxlJobAdminConfig.getAdminConfig().getJobAlarmer().alarm(info, log);
 									newAlarmStatus = alarmResult?2:3;
 								} else {
 									newAlarmStatus = 1;