SpringBoot通知机制的实现方式

这篇文章主要介绍了SpringBoot通知机制的实现方式，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教

1. 快速创建maven管理的SpringBoot项目

1、访问 http://start.spring.io/

2、 选择构建工具Maven Project、

Spring Boot版本1.3.6以及一些工程基本信息点击“Switch to the full version.”java版本选择1.7；

3、点击Generate Project下载项目压缩包

4、解压后

使用eclipse，Import -> Existing Maven Projects -> Next ->选择解压后的文件夹-> Finsh，OK done!使用IDEA的话，按如下步骤导入项目： File -> New -> Project fron Existing Sourses -> 选择解压后的直接包含pom.xml文件的demo文件夹，OK -> 选第二项Import project from external model, 选maven，Next -> Next -> 勾选左下角Open Project Structure after import, Next -> Next -> Finish -> 选Yes -> OK -> 大功告成！（记录自己踩过的坑：一定要选直接包含pom.xml的demo文件夹，一开始选择直接解压后的demo文件夹，结果找不到可以导入的maven项目。 ）

5、 运行刚导入的项目

访问localhost:8080/hello, 看到页面显示Hello World。

6、 在这个demo的基础上进行开发

2. 通知机制的流程

1、客户端向server订阅通知

订阅信息包括通知类型（notificationTypes）、过滤条件（filteringCriteria）、订阅者地址（subscriberUri）和 managerId。请求数据以json格式发送，因此在服务端用@RequestBody Map request 来处理请求中的json数据，创建JSONObject 对象，从而根据参数名获取请求中传入的参数值。服务端代码如下：@RequestMapping("/notifications") public void subscribeNotification(@RequestBody Map request, HttpServletResponse response) throws servletexception, IOException, JSONException { System.out.println("Enter localhost:8083/notifications. " ); JSONObject jsonObject = new JSONObject(request); String subscriptionId = (String) jsonObject.get("subscriptionId"); // 通过JSONObject 对象获取请求中传入的参数值 String notificationType = (String) jsonObject.get("notificationType"); String filteringCriteria = (String) jsonObject.get("filteringCriteria"); String managerId = (String) jsonObject.get("managerId"); System.out.println("subscriptionId=" + subscriptionId + ", notificationType=" + notificationType + ", filteringCriteria=" + filteringCriteria + ", managerId=" + managerId ); // some code... 省略了存数据库的操作 response.setHeader("Location", "http://localhost:8083/notifications/0101"); // 通过response.setHeader()方法设置响应头 PrintWriter out = response.getWriter(); String result = "Success to Subscribe a notification! "; out.write(result); }服务端端口设为8083，默认是8080，可以通过在resources 下的application.properties文件里加一条语句server.port=8083 修改为其他端口号。Postman的接口测试结果如下：

2、服务端将通知发送给客户端

请求信息包括订阅Id(subscriptionId)、通知类型（NotificationType）、发送者Id(producerId)、消息（message）。首先根据subscriptionId 从数据库查找到该订阅的通知类型、过滤条件和订阅者地址，然后判断该通知是否符合订阅条件，符合则将该通知发送给订阅者。服务端代码如下：@RequestMapping("/sendNotification") public void sendNotification(@RequestBody Map request, HttpServletResponse response) throws servletexception, IOException, JSONException { System.out.println("request:" + request); JSONObject jsonObject = new JSONObject(request); System.out.println("jsonObject:" + jsonObject); String subscriptionId = (String) jsonObject.get("subscriptionId"); String notificationType = (String) jsonObject.get("notificationType"); String producerId = (String) jsonObject.get("producerId"); String alarmType = (String) jsonObject.getJSONObject("message").get("alarmType"); System.out.println("subscriptionId=" + subscriptionId + ", notificationType=" + notificationType + ", producerId=" + producerId + ", alarmType=" + alarmType ); // some code... 查询数据库（省略） // 模拟数据库查询结果 String getNotificationType = ""; String getAlarmType = ""; String getsubscriberUri = ""; if(subscriptionId.equals("http://localhost:8081/notifications/0101")){ getNotificationType = "alarm"; getAlarmType = "01"; getsubscriberUri = "http://localhost:8081/notifications/001"; } if(subscriptionId.equals("http://localhost:8081/notifications/0102")){ getNotificationType = "alarm"; getAlarmType = "02"; getsubscriberUri = "http://localhost:8082/notifications/001"; } // 判断该通知是否符合订阅条件 String subscribeURL = ""; if(notificationType.equals(getNotificationType) && alarmType.equals(getAlarmType)){ subscribeURL = getsubscriberUri; } else return; // 建立连接，将通知发送给订阅者 HttpURLConnection subscribeConnection = null; StringBuffer responseBuffer = new StringBuffer(); try{ URL getsubscribeURL = new URL(subscribeURL); subscribeConnection = (HttpURLConnection) getsubscribeURL.openConnection(); // 建立连接 subscribeConnection.setDoOutput(true); subscribeConnection.setDoInput(true); subscribeConnection.setRequestMethod("POST"); subscribeConnection.setRequestProperty("Accept-Charset", "utf-8"); subscribeConnection.setRequestProperty("Content-Type", "application/json"); subscribeConnection.setRequestProperty("Charset", "UTF-8"); byte[] data = (jsonObject.toString()).getBytes(); subscribeConnection.setRequestProperty("Content-Length", String.valueOf(data.length)); // 开始连接请求 subscribeConnection.connect(); OutputStream out = subscribeConnection.getoutputStream(); // 写入请求的字符串 out.write((jsonObject.toString()).getBytes()); // 发送json数据 out.flush(); out.close(); }catch (IOException e) { } if (subscribeConnection.getResponseCode() == 200) { // 若响应码为200，则通知订阅成功 System.out.println("Success to send the notification." ); String readLine; BufferedReader responseReader = new BufferedReader(new InputStreamReader( subscribeConnection.getInputStream(), "utf-8")); while ((readLine = responseReader.readLine()) != null) { responseBuffer.append(readLine); } System.out.println("Http Response:" + responseBuffer); subscribeConnection.disconnect(); PrintWriter out = response.getWriter(); out.write(responseBuffer.toString()); }else return; }订阅者(8081端口)接收通知，代码如下：@RequestMapping("/notifications/001") public void receiveNotification(@RequestBody Map request, HttpServletResponse response) throws servletexception, IOException{ System.out.println("Receive a new notification." ); System.out.println("request:" + request); PrintWriter out = response.getWriter(); String result = "Success to Subscribe a notification! "; out.write(result); }

3. 运行过程及结果

首先，用Postman 向服务端（8083端口）发送通知：

服务端结果如下：

订阅者（8081端口）结果如下：

附上demo源码地址： https://github.com/bupt-lxl/SpringBoot-Notification