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后端开发/消息机制.md

+# 消息机制
+
+简介：实时弹出提示消息或待办
+
+### 1.消息机制入口
+
+对任何需要提示的操作，都需要将这个消息以键-值对的形式存入到redis中，调用setNoticeCache（）方法即可
+
+```java
+SysEventServieImpl.java   
+
+
+    @Override
+    public void setNoticeCache(HlsSystemNotice hlsSystemNotice) {
+        sysNoticePushService.sendUserNotice(hlsSystemNotice.getSource_user_id(),hlsSystemNotice);
+        List<HlsSystemNotice> noticeToList= hlsSystemNoticeService.selectSendNotice(hlsSystemNotice);
+        if(noticeToList!=null){
+            for(HlsSystemNotice hlsSystemNotice1:noticeToList){
+                sysNoticePushService.sendUserNotice(hlsSystemNotice1.getUserId(),hlsSystemNotice);
+            }
+        }
+    }
+```
+
+redis中的存在形式：
+
+```java
+   SysNoticePushServiceImpl.java
+   
+     @Override
+    public void sendUserNotice(Long userId, HlsSystemNotice hlsSystemNotice) {
+        String hashKey = "messageBox-" + userId.toString() + "-" + System.currentTimeMillis() + "-" + Math.random();
+        String key = "messageBox-" + userId.toString();
+        hashOperations.put(hashKey, "userId", hlsSystemNotice);
+        listOperations.rightPush(key, hashKey);
+    }
+```
+
+前端以ajax轮询的方法发送请求获取需要展示的消息：
+
+```js
+<script>
+   setInterval(moment_show,6000);
+   function moment_show(contextPath){
+        $.ajax({
+            type: 'POST',
+            async: false, //设为同步
+            url: '${base.contextPath}/hls/user/send/notice',
+            contentType: "application/json; charset=utf-8",
+            dataType: "json",
+            success: function (datas) {
+                if(datas.length>0) {
+                    push_float_msg(datas);
+                    setTimeout(function(){moment_hide(msgLength);},3000);
+                }
+            }
+        });
+    };
+</script>
+```
+
+redis中取值机制：
+
+```java
+  SysNoticePushServiceImpl.java 
+    
+      @Override
+    public List<HlsSystemNotice> getUserNotice(Long userId) {
+        String key = "messageBox-" + userId.toString();
+        List<HlsSystemNotice> retList = new ArrayList<HlsSystemNotice>();
+        if(listOperations!=null){
+            List<String> keys = listOperations.range(key, 0, -1);
+            for (int i = 0; i < keys.size(); i++) {
+                if (i == 5) {
+                    break;
+                }
+                boolean rep = true;
+                boolean currentUserTodo = false;
+                if(hashOperations!=null){
+                    HlsSystemNotice hlsSystemNotice = (HlsSystemNotice) hashOperations.get(keys.get(i), "userId");
+                    for (int m = 0; m < retList.size(); m++) {
+                        if (retList.get(m).getNotice_id() == hlsSystemNotice.getNotice_id()) {
+                            rep = false;
+                        }
+                    }
+                    if (hlsSystemNotice.getNotice_type() == "TO_DO") {
+                        if (hlsSystemNotice.getSource_user_id() == userId) {
+                            currentUserTodo = true;
+                        } else {
+                            currentUserTodo = false;
+                        }
+                    } else {
+                        currentUserTodo = true;
+                    }
+                    if (rep && currentUserTodo) {
+                        retList.add(hlsSystemNotice);
+                    }
+                    listOperations.remove(key,1,keys.get(i));
+                    hashOperations.delete(keys.get(i),"userId");
+                }
+            }
+        }else {
+            HlsSystemNotice notice = new HlsSystemNotice();
+            notice.setNotice_title("test");
+            notice.setUserId(Long.parseLong("10172"));
+            notice.setRead_flag("N");
+            notice.setDone_flag("N");
+            notice.setNotice_message("test-msg");
+            retList.add(notice);
+        }
+        return retList;
+    }
+}
+```
+
+
+