增加某类指令存在未完成状态时不重复插入多条的机制(例如更新操作避免同时执行多次)

app/src/main/java/com/bgycc/smartcanteen/command/CommandHelper.java

@@ -17,8 +17,7 @@ public class CommandHelper {
     private static final String CONFIG_LOG = "CONFIG_LOG";
 
     // 设备指令白名单
-    private static final Set<String> COMMAND_WHITELIST = new HashSet<String>()
-    {
+    private static final Set<String> COMMAND_WHITELIST = new HashSet<String>() {
         {
             add(LOG_UPLOAD);
             add(APP_UPDATE);
@@ -35,10 +34,25 @@ public class CommandHelper {
         return command.getAction().equals(CONFIG_LOG);
     }
 
+    /**
+     * 根据action检查是否为指令类型
+     */
     public static boolean isCommand(String action) {
         return COMMAND_WHITELIST.contains(action);
     }
 
+    /**
+     * 该条指令是否在数据库中只能存在一条"未完成"状态的数据 <br/>
+     *
+     * @param command 指令
+     * @return <br/>
+     * true => 数据库已有"未完成"状态的该类指令，不应该重复插入 <br/>
+     * false => 数据库中该类指令都"已完成"或没有该类指令，可插入新的指令 <br/>
+     */
+    public static boolean oneAtTime(Command command) {
+        return command.getAction().equals(APP_UPDATE);
+    }
+
     public static OneTimeWorkRequest createWorker(Gson gson, Command command, String deviceSN) {
         OneTimeWorkRequest worker = null;
         Class<? extends ListenableWorker> workerClass = null;

app/src/main/java/com/bgycc/smartcanteen/data/dao/CommandDao.java

@@ -17,6 +17,10 @@ public interface CommandDao {
     @Query("select * from command where finish == 0 order by id asc")
     LiveData<List<Command>> queryUndoneCommand();
 
+    // 根据action搜索未完成的指令数
+    @Query("select count(*) from command where finish == 0 and `action` == :action")
+    int queryUndoneCommandCountByAction(String action);
+
     @Insert(onConflict = OnConflictStrategy.REPLACE)
     long insertCommand(Command command);
 

app/src/main/java/com/bgycc/smartcanteen/repository/CommandRepository.java

@@ -18,6 +18,10 @@ public class CommandRepository {
         return dao.queryUndoneCommand();
     }
 
+    public int queryUndoneCommandCountByAction(String action) {
+        return dao.queryUndoneCommandCountByAction(action);
+    }
+
     public long insertCommand(Command command) {
         return dao.insertCommand(command);
     }

app/src/main/java/com/bgycc/smartcanteen/viewModel/CommandViewModel.java

@@ -114,6 +114,14 @@ public class CommandViewModel extends ViewModel {
         public void run() {
             // 指令插入到数据库，则会触发dataObserver
             Command command = new Command(response, action);
+            // 若为更新指令，则需要检查是否有未完成的，避免同时存在多条更新指令重复执行
+            if (CommandHelper.oneAtTime(command)) {
+                int count = commandRepository.queryUndoneCommandCountByAction(action);
+                if (count > 0) {
+                    LogUtils.d(TAG, "该指令已在数据库中记录并未执行完毕，不再插入重复指令");
+                    return;
+                }
+            }
             long lastInsertId = commandRepository.insertCommand(command);
             if (lastInsertId == -1) {
                 LogUtils.w(TAG, "指令插入到数据库失败: " + command.toString());