用单例实现数据库操作,弃用全局变量

app/DataBase/micro_msg.py

@@ -5,48 +5,71 @@ import threading
 lock = threading.Lock()
 DB = None
 cursor = None
-micromsg_path = "./app/Database/Msg/MicroMsg.db"
-if os.path.exists(micromsg_path):
-    DB = sqlite3.connect(micromsg_path, check_same_thread=False)
-    # '''创建游标'''
-    cursor = DB.cursor()
+db_path = "./app/Database/Msg/MicroMsg.db"
 
 
-def init_database():
-    global DB
-    global cursor
-    if not DB:
-        if os.path.exists(micromsg_path):
-            DB = sqlite3.connect(micromsg_path, check_same_thread=False)
-            # '''创建游标'''
-            cursor = DB.cursor()
+def singleton(cls):
+    _instance = {}
+
+    def inner():
+        if cls not in _instance:
+            _instance[cls] = cls()
+        return _instance[cls]
+
+    return inner
 
 
 def is_database_exist():
-    return os.path.exists(micromsg_path)
+    return os.path.exists(db_path)
 
 
-def get_contact():
-    try:
-        lock.acquire(True)
-        sql = '''select UserName,Alias,Type,Remark,NickName,PYInitial,RemarkPYInitial,ContactHeadImgUrl.smallHeadImgUrl,ContactHeadImgUrl.bigHeadImgUrl
-              from Contact inner join ContactHeadImgUrl on Contact.UserName = ContactHeadImgUrl.usrName
-              where  Type%2=1 and Alias is not null 
-              order by PYInitial
-              '''
-        cursor.execute(sql)
-        result = cursor.fetchall()
-    finally:
-        lock.release()
-    # DB.commit()
-    return result
+@singleton
+class MicroMsg:
+    def __init__(self):
+        self.DB = None
+        self.cursor = None
+        self.open_flag = False
+        self.init_database()
 
+    def init_database(self):
+        if not self.open_flag:
+            if os.path.exists(db_path):
+                self.DB = sqlite3.connect(db_path, check_same_thread=False)
+                # '''创建游标'''
+                self.cursor = self.DB.cursor()
+                self.open_flag = True
+                if lock.locked():
+                    lock.release()
 
-def close():
-    global DB
-    if DB:
-        DB.close()
+    def get_contact(self):
+        if not self.open_flag:
+            return None
+        try:
+            lock.acquire(True)
+            sql = '''select UserName,Alias,Type,Remark,NickName,PYInitial,RemarkPYInitial,ContactHeadImgUrl.smallHeadImgUrl,ContactHeadImgUrl.bigHeadImgUrl
+                  from Contact inner join ContactHeadImgUrl on Contact.UserName = ContactHeadImgUrl.usrName
+                  where  Type%2=1 and Alias is not null 
+                  order by PYInitial
+                  '''
+            self.cursor.execute(sql)
+            result = self.cursor.fetchall()
+        finally:
+            lock.release()
+        return result
+
+    def close(self):
+        if self.open_flag:
+            try:
+                lock.acquire(True)
+                self.open_flag = False
+                self.DB.close()
+            finally:
+                lock.release()
+
+    def __del__(self):
+        self.close()
 
 
 if __name__ == '__main__':
-    get_contact()
+    pass
+    # get_contact()