多个线程如何通过使用Java中的同一连接来写入数据库？

Question

I have a program that creates multiple threads, and i need that any one of them will write to the DB. the problem is that if i use the same connection the data is incorrect due to the access of multiple threads to the same Variables (like statment.setString()). if i use different connection it Takes all the benefit from the threads. In summary: i need that all threads will access a class or another thread that will hold 1 connection and will hold a batch of queries and once in a while will perfome execute batch. thank you!

Answer 1

I see no point in doing this but if you want to do it anyway, then I suggest you synchronize the access to the DB through this connection. Add some common LOCK object and do this:

synchronized(LOCK){
    // use connection by current thread including
    // sensitive operations which
    // need this synchronization
}

But then note that even though you're using multiple threads they will wait on each other, ie their access to the DB through this connection will be serialized (not simultaneous).

Answer 2

The situation you are describing (many threads accessing to a DB) is exactly what is current in web application. And the recommended practice is to set a pool of connections to mitigate between the contention that would arise with one single connection and the resource consumption with one connection per thread. Apache DBCP is one example of such connection pool.

Answer 3

如果您无法初始化多个连接，请在您的连接类中添加一个名为bound的布尔标志，单个线程不能使用连接“ if（bound）” ...使用该连接的任何线程都应在清除该标志时完成...在每个线程中添加while循环以检查该标志，直到它变为false，然后将其设置为true并开始使用它...相当容易...您还可以为所有接受网络的com创建第4个专用同步线程从队列中的其他线程执行任务并同步执行它们，因此不会混乱...无论如何，有大约一百万种方法，选择更适合您的应用程序的方法