在SQLite的，可以有任意多的读者，但是任何作家阻止所有其他读者和作者。

In SQLite, there can be arbitrarily many readers, but any writer blocks all other readers and writers.

您要为读者和作者使用一个锁。

You have to use a single lock for both readers and writers.

请注意，必须先把锁，只要你实际上是在访问数据库中保存。

Please note that locks must be held as long as you're actually accessing the database.

如果你想支持多个阅读器，使用实现ReadWriteLock$c$c>,如ReentrantReadWriteLock$c$c>.事情是这样的：

If you want to support multiple readers, use a lock that implements ReadWriteLock, such as ReentrantReadWriteLock. Something like this:

class MyData {
    private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
    private final Lock r = rwl.readLock();
    private final Lock w = rwl.writeLock();

    public Data ReadSomething(int id) {
        r.lock();
        try {
            Cursor c = readableDatabase.query(...);
            return c.getString(0);
        } finally {
            r.unlock();
        }
    }

    public void ChangeSomething(int id, int value) {
        w.lock();
        try {
            writeableDatabase.update(...);
        } finally {
            w.unlock();
        }
    }
}