import com.google.bitcoin.net.MessageWriteTarget; //导入依赖的package包/类
/**
 * Sets the {@link MessageWriteTarget} used to write messages to the peer. This should almost never be called, it is
 * called automatically by {@link com.google.bitcoin.net.NioClient} or
 * {@link com.google.bitcoin.net.NioClientManager} once the socket finishes initialization.
 */
@Override
public void setWriteTarget(MessageWriteTarget writeTarget) {
    checkArgument(writeTarget != null);
    lock.lock();
    boolean closeNow = false;
    try {
        checkArgument(this.writeTarget == null);
        closeNow = closePending;
        this.writeTarget = writeTarget;
    } finally {
        lock.unlock();
    }
    if (closeNow)
        writeTarget.closeConnection();
}