android - 为不同的线程创建数据库的构造函数

Question

为了操作数据库，我创建了一个扩展 SQLiteHelper 的类 DBAdapter()...这个类有这个构造函数:

public DBAdapter(Context context) {

    super(context, DATABASE_NAME, null, 1);

    this.myContext = context;

}

现在在包的任何 Activity 中都可以正常工作:

DBAdapter db=new DBAdapter(this);

我想做的是创建一个新线程并从该线程访问数据库。

问题是当我尝试做的时候

db=new DBAdapter(this); 在该类中它告诉我“错误的上下文”!!!

我应该在 DBAdapter() 类中为我的新类创建一个新的构造函数吗？？？在 DBAdapter() 中是否允许有两个构造函数？？

我的类(class)是这样的:

public class WorkerRunnable implements Runnable{


public WorkerRunnable(Socket clientSocket){
    this.clientSocket=clientSocket;
}



public void run(){
    try{        
         Scanner is =new Scanner(new DataInputStream(this.clientSocket.getInputStream()));

         while (is.hasNext()) {
             longitude = is.next();

             Log.d("Longitudine:",longitude); 
             latitude=is.next();
             Log.d("Latitudine:",latitude); 

         }

        is.close();
        clientSocket.close();
            }
    catch(IOException e){
    e.printStackTrace();
    }
       }
}

我的构造函数应该是什么样子的？应该在这个类的run()方法中调用吧？Thx!

---

public class Server1 extends Activity {

    public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);


    setContentView(R.layout.server1);
    DBAdapter db=new DBAdapter(this);

    MultiThreadedServer server = new MultiThreadedServer(6000);

    new Thread(server).start();
}

}

如何将 Server1 Activity 传递给线程？？？？

这是 WorkerRunnable 类的 MultiThreadedServer:

公共(public)类 MultiThreadedServer 实现 Runnable {

protected int serverPort=6000;

public static String SERVERIP="10.0.2.15";

protected ServerSocket serverSocket=null;

protected boolean isStopped=false;

protected Thread runningThread=null;

 public static int clientconnection = 0;

public MultiThreadedServer(int port){

    this.serverPort=port;
}


 public void run(){

        synchronized(this){

            this.runningThread = Thread.currentThread();

        }

openServerSocket();


while(!isStopped()){

    Socket clientSocket=null;

    try{
        System.out.println("Serverul asteapta clienti spre conectare");

        clientSocket=this.serverSocket.accept();

        clientconnection++;

        System.out.println("Serverul a acceptat clientul cu numarul:"+clientconnection) ;
        //Log.d("Server:","s-a acceptat un nou client");




        }
    catch(IOException e){

        if(isStopped()) {

            System.out.println("Server Stopped.") ;
            return;
        }
        throw new RuntimeException(

            "Error accepting client connection", e);

    }
      new Thread(new WorkerRunnable(clientSocket)).start();
}
  System.out.println("Server Stopped.") ;
}

 private synchronized boolean isStopped() {
        return this.isStopped;
    }

    public synchronized void stop(){
        this.isStopped = true;
        try {
            this.serverSocket.close();
        } catch (IOException e) {
            throw new RuntimeException("Error closing server", e);
        }
    }

    private void openServerSocket() {
        try {
            InetSocketAddress serverAddr =new InetSocketAddress(SERVERIP,serverPort);
            serverSocket = new ServerSocket();
            serverSocket.bind(serverAddr);
            Log.d("Server:","bind-ul a fost realizat!");
        } catch (IOException e) {
            throw new RuntimeException("Cannot open port 6000", e);
        }
    }

Answer 1

您可以调用 DBAdapter db=new DBAdapter(this);在您的主 Activity 中，然后通过其构造函数将其传递给您的 Thread。
或者您可以将主 Activity 传递给 Thread(通过构造函数)，然后使用 DBAdapter db=new DBAdapter(<activityVar>); 创建 DBAdapter

编辑:所以，你的 MultiThreadedServer的构造函数将如下所示 public MultiThreadedServer(int port, DBAdatpter db){你将传递 db来自 Server1 .将其放入 MultiThreadedServer 内的全局变量中并将其传递给 WorkerRunnable通过更新的构造函数 public WorkerRunnable(Socket clientSocket, DBAdapter db){ .