Question

我一直试图在我正在处理的Android应用程序中找出异步i / o的问题。

此应用程序需要从Microsoft Dynamics CRM的一系列表中下载数据。

一旦数据停止，它必须对数据执行一系列操作以填写某些表格。

我的问题是我必须等待下载完成才能开始更新过程。

如果我在代码中添加任何形式的等待，它似乎无限期地阻塞并且永远不会执行回调。

我尝试使用AtomicBooleans，AtomicIntegers和CountDownLatchs的方法没有成功。

以下是使用AtomicInteger的示例。

final CountDownLatch latch = new CountDownLatch（1）;

OrganizationServiceProxy orgService;
orgService = new OrganizationServiceProxy(Constant.ENDPOINT, CRMLogin.getRequestInterceptor());

ColumnSet columnSet = new ColumnSet();

columnSet.AddColumns(AccountEntry.FETCH_COLS);

orgService.Retrieve(AccountEntry.ENTITY, UUID.fromString(accountid), columnSet, new Callback<Entity>() {
    @Override
    public void success(Entity entity, Response response) {

        Account account = new Account();
        //Load the existing fields for the account

        account.load(index);
        String activityid = account.getValue(AccountEntry.ACTIVITY_ID);
        String recordid = account.getValue(AccountEntry.RECORD_ID);
        String name = account.getValue(AccountEntry.ACCOUNT_NAME);
        //Overload the fields for the account

        account.load(entity);
        //Reset overloaded fields on the account.
        account.setValue(AccountEntry.ACTIVITY_ID, activityid);
        account.setValue(AccountEntry.RECORD_ID, recordid);
        account.setValue(AccountEntry.ACCOUNT_NAME, name);
        //overwrite the record in the database.

        account.setValue(AccountEntry.SYNCED, "1");
        account.update();
        Log.d("pullAccount>>>", accountid + " " + "pulled.");

        latch.countDown();

    }

    @Override
    public void failure(RetrofitError error) {
        Log.d("pullAccount>>>", accountid + " " + error.getMessage());

        latch.countDown();

    }
});

try{
    latch.await(); //THIS BLOCKS FOREVER AND EVER
}
catch (Exception e){

}

值得注意的是CallBack是使用Retrofit实现的。

非常感谢任何指导。

谢谢。

Answer 1

看看AsyncTask它会以Android优化的方式处理您想要的内容。这里有示例用法

http://developer.android.com/reference/android/os/AsyncTask.html

编辑：

我有点把它扔在一起，让我知道它是否像你期望的那样工作

public class AsyncOrganizationService extends AsyncTask<Void, Void, Entity> {
@Override
protected Entity doInBackground(Void... params) {
    final CountDownLatch blocker = new CountDownLatch(1);
    OrganizationServiceProxy orgService;
    orgService = new OrganizationServiceProxy(Constant.ENDPOINT, CRMLogin.getRequestInterceptor());
    ColumnSet columnSet = new ColumnSet();
    columnSet.AddColumns(AccountEntry.FETCH_COLS);
    final SettableFuture<Entity> result = SettableFuture.create();
    orgService.Retrieve(AccountEntry.ENTITY, UUID.fromString(accountid), columnSet, new SortedList.Callback<Entity>() {
        @Override
        public void success(Entity entity, HttpHelper.Response response) {
            result.set(entity);
            blocker.countDown();
        }
    });
    try {
        blocker.await();
        return result.get();
    } catch (InterruptedException | ExecutionException e) {
        throw new RuntimeException(e);
    }
}

@Override
protected void onPostExecute(Entity entity) {
    Account account = new Account();
    //Load the existing fields for the account

    account.load(index);
    String activityid = account.getValue(AccountEntry.ACTIVITY_ID);
    String recordid = account.getValue(AccountEntry.RECORD_ID);
    String name = account.getValue(AccountEntry.ACCOUNT_NAME);
    //Overload the fields for the account

    account.load(entity);
    //Reset overloaded fields on the account.
    account.setValue(AccountEntry.ACTIVITY_ID, activityid);
    account.setValue(AccountEntry.RECORD_ID, recordid);
    account.setValue(AccountEntry.ACCOUNT_NAME, name);
    //overwrite the record in the database.

    account.setValue(AccountEntry.SYNCED, "1");
    account.update();
    Log.d("pullAccount>>>", accountid + " " + "pulled.");
}

我正在使用Guava的SettableFuture类（http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/util/concurrent/SettableFuture.html）。番石榴是一个非常棒的图书馆 - 如果你不使用它，你应该考虑这样做。否则，你可以快速鞭打什么

等待Android上的异步I / O.

1 个答案: