Android 主线程上的 Okhttp 响应回调
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/24246783/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Okhttp response callbacks on the main thread
提问by Michael
I have created a helper class to handle all of my http calls in my app. It is a simple singleton wrapper for okhttp that looks like this (I have omitted some unimportant parts):
我创建了一个帮助程序类来处理我的应用程序中的所有 http 调用。它是一个简单的 okhttp 单例包装器，如下所示（我省略了一些不重要的部分）：
public class HttpUtil {
private OkHttpClient client;
private Request.Builder builder;
...
public void get(String url, HttpCallback cb) {
call("GET", url, cb);
}
public void post(String url, HttpCallback cb) {
call("POST", url, cb);
}
private void call(String method, String url, final HttpCallback cb) {
Request request = builder.url(url).method(method, method.equals("GET") ? null : new RequestBody() {
// don't care much about request body
@Override
public MediaType contentType() {
return null;
}
@Override
public void writeTo(BufferedSink sink) throws IOException {
}
}).build();
client.newCall(request).enqueue(new Callback() {
@Override
public void onFailure(Request request, Throwable throwable) {
cb.onFailure(null, throwable);
}
@Override
public void onResponse(Response response) throws IOException {
if (!response.isSuccessful()) {
cb.onFailure(response, null);
return;
}
cb.onSuccess(response);
}
});
}
public interface HttpCallback {
/**
* called when the server response was not 2xx or when an exception was thrown in the process
* @param response - in case of server error (4xx, 5xx) this contains the server response
* in case of IO exception this is null
* @param throwable - contains the exception. in case of server error (4xx, 5xx) this is null
*/
public void onFailure(Response response, Throwable throwable);
/**
* contains the server response
* @param response
*/
public void onSuccess(Response response);
}
}
Then, in my main activity, I use this helper class :
然后，在我的主要活动中，我使用这个助手类：
HttpUtil.get(url, new HttpUtil.HttpCallback() {
@Override
public void onFailure(Response response, Throwable throwable) {
// handle failure
}
@Override
public void onSuccess(Response response) {
// <-------- Do some view manipulation here
}
});
onSuccessthrows an exception when the code runs :
onSuccess代码运行时抛出异常：
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
android.view.ViewRootImpl$CalledFromWrongThreadException：只有创建视图层次结构的原始线程才能触摸其视图。
From my understanding, Okhttp callbacks run on the main thread so why do I get this error ?
根据我的理解，Okhttp 回调在主线程上运行，为什么会出现此错误？
** Just as a side note, I have created HttpCallbackinterface to wrap Okhttp's Callbackclass because I wanted to change the behaviour of onResponseand onFailureso I could unite the logic of handling failed responses due to i/o exception and failed responses due to server problems.
**正如一个方面说明，我已经创建HttpCallback界面包Okhttp的Callback类，因为我想改变的行为onResponse和onFailure这样我就可以统一处理O异常，由于我没有反应/和由于服务器问题的失败响应的逻辑。
Thanks.
谢谢。
回答by Jake Wharton
From my understanding, Okhttp callbacks run on the main thread so why do I get this error ?
根据我的理解，Okhttp 回调在主线程上运行，为什么会出现此错误？
This is not true. Callbacks run on a background thread. If you want to immediately process something in the UI you will need to post to the main thread.
这不是真的。回调在后台线程上运行。如果您想立即处理 UI 中的某些内容，您将需要发布到主线程。
Since you already have a wrapper around the callback you can do this internally in your helper so that all HttpCallbackmethods are invoked on the main thread for convenience.
由于您已经在回调周围有了一个包装器，因此您可以在帮助程序内部执行此操作，以便HttpCallback为方便起见在主线程上调用所有方法。
回答by Michael
As Jake Wharton suggested, I had to run the callbacks on the main thread explicitly.
正如 Jake Wharton 所建议的，我必须在主线程上显式运行回调。
So I wrapped the calls to the callbacks with Runnablelike this:
所以我用这样的方式包装了对回调的调用Runnable：
private void call(String method, String url, final HttpCallback cb) {
...
client.newCall(request).enqueue(new Callback() {
Handler mainHandler = new Handler(context.getMainLooper());
@Override
public void onFailure(Request request,final Throwable throwable) {
mainHandler.post(new Runnable() {
@Override
public void run() {
cb.onFailure(null, throwable);
}
});
}
@Override
public void onResponse(final Response response) throws IOException {
mainHandler.post(new Runnable() {
@Override
public void run() {
if (!response.isSuccessful()) {
cb.onFailure(response, null);
return;
}
cb.onSuccess(response);
}
});
}
});
}
回答by Marcos Casagrande
I know it's an old question, but recently I encountered the same issue. If you need to update any view, you will need to use runOnUiThread()or post the result back on the main thread.
我知道这是一个老问题，但最近我遇到了同样的问题。如果您需要更新任何视图，则需要runOnUiThread()在主线程上使用或发布结果。
HttpUtil.get(url, new Callback() { //okhttp3.Callback
@Override
public void onFailure(Call call, IOException e) { /* Handle error **/ }
@Override
public void onResponse(Call call, Response response) throws IOException {
String myResponse = response.body().string();
//Do something with response
//...
MyActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
//Handle UI here
findViewById(R.id.loading).setVisibility(View.GONE);
}
});
}
});
回答by Manish Goyal
According to Retrofit documentation Callbackmethods are executed on UI thread by default until you provide a callback executor to RetrofitOR when using custom method return types using CallAdapterFactory
根据 Retrofit 文档，回调方法默认在 UI 线程上执行，直到您向Retrofit提供回调执行程序或使用CallAdapterFactory使用自定义方法返回类型时
