创建 OkHttp3.OkHttpClient 的新实例时出现异常

Question

我正在尝试使用OkHttp从 Android 应用程序中的网络服务器下载文件。使用 Android Studio（API 级别 28）创建新项目后，我添加了一个按钮，并将 ImageView 添加到我的活动中。这个想法是当我按下按钮并在屏幕上显示时下载图像。

我正在使用最新版本的 OkHttp，3.14.0。

我添加<uses-permission android:name="android.permission.INTERNET"/>到 AndroidManifest.xml 文件中。

我尝试完全按照示例中的描述使用 OkHttpClient 。这是我的代码的样子：

public class MainActivity extends AppCompatActivity {

    ... // onCreate method

    public void btnClicked(View view) {
        new DownloadImageAsyncTask().execute("https://link.to/image.jpg");
    }

    public class DownloadImageAsyncTask extends AsyncTask<String, Void, Bitmap> {

        OkHttpClient client = new OkHttpClient();

        ... // override doInBackground()
    }
}

当我运行应用程序并按下按钮时，该btnClicked()方法被执行并且应用程序崩溃。OkHttpClient()无论我是将它作为DownloadImageAsyncTask类中的一个字段，作为方法的局部变量doInBackground()还是作为类中的一个字段，调用时都会发生错误ManActivity。

我还尝试使用 Builder ( new OkHttpClient.Builder().build()) 来初始化对象，但结果相同。

这是堆栈跟踪：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.myapp.httpstuff, PID: 17796
    java.lang.IllegalStateException: Could not execute method for android:onClick
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:390)
        at android.view.View.performClick(View.java:6597)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385)
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
     Caused by: java.lang.BootstrapMethodError: Exception from call site #4 bootstrap method
        at okhttp3.internal.Util.<clinit>(Util.java:87)
        at okhttp3.internal.Util.immutableList(Util.java:234)
        at okhttp3.OkHttpClient.<clinit>(OkHttpClient.java:124)
        at com.myapp.httpstuff.MainActivity$DownloadImageAsyncTask.<init>(MainActivity.java:31)
        at com.myapp.httpstuff.MainActivity.btnClicked(MainActivity.java:26)
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 
     Caused by: java.lang.ClassCastException: Bootstrap method returned null
        at okhttp3.internal.Util.<clinit>(Util.java:87) 
        at okhttp3.internal.Util.immutableList(Util.java:234) 
        at okhttp3.OkHttpClient.<clinit>(OkHttpClient.java:124) 
        at com.myapp.httpstuff.MainActivity$DownloadImageAsyncTask.<init>(MainActivity.java:31) 
        at com.myapp.httpstuff.MainActivity.btnClicked(MainActivity.java:26) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:385) 
        at android.view.View.performClick(View.java:6597) 
        at android.view.View.performClickInternal(View.java:6574) 
        at android.view.View.access$3100(View.java:778) 
        at android.view.View$PerformClick.run(View.java:25885) 
        at android.os.Handler.handleCallback(Handler.java:873) 
        at android.os.Handler.dispatchMessage(Handler.java:99) 
        at android.os.Looper.loop(Looper.java:193) 
        at android.app.ActivityThread.main(ActivityThread.java:6669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858) 

Answer 1

OkHttp 3.13+ 需要 Java 8+ 或 Android 5+。我认为您遇到过 ART 运行时不期望 Java 8 lambda 的情况。

https://android.googlesource.com/platform/art/+/master/runtime/interpreter/interpreter_common.cc#1399

Handle<mirror::Object> object(hs.NewHandle(result.GetL()));
if (UNLIKELY(object.IsNull())) {
  // This will typically be for LambdaMetafactory which is not supported.
  ThrowClassCastException("Bootstrap method returned null");
  return nullptr;
}

您可能会成功更新 build.gradle。

android { 
  compileOptions { 
    targetCompatibility = "8"
    sourceCompatibility = "8"
   }
 }

https://github.com/square/okhttp/issues/4597