使用GoogleDriveApi for Android與Groovy的奇怪的ClassCastException錯誤

Question

我試圖使用適用於Android和Groovy的GoogleDriveApi從Android訪問Google雲端硬盤帳戶內容。 但是我在logcat中遇到了一個錯誤，關於DriveApi類的ClassCastException，盡管我遵循了官方的Google教程，但使用了Groovy語言。 （為了簡化問題，我創建了一個小項目，該項目再現了與原始項目相同的錯誤。）

這是構建gradle（該項目是從命令行生成的：有一個唯一的gradle.build文件。提交此gradle構建是我以一種簡單的方式為您提供依賴項的方法）

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.5.0'
        classpath 'org.codehaus.groovy:gradle-groovy-android-plugin:0.3.10'
    }
}

apply plugin: 'android'
apply plugin: 'groovyx.grooid.groovy-android'

android {
    compileSdkVersion 'Google Inc.:Google APIs:23'
    buildToolsVersion '23.0.2'

    defaultConfig {
        minSdkVersion 15
        targetSdkVersion 23
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFile getDefaultProguardFile('proguard-android.txt')
        }
    }
}

repositories {
   jcenter()
}

project.androidGroovy {
    options {
        sourceCompatibility = '1.7'
        targetCompatibility = '1.7'
    }
}

dependencies {
    compile 'org.codehaus.groovy:groovy:2.4.6:grooid'
    compile 'com.arasthel:swissknife:1.4.0'
    compile 'com.google.android.gms:play-services-drive:8.4.0'
}

這是GoogleApiGroovyTest.groovy

package com.loloof64.android.google_api_test

import android.app.Activity
import android.os.Bundle
import android.content.IntentSender 
import android.widget.Toast
import android.content.Context
import android.util.Log

import groovy.transform.CompileStatic

import com.arasthel.swissknife.dsl.components.GAsyncTask

import com.google.android.gms.common.api.GoogleApiClient
import com.google.android.gms.common.api.GoogleApiClient.Builder
import com.google.android.gms.drive.Drive
import com.google.android.gms.common.ConnectionResult
import com.google.android.gms.common.GooglePlayServicesUtil
import com.google.android.gms.common.api.GoogleApiClient.ConnectionCallbacks
import com.google.android.gms.common.api.GoogleApiClient.OnConnectionFailedListener

import com.google.android.gms.drive.DriveFolder
import com.google.android.gms.drive.DriveApi
import com.google.android.gms.common.api.PendingResult

@CompileStatic
public class GoogleApiGroovyTest extends Activity
implements GoogleApiClient.ConnectionCallbacks,     GoogleApiClient.OnConnectionFailedListener
{

    private GoogleApiClient googleApiClient
    private final static int RESOLVE_CONNECTION_REQUEST_CODE = 4
    private final static String APP_LOGGER_REF = "GoogleApiGroovyTest"

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main)

        googleApiClient = new     GoogleApiClient.Builder(this).addApi(Drive.API).addScope(Drive.SCOPE_APPFOLDER).addConnectionCallbacks(this).addOnConnectionFailedListener(this).build()
        googleApiClient.connect()
    }

    @Override
    public void onConnected(Bundle connectionHint){
        Toast.makeText(this, "Connected to Google Drive", Toast.LENGTH_SHORT).show()
        Context myThis = this
        async { context, GAsyncTask task ->
            task.after {
                Toast.makeText(myThis, "Finally printed items into screen", Toast.LENGTH_SHORT).show()
            }

            task.error { err ->
                Toast.makeText(this, "Error updating list files !", Toast.LENGTH_SHORT).show()
                Log.e(APP_LOGGER_REF, err.message)
                err.stackTrace.each { element ->
                    Log.e(APP_LOGGER_REF, element.toString())
                }
            } 

            loadExplorerItems()

            true // Seem as returning a value is needed for the async task code to be executed
        }
    }

    @Override
    public void onConnectionSuspended(int cause) {
        //TODO
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult)     {
        // This block section is mandatory for GoogleApiClient to recover connection failure
        if (connectionResult.hasResolution()) {
            try {
                connectionResult.startResolutionForResult(this, RESOLVE_CONNECTION_REQUEST_CODE)
            } catch (IntentSender.SendIntentException e) {
                // Unable to resolve
                Toast.makeText(this, "Failed to connect to Google account !", Toast.LENGTH_SHORT).show()
            }
        } else {
                GooglePlayServicesUtil.getErrorDialog(connectionResult.getErrorCode(), this, 0).show()
        }
        // End of block section
    }

    private void loadExplorerItems(){
        Context myThis = this
        DriveFolder appFolder = DriveApi.getAppFolder(googleApiClient)
        PendingResult<DriveApi.MetadataBufferResult> pendingChildren = appFolder.listChildren(googleApiClient)
        pendingChildren.setResultCallback     {DriveApi.MetadataBufferResult result -> processResult:{
            if (result.getStatus().isSuccess()){
                Toast.makeText(myThis, "Retrieved root content", Toast.LENGTH_SHORT).show()
            }
            else {
               Toast.makeText(myThis, "Failed to get root content", Toast.LENGTH_SHORT).show() 
            }
        }}
    }
}

這是錯誤stacktrace：

04-08 16:58:53.549  3261  3261 E GoogleApiGroovyTest: Cannot cast object 'interface com.google.android.gms.drive.DriveApi' with class 'java.lang.Class' to class 'com.google.android.gms.drive.DriveApi'
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.continueCastOnSAM(DefaultTypeTransformation.java:405)
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.continueCastOnNumber(DefaultTypeTransformation.java:319)
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation.castToType(DefaultTypeTransformation.java:232)
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.runtime.ScriptBytecodeAdapter.castToType(ScriptBytecodeAdapter.java:603)
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: com.loloof64.android.google_api_test.GoogleApiGroovyTest.loadExplorerItems(GoogleApiGroovyTest.groovy:91)
04-08 16:58:53.575  3261  3261 E GoogleApiGroovyTest: com.loloof64.android.google_api_test.GoogleApiGroovyTest.access$0(GoogleApiGroovyTest.groovy)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: com.loloof64.android.google_api_test.GoogleApiGroovyTest$_onConnected_closure1.doCall(GoogleApiGroovyTest.groovy:62)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: java.lang.reflect.Method.invoke(Native Method)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:294)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1021)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: groovy.lang.Closure.call(Closure.java:426)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: com.arasthel.swissknife.dsl.components.GAsyncTask.doInBackground(GAsyncTask.groovy:49)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: android.os.AsyncTask$2.call(AsyncTask.java:295)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: java.util.concurrent.FutureTask.run(FutureTask.java:237)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
04-08 16:58:53.576  3261  3261 E GoogleApiGroovyTest: java.lang.Thread.run(Thread.java:818)

同時，DriveApi.getAppFolder方法具有以下簽名：

abstract DriveFolder getAppFolder(GoogleApiClient apiClient)

DriveApi類和DriveFolder類都不采用類參數。 所以我無法理解Stacktrace錯誤的真正含義。

請參閱Drive API Android參考

Answer 1

嗯，我不知道該錯誤來自何處，但是您試圖像在類上調用靜態方法一樣嘗試在接口上調用方法這一事實可能與它有關：

DriveFolder appFolder = DriveApi.getAppFolder(googleApiClient)

DriveApi是一個接口，因此沒有任何方法實現。 而且， getAppFolder()是實例方法，而不是靜態方法。 因此，您需要的是DriveApi的實現，可以從Drive獲得：

DriveFolder appFolder = Drive.DriveApi.getAppFolder(googleApiClient)