今天升级了android studio3.4.1，导入以前的一个旧项目，并且升级了lottie-android动画库到最新版本3.0.3，编译发现出现如下报错：
Manifest merger failed : Attribute application@appComponentFactory value=(android.support.v4.app.CoreComponentFactory) from [com.android.support:support-compat:28.0.0] AndroidManifest.xml:22:18-91 is also present at [androidx.core:core:1.0.0] AndroidManifest.xml:22:18-86 value=(androidx.core.app.CoreComponentFactory). Suggestion: add 'tools:replace="android:appComponentFactory"' to <application> element at AndroidManifest.xml:5:5-20:19 to override.于是按照报错日志提示，在AndroidManifest.xml的application中添加tools:replace="android:appComponentFactory"，如下所示：
<application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme" tools:ignore="AllowBackup,GoogleAppIndexingWarning" tools:replace="android:appComponentFactory">然后编译继续报错如下：
Caused by: org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:processDebugManifest'. at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:95) at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:91) at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:57) at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:119) at org.gradle.api.internal.tasks.execution.ResolvePreviousStateExecuter.execute(ResolvePreviousStateExecuter.java:43) at org.gradle.api.internal.tasks.execution.CleanupStaleOutputsExecuter.execute(CleanupStaleOutputsExecuter.java:93) at org.gradle.api.internal.tasks.execution.FinalizePropertiesTaskExecuter.execute(FinalizePropertiesTaskExecuter.java:45) at org.gradle.api.internal.tasks.execution.ResolveTaskArtifactStateTaskExecuter.execute(ResolveTaskArtifactStateTaskExecuter.java:94) at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:56) at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:55) at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36) at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:67) at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:52) at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:49) at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:315) at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:305) at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:175) at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:101) at org.gradle.internal.operations.DelegatingBuildOperationExecutor.call(DelegatingBuildOperationExecutor.java:36) at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:49) at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:43) at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:355) at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$InvokeNodeExecutorsAction.execute(DefaultTaskExecutionGraph.java:343) at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:336) at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$BuildOperationAwareExecutionAction.execute(DefaultTaskExecutionGraph.java:322) at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker$1.execute(DefaultPlanExecutor.java:134) at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker$1.execute(DefaultPlanExecutor.java:129) at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.execute(DefaultPlanExecutor.java:202) at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.executeNextNode(DefaultPlanExecutor.java:193) at org.gradle.execution.plan.DefaultPlanExecutor$ExecutorWorker.run(DefaultPlanExecutor.java:129) ... 6 more Caused by: java.lang.RuntimeException: Manifest merger failed with multiple errors, see logs at com.android.builder.core.AndroidBuilder.mergeManifestsForApplication(AndroidBuilder.java:558) at com.android.build.gradle.tasks.ProcessApplicationManifest.doFullTaskAction(ProcessApplicationManifest.java:208) at com.android.build.gradle.internal.tasks.IncrementalTask.taskAction(IncrementalTask.java:106) at sun.reflect.GeneratedMethodAccessor849.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73) at org.gradle.api.internal.project.taskfactory.IncrementalTaskAction.doExecute(IncrementalTaskAction.java:47) at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:41) at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:28) at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$2.run(ExecuteActionsTaskExecuter.java:284) at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:301) at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:293) at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:175) at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:91) at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31) at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:273) at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:258) at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.access$200(ExecuteActionsTaskExecuter.java:67) at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$TaskExecution.execute(ExecuteActionsTaskExecuter.java:145) at org.gradle.internal.execution.impl.steps.ExecuteStep.execute(ExecuteStep.java:49) at org.gradle.internal.execution.impl.steps.CancelExecutionStep.execute(CancelExecutionStep.java:34) at org.gradle.internal.execution.impl.steps.TimeoutStep.executeWithoutTimeout(TimeoutStep.java:69) at org.gradle.internal.execution.impl.steps.TimeoutStep.execute(TimeoutStep.java:49) at org.gradle.internal.execution.impl.steps.CatchExceptionStep.execute(CatchExceptionStep.java:33) at org.gradle.internal.execution.impl.steps.CreateOutputsStep.execute(CreateOutputsStep.java:50) at org.gradle.internal.execution.impl.steps.SnapshotOutputStep.execute(SnapshotOutputStep.java:43) at org.gradle.internal.execution.impl.steps.SnapshotOutputStep.execute(SnapshotOutputStep.java:29) at org.gradle.internal.execution.impl.steps.CacheStep.executeWithoutCache(CacheStep.java:134) at org.gradle.internal.execution.impl.steps.CacheStep.lambda$execute$3(CacheStep.java:83)通过查看日志知道这是AndroidManifest中的报错，然后到AndroidManifest.xml的Merged Manifest中查看报错信息为：
Merging Errors: Error: tools:replace specified at line:5 for attribute android:appComponentFactory, but no new value specified app main manifest (this file), line 4 Error: Validation failed, exiting app main manifest (this file)上面所说的意思就是，我们没有给android:appComponentFactory指定新的值，所以在application中继续添加android:appComponentFactory="android.support.v4.app.CoreComponentFactory"，如下：
<application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme" tools:ignore="AllowBackup,GoogleAppIndexingWarning" tools:replace="android:appComponentFactory" android:appComponentFactory="android.support.v4.app.CoreComponentFactory">结果编译又出现报错，如下：
Caused by: com.android.ide.common.workers.WorkerExecutorException: 1 exception was raised by workers: java.lang.RuntimeException: Duplicate class android.support.v4.app.INotificationSideChannel found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.IResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.ResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.ResultReceiver$1 found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class android.support.v4.os.ResultReceiver$MyRunnable found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class androidx.core.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class androidx.core.internal.package-info found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0) Duplicate class androidx.versionedparcelable.CustomVersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.NonParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.ParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.ParcelImpl found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.ParcelImpl$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.ParcelUtils found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcel$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcel$ParcelException found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelStream found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelStream$FieldBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelStream$InputBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0) Duplicate class androidx.versionedparcelable.VersionedParcelize found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)从日志中可以看出，这是因为Android support和Androidx库不能共存引起的编译报错。因为最新的lottie-android动画库已经使用了Androidx库，而我的项目使用的还是Android support库，从而引起的冲突。因此解决办法有两种。
（1）将build tools更新到3.4.1，如下：
dependencies { classpath 'com.android.tools.build:gradle:3.4.1' }gradle更新到5.1.1，如下：
distributionBase=GRADLE_USER_HOME distributionPath=wrapper/dists zipStoreBase=GRADLE_USER_HOME zipStorePath=wrapper/dists distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-all.zip依赖库统一更新到28.0.0，如下：
dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation 'com.android.support:appcompat-v7:28.0.0' implementation 'com.airbnb.android:lottie:3.0.3' }这一步非常重要，不然会导致第二步转换不成功。
（2）完成（1）之后，右键工程→Refactor→Migrate to AndroidX…，如下图所示： （3）选中所有需要重命名的目录，点击Do Refactor，如下图所示： （4）执行上面的步骤之后，发现Android support库已经被全部替换成了Androidx库了，至此项目已经可以成功的运行了。
前面已经说过了，这个问题是由于升级了lottie-android动画库到最新版本引起的，所以我们只需要将lottie-android动画库的版本降低到它使用Android support库的版本就可以了，其他的第三方库也是同样的解决方法，但是由于后续会更新升级第三方库，所以不推荐使用此方案解决这个问题，推荐使用方法一解决这样的报错问题。
