JDBC：找不到合適的驅動程序

Question

首先，我真的很抱歉。 我知道這個問題現在已經被問過很多次了，但我就是找不到適合我的解決方案。 我正在重試我們必須為學校做的一個項目，但是在嘗試添加我的數據庫時，我收到錯誤消息：'java.sql.SQLException：找不到適合 jdbc:mysql://localhost:3308/pandemic 的驅動程序'

這是我正在使用的代碼：

package main;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Run {

    private static final String URL = "jdbc:mysql://localhost:3308/pandemic";
    private static final String USERNAME = null;
    private static final String PASSWORD = "";

    private final Logger logger = Logger.getLogger(this.getClass().getName());

    public static void main(String[] args) {
        new Run().run();
    }
    private void run() {
        try(Connection connection = DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            System.out.println("Connected to db");
        } catch (SQLException exception) {
            logger.log(Level.SEVERE, "Unable to connect to Database");
            exception.printStackTrace();
        }
    }
}

而我的 Gradle 看起來是這樣的：

plugins {
    id 'java'
}

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    // https://mvnrepository.com/artifact/mysql/mysql-connector-java
    compile group: 'mysql', name: 'mysql-connector-java', version: '8.0.18'
}

非常感謝您的幫助，如果您需要更多信息，請告訴我，我很樂意提供。

更新堆棧跟蹤：

16:21:55: Executing task 'Run.main() --stacktrace'...

> Task :compileJava FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileJava'.
> Could not resolve all files for configuration ':compileClasspath'.
   > Could not resolve mysql:mysql-connector-java:8.0.18.
     Required by:
         project :
      > No cached version of mysql:mysql-connector-java:8.0.18 available for offline mode.

* Try:
Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':compileJava'.
    at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:38)
    at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.executeTask(EventFiringTaskExecuter.java:63)
    at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:49)
    at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter$1.call(EventFiringTaskExecuter.java:46)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:416)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$CallableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:406)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$1.execute(DefaultBuildOperationExecutor.java:165)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:250)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:158)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.call(DefaultBuildOperationExecutor.java:102)
    at org.gradle.internal.operations.DelegatingBuildOperationExecutor.call(DelegatingBuildOperationExecutor.java:36)
    at org.gradle.api.internal.tasks.execution.EventFiringTaskExecuter.execute(EventFiringTaskExecuter.java:46)
    at org.gradle.execution.plan.LocalTaskNodeExecutor.execute(LocalTaskNodeExecutor.java:43)
    at org.gradle.execution.taskgraph.DefaultTaskExecutionGraph$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)
    at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
    at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
    at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
Caused by: org.gradle.api.internal.artifacts.ivyservice.DefaultLenientConfiguration$ArtifactResolveException: Could not resolve all files for configuration ':compileClasspath'.
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.rethrowFailure(DefaultConfiguration.java:1176)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.access$2100(DefaultConfiguration.java:136)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration$ConfigurationFileCollection.getFiles(DefaultConfiguration.java:1151)
    at org.gradle.api.internal.file.AbstractFileCollection.iterator(AbstractFileCollection.java:72)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.iterator(DefaultConfiguration.java:463)
    at org.gradle.internal.snapshot.impl.DefaultFileSystemSnapshotter$FileCollectionLeafVisitorImpl.visitCollection(DefaultFileSystemSnapshotter.java:240)
    at org.gradle.api.internal.file.AbstractFileCollection.visitLeafCollections(AbstractFileCollection.java:233)
    at org.gradle.api.internal.file.CompositeFileCollection.visitLeafCollections(CompositeFileCollection.java:205)
    at org.gradle.internal.snapshot.impl.DefaultFileSystemSnapshotter.snapshot(DefaultFileSystemSnapshotter.java:126)
    at org.gradle.internal.fingerprint.impl.AbstractFileCollectionFingerprinter.fingerprint(AbstractFileCollectionFingerprinter.java:47)
    at org.gradle.internal.fingerprint.classpath.impl.DefaultCompileClasspathFingerprinter.fingerprint(DefaultCompileClasspathFingerprinter.java:45)
    at org.gradle.api.internal.tasks.execution.DefaultTaskFingerprinter.fingerprintTaskFiles(DefaultTaskFingerprinter.java:46)
    at org.gradle.api.internal.tasks.execution.ResolveBeforeExecutionStateTaskExecuter.createExecutionState(ResolveBeforeExecutionStateTaskExecuter.java:92)
    at org.gradle.api.internal.tasks.execution.ResolveBeforeExecutionStateTaskExecuter.execute(ResolveBeforeExecutionStateTaskExecuter.java:72)
    at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
    at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:109)
    at org.gradle.api.internal.tasks.execution.ResolveBeforeExecutionOutputsTaskExecuter.execute(ResolveBeforeExecutionOutputsTaskExecuter.java:67)
    at org.gradle.api.internal.tasks.execution.ResolveAfterPreviousExecutionStateTaskExecuter.execute(ResolveAfterPreviousExecutionStateTaskExecuter.java:46)
    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.ResolveTaskExecutionModeExecuter.execute(ResolveTaskExecutionModeExecuter.java:94)
    at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:57)
    at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:56)
    at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:36)
    ... 24 more
Caused by: org.gradle.internal.resolve.ModuleVersionResolveException: Could not resolve mysql:mysql-connector-java:8.0.18.
Required by:
    project :
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.RepositoryChainComponentMetaDataResolver.resolveModule(RepositoryChainComponentMetaDataResolver.java:103)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.RepositoryChainComponentMetaDataResolver.resolve(RepositoryChainComponentMetaDataResolver.java:63)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.ComponentResolversChain$ComponentMetaDataResolverChain.resolve(ComponentResolversChain.java:95)
    at org.gradle.api.internal.artifacts.ivyservice.clientmodule.ClientModuleResolver.resolve(ClientModuleResolver.java:63)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.ComponentState.resolve(ComponentState.java:189)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.ComponentState.getMetadata(ComponentState.java:139)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.EdgeState.calculateTargetConfigurations(EdgeState.java:175)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.EdgeState.attachToTargetConfigurations(EdgeState.java:131)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.DependencyGraphBuilder.attachToTargetRevisionsSerially(DependencyGraphBuilder.java:331)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.DependencyGraphBuilder.resolveEdges(DependencyGraphBuilder.java:230)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.DependencyGraphBuilder.traverseGraph(DependencyGraphBuilder.java:170)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.graph.builder.DependencyGraphBuilder.resolve(DependencyGraphBuilder.java:131)
    at org.gradle.api.internal.artifacts.ivyservice.resolveengine.DefaultArtifactDependencyResolver.resolve(DefaultArtifactDependencyResolver.java:121)
    at org.gradle.api.internal.artifacts.ivyservice.DefaultConfigurationResolver.resolveGraph(DefaultConfigurationResolver.java:171)
    at org.gradle.api.internal.artifacts.ivyservice.ShortCircuitEmptyConfigurationResolver.resolveGraph(ShortCircuitEmptyConfigurationResolver.java:86)
    at org.gradle.api.internal.artifacts.ivyservice.ErrorHandlingConfigurationResolver.resolveGraph(ErrorHandlingConfigurationResolver.java:73)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration$7.run(DefaultConfiguration.java:581)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:402)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:394)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$1.execute(DefaultBuildOperationExecutor.java:165)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:250)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:158)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:92)
    at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.resolveGraphIfRequired(DefaultConfiguration.java:572)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.access$600(DefaultConfiguration.java:136)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration$6.run(DefaultConfiguration.java:552)
    at org.gradle.api.internal.project.DefaultProjectStateRegistry$SafeExclusiveLockImpl.withLock(DefaultProjectStateRegistry.java:244)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.resolveExclusively(DefaultConfiguration.java:548)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.resolveToStateOrLater(DefaultConfiguration.java:543)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration.access$2200(DefaultConfiguration.java:136)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration$ConfigurationFileCollection.getSelectedArtifacts(DefaultConfiguration.java:1159)
    at org.gradle.api.internal.artifacts.configurations.DefaultConfiguration$ConfigurationFileCollection.getFiles(DefaultConfiguration.java:1148)
    ... 45 more
Caused by: org.gradle.internal.resolve.ModuleVersionResolveException: No cached version of mysql:mysql-connector-java:8.0.18 available for offline mode.
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.StartParameterResolutionOverride$FailedRemoteAccess.resolveComponentMetaData(StartParameterResolutionOverride.java:96)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.CachingModuleComponentRepository$ResolveAndCacheRepositoryAccess.resolveComponentMetaData(CachingModuleComponentRepository.java:373)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.lambda$resolveComponentMetaData$3(ErrorHandlingModuleComponentRepository.java:159)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.lambda$tryResolveAndMaybeBlacklist$15(ErrorHandlingModuleComponentRepository.java:228)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.tryResolveAndMaybeBlacklist(ErrorHandlingModuleComponentRepository.java:242)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.tryResolveAndMaybeBlacklist(ErrorHandlingModuleComponentRepository.java:227)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.performOperationWithRetries(ErrorHandlingModuleComponentRepository.java:220)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ErrorHandlingModuleComponentRepository$ErrorHandlingModuleComponentRepositoryAccess.resolveComponentMetaData(ErrorHandlingModuleComponentRepository.java:158)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ComponentMetaDataResolveState.process(ComponentMetaDataResolveState.java:69)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.ComponentMetaDataResolveState.resolve(ComponentMetaDataResolveState.java:61)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.RepositoryChainComponentMetaDataResolver.findBestMatch(RepositoryChainComponentMetaDataResolver.java:138)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.RepositoryChainComponentMetaDataResolver.findBestMatch(RepositoryChainComponentMetaDataResolver.java:119)
    at org.gradle.api.internal.artifacts.ivyservice.ivyresolve.RepositoryChainComponentMetaDataResolver.resolveModule(RepositoryChainComponentMetaDataResolver.java:92)
    ... 77 more


* Get more help at https://help.gradle.org

Deprecated Gradle features were used in this build, making it incompatible with Gradle 6.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/5.2.1/userguide/command_line_interface.html#sec:command_line_warnings

BUILD FAILED in 0s
1 actionable task: 1 executed
16:21:56: Task execution finished 'Run.main() --stacktrace'.

Answer 1

由於 Gradle 無法下載正確的依賴項（在本例中為mysql-connector ），您所做的似乎失敗了。 從以下失敗的 Gradle 運行任務日志中可以明顯看出這一點：

* What went wrong:
Execution failed for task ':compileJava'.
> Could not resolve all files for configuration ':compileClasspath'.
   > Could not resolve mysql:mysql-connector-java:8.0.18.
     Required by:
         project :
      > No cached version of mysql:mysql-connector-java:8.0.18 available for offline mode.

我假設您正在從 IDE（最有可能是想法）委托給 Gradle 作為您的構建工具中運行main 。 我首先建議檢查是否啟用了自動導入功能。 如果沒有嘗試運行：

gradle clean build

從命令行看看它是怎么回事。 Maven Central 和 JCenter 似乎都部署了工件（mysql-connector - 請求的版本）所以依賴性沒有問題，而不是你的 Gradle 腳本/配置。

Answer 2

嘗試將您的驅動程序添加到DriverManager ，如下所示：

Class.forName("com.mysql.cj.jdbc.Driver").newInstance();

另請參閱： 7.1 使用 JDBC DriverManager 接口連接到 MySQL