Spring Tool Suite/Gradle/MapStruct - 找不到映射器的实现答案

【问题标题】：Spring Tool Suite/Gradle/MapStruct - Cannot find implementation for mapperSpring Tool Suite/Gradle/MapStruct - 找不到映射器的实现
【发布时间】：2022-11-07 17:13:46
【问题描述】：

我已经在 StackOverflow 上搜索了我的问题的答案。虽然我找到了许多提供的解决方案，但没有一个适合我的情况。

我必须在工作项目中使用 MapStruct，所以我试图通过Tutorialspoint 学习它。但是，我没有像教程建议的那样使用 Maven，而是使用 Gradle，我必须这样做，因为我的公司使用 Gradle 而不是 Maven。我在 StackOverflow 中看到了将项目移动到 Maven 的答案，但这不是我的选择。

我使用的是版本 1.4.2.Final 而不是 1.5.0.RC1，因为在使用后者时我遇到了一个不同的问题，通过切换到前者来解决。

以下是我的代码部分：

构建.gradle

plugins {
    id 'org.springframework.boot' version '2.6.5'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'
}

group = 'com.tutorialspoint'
version = '2.4.2'
sourceCompatibility = '1.8'

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    implementation group: 'org.mapstruct', name: 'mapstruct', version: '1.4.2.Final'
    implementation 'org.mapstruct:mapstruct:1.4.2.Final'
    annotationProcessor "org.mapstruct:mapstruct-processor:1.4.2.Final"
    compileOnly 'org.mapstruct:mapstruct-processor:1.4.2.Final'
}

tasks.named('test') {
    useJUnitPlatform()
}

compileJava {
    options.compilerArgs += [
        '-Amapstruct.suppressGeneratorTimestamp=true',
        '-Amapstruct.suppressGeneratorVersionInfoComment=true',
        '-Amapstruct.verbose=true'
    ]
}

学生.java

package com.tutorialspoint.mapstructproject;

public class Student {
    private int id;
    private String name;
    private String className;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getClassName() {
        return className;
    }

    public void setClassName(String className) {
        this.className = className;
    }
}

StudentEntity.java

package com.tutorialspoint.mapstructproject;

public class StudentEntity {
    private int id;
    private String name;
    private String classVal;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getClassVal() {
        return classVal;
    }

    public void setClassVal(String classVal) {
        this.classVal = classVal;
    }
}

StudentMapper.java

package com.tutorialspoint.mapstructproject;

import org.mapstruct.Mapper;
import org.mapstruct.Mapping;

@Mapper(componentModel="spring")
public interface StudentMapper {
    @Mapping(target="className", source="classVal")
    Student getModelFromEntity(StudentEntity student);

    @Mapping(target="classVal", source="className")
    StudentEntity getEntityFromModel(Student student);
}

StudentMapperTest.java

package com.tutorialspoint.mapstructproject;

import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
import org.mapstruct.factory.Mappers;
import com.tutorialspoint.mapstructproject.StudentEntity;
import com.tutorialspoint.mapstructproject.StudentMapper;
import com.tutorialspoint.mapstructproject.Student;

public class StudentMapperTest {
    private StudentMapper studentMapper = Mappers.getMapper(StudentMapper.class);

    @Test
    public void testEntityToModel() {
        StudentEntity entity = new StudentEntity();
        entity.setClassVal("X");
        entity.setName("John");
        entity.setId(1);
        Student model = studentMapper.getModelFromEntity(entity);
        assertEquals(entity.getClassVal(), model.getClassName());
        assertEquals(entity.getName(), model.getName());
        assertEquals(entity.getId(), model.getId());
    }

    @Test
    public void testModelToEntity() {
        Student model = new Student();
        model.setId(1);
        model.setName("John");
        model.setClassName("X");
        StudentEntity entity = studentMapper.getEntityFromModel(model);
        assertEquals(entity.getClassVal(), model.getClassName());
        assertEquals(entity.getName(), model.getName());
        assertEquals(entity.getId(), model.getId());
    }
}

这是堆栈跟踪：

java.lang.RuntimeException: java.lang.ClassNotFoundException: Cannot find implementation for com.tutorialspoint.mapstructproject.StudentMapper
    at org.mapstruct.factory.Mappers.getMapper(Mappers.java:61)
    at com.tutorialspoint.mapstructproject.StudentMapperTest.<init>(StudentMapperTest.java:11)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at org.junit.platform.commons.util.ReflectionUtils.newInstance(ReflectionUtils.java:550)
    at org.junit.jupiter.engine.execution.ConstructorInvocation.proceed(ConstructorInvocation.java:56)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
    at org.junit.jupiter.api.extension.InvocationInterceptor.interceptTestClassConstructor(InvocationInterceptor.java:73)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
    at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:77)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestClassConstructor(ClassBasedTestDescriptor.java:355)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateTestClass(ClassBasedTestDescriptor.java:302)
    at org.junit.jupiter.engine.descriptor.ClassTestDescriptor.instantiateTestClass(ClassTestDescriptor.java:79)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:280)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$4(ClassBasedTestDescriptor.java:272)
    at java.base/java.util.Optional.orElseGet(Optional.java:369)
    at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$5(ClassBasedTestDescriptor.java:271)
    at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:31)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:102)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:101)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:66)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$2(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:123)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:90)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
    at java.base/java.util.ArrayList.forEach(ArrayList.java:1541)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
    at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
    at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
    at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
    at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:108)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
    at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:96)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:84)
    at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:98)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:768)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)
Caused by: java.lang.ClassNotFoundException: Cannot find implementation for com.tutorialspoint.mapstructproject.StudentMapper
    at org.mapstruct.factory.Mappers.getMapper(Mappers.java:75)
    at org.mapstruct.factory.Mappers.getMapper(Mappers.java:58)
    ... 68 more

更新：有人询问构建文件。我在我的项目中没有看到构建文件，可能是因为错误导致构建永远不会成功。这是我的文件结构：

【问题讨论】：

不知道这是否有帮助，但我在使用 gradle 时只有这 2 个 mapstruct 依赖行。 implementation 'org.mapstruct:mapstruct:1.4.2.Final' 和 annotationProcessor 'org.mapstruct:mapstruct-processor:1.4.2.Final'。您还可以检查生成的实现类是否在构建文件夹中生成。
@BenZegveld 我只从这两个依赖行开始，并添加了其他依赖行以尝试解决问题。至于检查是否生成的实现，我没有构建文件。我将编辑问题以显示项目的文件夹和文件结构。
你用什么来运行构建/测试？ ./gradlew build?还是IDE？
@BenZegveld 我正在使用 Spring Tool Suite 来运行构建和测试。
如果您发现请添加解决方案

标签： spring-boot gradle classnotfoundexception mapstruct

【解决方案1】：

对我来说工作：

implementation group: 'org.mapstruct', name: 'mapstruct', version: '1.5.3.Final'
implementation group: 'org.mapstruct', name: 'mapstruct-processor', version: '1.5.3.Final'
compileOnly group: 'org.projectlombok', name: 'lombok', version: '1.18.24'


annotationProcessor group: 'org.projectlombok', name: 'lombok', version: '1.18.24'
annotationProcessor group: 'org.mapstruct', name: 'mapstruct-processor', version: '1.5.3.Final'

取自https://github.com/mapstruct/mapstruct-examples/blob/main/mapstruct-lombok/build.gradle

【讨论】：