Junit中的java.lang.reflect.invocationtargetexception导致null

我试图运行我的junit测试用例，但它显示为nullpointerexception。当我调试它时，显示为java.lang.reflect.invocationtargetexception会导致null。请帮帮我

公开课学生测验{

学生服务

StudentDAO stuDAO;
StudentVO stuVo;

@Before
public void setUp() throws Exception {
    System.out.println("In Setup");
    stuVo=new StudentVO ();
    stuService=new StudentService();
   stuDAO=Mockito.mock(StudentDAO.class);
    //MockitoAnnotations.initMocks(this);
    stuVo.setStudId("123");
    stuVo.setName("user1");
   Mockito.when(stuDAO.getStudent(stuVo.getStuId())).thenReturn(student);

}

@Test
public void getStudent() throws DataAccessException {
    StudentVO stVO=stuService.getStudent(123)   ;
    Assert.assertEquals("123", stVO.getStuId());
}

}

我的服务班是

public class StudentService {
@Inject
StudentDAO stuDao;
public StudentVo getStudent(String id){
    return stuDao.getStudent(id);
}
public StudentDAO getStuDao() {
    return stuDao;
}
}

在故障跟踪中，其仅显示为“java.lang.NullPointerException”

at com.stu.StudentService.getStudent(StudentService.java:104)
at com.stu.junit.POCJunit.getgetStudent(StudentTest.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

---

您的代码存在一些问题

首先是DAO的模拟。在名为student的测试类中没有变量。这可能是stuVO，除非您从其他对象转换为stuVO对象。无论哪种方式，都需要在该模拟中定义或替换变量student

另一件事是您的输入和输出没有意义。您在setter中将StudId作为“123”，但在assert中作为int。您可能在setter或getter中进行转换，但请确保您的类型在assert中匹配

我刚刚注意到另一件事

您没有在服务内部设置模拟DAO。这会导致空指针，因为您的服务正在尝试调用空DAO上的方法，我假设该方法是自动连接的

试试这个

public class StudentTest {
    @ObjectUnderTest
    StudentService stuService;
    @Inject
    StudentDAO stuDAO;
    StudentVO stuVo;

    @Before
    public void setUp() throws Exception {
        System.out.println("In Setup");
        stuVo=new StudentVO ();   
        stuVo.setStudId("123");
        stuVo.setName("user1");
        Mockito.when(stuDAO.getStudent(stuVo.getStuId())).thenReturn(student);
    }

    @Test
    public void getStudent() throws DataAccessException {
        StudentVO stVO=stuService.getStudent(123)   ;
        Assert.assertEquals("123", stVO.getStuId());
    }
}

---

我通过添加以下代码解决了这个问题

@Mock
StudentDAO stuDAO;

@InjectMocks
StudentService stuService;

在我编写的setUp（）方法中

 MockitoAnnotations.initMocks(this);

---

请包含完整的stacktrace，好吗？我已经粘贴了我所有的代码和错误。当我调用KafkaTemplate.send（）.get（）时，我面临同样的异常。有人能帮忙吗。您好，谢谢您的回复，我已经在我的服务程序中使用了@Inject来注入DAO。好的..您在测试类中的DAO上有@Inject吗？代码段位于该部分之间我的服务类公共类StudentService{@Inject StudentDAO stuDao；public StudentVo getStudent（int id）{return stuDao.getStudent（id）；}public StudentDAO getStuDao（）{return stuDao；}}Hii在servicer中如果我把StudentDAO stuDao=new StudentDAO，那么它就工作了。但是当我使用@inject时它就不工作了。试试我刚才添加的