休眠條件+限制上的錯誤LazyInitializationException（Spring）

Question

使用休眠查詢時出現此錯誤

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:167)
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:215)
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
    at com.javalabs.web.dao.Task_$$_javassist_1.toString(Task_$$_javassist_1.java)
    at java.lang.String.valueOf(Unknown Source)
    at java.lang.StringBuilder.append(Unknown Source)
    at com.javalabs.web.dao.TaskAction.toString(TaskAction.java:175)
    at java.lang.String.valueOf(Unknown Source)
    at java.lang.StringBuilder.append(Unknown Source)
    at java.util.AbstractCollection.toString(Unknown Source)
    at java.lang.String.valueOf(Unknown Source)
    at org.junit.Assert.format(Assert.java:752)
    at org.junit.Assert.failNotEquals(Assert.java:743)
    at org.junit.Assert.assertEquals(Assert.java:118)
    at com.javalabs.web.test.tests.TaskActionDaoTests.testTaskActionCreate(TaskActionDaoTests.java:120)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:88)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    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:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

拋出錯誤的JUnit測試

@Test
public void testTaskActionCreate() {
    taskPriorityDao.saveOrUpdate(priority);
    taskCategoryDao.saveOrUpdate(category);
    taskStateDao.saveOrUpdate(state);
    userDao.saveOrUpdate(user);

    Date rightnow = Calendar.getInstance().getTime();

    Task t1 = new Task("My first task", "This is a task", rightnow,
            rightnow, category, priority, state, user, user, "okey", 0);

    TaskAction ta1 = new TaskAction(t1, rightnow, "Task action 1",
            "Task action 1 description", user);
    TaskAction ta2 = new TaskAction(t1, rightnow, "Task action 2",
            "Task action 2 description", user);
    TaskAction ta3 = new TaskAction(t1, rightnow, "Task action 3",
            "Task action 3 description", user);
    TaskAction ta4 = new TaskAction(t1, rightnow, "Task action 4",
            "Task action 4 description", user);

    t1.addAction(ta1);
    t1.addAction(ta2);
    t1.addAction(ta3);
    t1.addAction(ta4);

    taskDao.save(t1);

    Task t2 = taskDao.get(t1.getIdTask());
    assertEquals("Should be 4 taskActions with getAllTaskActions.", 4,
            taskActionDao.getAllTaskActions(t2.getIdTask()));
}

TaskActionDao.java

...
@SuppressWarnings("unchecked")
public List<TaskAction> getAllTaskActions(long idTask) {
    Criteria crit = session().createCriteria(TaskAction.class);
    crit.add(Restrictions.eq("task.idTask", idTask)); //error task.idTask?
    return crit.list();
}
...

TaskAction.java

@Entity
@Table(name = "t_taskaction")
public class TaskAction {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "idTaskAction")
    private long idTaskAction;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "idTask", nullable = false)
    private Task task;
    private Date date;
    private String actionname;
    private String description;
    private int duration;
    @ManyToOne
    @JoinColumn(name = "idUser", nullable = false)
    private User user;
    private Date timestamp;
        ...

Task.java

@Entity
@Table(name = "t_task")
public class Task {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "idTask")
    private long idTask;
    ...

Answer 1

獲得LazyInitializationException是有意義的。 由於您使用toString隱含在TaskAction ， task是要試圖訪問是延遲加載。

如果您嘗試assertEquals("Should be 4 taskActions with getAllTaskActions.", 4, taskActionDao.getAllTaskActions(t2.getIdTask()).size());