手動new對象出現空指針的解決辦法詳解

java.lang.NullPointerException
    at com.example.new_oa.identity.service.impl.IdentityServiceImpl.getAllDepts(IdentityServiceImpl.java:51)
    at com.example.new_oa.NewOaApplicationTests.initDb(NewOaApplicationTests.java:31)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)

筆者在進行開發測試的時候，代碼中是通過注解將業務層對象放入spring容器的，而在測試時，時通過手動new的業務層對象，去調用的方法，但是在方法的內部卻出現了空指針的情況，這是怎么回事呢？后來發現，在我的業務層方法中，是依賴了持久層對象的，而持久層對象又是通過注解引入的，前面由于業務層對象是通過手動new出來的，所以該對象中并沒有把持久層對象注入進去，所以出現了空指針的情況。所以將手動的new的對象，修改為從容器中獲取就好了。