不能标志成resour'ces root是怎么回事？

慕粉1469801537 2019-03-28

源自：基于AspectJ的AOP开发 3-1 入门案例

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3回答

好帮手慕阿莹回答被采纳获得+3积分 2019-03-28 14:57:45

空指针异常，既有值为null的对象调用方法或属性导致的

同学看看具体是哪一行代码报空指针异常了呢？那个对象去调用方法了呢？对象就应该是null

然后再看一下为什么是null。

，如果还是不清楚，请同学再贴一下代码，注意不要贴在回复里，会失去代码的格式。可以在回答里贴一下。并且告诉老师报错的具体是哪个代码。（不用只说行数，粘进来的代码老师的行数不一定和你的一样）

祝学习愉快

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提问者慕粉1469801537 2019-03-28 15:01:07

package com.imooc.aspect.demo1;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.annotation.Resource;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class AspectTest {
@Resource(name="productDao")
private ProductDao productDao;
@Test
public void demo1(){
// ApplicationContext application = new ClassPathXmlApplicationContext("applicationContext.xml");
// ProductDao productDao = (ProductDao) application.getBean("productDao");
productDao.save();
productDao.update();
productDao.delete();
};

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<aop:aspectj-autoproxy/>

<bean id="productDao" class="com.imooc.aspect.demo1.ProductDao"/>

<bean class="com.imooc.aspect.demo1.MyAspectj"/>
</beans>

productDao.save();这一行报错

java.lang.NullPointerException

at com.imooc.aspect.demo1.AspectTest.demo1(AspectTest.java:21)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:564)

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.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)

at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)

at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:254)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:89)

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:70)

at org.junit.runners.ParentRunner.run(ParentRunner.java:309)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:193)

at org.junit.runner.JUnitCore.run(JUnitCore.java:160)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)

at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Process finished with exit code -1

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好帮手慕阿莹 #1

应该是没有注入成功，可能会和jdk的版本有关，请问同学的jdk版本是否是jdk10 呢？如果是，同学参考一下这个问答下的回复：http://class.imooc.com/course/qadetail/73633 如果我的回答解决了你的疑惑，请采纳！祝学习愉快！

2019-03-28 15:11:39
提问者慕粉1469801537 回复好帮手慕阿莹 #2

谢谢老师终于解决了，但是这是什么依赖，什么原因呢

2019-03-28 15:21:18
好帮手慕阿莹回复提问者慕粉1469801537 #3

经测试jdk10的这个jar包对Resource支持不好，猜测可能是jdk10自带的这个jar包对Resource有冲突，我们自己手动引入一下这个注解的依赖就可以了。祝学习愉快。

2019-03-28 15:26:23

好帮手慕阿莹 2019-03-28 14:23:41

因为你的文件夹已经是了：

如果我的回答解决了你的疑惑，请采纳！祝学习愉快！

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提问者慕粉1469801537 #1

那老师我报空指针什么原因，我原来以为是我不能标志成resources root package com.imooc.aspect.demo1; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import javax.annotation.Resource; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration("classpath:applicationContext.xml") public class AspectTest { @Resource(name="productDao") private ProductDao productDao; @Test public void demo1(){ productDao.save(); productDao.update(); productDao.delete(); }; } <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> <aop:aspectj-autoproxy/>  <bean id="productDao" class="com.imooc.aspect.demo1.ProductDao"/>  <bean class="com.imooc.aspect.demo1.MyAspectj"/> </beans>

2019-03-28 14:30:08