Java Spring3-自动连线没有发生。对象为空_Java_Spring_Spring Mvc_Autowired

Java Spring3-自动连线没有发生。对象为空

java spring spring-mvc

Java Spring3-自动连线没有发生。对象为空,java,spring,spring-mvc,autowired,Java,Spring,Spring Mvc,Autowired,servlet.xml 我正在使用注释，而不是在XML中创建bean 我在XML中添加了“context:annotation-config” <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/sc

servlet.xml

我正在使用注释，而不是在XML中创建bean

我在XML中添加了“context:annotation-config”

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
    <context:component-scan base-package="com.hemanths.expense.manager"/>
    <mvc:annotation-driven/>
    <tx:annotation-driven/>
    <context:annotation-config />

    <bean id="sessionFactory"
          class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="configLocation" value="WEB-INF/hibernate.cfg.xml"/>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

</beans>

UserService.java

package com.hemanths.expense.manager.service.impl;

import com.hemanths.expense.manager.hibernate.dao.UserDao;
import com.hemanths.expense.manager.hibernate.entity.User;
import com.hemanths.expense.manager.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    public UserServiceImpl() {
    }

    public UserServiceImpl(UserDao userDao){
        this.userDao = userDao;
    }

    public void setUserDao(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    @Transactional
    public void addUser(User user) {
        userDao.addUser(user);
    }

UserServiceImplTest.java

public class UserServiceImplTest {

    @Autowired
    UserService userService;

    @Test
    public void shouldAddUser() {
        User user = new User("firstName", "lastName", new Date(), "M", "username", "password");
        userService.addUser(user);
    }
}

堆栈跟踪

java.lang.NullPointerException
    at com.hemanths.expense.manager.service.impl.UserServiceImplTest.shouldAddUser(UserServiceImplTest.java:18)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:74)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:211)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:67)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

目录结构

您的hibernate的示例用法

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

<context:component-scan base-package="com.base.package"/>
<mvc:annotation-driven/>
<tx:annotation-driven/>
<context:annotation-config />

<bean id="_hibernateSessionFactory"
      class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="configLocation" value="WEB-INF/hibernate.cfg.xml"/>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.show_sql">true</prop>
        </props>
    </property>
</bean>

 <!-- userDao Repo -->
    <bean id="_userDao"
        class="com.hemanths.expense.manager.hibernate.dao.impl.UserDaoImpl">
        <property name="_hibernateSessionFactory">
            <ref bean="_hibernateSessionFactory"></ref>
        </property>
    </bean>


 <!-- userService Repo -->
    <bean id="_userDao"
        class="com.hemanths.expense.manager.service.impl.UserServiceImpl">
        <property name="_hibernateSessionFactory">
            <ref bean="_hibernateSessionFactory"></ref>
        </property>
    </bean>

</beans>

在控制器中需要的位置使用autowire：

@Autowired
private UserServiceImpl _userServiceImpl;

正如评论中提到的，您不需要在

servlet.xml

文件中为服务和DAO类创建bean：

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context.xsd     http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

<context:component-scan base-package="com.hemanths.expense.manager"/>
<mvc:annotation-driven/>
<tx:annotation-driven/>
<context:annotation-config />

<bean id="sessionFactory"
  class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="configLocation" value="WEB-INF/hibernate.cfg.xml"/>
<property name="hibernateProperties">
    <props>
        <prop key="hibernate.show_sql">true</prop>
    </props>
</property>
</bean>

</beans>

我得到了答案。谢谢@Andrei Stefan

因为我正在运行一个测试，所以我必须用xml文件路径对测试进行如下注释

@ContextConfiguration(locations = {"classpath:mvc-dispatcher-servlet.xml"})
@RunWith(SpringJUnit4ClassRunner.class)
public class UserServiceImplTest {

@Autowired
UserService userService;

@Test
public void shouldAddUser() {
    User user = new User("firstName", "lastName", new Date(), "M", "username", "password");
    userService.addUser(user);
}
}

每个类的包是什么？如果您计划自动检测它们，为什么要为

userDao

和

userService

手动创建两个bean？或者，

组件扫描的基本包

没有覆盖dao和服务所在的包？您应该这样做，因为没有创建应用程序上下文。方法如下：

@ContextConfiguration（locations={“classpath:servlet.xml”}@RunWith（SpringJUnit4ClassRunner.class）

。在

locations

下，您需要放置servlet.xml文件的路径。

userserviceinmpltest

是一个测试类（可能与JUnit一起），为了使它工作，您需要告诉Spring使用什么xml文件来构建您的测试将使用的应用程序上下文。这两个注释是这样一个类成功执行所必需的。我建议阅读Spring参考文档中的相关章节。你的控制器与你的测试类无关，这是另外一个故事。你不需要getter和setter吗？我已经删除并检查了它，但仍然抛出NullPointerException。我已经更新了问题。请check@HemanthGowda：干吗？当您使用autowire bean时，您将在已创建实例的依赖类中隐式设置它们。如果你能发布你的用户类的代码？Hibernate可能没有正确识别和映射您的类。

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:context="http://www.springframework.org/schema/context"
   xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:tx="http://www.springframework.org/schema/tx"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context.xsd     http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">

<context:component-scan base-package="com.hemanths.expense.manager"/>
<mvc:annotation-driven/>
<tx:annotation-driven/>
<context:annotation-config />

<bean id="sessionFactory"
  class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="configLocation" value="WEB-INF/hibernate.cfg.xml"/>
<property name="hibernateProperties">
    <props>
        <prop key="hibernate.show_sql">true</prop>
    </props>
</property>
</bean>

</beans>

@Repository("userDao")
public class UserDaoImpl implements UserDao {

    @Autowired
    private SessionFactory sessionFactory;

    // Methods here

}


@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    // Methods here

}

@ContextConfiguration(locations = {"classpath:mvc-dispatcher-servlet.xml"})
@RunWith(SpringJUnit4ClassRunner.class)
public class UserServiceImplTest {

@Autowired
UserService userService;

@Test
public void shouldAddUser() {
    User user = new User("firstName", "lastName", new Date(), "M", "username", "password");
    userService.addUser(user);
}
}