Spring @Autowired 不工作(并非总是如此) [英] Spring @Autowired not working (not always)

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本文介绍了Spring @Autowired 不工作(并非总是如此)的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我的一项服务中的自动装配注释存在一些问题.我花了很多时间来寻找解决方案，但我不知道我做错了什么.我的应用看起来像这样.

I have some problems with autowire annotation in one of my services. I have spent a lot of hours to find a solution but I don't have idea what I'm doing wrong. My app looks like this.

这是我的控制器:

package control.peso.controller;

import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import control.peso.data.ResumenMedicionPeso;
import control.peso.service.HomeService;

@Controller
public class HomeController {

    @Autowired
    private HomeService homeService; //NOPMD

    @RequestMapping(value = "json/resumen_mediciones.action")
    @ResponseBody
    public final ResumenMedicionPeso
            dataJsonPeso(final HttpServletRequest req) {
        final ResumenMedicionPeso peso = homeService.getResumenMediciones();

        return peso;
    }
}

我的服务层:

package control.peso.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import control.peso.dao.PesoDAO;
import control.peso.data.ResumenMedicionPeso;

@Service
@Transactional(readOnly = true)
public class HomeService {

    @Autowired
    private PesoDAO pesoDAO; //NOPMD

    public final ResumenMedicionPeso getResumenMediciones() {
        final ResumenMedicionPeso resumMedicionPeso = new ResumenMedicionPeso();
        resumMedicionPeso.setMaxPeso(pesoDAO.getMaxPeso());
        resumMedicionPeso.setMinPeso(pesoDAO.getMinPeso());
        resumMedicionPeso.setMaxGrasa(pesoDAO.getMaxGrasa());
        resumMedicionPeso.setMinGrasa(pesoDAO.getMinGrasa());
        resumMedicionPeso.setMaxPorcenGrasa(pesoDAO.getMaxPorcenGrasa());
        resumMedicionPeso.setMinPorcenGrasa(pesoDAO.getMinPorcenGrasa());
        resumMedicionPeso.setMaxMusculo(pesoDAO.getMaxMusculo());
        resumMedicionPeso.setMinMusculo(pesoDAO.getMinMusculo());
        resumMedicionPeso.setMaxPorcenMusculo(pesoDAO.getMaxPorcenMusculo());
        resumMedicionPeso.setMinPorcenMusculo(pesoDAO.getMinPorcenMusculo());

        return resumMedicionPeso;
    }
}

我的道:

package control.peso.dao;

import java.util.List;

import org.hibernate.SessionFactory;

import control.peso.model.MedicionPeso;

public class PesoDAO implements IPesoDAO {

    private SessionFactory sessionFactory;

    public final SessionFactory getSessionFactory() {
        return sessionFactory;
    }

    public final void setSessionFactory(
            final SessionFactory pSessionFactory) {
        this.sessionFactory = pSessionFactory;
    }

    @Override
    public final void addPeso(final MedicionPeso peso) {
        getSessionFactory().getCurrentSession().save(peso); //NOPMD
    }

    @Override
    public final void updatePeso(final MedicionPeso peso) {
        getSessionFactory().getCurrentSession().update(peso);  //NOPMD
    }

    @Override
    public final void deletePeso(final Integer idPeso) {
        getSessionFactory().getCurrentSession()
        .delete(new MedicionPeso(idPeso));
    }

    @Override
    public final MedicionPeso getPesoById(final Integer idPeso) {
        @SuppressWarnings("unchecked") //NOPMD
        final List<MedicionPeso> list = getSessionFactory() // NOPMD
                .getCurrentSession()
                        .createQuery("from MedicionPeso where idPeso = ?")
                .setParameter(0, idPeso).list();

        return list.get(0); //NOPMD
    }

    @Override
    public final List<MedicionPeso> getPesos() {
        @SuppressWarnings("unchecked")
        final List<MedicionPeso> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("from MedicionPeso medicionPeso "
                        + "order by medicionPeso.fechaMedicion desc")
                .list();

        return list;
    }

    public final Float getMaxPeso() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(peso) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMinPeso() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select min(peso) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMaxGrasa() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(pesoGrasa) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMinGrasa() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select min(pesoGrasa) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMaxPorcenGrasa() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(pesoGrasa) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMinPorcenGrasa() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select min(porcentajeGrasa) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    /**
     * Recupera la medicion de musculo con valor maximo.
     * @return El valor maximo de las mediciones de musculo.
     */
    public final Float getMaxMusculo() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(porcentajeGrasa) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMinMusculo() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select min(pesoMusculo) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMaxPorcenMusculo() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(porcentajeMusculo) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

    public final Float getMinPorcenMusculo() {
        @SuppressWarnings("unchecked")
        final List<Float> list = getSessionFactory() //NOPMD
                .getCurrentSession()
                .createQuery("select max(porcentajeMusculo) from MedicionPeso")
                .list();

        return (Float) list.get(0); //NOPMD
    }

}

我的dao界面:

package control.peso.dao;

import java.util.List;

import control.peso.model.MedicionPeso;

public interface IPesoDAO {

    void addPeso(MedicionPeso peso);

    void updatePeso(MedicionPeso peso);

    void deletePeso(Integer idPeso);

    MedicionPeso getPesoById(Integer idPeso);

    List<MedicionPeso> getPesos();
}

这是我的 dispatcher-servlet.xml:

This is my dispatcher-servlet.xml:

<?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:mvc="http://www.springframework.org/schema/mvc"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

    <!--Routes -->
    <mvc:view-controller path="/" view-name="home"/>
    <mvc:view-controller path="/home" view-name="home"/>
    <mvc:view-controller path="/medicion" view-name="medicion_peso"/>

    <!-- Scans the classpath of this application for @Components to deploy as beans -->
    <context:component-scan base-package="control.peso" />

    <!-- Configures the @Controller programming model -->
    <mvc:annotation-driven />

    <!-- misc -->
    <!--
    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/jsp/" />
        <property name="suffix" value=".jsp" />
    </bean>
    -->
    <!-- Tiles Resolver -->
    <bean id="viewResolver"
        class="org.springframework.web.servlet.view.UrlBasedViewResolver">
        <property name="viewClass">
            <value>
                org.springframework.web.servlet.view.tiles2.TilesView
            </value>
        </property>
    </bean>
    <bean id="tilesConfigurer"
        class="org.springframework.web.servlet.view.tiles2.TilesConfigurer">
        <property name="definitions">
            <list>
                <value>/WEB-INF/tiles.xml</value>
            </list>
        </property>
    </bean>

    <!-- Application Message Bundle -->
    <bean id="messageSource"
        class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
        <property name="basename" value="classpath:messages" />
        <property name="defaultEncoding" value="UTF-8" />
    </bean>

    <!-- JSON Objets Definition -->
    <bean
        class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="messageConverters">
            <list>
                <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter" />
            </list>
        </property>
    </bean>

    <!-- Beans Declaration -->
    <bean id="MedicionPeso" class="control.peso.model.MedicionPeso" />

    <!-- User DAO Declaration -->
    <bean id="PesoDAO" class="control.peso.dao.PesoDAO">
        <property name="sessionFactory" ref="SessionFactory" />
    </bean>

    <!-- Data Source Declaration -->
    <bean id="DataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
        destroy-method="close">
        <property name="driverClass" value="com.mysql.jdbc.Driver" />
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/juan" />
        <property name="user" value="root" />
        <property name="password" value="" />
        <property name="maxPoolSize" value="10" />
        <property name="maxStatements" value="0" />
        <property name="minPoolSize" value="5" />
    </bean>

    <!-- Session Factory Declaration -->
    <bean id="SessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="DataSource" />
        <property name="annotatedClasses">
            <list>
                <value>control.peso.model.MedicionPeso</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
            </props>
        </property>
    </bean>

    <!-- Enable the configuration of transactional behavior based on annotations -->
    <tx:annotation-driven transaction-manager="txManager" />

    <!-- Transaction Manager is defined -->
    <bean id="txManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="SessionFactory" />
    </bean>

</beans>

因此，当我启动我的网络应用程序时，我的控制器正确地自动装配服务，但我的服务中的 DAO 对象具有空值(未正确注入).

So when I launch my web-app, my controller Autowires correctly the service, but my DAO object in my service has null value (not injected properly).

有什么想法吗?

这很奇怪，因为从另一个服务正确注入了相同的 DAO.

It's curious because from another service, the same DAO is properly injected.

谢谢

推荐答案

在您的 HomeService 中，您已经指定了 IPesoDAO 的实现，而不是接口.尝试将其更改为 IPesoDAO ，看看是否有帮助.

in your HomeService, you've specified the implementation of IPesoDAO, not the interface. try changing it to IPesoDAO instead and see if that helps.

此外，您可能还想创建一个接口 IHomeService 并让您现有的 HomeService 实现它，再次更改控制器以引用接口，而不是实现

in addition, you may also want to create an interface IHomeService and have your existing HomeService implement it, again, changing the controller to reference the interface, not the implementation

这篇关于Spring @Autowired 不工作(并非总是如此)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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