Question

我开始使用Spring进行依赖注入。

我添加了jar spring-context-4.0.1

添加了@Configuration

@Configuration
public class SpringConfig {

    @Bean
    public CategoryDAO categoryDAO() {
        return new HibernateCategoryDAO();
    }

}


public interface CategoryDAO{
}

和

public class HibernateCategoryDAO implements CategoryDAO{
}

然而，当我尝试@autowire时

@Repository
public class MyCategoryManager implements CategoryManager {

    @Autowired
    CategoryDAO categoryDAO;

}

categoryDAO为null，我在调试模式下看到它没有在配置文件中停止。

我错过了什么？

我不想在Spring中使用XML，但是我还需要添加应用程序上下文文件吗？

编辑：

在@Gummyball回答之后，我添加了配置。它没有帮助。

我使用Reflections util：

初始化MyCategoryManager类

Set<?> managers = Reflections.getSubTypesOf(CategoryManager.class);

可能是原因吗？我该怎样克服它？

Answer 1

是的，您需要通过向web.xml添加侦听器类来引导Spring。通过提供@Configuration类（.i.e您的SpringConfig类）作为上下文参数，您的配置类将被Spring选中。

<web-app>
    <!-- Configure ContextLoaderListener to use AnnotationConfigWebApplicationContext instead of the default XmlWebApplicationContext -->
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>

    <!-- Configuration locations must consist of one or more comma- or space-delimited fully-qualified @Configuration classes. Fully-qualified packages may also be specified for component-scanning -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>your.own.package.SpringConfig</param-value>
    </context-param>

    <!-- Bootstrap the root application context as usual using ContextLoaderListener -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    // Your jersey config here
</web-app>

更新

基于官方Jersey Spring Example，我制作了这个hello world示例，它将Spring与Jersey一起使用。

您需要具有以下依赖项：spring framework，jersey-container-servlet和jersey-spring3。或者如果使用maven：

的pom.xml

<project
    xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
    http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.stackoverflow.question.jersey.with.spring</groupId>
    <artifactId>SpringConfig</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>SpringConfig</name>

    <properties>
        <!-- Spring -->
        <spring-framework.version>4.0.1.RELEASE</spring-framework.version>
        <jersey.version>2.6</jersey.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring-framework.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet</artifactId>
            <version>${jersey.version}</version>
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.ext</groupId>
            <artifactId>jersey-spring3</artifactId>
            <version>${jersey.version}</version>
        </dependency>
    </dependencies>
</project>

在web.xml中，您需要配置Spring和Jersey

的web.xml

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    version="3.0">

    <!-- Configure ContextLoaderListener to use AnnotationConfigWebApplicationContext instead of the default XmlWebApplicationContext -->
    <context-param>
        <param-name>contextClass</param-name>
        <param-value>
            org.springframework.web.context.support.AnnotationConfigWebApplicationContext
        </param-value>
    </context-param>

    <!-- Configuration locations must consist of one or more comma- or space-delimited fully-qualified @Configuration classes. -->
    <!-- Fully-qualified packages may also be specified for component-scanning -->
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>com.stackoverflow.question.jersey.with.spring.SpringConfig</param-value>
    </context-param>

    <!-- Bootstrap the root application context as usual using ContextLoaderListener -->
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <!-- Jersey config -->
    <servlet>
        <servlet-name>SpringConfig</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>com.stackoverflow.question.jersey.with.spring.MyApplication</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>SpringConfig</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

这里的诀窍是告诉泽西岛要扫描哪个包。或者，您可以使用寄存器（.class）单独注册每个组件。

MyApplication.java

package com.stackoverflow.question.jersey.with.spring;

import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.server.spring.scope.RequestContextFilter;

/**
 * Spring HelloWorld Web Application configuration.
 * 
 * @author Jakub Podlesak (jakub.podlesak at oracle.com)
 */
public class MyApplication extends ResourceConfig
{

    /**
     * Register JAX-RS application components.
     */
    public MyApplication()
    {
        packages(true, "com.stackoverflow.question.jersey.with.spring");
    }
}

您可以通过向@ComponentScan提供包来告诉Spring使用组件扫描。或者，如果您想要更多地控制Spring bean的初始化方式，您可以使用单独的@Bean注释（就像您在问题中所做的那样）来单独指定每个Spring bean。

SpringConfig.java

package com.stackoverflow.question.jersey.with.spring;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("com.stackoverflow.question.jersey.with.spring")
public class SpringConfig
{
}

根据您对不同CategoryManager实现的评论，我创建了一个帮助器类，它将根据您提供的枚举类型返回不同的CategoryManager（这将是用户提供的值）。

CategoryManagerFactory.java

package com.stackoverflow.question.jersey.with.spring;

import javax.inject.Inject;
import org.springframework.stereotype.Component;

@Component
public class CategoryManagerFactory
{
    @Inject
    private MyCategoryManager myCategoryManager;

    @Inject
    private OtherCategoryManager otherCategoryManager;

    public CategoryManager obtainCategoryManager(CategoryManagerTypes type)
    {
        switch (type) {
            case MY:
                return myCategoryManager;
            case OTHER:
                return otherCategoryManager;
            default:
                throw new IllegalArgumentException(String.format("Category %s not supported", type));
        }
    }

    public enum CategoryManagerTypes
    {
        MY, OTHER;
    }
}

MyCategoryManager.java

package com.stackoverflow.question.jersey.with.spring;

import javax.inject.Inject;
import org.springframework.stereotype.Component;

@Component
public class MyCategoryManager implements CategoryManager
{
    @Inject
    private CategoryDAO categoryDAO;

    @Override
    public String saySomething()
    {
        return "Using MyCategoryManager!";
    }
}

OtherCategoryManager.java

package com.stackoverflow.question.jersey.with.spring;

import javax.inject.Inject;
import org.springframework.stereotype.Component;

@Component
public class OtherCategoryManager implements CategoryManager
{
    @Inject
    private CategoryDAO categoryDAO;

    @Override
    public String saySomething()
    {
        return "Using OtherCategoryManager!";
    }
}

在泽西资源中使用Spring将所有内容整合在一起：

JerseyResource.java

package com.stackoverflow.question.jersey.with.spring;

import javax.inject.Inject;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import com.stackoverflow.question.jersey.with.spring.CategoryManagerFactory.CategoryManagerTypes;

@Path("jersey-hello")
public class JerseyResource
{
    @Inject
    private CategoryManagerFactory categoryManagerFactory;

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getHello(@Context HttpHeaders headers, @QueryParam("category") CategoryManagerTypes category)
    {
        CategoryManager categoryManager = categoryManagerFactory.obtainCategoryManager(category);

        return categoryManager.saySomething();
    }
}

转到http://localhost:8080/SpringConfig/jersey-hello?category=MY，你会得到'使用MyCategoryManager！'

Answer 2

从你的代码中不清楚Spring如何知道MyCategoryManager。尝试将其添加到配置

@Configuration
public class SpringConfig {

    @Bean
    public CategoryDAO categoryDAO() {
        return new HibernateCategoryDAO();
    }

    @Bean
    public MyCategoryManager myCategoryManager() {
        return new MyCategoryManager();
    }

    public static void main(String[] args) {
    AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);
    System.out.println(ctx.getBean(MyCategoryManager.class).categoryDAO);
}

没有调用Spring java配置

2 个答案: