java - 未调用 Spring Java 配置

Question

我开始使用 Spring 进行依赖注入(inject)。

我添加了 jar spring-context-4.0.1

我在类中添加了@Configuration

@Configuration
public class SpringConfig {

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

在哪里

public interface CategoryDAO{
}

和

public class HibernateCategoryDAO implements CategoryDAO {
}

但是，当我尝试在 Component(更准确地说是 Repository)中 @Autowired 时

@Repository
public class MyCategoryManager implements CategoryManager {

    @Autowired
    CategoryDAO categoryDAO;

}

categoryDAO 为 null。此外，我看到在 Debug模式下单步执行代码时它从不执行配置文件。

我错过了什么？

我不想在 Spring 中使用 XML，但我是否仍需要添加应用程序上下文文件？

编辑:

按照@Gummyball 的回答，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);

会不会是这个原因？我该如何克服它？

Answer 1

是的，您需要通过向 web.xml 添加一个监听器类来引导 Spring。通过提供您的 @Configuration 类(即您的 SpringConfig 类)作为上下文参数，您的配置类将由 Spring 获取。

<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 ，我制作了这个将 Spring 与 Jersey 一起使用的 hello world 示例。

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:

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 中你需要配置 Spring 和 Jersey

网络.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>

这里的技巧是告诉 Jersey 要扫描哪些包。或者，您可以使用 register(.class) 单独注册每个组件。

我的应用程序.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 提供一个包来告诉Spring 使用组件扫描。或者，如果您想更多地控制 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)来独立指定每个 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，我创建了一个帮助程序类，它将根据您提供的枚举类型(这将是用户提供的值)返回不同的 CategoryManager。

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!";
    }
}

并在 Jersey 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();
    }
}

通过访问 http://localhost:8080/SpringConfig/jersey-hello?category=MY 你会得到“Using MyCategoryManager!”