WildFly 27上JakartaEE REST服务CDI注入失败问题及解决

更新：问题已解决 #

问题根源在于web.xml。我之前按照教程创建了包含如下servlet定义的web.xml：

<servlet>
    <servlet-name>Jersey REST Service</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
    <init-param>
        <param-name>jersey.config.server.provider.packages</param-name>
        <param-value>de.gst.lern.javaee.products.backend.rest</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>Jersey REST Service</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

我移除了该servlet定义，转而添加了一个简单的Application类：

package de.gst.lern.javaee.products.backend.rest;

import jakarta.ws.rs.ApplicationPath;
import jakarta.ws.rs.core.Application;

@ApplicationPath("/rest")
public class ProductServiceApplication extends Application {

}

现在CDI可以正常工作了，虽然我还有些困惑，但问题确实解决了。

原问题描述 #

我正在重新学习JakartaEE技术，开发一个基础REST应用，项目结构如下：

products-backend
|- pom.xml

\ products-backend-entities
|- pom.xml
|-- src/main/java/{}/Product.java -> 简单的实体Bean

\ products-backend-dao
|- pom.xml
|- src/main/java/{}/ProductDao.java -> 包含增删改查方法的基础DAO
|- src/main/resources/META-INF/beans.xml: JakartaEE的beans.xml，bean-discovery-mode="annotated"

\ products-backend-rest
|- pom.xml
|- src/main/java/{}/ProductService.java -> 包含REST注解的服务类
|- src/main/webapp/WEB-INF/beans.xml: JakartaEE的beans.xml，bean-discovery-mode="annotated"

项目部署到WildFly 27成功，但访问REST服务URL触发依赖注入时，出现如下错误：

Caused by: org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available in __HK2_Generated_0 for injection at SystemInjecteeImpl(requiredType=ProductHelpDao,parent=ProductService,qualifiers={},position=-1,optional=false,self=false,unqualified=null,856067323)

请问我遗漏了什么配置？

开发环境为Eclipse 2023。

细节补充 #

ProductService使用@Inject注入ProductDao实例：

import jakarta.inject.Inject;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.PathParam;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
import jakarta.ws.rs.core.Response;

@Path("/products")
public class ProductService {
    @Inject
    private ProductDao productDao;
    
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public List<Product> getAllProducts() {
        return productDao.listAllProducts();
    }
    
    @GET
    @Path("{id}")
    @Produces(MediaType.APPLICATION_JSON)
    public Response getById(@PathParam("id") int id) {
        Optional<Product> byId = productDao.findById(id);
        if(byId.isEmpty()) {
            return Response.status(Response.Status.NOT_FOUND).build();
        }
        
        return Response.ok(byId.get()).build();
    }
}

ProductDao标注了@ApplicationScoped，作为模拟数据库后端：

import jakarta.enterprise.context.ApplicationScoped;

@ApplicationScoped
public class ProductDao {
    private final Map<Integer, Product> productsById = new HashMap<>();
    
    public List<Product> listAllProducts() {
        return new ArrayList<>(productsById.values());
    }
    
    public Optional<Product> findById(int id) {
        Product product = productsById.get(id);
        return product == null ? Optional.<Product> empty() : Optional.of(product);
    }
    
    public boolean add(final Product product) {
        return productsById.putIfAbsent(product.getId(), product) == null;
    }
    
    public boolean replace(final Product product) {
        if(!productsById.containsKey(product.getId())) {
            productsById.put(product.getId(), product);
            return true;
        }
        Product current = productsById.get(product.getId());
        if(!current.equals(product)) {
            productsById.put(product.getId(), product);
            return true;
        }
        return false;
    }
    
    public boolean remove(Product product) {
        return productsById.remove(product.getId()) != null;
    }
}

products-backend的pom.xml：

<packaging>pom</packaging>
<modules>
  <module>products-backend-entities</module>
  <module>products-backend-dao</module>
  <module>products-backend-rest</module>
</modules>

products-backend-dao的pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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>
  <parent>
    <artifactId>products-backend</artifactId>
    <groupId>de.gst.lern.javaee.products</groupId>
    <version>1.0-SNAPSHOT</version>
  </parent>

  <artifactId>products-backend-dao</artifactId>
  <packaging>jar</packaging>
  
  <name>products-backend-dao</name>
  <!-- FIXME change it to the project's website -->
  <url>http://www.example.com</url>

  <properties>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>de.gst.lern.javaee.products</groupId>
        <artifactId>products-backend-entities</artifactId>
        <version>${project.version}</version>
    </dependency>
    <dependency>
        <groupId>jakarta.platform</groupId>
        <artifactId>jakarta.jakartaee-api</artifactId>
        <version>10.0.0</version>
    </dependency>
    <!-- https://mvnrepository.com/artifact/jakarta.enterprise/jakarta.enterprise.cdi-api -->

  </dependencies>

  <build>
      <plugins>
          <plugin>
              <groupId>org.apache.maven.plugins</groupId>
              <artifactId>maven-compiler-plugin</artifactId>
          </plugin>
      </plugins>
  </build>
</project>

products-backend-entities的pom.xml：

<packaging>jar</packaging>
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
        </plugin>
    </plugins>
</build>
</project>

我查阅了大量教程，多数提到添加beans.xml启用CDI，我已配置，但问题仍存在，寻求解决方案。

内容的提问来源于stack exchange，提问作者Gunnar Stahl