优化HK2依赖注入：如何通过自定义绑定扩展组件扫描与生命周期管理

// Repository.java
package com.example.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface Repository {
    // 标记DAO层接口
}

// BeanAddress.java
package com.example.annotations;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface BeanAddress {
    String implClassName(); // 存储实现类的全限定名
}

// UserDao.java
package com.example.dao;

import com.example.annotations.BeanAddress;
import com.example.annotations.Repository;

@Repository
@BeanAddress(implClassName = "com.example.dao.impl.UserDaoImpl")
public interface UserDao {
    void save(Object entity);
    // ... 其他DAO方法
}

// UserDaoImpl.java
package com.example.dao.impl;

// 注意：这里不需要HK2的@Service或@Contract注解
public class UserDaoImpl implements UserDao {
    @Override
    public void save(Object entity) {
        System.out.println("Saving entity: " + entity.getClass().getSimpleName());
        // 实际的数据库操作逻辑
    }
}

<dependency>
    <groupId>org.reflections</groupId>
    <artifactId>reflections</artifactId>
    <version>0.10.2</version> <!-- 使用最新稳定版本 -->
</dependency>

package com.example.di;

import com.example.annotations.BeanAddress;
import com.example.annotations.Repository;
import jakarta.inject.Singleton;
import org.glassfish.hk2.utilities.binding.AbstractBinder;
import org.reflections.Reflections;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;

public class CustomRepositoryBinder extends AbstractBinder {

    private static final Logger LOGGER = Logger.getLogger(CustomRepositoryBinder.class.getName());
    private final String packageName;

    public CustomRepositoryBinder(String packageName) {
        this.packageName = packageName;
    }

    @Override
    protected void configure() {
        LOGGER.info("Starting custom HK2 binding for package: " + packageName);
        Reflections reflections = new Reflections(packageName);

        // 1. 扫描所有带有 @Repository 注解的接口/类
        Set<Class<?>> repositoryInterfaces = reflections.getTypesAnnotatedWith(Repository.class, true);

        repositoryInterfaces.forEach(repoInterface -> {
            if (repoInterface.isInterface()) { // 确保是接口
                // 2. 获取 @BeanAddress 注解，从中提取实现类的全限定名
                BeanAddress beanAddress = repoInterface.getAnnotation(BeanAddress.class);
                if (beanAddress == null) {
                    LOGGER.warning("Interface " + repoInterface.getName() + " has @Repository but no @BeanAddress. Skipping.");
                    return;
                }

                try {
                    // 3. 根据实现类名加载实现类
                    Class<?> implementationClass = Class.forName(beanAddress.implClassName());

                    // 4. 绑定接口到实现类，并指定为单例
                    bind(implementationClass).to(repoInterface).in(Singleton.class);
                    LOGGER.info(String.format("Bound %s to %s as Singleton.", implementationClass.getName(), repoInterface.getName()));

                } catch (ClassNotFoundException e) {
                    LOGGER.log(Level.SEVERE, "Could not find implementation class for " + repoInterface.getName() + ": " + beanAddress.implClassName(), e);
                    throw new RuntimeException("Failed to bind repository: " + repoInterface.getName(), e);
                }
            } else {
                LOGGER.warning("Class " + repoInterface.getName() + " has @Repository but is not an interface. Skipping.");
            }
        });
        LOGGER.info("Custom HK2 binding completed.");
    }
}

package com.example.app;

import com.example.di.CustomRepositoryBinder;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.server.ServerProperties;

public class MyApplication extends ResourceConfig {

    public MyApplication() {
        // 注册JAX-RS资源包
        packages("com.example.resources"); // 你的JAX-RS资源类所在的包

        // 禁用HK2的默认自动扫描（如果你的AutoScanFeature已经处理了，这里可能不需要）
        // property(ServerProperties.BV_SEND_ERROR_IN_RESPONSE, true);
        // property(ServerProperties.MOXY_JSON_FEATURE_DISABLE, true);

        // 注册自定义的Binder
        register(new CustomRepositoryBinder("com.example")); // 替换为你的根包名，以便Reflections扫描

        // 注册HK2的元数据生成器，确保HK2能正确处理注解和类路径
        // 如果你的pom.xml中已经包含了jersey-hk2和hk2-metadata-generator，通常不需要额外代码
        // 但如果遇到警告或问题，可以考虑显式配置
        // register(org.glassfish.hk2.utilities.binding.ServiceLocatorBinder.class); // 示例，不一定需要
    }
}

import org.glassfish.jersey.grizzly2.httpserver.GrizzlyHttpServerFactory;
import org.glassfish.grizzly.http.server.HttpServer;
import java.io.IOException;
import java.net.URI;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Main {
    private static final URI BASE_URI = URI.create("http://localhost:8080/api/");

    public static HttpServer startServer() {
        // 创建应用程序配置实例
        final MyApplication config = new MyApplication();
        return GrizzlyHttpServerFactory.createHttpServer(BASE_URI, config);
    }

    public static void main(String[] args) throws IOException {
        final HttpServer server = startServer();
        System.out.println(String.format("Jersey app started with WADL available at "
                + "%sapplication.wadl\nHit enter to stop it...", BASE_URI));
        System.in.read();
        server.shutdownNow();
    }
}

import jakarta.inject.Inject;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;
import com.example.dao.UserDao; // 引入你的DAO接口

@Path("/users")
public class UserResource {

    @Inject
    private UserDao userDao; // HK2现在可以注入UserDao的单例实例了

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String getUsers() {
        userDao.save(new Object()); // 调用DAO方法
        return "User data accessed!";
    }
}