使用bindFactory时No object available for injection错误

Question

我有以下 Jersey (2.18) 应用程序的实现：

public class RootApplication extends ResourceConfig {

    public RootApplication() {
        packages("com.foo.bar");

        register(new AbstractBinder() {

            @Override
            protected void configure() {       
                bindFactory(RepositoryFactory.class).to(Repository.class);

                // if I use following line instead of bindFactory it works
                // bind(OracleRepository.class).to(Repository.class);
            }
        });
    }

    public class RepositoryFactory implements Factory<Repository> {

        private final Repository repo;

        public RepositoryFactory() {
            this.repo = new OracleRepository();
        }

        @Override
        public Repository provide() {
            return repo;
        }

        @Override
        public void dispose(Repository repo) {
        }
    }
}

并在访问注入存储库的服务时出现以下异常

javax.servlet.ServletException: A MultiException has 3 exceptions.  They are:
1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at SystemInjecteeImpl(requiredType=Repository,parent=MeasureService,qualifiers={},position=-1,optional=false,self=false,unqualified=null,56464420)
2. java.lang.IllegalArgumentException: While attempting to resolve the dependencies of com.fidelity.pi.dashboard.rest.MeasureService errors were found
3. java.lang.IllegalStateException: Unable to perform operation: resolve on com.fidelity.pi.dashboard.rest.MeasureService

如果我注释掉 bindFactory 并使用注释掉的绑定，一切都有效。我是否遗漏了工厂实施方面的内容？异常似乎甚至在 RepositoryFactory 构造函数被命中之前就发生了。我需要工厂，因为我要对 OracleRepository 实例进行一些其他初始化。

Answer 1

我能够重现问题的唯一方法（使用您的不完整信息 - 即缺少注入点）是尝试注入 OracleRepository 而不是 Repository。我不知道注入失败的确切原因，但我猜这是因为你绑定的是 Repository 而不是 OracleRepository。如果这是问题所在，最简单的解决方法是将工厂绑定到 OracleRepository 或者简单地注入 Repository.

对于 Repository 的注入，如果你想限定不同的实现，你可以通过将 named 或 qaulifiedBy 链接到绑定来实现，如下例所示（我在其中使用 named 并用 @Named).

注释注入点

在示例中我使用了 Jersey Test Framework

<dependency>
    <groupId>org.glassfish.jersey.test-framework.providers</groupId>
    <artifactId>jersey-test-framework-provider-inmemory</artifactId>
    <version>${jersey2.version}</version>
    <scope>test</scope>
</dependency>

这是完整的测试。您可以更改 "Sql" 和 "Oracle" 之间的 @Named 以查看差异。

import javax.inject.Inject;
import javax.inject.Named;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.core.Application;
import javax.ws.rs.core.Response;
import org.glassfish.hk2.api.Factory;
import org.glassfish.hk2.utilities.binding.AbstractBinder;
import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.test.JerseyTest;
import org.junit.Assert;
import org.junit.Test;

public class InjectionTest extends JerseyTest {

    @Path("test")
    public static class SimpleResource {

        @Inject
        @Named("Oracle")
        private Repository repo;

        @GET
        public String getRepoName() {
            return repo.getClass().getSimpleName();
        }
    }

    @Override
    public Application configure() {
        ResourceConfig config = new ResourceConfig();
        config.register(SimpleResource.class);
        config.register(new AbstractBinder(){
            @Override
            protected void configure() {
                bindFactory(SqlFactory.class)
                        .to(Repository.class).named("Sql");
                bindFactory(OracleFactory.class)
                        .to(Repository.class).named("Oracle");
            }
        });
        return config;       
    }


    public static interface Repository {}

    public static class OracleRepository implements Repository {}

    public static class SqlRepository implements Repository {}

    public static class SqlFactory implements Factory<Repository> {

        @Override
        public Repository provide() {
            return new SqlRepository();
        }

        @Override
        public void dispose(Repository t) {}
    }

    public static class OracleFactory implements Factory<Repository> {

        @Override
        public Repository provide() {
            return new OracleRepository();
        }

        @Override
        public void dispose(Repository t) {}
    }

    /**
     * Change the `Assert` from "OracleRepository" to "SqlRepository"
     * when switching the `@Named` on the injection point.
     */
    @Test
    public void testInjectOk() {
        Response response = target("test").request().get();
        String respString = response.readEntity(String.class);
        Assert.assertEquals("OracleRepository", respString);
        System.out.println(respString);
    }
}

如果您仍然有问题，请 post 一个完整的单个 class 测试用例，就像我上面的那样，以证明问题。

使用bindFactory时No object available for injection错误

No object available for injection error when using bindFactory

java

dependency-injection

jersey

jersey-2.0

hk2