13

我无法使用 Jersey 2 (2.7) 和仅 Jersey 的内置 HK2 依赖注入来实现一个非常基本的单例类。我在Tomcat上运行它。

我的目标是创建一个支持类的单例实例，供各种 Web 服务方法使用。我在构造函数注入、方法注入和注释类成员之间没有强烈的偏好（如下所示）。

这是我的单身课程：

package singletest;

import javax.inject.Singleton;

@Singleton
public class JustOne {
    private int secretNumber = 0;

    public void hitMe(int input) {
        secretNumber += input;
    }

    @Override
    public String toString() {
        return String.format("{ \"secretNumber\": %s }", secretNumber);
    }
}

这是我的应用程序类：

package singletest;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;
import java.util.HashSet;
import java.util.Set;

@ApplicationPath("/*")
public class MainApplication extends Application {
    @Override
    public Set<Class<?>> getClasses() {
        Set<Class<?>> classes = new HashSet<>();
        classes.add(TestResource.class);
        return classes;
    }

    @Override
    public Set<Object> getSingletons() {
        Set<Object> singletons = new HashSet<>();
        singletons.add(new JustOneProvider());
        return singletons;
    }
}

这是我的 Provider/ContextResolver 类：

package singletest;

import javax.ws.rs.ext.ContextResolver;
import javax.ws.rs.ext.Provider;

@Provider
public class JustOneProvider implements ContextResolver<JustOne> {
    private static JustOne justOne = new JustOne();

    @Override
    public JustOne getContext(Class<?> type) {
        return justOne;
    }
}

网页.xml：

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.5" 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_2_5.xsd">
    <filter>
        <filter-name>singletest.MainApplication</filter-name>
        <filter-class>org.glassfish.jersey.servlet.ServletContainer</filter-class>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>singletest.MainApplication</param-value>
        </init-param>
        <!-- pass to next filter if Jersey/App returns 404 -->
        <init-param>
            <param-name>jersey.config.servlet.filter.forwardOn404</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>singletest.MainApplication</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

我打算注入 JustOne 类的单例实例的资源：

package singletest;

import javax.inject.Inject;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("/test")
public class TestResource {

    @Inject
    private JustOne justOne;

    @GET
    @Consumes(MediaType.TEXT_PLAIN)
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/func1/{input}")
    public Response func1(@PathParam("input") int input) {
        justOne.hitMe(input);
        String responseData = justOne.toString();
        return Response.ok(responseData).build();
    }
}

在泽西岛部署/初始化战争时会发出此警告：

Apr 28, 2014 11:48:25 AM org.glassfish.jersey.server.ApplicationHandler initialize
INFO: Initiating Jersey application, version Jersey: 2.7 ${buildNumber}...
Apr 28, 2014 11:48:25 AM org.glassfish.jersey.internal.inject.Providers checkProviderRuntime
WARNING: A provider java.lang.Class registered in SERVER runtime does not implement any provider interfaces applicable in the SERVER runtime. Due to constraint configuration problems the provider java.lang.Class will be ignored.

当我调用这个网络服务时，我得到的错误：

type Exception report

message A MultiException has 3 exceptions. They are:

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: A MultiException has 3 exceptions.  They are:
1. org.glassfish.hk2.api.UnsatisfiedDependencyException: There was no object available for injection at Injectee(requiredType=JustOne,parent=TestResource,qualifiers={}),position=-1,optional=false,self=false,unqualified=null,58952407)
2. java.lang.IllegalArgumentException: While attempting to resolve the dependencies of singletest.TestResource errors were found
3. java.lang.IllegalStateException: Unable to perform operation: resolve on singletest.TestResource

    org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:333)
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:372)
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:335)
    org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:218)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)

所以，我明白了：hk2 没有获得足够的信息来创建/绑定 JustOne 实例和/或查找/使用我的 JustOneProvider。我确定我缺少一些基本的东西。任何指导将不胜感激。

4

2 回答 2

19 
bind(JustOne.class).to(JustOne.class).in(Singleton.class);

是最重要的部分。如果没有“in(Singleton.class)”，将创建多个 JustOne 实例。

于 2014-11-11T00:48:54.407 回答
15

好的，在花了很多时间在这上面之后，我让它工作了。

我使用了 HK2 AbstractBinder 和 JAX-RS Feature (javax.ws.rs.core.Feature)。

事实证明，不需要 Provider/ContextResolver。

应用：

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;
import java.util.HashSet;
import java.util.Set;

@ApplicationPath("/*")
public class MainApplication extends Application {

    @Override
    public Set<Class<?>> getClasses() {
        Set<Class<?>> classes = new HashSet<>();
        classes.add(TestResource.class);
        classes.add(JustOneFeature.class);
        return classes;
    }

}

准单身人士班级：

public class JustOne {
    private int secretNumber = 0;

    public int getSecretNumber() {
        return secretNumber;
    }

    public void bumpSecretNumber() {
        secretNumber += 1;
    }
}

粘合剂：

import org.glassfish.hk2.utilities.binding.AbstractBinder;

public class JustOneBinder extends AbstractBinder {
    @Override
    protected void configure() {
        bind(new JustOne()).to(JustOne.class);
    }
}

特征：

import javax.ws.rs.core.Feature;
import javax.ws.rs.core.FeatureContext;

public class JustOneFeature implements Feature {

    @Override
    public boolean configure(final FeatureContext context) {
        context.register(new JustOneBinder());
        return true;
    }
}

被单例注入的资源：

import javax.inject.Inject;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;

@Path("/test")
public class TestResource {

    @Inject
    private JustOne justOne;

    @GET
    @Consumes(MediaType.TEXT_PLAIN)
    @Produces(MediaType.APPLICATION_JSON)
    @Path("/func1/{input}")
    public Response func1(@PathParam("input") int input) {
        justOne.bumpSecretNumber();
        String responseData = String.format("{ \"result\": %s }", input + justOne.getSecretNumber());
        return Response.ok(responseData).build();
    }
}
于 2014-04-28T04:51:47.493 回答