How to fix DaggerSingletonComponent not resolved in HiveMQ (MQTT protocol)

问题

I'm trying to set create the client first to test that the MQTT works without errors then I will implement the connect() method. I downloaded the latest version of HiveMQ (an open source MQTT implementation done in Java) and after importing the project properly as a Gradle build in Eclipse and using GIT I was greeted with an error message. It said "DaggerSingletonComponent cannot be resolved." My program can't run at all.

Link to the open source I downloaded: https://github.com/hivemq/hivemq-mqtt-client

I've tried manually editing the build files to see if there was some code left out for dagger in dependencies but there wasn't.

package com.hivemq.client.internal.mqtt.ioc;

import com.hivemq.client.internal.mqtt.netty.NettyEventLoopProvider;
import com.hivemq.client.internal.mqtt.netty.NettyModule;
import dagger.Component;
import org.jetbrains.annotations.NotNull;

import javax.inject.Singleton;

/**
 * Singleton component for all clients. It exists the whole application lifetime.
 *
 * @author Silvio Giebl
 */
@Component(modules = {NettyModule.class})
@Singleton  
public interface SingletonComponent {

    @NotNull SingletonComponent INSTANCE = DaggerSingletonComponent.create();

    @NotNull ClientComponent.Builder clientComponentBuilder();

    @NotNull NettyEventLoopProvider nettyEventLoopProvider();
}


__________________________
For the module: NettyModule.class


package com.hivemq.client.internal.mqtt.netty;

import dagger.Module;

import dagger.Provides;
import io.netty.channel.epoll.Epoll;
import io.netty.channel.epoll.EpollEventLoopGroup;
import io.netty.channel.epoll.EpollSocketChannel;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioSocketChannel;
import org.jetbrains.annotations.NotNull;

import javax.inject.Singleton;

/**
 * @author Silvio Giebl
 */
@Module
public abstract class NettyModule {

    @Provides
    @Singleton
    static @NotNull NettyEventLoopProvider provideNettyEventLoopProvider() {
        if (Epoll.isAvailable()) {
            return new NettyEventLoopProvider(EpollEventLoopGroup::new, EpollSocketChannel::new);
        } else {
            return new NettyEventLoopProvider(NioEventLoopGroup::new, NioSocketChannel::new);
        }
    }
}

Error Message: DaggerSingletonComponent cannot be resolved

回答1:

Dagger is a library that generates code for dependency injection at compile time. The mentioned class is one of the generated classes.

Please use gradle to build the project:

Open a terminal
Navigate to the project directory
Execute ./gradlew build (Linux/Mac) or gradlew build (Windows)

You need to ensure that the directory build/generated/source/apt/main/ is configured as a source directory so that the IDE picks up the generated classes.

Then you should be able to use the build methods of your IDE after the first build with gradle.

来源：https://stackoverflow.com/questions/56447008/how-to-fix-daggersingletoncomponent-not-resolved-in-hivemq-mqtt-protocol

标签

java

eclipse

mqtt

hivemq