如何将我的课程实例注入另一个课程？

Question

我正在使用play framework 2.8.x，我需要将配置类注入另一个类，并且我已经编写了用于创建配置的自定义模块。我的模块如下所示：

public class ConfigModule extends AbstractModule {
    private Config config;

    public ConfigModule(Environment environment, Config config) {
        this.config = config;
    }

    @Override
    protected void configure() {
        bindRedisConfig();
    }

    void bindRedisConfig() {
        System.out.println("LOAD");
        RedisConfig redisConfig = new RedisConfig(
                config.getString("configuration.redis.host")
                , config.getInt("configuration.redis.port")
                , config.getString("configuration.redis.password")
                , config.getString("configuration.redis.domain")
        );
        bind(RedisConfig.class).annotatedWith(Names.named(Constant.CONFIG_REDIS)).toInstance(redisConfig);
    }
}

并且我尝试像这样注入它：

public class ProcessDataStore {
    private final JedisPool jedisPool;
    private final RedisConfig config;

    @Inject
    public ProcessDataStore(RedisConfig config) {
        this.config = config;
    }
}

我的配置类非常简单：

@Singleton
public class RedisConfig {
    public final String host;
    public final int port;
    public final String password;
    public final String domain;

    public RedisConfig(String host, int port, String password, String domain) {
        this.host = host;
        this.port = port;
        this.password = password;
        this.domain = domain;
    }
}

但是当我运行我的应用程序时，出现异常：

1) Could not find a suitable constructor in config.RedisConfig. Classes must have either one (and only one) constructor annotated with @Inject or a zero-argument constructor that is not private.
  at config.RedisConfig.class(RedisConfig.java:17)
  while locating config.RedisConfig
    for the 1st parameter of repository.ProcessDataStore.<init>(ProcessDataStore.java:25)
  while locating repository.ProcessDataStore
    for field at controllers.DashboardController.db(DashboardController.java:19)
  while locating controllers.DashboardController
    for the 5th parameter of router.Routes.<init>(Routes.scala:38)
  at play.api.inject.RoutesProvider$.bindingsFromConfiguration(BuiltinModule.scala:137):
Binding(class router.Routes to self) (via modules: com.google.inject.util.Modules$OverrideModule -> play.api.inject.guice.GuiceableModuleConversions$$anon$4)

如果我创建不带参数的默认构造函数，则我的应用程序不会引发任何异常，但是注入的RedisConfig为空。我将模块加载到我的应用中：

play.modules.enabled += "modules.ConfigModule"

我该怎么办？

Answer 1

我看到2可疑的东西。

1）@Singleton类上的RedisConfig注释。它可以使注入器创建并注入RedisConfig类的新实例，而不是redisConfig。

2）绑定定义包含.annotatedWith(Names.named(Constant.CONFIG_REDIS))。因此，ProcessDataStore的构造函数参数应以@Named注释：

 @Inject
 public ProcessDataStore( @Named(Constant.CONFIG_REDIS) RedisConfig config) {...}