为什么这个构造函数参数不起作用

Question

我创建了一个具有以下逻辑的新类。

import com.google.cloud.bigtable.data.v2.stub.EnhancedBigtableStubSettings;
import com.google.protobuf.ByteString;
import java.util.List;
import java.util.logging.Logger;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.stereotype.Component;
import org.threeten.bp.Duration;

@Component
@RefreshScope
public class PrimeChannel {

    private final EnhancedBigtableStubSettings enhancedBigtableStubSettings;
    private final List<String> tableIds;

    public PrimeChannel(EnhancedBigtableStubSettings enhancedBigtableStubSettings, List<String> tableIds) {
        this.enhancedBigtableStubSettings = enhancedBigtableStubSettings;
        this.tableIds = tableIds;
    }
}

运行时出现以下错误

Parameter 0 of constructor in myPackage.PrimeChannel required a bean of type 'com.google.cloud.bigtable.data.v2.stub.EnhancedBigtableStubSettings' that could not be found.

Action:

Consider defining a bean of type 'com.google.cloud.bigtable.data.v2.stub.EnhancedBigtableStubSettings' in your configuration.

我将 EnhancedBigtableStubSettings 对象作为第一个参数传递，那么为什么不考虑它。

如果我通过将 EnhancedBigtableStubSettings 初始化为 null 来尝试使用 0 参数构造函数，则会在后期抛出空指针异常。

如何处理？

有人可以帮忙吗？

Answer 1

首先，您必须创建一个增强型BigtableStubSettings 类的bean。你可以在applicationContext.xml或者@Configuration类中定义，然后用@Autowired注解构造函数。

<bean name="beanName" class="foo.EnhancedBigtableStubSettings"/>

@Bean(name = "beanName")
public EnhancedBigtableStubSettings getEnhancedBigtableStubSettings() {
    //return object somehow
    return new EnhancedBigtableStubSettings();
}