java - Spring - 注入(inject)一些未通过构造函数传递的字段

Question

我有三节课。CurrencyUtil 需要 NumberFormatter。NumberFormatter 被注入(inject)到 CurrencyUtilFactory 中只是因为 CurrencyUtil 需要它。

有没有办法将NumberFormatter直接注入(inject)CurrencyUtil？

谢谢!

CurrencyUtil

public class CurrencyUtil {
    private final LocalizationHelper localizationHelper; 
    private final NumberFormatter numberFormatter;

    public CurrencyFormatter(final LocalizationHelper localizationHelper, final NumberFormatter numberFormatter) {
        this.localizationHelper = localizationHelper;
        this.numberFormatter = numberFormatter;
    }

    public String prettyPrint(final Currency amount) {

    }
}

CurrencyUtilFactory

public class CurrencyUtilFactory {
    @Autowired
    private NumberFormatter numberFormatter;

    public CurrencyUtil create() {
        ...
        final LocalizationHelper localizationHelper = ....;
        return new CurrencyUtil(localizationHelper, numberFormatter)();
    }

}

数字格式化程序

@Component
public class NumberFormatter {}

PS:对这个虚构的例子表示歉意:)

Answer 1

类似下面的代码片段对您有用吗？这样您就可以使用不同的 amount 值重复使用 CurrencyUtil。

@Component
public class CurrencyUtil {

    private final NumberFormatter numberFormatter;

    @Autowired
    public CurrencyFormatter(NumberFormatter numberFormatter) {
        this.numberFormatter = numberFormatter;
    }

    public String prettyPrint(Currency amount) {
        // ...
    }
}

更新(基于调整后的问题)

Spring 只能 Autowiring 它知道的 bean。如果你的bean(或其中一些)不是用Spring管理的，你必须自己 Autowiring 它们(例如通过构造函数，就像你所做的那样)。解决方案可能是:

@Configuration
public class AppConfig {

    @Autowired
    private NumberFormatter numberFormatter;

    @Autowired
    private LocalizationHelper localizationHelper;

    @Bean
    public CurrencyUtil curencyUtil() {
        return new CurrencyUtil(localizationHelper, numberFormatter);
    }

    // ...
}

或者

@Component
public class CurrencyUtil {

    private LocalizationHelper helper;

    private NumberFormatter numberFormatter;

    @Autowired
    public CurrencyFormatter(LocalizationHelper helper, NumberFormatter numberFormatter) {
        this.helper = helper;
        this.numberFormatter = numberFormatter;
    }

    public String prettyPrint(Currency amount) {
        // ...
    }
}