如何在春季使用setter注入@Required註解？

Question

@必需的註釋用法。我試着給上面這個setter方法，並試圖從上下文中找到bean而不設置這個依賴關係。我得到的對象與依賴項設置爲空，我的期望是春天會拋出一些異常。請指導我在哪裏做錯了？

Answer 1

@Required to make it mandatory that the dependency has to be injected 

讓我們例如： 我們需要使用RequiredAnnotationPostProcessor，檢查@Required依賴是否已經注入或不

public class BankService { 
    private CustomerService customerService; 
    private BillPaymentService billPaymentService; 
    @Required 
    public void setCustomerService(CustomerService customerService) { 
    this.customerService = customerService; 
    } 
    @Required 
    public void setBillPaymentService(BillPaymentService billPaymentService) { 
    this.billPaymentService = billPaymentService; 
} 
} 

的配置是這樣

<bean id="custService" class="xml.CustomerServiceImpl" /> 
<bean id="billingService" class="xml.BillPaymentServiceImpl" /> 
<bean id="bankService" class="xml.BankServiceImpl"> 
<property name="customerService" ref="custService" /> 
<property name="billPaymentService" ref="billingService" /> 
</bean> 
<bean class=」o.s.beans.factory.annotation.RequiredAnnotationBeanPostProcessor" /> 

如果我們不」 t設置這兩個屬性，我們將得到BankService配置的錯誤，因爲它們都是@Required。

我希望這有助於！

Answer 2

Same anwer by bmt - just adding here what i did to verify. 

package com.requiredAnnotation; 

import org.springframework.beans.factory.annotation.Required; 

public class BankService { 
    private CustomerService customerService; 
    private BillPaymentService billPaymentService; 

    @Required 
    public void setCustomerService(CustomerService customerService) { 
     this.customerService = customerService; 
    } 

    @Required 
    public void setBillPaymentService(BillPaymentService billPaymentService) { 
     this.billPaymentService = billPaymentService; 
    } 

    public BillPaymentService getBillPaymentService() { 
     return billPaymentService; 
    } 

    public CustomerService getCustomerService() { 
     return customerService; 
    } 
} 

package com.requiredAnnotation; 

public class CustomerService { 

} 


package com.requiredAnnotation; 

public class BillPaymentService { 

} 


<?xml version="1.0" encoding="UTF-8"?> 
<beans xmlns="http://www.springframework.org/schema/beans" 
    xmlns:aop="http://www.springframework.org/schema/aop" xmlns:context="http://www.springframework.org/schema/context" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd 
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> 


    <bean id="customerService" class="com.requiredAnnotation.CustomerService" /> 
    <bean id="billPaymentService" class="com.requiredAnnotation.BillPaymentService" /> 
    <bean id="bankService" class="com.requiredAnnotation.BankService"> 
     <property name="customerService" ref="customerService" /> 
     <!-- <property name="billPaymentService" ref="billPaymentService" /> --> 
    </bean> 
    <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor" /> 

</beans> 

package com.requiredAnnotation; 

import org.springframework.context.ConfigurableApplicationContext; 
import org.springframework.context.support.ClassPathXmlApplicationContext; 

public class Test { 
    public static void main(String[] args) { 
     ConfigurableApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath:com/requiredAnnotation/beans-required.xml"); 

     BankService bankService = applicationContext.getBean(BankService.class); 
     System.out.println("bankService got."); 
     System.out.println("getCustomerService - " + bankService.getCustomerService()); 
     System.out.println("getBillPaymentService - " + bankService.getBillPaymentService()); 
    } 
}