java - 如何在 Spring Boot 中的组件中 Autowiring 存储库接口(interface)

Question

我正在使用 Spring + Mysql，我可以成功 Autowiring 从 PagingAndSortingRepository<T,E> 扩展的类。在我的RepositoryRestController类。

我可以在下面的 Controller 中自动连接我的存储库。

package com.fallavi.api.user.controller;

import com.fallavi.api.MyConfig;
import com.fallavi.api.purchase.model.Purchase;
import com.fallavi.api.purchase.repository.PurchaseRepository;
import com.fallavi.api.reader.model.Reader;
import com.fallavi.api.reader.repository.ReaderRepository;
import com.fallavi.api.user.calculator.UserCreditHelper;
import com.fallavi.api.user.exceptions.UserCanNotFindException;
import com.fallavi.api.user.model.UserCreditEnoughModel;
import com.fallavi.api.user.model.UserCreditModel;
import com.fallavi.api.user.repository.UsersRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.data.rest.webmvc.PersistentEntityResourceAssembler;
import org.springframework.data.rest.webmvc.RepositoryRestController;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestHeader;
import org.springframework.web.bind.annotation.RequestMapping;

import java.util.List;

@RepositoryRestController
@RequestMapping("/user")
public class UserCreditController {

    @Autowired
    private ReaderRepository readerRepository;

    @Autowired
    private UsersRepository usersRepository;

    @Autowired
    private PurchaseRepository purchaseRepository;

    @GetMapping(
            value = "/userHasCreditEnough/{reader_id}",
            headers = "Content-Type=application/json")
    public ResponseEntity<UserCreditEnoughModel> userHasCreditEnough(
            @RequestHeader(value = "Authorization") String token,
            @PathVariable Long reader_id) {

        UserCreditHelper userCreditHelper = new UserCreditHelper();

        // Find user ID from authorization code START //
        Long userID = usersRepository.getUserIDByAuthToken(token);
        if (userID == null) {
            throw new UserCanNotFindException();
        }
        // Find user ID from authorization code END //

        // Find user credit START //
        List<Purchase> purchaseList = this.purchaseRepository.findByUserID(userID);
        Integer userCreditLeft = userCreditHelper.userCreditLeft(purchaseList);
        // Find user credit END //

        // Find user's credit left for Reader START //
        Reader reader = this.readerRepository.findByReaderID(reader_id);
        boolean isUserCreditEnough = userCreditHelper.userHasCreditEnough(userCreditLeft, reader);
        // Find user's credit left for Reader END //

        return ResponseEntity.ok(new UserCreditEnoughModel(isUserCreditEnough, reader.getOnline()));
    }
}

当然，我想将所有层分离为服务、存储库和 Controller ，这就是我创建一个新的帮助程序类(即服务层)的原因。

@Service
public class UserCreditHelper {

   @Autowired
   UsersRepository usersRepository;

   ....some methods...
}

为了调用UserCreditHelper我正在使用 ApplicationContext 中的类(class)在下面我的 Controller 类示例中。

@RepositoryRestController
@RequestMapping("/user")
public class UserCreditController {

    @Autowired
    private ReaderRepository readerRepository;

    @Autowired
    private UsersRepository usersRepository;

    @Autowired
    private PurchaseRepository purchaseRepository;

    @GetMapping(
            value = "/userHasCreditEnough/{reader_id}",
            headers = "Content-Type=application/json")
    public ResponseEntity<String> userHasCreditEnough(
            @RequestHeader(value = "Authorization") String token) {

        // com.fallavi.api.user.calculator is the package of UserCreditHelper.
        ApplicationContext ctx = new AnnotationConfigApplicationContext( "com.fallavi.api.user.calculator" );

        return ResponseEntity.ok("test");
    }
}

当我尝试请求/userHasCreditEnough/{reader_id}时端点总是给出错误。

"Error creating bean with name 'userCreditHelper': Unsatisfied dependency expressed through field 'usersRepository'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.fallavi.api.user.repository.UsersRepository' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}",

Answer 1

您应该创建一个接口(interface)作为您的服务层。然后将该接口(interface)注入(inject)到 Controller 中，并在 Controller 的所需端点中调用所需的方法。从那里从这个注入(inject)的接口(interface)调用您想要的植入。