自動裝配的DAO對象為空Spring Boot

Question

我正在編程一個rest服務，該服務可以訪問數據庫以查看，添加和更新mysql表中的字段。 我已經用Spring Boot實現了這一點。

事實是，當我嘗試自動裝配DAO對象時，它是無效的，因此我的應用程序始終拋出NullPointerException。

這是我的應用程序類：

@SpringBootApplication
@EnableSwagger2
@ComponentScan(basePackages = "com.setoncios.api")
@EnableJpaRepositories("com.setoncios.api.dao.workers.WorkerDAO.java")
public class GenericApiApplication {

    public static void main(String[] args) {
        SpringApplication.run(GenericApiApplication.class, args);
    }

    @Bean
    public Docket swaggerSettings() {
        return new Docket(DocumentationType.SWAGGER_2)
                .select()
                .apis(RequestHandlerSelectors.any())
                .paths(PathSelectors.any())
                .build()
                .pathMapping("/");
    }

這是我的pom.xml：

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
    </dependency>

    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>2.6.1</version>
    </dependency>

    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>2.6.1</version>
    </dependency>


</dependencies>

這是我的DAO實現：

@Component
public interface WorkerDAO extends CrudRepository<Persona,String>{

}

包含引發異常的方法的其余方法：

@RequestMapping(value = "/worker", method = RequestMethod.POST)
public ResponseEntity<?> addWorkerInDatabase(HttpServletRequest request,
        @RequestParam(value = "json", defaultValue = 
        "{\"dni\":\"00000000A\",\"nombre\":\"Paco\",\"apellido1\":\"Ruiz\",\"apellido2\":\"Díaz\"}") final String json){
    ProcessAction object = new AddWorkerInDatabaseAction(request, json);
    return object.createResponse();
}

和類本身：

public class AddWorkerInDatabaseAction extends ProcessAction{
private String json;

@Autowired
private UserDatabase userDb = new UserDatabase();

@Autowired
private WorkerDAO workDb;

public AddWorkerInDatabaseAction(HttpServletRequest request, String json) {
    super(request);
    this.json = json;
}

@Override
protected Object action() throws ExpectedException {
    Persona newWorker = new Gson().fromJson(json, Persona.class);
    Cookie c = findCookie("userdata");
    String[] loggedUser = null;

    if(newWorker == null){
        LOGGER.warning("Unable to decrypt from json to Persona.");

    } else if(c == null){
        LOGGER.info("Couldn't find cookie. Unable to add a worker.");
        newWorker = null;

    } else {            
        try {
            userDb.connect();

            loggedUser = c.getValue().split(":");

            if(!loggedUser[0].equals("00000000A") || !loggedUser[1].equals(userDb.selectPassword("00000000A"))){
                LOGGER.warning("You need privileges to add a worker.");

            } else if(newWorker.getNombre() == null || newWorker.getApellido1() == null || newWorker.getApellido2() == null){
                workDb.save(newWorker); //Here's where the exception is being thrown. 

            } else {
                workDb.save(newWorker); //Here's where the exception is being thrown. 
            }


        } catch (ClassNotFoundException e) {
            userDb.rollback();
            newWorker = null;
            LOGGER.warning("Exception with driver encountered.");
            throw new ExpectedException(1, e.getMessage());

        } catch (SQLException e) {
            userDb.rollback();
            newWorker = null;
            throw new ExpectedException(2, e.getMessage());

        } finally {
            userDb.commit();
            userDb.disconnect();
        }
    }


    return newWorker;
}

}

我已經閱讀了很多文章，但是找不到有效的方法。 有我想寫的注釋嗎？

預先感謝您：3

編輯。 應用答案后，我的主要班級：

@SpringBootApplication
@EnableSwagger2
@ComponentScan(basePackages = "com.setoncios.api")
@EnableJpaRepositories("com.setoncios.api.dao.workers")
public class GenericApiApplication {

public static void main(String[] args) {
    SpringApplication.run(GenericApiApplication.class, args);
}

@Bean
public Docket swaggerSettings() {
    return new Docket(DocumentationType.SWAGGER_2)
            .select()
            .apis(RequestHandlerSelectors.any())
            .paths(PathSelectors.any())
            .build()
            .pathMapping("/");
}

}

其余方法：

@RequestMapping(value = "/worker", method = RequestMethod.POST)
public ResponseEntity<?> addWorkerInDatabase(HttpServletRequest request,
        @RequestParam(value = "json", defaultValue = 
        "{\"dni\":\"00000000A\",\"nombre\":\"Paco\",\"apellido1\":\"Ruiz\",\"apellido2\":\"Díaz\"}") final String json){
    return addDB.createResponse(request, json);
}

還有AddWorkerInDatabaseAction類：

@Service
public class AddWorkerInDatabaseAction extends ProcessAction{
@Autowired
private UserDatabase userDb = new UserDatabase();

@Autowired
private WorkerDAO workDb;

public AddWorkerInDatabaseAction() {
}

@Override
protected Object action(Object...args) throws ExpectedException {
    Persona newWorker = new Gson().fromJson((String) args[1], Persona.class);
    workDb.save(newWorker);


    return newWorker;
}

}

希望它可以幫助某人。

Answer 1

我想可能是您的注釋

@EnableJpaRepositories("com.setoncios.api.dao.workers.WorkerDAO.java")

是錯的。 此批注的默認值是用於掃描已批注的類的基本包。 因此，在您的情況下，應為"com.setoncios.api.dao.workers" 。

您還可以設置basePackageClasses以獲得更多類型安全性，然后可以將其WorkerDAO.class

另外，正如另一個答案所建議的那樣，您應該使AddWorkerInDatabaseAction服務成為一種服務，並將其自動連接到控制器中。 這樣春天將注入必要的豆子。

Answer 2

您可以將AddWorkerInDatabaseAction類AddWorkerInDatabaseAction Spring Service。 同樣，您也可以將參數直接傳遞給實際方法，而不是將參數傳遞給構造函數。

 @Service
 public class AddWorkerInDatabaseAction extends ProcessAction{
     .....

     protected Object action(HttpServletRequest request, String json) throws ExpectedException {
     .....
 }

在您的控制器中，您可以自動連接spring創建的此類的bean，

 private class MyController{

     @Autowire
     ProcessAction object;

     @RequestMapping(value = "/worker", method = RequestMethod.POST)
     public ResponseEntity<?> addWorkerInDatabase(HttpServletRequest request,
             @RequestParam(value = "json", defaultValue = 
    "{\"dni\":\"00000000A\",\"nombre\":\"Paco\",\"apellido1\":\"Ruiz\",\"apellido2\":\"Díaz\"}") final String json){
         return object.createResponse(request, json);
 }