Question

我使用Spring将数据存储在数据库中（当我开始正确地将数据写入数据库时）

我将JSON POST发送到我的Spring服务器请求，如下所示：

{
"productName": "name",
"restaurantId": 2,
"categoryId": 3,
"description": "des",
"price": 33.23
}

和接收功能

@RestController
public class NewProductController{
 @RequestMapping(value = "/addNewProduct", method = RequestMethod.POST)
    public ResponseEntity<NewProduct> update(@RequestBody NewProduct newProduct){

        productName = newProduct.getProductName();
        categoryId = newProduct.getCategoryId();
        restaurantId = newProduct.getRestaurantId();
        description = newProduct.getDescription();
        price = newProduct.getPrice();

        System.out.println(productName);
        System.out.println(categoryId);
        System.out.println(restaurantId);
        System.out.println(description);
        System.out.println(price);

        NewProductService newProductService = new NewProductService();

        newProductService.setData();

        return new ResponseEntity<NewProduct>(newProduct, HttpStatus.OK);

    }

来自println的数据显示正确。

并从NewProductService

设置setData函数

public class NewProductService {

    @Autowired
    CategoryRepository categoryRepository;

    private String productName;
    private Long categoryId;
    private Long restaurantId;
    private String description;
    private Double price;

    //[...]

    @Transactional
    public void setData(){

        Category customer = categoryRepository.findOne(1L);
        System.out.println("Customer found with findOne(1L):");
        System.out.println("--------------------------------");
        System.out.println(customer);
        System.out.println();
    }

在Category customer = categoryRepository.findOne(1L);我收到错误：

2015-08-18 23:12:27.716 ERROR 8092 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause

java.lang.NullPointerException: null
    at com.drinkandfood.server.Services.NewProductService.setData(NewProductService.java:46)

当我将此代码放入

时

@Override
    public void run(String... strings) throws Exception {

        Category customer = categoryRepository.findOne(1L);
        System.out.println("Customer found with findOne(1L):");
        System.out.println("--------------------------------");
        System.out.println(customer);
        System.out.println();
}

我没有收到错误，但预期的答案。问题出在哪儿？

Spring从repository和NullPointerException获取findOne

0 个答案: