Java控制器未将JSON转换为实体

Question

我无法通过POST请求接收JSON发送的信息，如下所示：

[{
 "idVehicule": 1,
 "vacancies": 3
}]

我有一个简单的控制器，它尝试从前端发送JSON，并将其转换为testModel：

import com.fasterxml.jackson.annotation.JsonProperty;

public class testModel {

    @JsonProperty( "idvehicle" )
    private int idvehicle;
    @JsonProperty( "vacancies" )
    private String vacancies;

    public int getIdvehicle() {
        return idvehicle;
    }
    public void setIdvehicle(int idvehicle) {
        this.idvehicle = idvehicle;
    }
    public String getVacancies() {
        return vacancies;
    }
    public void setVacancies(String vacancies) {
        this.vacancies = vacancies;
    }

}

然后它只打印其中一个值

@RequestMapping(value = "/vehicle", method = RequestMethod.POST)
    public ResponseEntity<String> vehicleTest(@RequestBody testModel testModel){
        System.out.println(testModel.getVacancies());
        return new ResponseEntity<String>(HttpStatus.OK);;
    }

在与postman一起尝试该方法后，我不断遇到以下错误：

{
  "timestamp": 1472819769941,
  "status": 400,
  "error": "Bad Request",
  "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
  "message": "Could not read document: Can not deserialize instance of testModel out of START_ARRAY token\n at [Source: java.io.PushbackInputStream@646345e6; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of testModel out of START_ARRAY token\n at [Source: java.io.PushbackInputStream@646345e6; line: 1, column: 1]",
  "path": "/vehicle"
}

我还尝试更改JSON，问题是该方法无法将其转换为enity，从而使变量“testModel”始终为空

{"testModel":{"idvehicle":1,"vacancies":3}}

删除“@RequestBoby”注释会产生与前面段落相同的问题

有什么办法能帮我解决这个问题吗？谢谢

Answer 1

您正在POST使用一个testModel对象数组（快速抱怨，类名应该以大写字母开头，所以应该是TestModel），但是您的方法接受一个testModel作为@RequestBody。将方法声明更改为public ResponseEntity<String> vehicleTest(@RequestBody List<testModel> testModel){

Answer 2

JsonProperty区分大小写。您需要使密钥名与Json中的密钥名完全相同。所以像这样修改它，并检查拼写

@JsonProperty( "idVehicule" )

Answer 3

您在testModel中指定@JsonProperty为idvehicle，因此请更正您要发布到的JSON：

 [{
     "idvehicle": 1,
     "vacancies": 3
 }]

接下来，您将发送testModel的数组，并期望testModel当然不会反序列化

请更正要发送到{"idvehicle": 1,"vacancies": 3}的JSON，或将Controller更改为接受testModel的数组，如下所示：

@RequestMapping(value = "/vehicle", method = RequestMethod.POST)
public ResponseEntity<String> vehicleTest(@RequestBody List<testModel> testModel){

        return new ResponseEntity<String>(HttpStatus.OK);;
}