java - 在 spring 中从 json 字符串创建模型时验证模型

Question

我正在 spring 中使用 json jackson 对象映射器从 json 字符串准备一个模型。

我的代码是

   ObjectMapper mapper = new ObjectMapper();
   String empValue =  mapper.writeValueAsString(employeeMap);
   Employees employee = mapper.readValue(empValue, Employees.class);

在准备员工对象之前，我想验证 json，因为如果在准备模型时通过异常设置了任何不匹配的数据。我该怎么做？

Answer 1

您可以从异常中获取一些有值(value)的信息，主要来自 JsonMappingException类及其子类(在 com.fasterxml.jackson.databind.exc 包下)使用 getPath 和 getPathReference 方法

这里有两个例子:

public class ObjectMapperTest {
    private   ObjectMapper objectMapper;

    @Before
    public void setup() {
        objectMapper = new ObjectMapper();
    }

    @Test
    public void testWrongDataType() {
        String personStr = "{\"age\":\"100Y\",\"firstName\":\"Jackson\",\"lastName\":\"Pollock\",\"gender\":\"M\"}";
        try {
            objectMapper.readValue(personStr, Person.class);
        } catch (JsonMappingException jme) {
                System.out.println(jme.getMessage());
                if(jme instanceof InvalidFormatException) {
                    InvalidFormatException ife = (InvalidFormatException)jme;
                    System.out.println("Mapping failure on field:" + ife.getPathReference());
                    System.out.println("Expected type: " + ife.getTargetType());
                    System.out.println("provided value: " + ife.getValue());
                }
        }catch (Exception  e){
            System.out.println(e.getMessage());
        }
    }

    @Test
    public void testUnrecognizedProperty() {
        String personStr = "{\"gae\":\"100\",\"firstName\":\"Jackson\",\"lastName\":\"Pollock\",\"gender\":\"M\"}";
        try {
            objectMapper.readValue(personStr, Person.class);
        } catch (JsonMappingException jme) {
            System.out.println(jme.getMessage());
            if(jme instanceof PropertyBindingException) {
                PropertyBindingException pbe = (PropertyBindingException) jme;
                System.out.println("Mapping failure on field:" + pbe.getPathReference());
                System.out.println("UnExpected field: " + pbe.getPropertyName());
            }
        }catch (Exception  e){
            System.out.println(e.getMessage());
        }
    }
}

输出将是

testUnrecognizedProperty:
========================
Unrecognized field "gae" (class Person), not marked as ignorable (4 known properties: "lastName", "gender", "firstName", "age"])
 at [Source: {"gae":"100","firstName":"Jackson","lastName":"Pollock","gender":"M"}; line: 1, column: 9] (through reference chain: Person["gae"])
Mapping failure on field:Person["gae"]
UnExpected field: gae
testWrongDataType:
======================== 
Can not construct instance of java.lang.Integer from String value '100Y': not a valid Integer value
 at [Source: {"age":"100Y","firstName":"Jackson","lastName":"Pollock","gender":"M"}; line: 1, column: 2] (through reference chain: Person["age"])
Mapping failure on field:Person["age"]
Expected type: class java.lang.Integer
provided value: 100Y