Java 8 Jackson验证

Question

我有一个springboot休息服务.用户传入一个json对象,该对象被反序列化到这个java pojo中:

public final class Request {
    private String id;
    private double code;
    private String name;

    public String getId() {
        return id;
    }

    public double getCode() {
        return code;
    }

    public String getName() {
        return name;
    }
}

所以用户需要传入以下json:

{
    "id": “123457896”,
    "code": "Foo",
    "name": "test"
} 

我想要完成所有这些领域.提供更少或更多的东西会引发异常.有没有办法告诉杰克逊在反序列化时验证输入？我试过@JsonProperty(required=true)但这不起作用; 显然从这里和这里看起来JsonProperty注释没有得到尊重.

我在我的控制器中调用了这个验证器:

@Component
public class RequestValidator implements Validator {
    @Override
    public boolean supports(Class<?> clazz) {
        return false;
    }

    @Override
    public void validate(Object target, Errors errors) {
        String id = ((Request) target).getId();
        if(id == null || id.isEmpty()) {
            throw new InvalidRequestException("A valid id is missing. Please provide a non-empty or non-null id.");
        }
    }
}

但是,检查每个领域似乎都很乏味和丑陋.所以鉴于我使用的是java 8,spring boot和jackson的最新版本,在验证传入的json输入方面,最佳做法是什么？或者我是否已经以最新的方式做到了？

Answer 1

有没有必要自定义的验证.有办法告诉杰克逊扔

• JsonMappingException 如果您没有必填字段

• UnrecognizedPropertyException如果你有额外的字段(UnrecognizedPropertyException只是扩展JsonMappingException).

您只需要添加@JsonCreator或自定义构造函数.这样的事情应该有效:

public Request(@JsonProperty(value= "id", required = true)String id,
               @JsonProperty(value= "code",required = true)double code,
               @JsonProperty(value= "name",required = true)String name) {
    this.id = id;
    this.code = code;
    this.name = name;
}

完整演示:

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;

public class Main {

public static void main(String[] args) throws IOException {
    test("{\"id\": \"123457896\",\"code\": 1,\"name\": \"test\"}");
    test("{\"id\": \"123457896\",\"name\": \"test\"}");
    test("{\"id\": \"123457896\",\"code\": 1, \"c\": 1,\"name\": \"test\"}");
}

public static void test(String json) throws IOException{
    ObjectMapper mapper = new ObjectMapper();
    try {
        Request deserialized = mapper.readValue(json, Request.class);
        System.out.println(deserialized);
        String serialized = mapper.writeValueAsString(deserialized);
        System.out.println(serialized);
    } catch (JsonMappingException e) {
        System.out.println(e.getMessage());
    }
}

public static class Request {
    private String id;
    private double code;
    private String name;

    public Request(@JsonProperty(value= "id", required = true)String id,
                   @JsonProperty(value= "code",required = true)double code,
                   @JsonProperty(value= "name",required = true)String name) {
        this.id = id;
        this.code = code;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public double getCode() {
        return code;
    }

    public void setCode(double code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Request{" +
                "id='" + id + '\'' +
                ", code=" + code +
                ", name='" + name + '\'' +
                '}';
    }
}
}

结果:

Request{id='123457896', code=1.0, name='test'}
{"id":"123457896","code":1.0,"name":"test"}
Missing required creator property 'code' (index 1)
 at [Source: {"id": "123457896","name": "test"}; line: 1, column: 34]
Unrecognized field "c" (class Main7$Request), not marked as ignorable (3 known properties: "id", "code", "name"])
 at [Source: {"id": "123457896","code": 1, "c": 1,"name": "test"}; line: 1, column: 53] (through reference chain: Request["c"])

Answer 2

您使用了Spring Validator方法.还有另一种方法:

J2EE JSR-303/JSR-349 Bean Validation API.它提供验证注释(javax,而不是jackson).

在这里看到两个好例子

Answer 3

在构造函数上使用@JsonCreator注释与 一起@JsonProperty使用将起作用。也检查这个答案。

public final class Request {
    private String id;
    private double code;
    private String name;

    @JsonCreator
    public Request(@JsonProperty(required = true) String id,
                   @JsonProperty(required = true) double code,
                   @JsonProperty(required = true) String name) {
        this.id = id;
        this.code = code;
        this.name = name;
    }

    public String getId() {
        return id;
    }

    public double getCode() {
        return code;
    }

    public String getName() {
        return name;
    }
}