java - 不使用默认构造函数反序列化 JSON

Question

我正在迁移现有的通信层以将 REST 与 JSON 结合使用。以前的框架不需要传输 POJO 的默认构造函数。

我无法对正在传输的模型类进行更改，因此注释不是一个选项。 Mixin 也不是一个选择。它应该是一个中心配置。

这是当前的配置和测试代码:

ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(Include.NON_NULL);
mapper.setDefaultPropertyInclusion(Include.NON_NULL);
mapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE);
mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
mapper.setVisibility(PropertyAccessor.CREATOR, Visibility.ANY);
mapper.configure(DeserializationFeature.FAIL_ON_MISSING_CREATOR_PROPERTIES, false);

PrivateObject object = new PrivateObject(1234, "test");
String jsonString = mapper.writeValueAsString(object);
PrivateObject result = mapper.readValue(jsonString, PrivateObject.class);

POJO 示例:

public class PrivateObject {
    private int id;
    private String name;

    public PrivateObject(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }
}

JSON 示例:

{"id":1234,"name":"test"}

产生的异常:

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.softmodeler.common.pojo.PrivateObject` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (String)"{"id":1234,"name":"test"}"; line: 1, column: 2]

Answer 1

如果您使用 Java 8 或更高版本，则无需注释或 mixins 即可完成:

• 编译将-parameters参数传递给javac
• 在您的依赖项中包含模块 jackson-module-parameter-names 并注册它，例如mapper.registerModule(new ParameterNamesModule());

更多详情here