忽略基于另一个字段值的序列化字段

Question

我有这样的课：public class Profile {        private String firstName;        private String lastName;        private String nickName;        @JsonIgnore        private boolean isNameSecret;}序列化对象时可以隐藏属性firstName，lastName如果isNameSecret值为true？

Answer 1

您需要编写自定义序列化程序并实现该逻辑。它可能如下所示：

import com.fasterxml.jackson.core.JsonGenerator;

import com.fasterxml.jackson.databind.JsonSerializer;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.fasterxml.jackson.databind.SerializationFeature;

import com.fasterxml.jackson.databind.SerializerProvider;

import com.fasterxml.jackson.databind.annotation.JsonSerialize;

import java.io.IOException;

public class ProfileApp {

    public static void main(String[] args) throws Exception {

        ObjectMapper mapper = new ObjectMapper();

        mapper.enable(SerializationFeature.INDENT_OUTPUT);

        System.out.println(mapper.writeValueAsString(new Profile()));

    }

}

class ProfileJsonSerialize extends JsonSerializer<Profile> {

    @Override

    public void serialize(Profile profile, JsonGenerator gen, SerializerProvider serializers) throws IOException {

        gen.writeStartObject();

        if (!profile.isNameSecret()) {

            gen.writeStringField("firstName", profile.getFirstName());

            gen.writeStringField("lastName", profile.getLastName());

        }

        gen.writeStringField("nickName", profile.getNickName());

        gen.writeEndObject();

    }

}

@JsonSerialize(using = ProfileJsonSerialize.class)

class Profile {

    private String firstName = "Rick";

    private String lastName = "Sanchez";

    private String nickName = "Pickle Rick";

    private boolean isNameSecret = true;

    public String getFirstName() {

        return firstName;

    }

    public void setFirstName(String firstName) {

        this.firstName = firstName;

    }

    public String getLastName() {

        return lastName;

    }

    public void setLastName(String lastName) {

        this.lastName = lastName;

    }

    public String getNickName() {

        return nickName;

    }

    public void setNickName(String nickName) {

        this.nickName = nickName;

    }

    public boolean isNameSecret() {

        return isNameSecret;

    }

    public void setNameSecret(boolean nameSecret) {

        isNameSecret = nameSecret;

    }

}

上面的代码打印：

{

  "nickName" : "Pickle Rick"

}

Answer 2

这可以使用 Jackson 的Mixin功能来实现。它允许在运行时应用来自外部类的注释。通过指定相同的属性名称来完成匹配（也适用于 getter/setter 等方法名称）

这是根据问题（为简单起见将实例变量公开）的示例，请注意 mixin 类仅包含您要覆盖的属性。此外，它不需要初始化。

具有相同属性名称并添加注释的 mixin 类

public class ProfileIgnoreFirstLastName

{

    @JsonIgnore

    public String firstName;

    @JsonIgnore

    public String lastName;

}

使用 mixin 类的条件应用进行序列化：

public static String serializeProfile(Profile profile) throws IOException {

    ObjectMapper mapper = new ObjectMapper();

    if (profile.isNameSecret) {

        mapper.addMixIn(Profile.class, ProfileIgnoreFirstLastName.class);

    }

    return mapper.writeValueAsString(profile);

}

测试方法

public static void main(String[] args) {

    try {

        Profile profile = new Profile();

        profile.isNameSecret = false;

        System.out.println(serializeProfile(profile));

        profile.isNameSecret = true;

        System.out.println(serializeProfile(profile));

    } catch (Exception e) {

        e.printStackTrace();

    }

}

输出

{"firstName":"my first name","lastName":"my last name","nickName":"my nick name"}

{"nickName":"my nick name"}