java - @jsonIgnore 注释不起作用

Question

我使用@JsonIgnore属性来忽略pojo中的一些属性，但是使用Gson库解析json后，这些字段在json响应中不会被忽略，请帮忙。

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown=true)
public class RideInvite extends RideInviteOld  implements Serializable
{
    private static final long serialVersionUID = -3729010679180341959L;


    private double newFare = -1;
    @JsonIgnore
    private long prefPickupDropId;
    @JsonIgnore
    private String pickupLandmark;
    @JsonIgnore
    private String dropLandmark;
}

使用以下代码进行解析

 GsonBuilder builder = new GsonBuilder();
        Gson gson = builder.create();
        jsonText = gson.toJson(msgObject);

解析后的响应

{"newFare":-1.0,"prefPickupDropId":2,"savePickupDropPoints":false,"pickupDropBasedOnTraffic":true,"allowFareChange":true}

这里 prefPickupDropId 和 savePickupDropPoints 被 json 忽略，但 value 属性仍然存在于 json 文本中

我不能对字段使用@Expose，因为我的项目是这样构建的，忽略不需要的字段，json忽略并且相同的pojos用于准备http响应。早些时候这工作正常，但最近我遇到了这个问题

提前致谢

Answer 1

方法1:
您应该使用而不是使用 com.fasterxml.jackson.annotation.JsonIgnore com.google.gson.annotations.Expose达到您的要求。

这是工作代码片段 -

import java.io.Serializable;

import com.google.gson.annotations.Expose;

public class RideRecord implements Serializable {
    @Expose
    private double newFare = -1;

    private long prefPickupDropId;

    private String pickupLandmark;

    private String dropLandmark;

    public RideRecord(double newFare, long prefPickupDropId, String pickupLandmark, String dropLandmark) {
        super();
        this.newFare = newFare;
        this.prefPickupDropId = prefPickupDropId;
        this.pickupLandmark = pickupLandmark;
        this.dropLandmark = dropLandmark;
    }

}

使用如下代码进行解析:

RideRecord msgObject = new RideRecord(-1.0, 2, "sfo", "powell bart station");
        GsonBuilder builder = new GsonBuilder();
        builder.excludeFieldsWithoutExposeAnnotation();
        Gson gson = builder.create();
        String jsonText = gson.toJson(msgObject);
        System.out.println(jsonText);

它将给出输出:

{"newFare":-1.0}

因为只有 newFare 是公开的字段。您可以使用 @Expose 属性来满足您的要求。

方法2:

If you don't want to use @Expose then also you can achieve your requirement by just creating Gson object as below -

RideRecord msgObject = new RideRecord(-1.0, 2, "sfo", "powell bart station");
        GsonBuilder builder = new GsonBuilder();
        builder.addSerializationExclusionStrategy(new ExclusionStrategy() {

            @Override
            public boolean shouldSkipField(FieldAttributes fieldAttributes) {

                return fieldAttributes.getName().equals("prefPickupDropId") || fieldAttributes.getName().equals("pickupLandmark") || fieldAttributes.getName().equals("dropLandmark");
            }

            @Override
            public boolean shouldSkipClass(Class<?> arg0) {
                // TODO Auto-generated method stub
                return false;
            }
        });

        Gson gson = builder.create();
        String jsonText = gson.toJson(msgObject);
        System.out.println(jsonText);

在这种情况下，您也会得到相同的输出:

{"newFare":-1.0}