Question

我想将一个json解析为一个对象，该对象为我提供了附加到银行的每个实体的详细信息。

我的json看起来像：

{
    "href" : "abc", 
    "configurations" : 
    [
        {
           "type" : "bank-customer",
           "properties" : {
                "cust-name" : "foo",
                "acc-no" : "12345"
            }
        }, 
        {
           "type" : "bank-employee",
           "properties" : {
                "empl-name" : "foo",
                "empl-no" : "12345"
            }
        }
    ]
}

各种实体的属性＆＃34;类型＆＃34;是不同的。

为此创建一个pojo是挑战。我的properties.java必须包含所有属性，而不管属性的类型如何：

public class Configurations {
    @SerializedName("type")
    @Expose
    private String entityType;
    @SerializedName("properties")
    @Expose
    private Properties properties;
}

public class Properties {
    @SerializedName("cust-name")
    @Expose
    private String custName;
    @SerializedName("empl-no")
    @Expose
    private String emplNo;
    @SerializedName("empl-name")
    @Expose
    private String emplName;
    @SerializedName("acc-no")
    @Expose
    private String accNo;
}

当每个实体类型有很多实体类型和属性时，这很痛苦。有没有其他方法我可以将这个json解析为不同的属性对象为不同的实体类型？我正在使用gson来解析JSON

注意：我无法对json本身进行任何更改。

Answer 1

您可能需要创建自己的反序列化程序，请查看此example。

可能的实施

解串器：

package it.test.gson;

import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.JsonArray;
import com.google.gson.JsonDeserializationContext;
import com.google.gson.JsonDeserializer;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;

public class BankDeserializer implements JsonDeserializer<Bank> {

    @Override
    public Bank deserialize(final JsonElement json, final Type typeOfT, final JsonDeserializationContext context) throws JsonParseException {
        final JsonObject jsonObject = json.getAsJsonObject();

        final JsonElement jsonHref = jsonObject.get("href");
        final String href = jsonHref.getAsString();

        final JsonArray jsonConfigurationsArray = jsonObject.get("configurations").getAsJsonArray();
        final String[] configurations = new String[jsonConfigurationsArray.size()];
        List<IPerson> persons = new ArrayList<>();
        for (int i = 0; i < configurations.length; i++) {
            final JsonElement jsonConfiguration = jsonConfigurationsArray.get(i);
            final JsonObject configJsonObject = jsonConfiguration.getAsJsonObject();
            final String type = configJsonObject.get("type").getAsString();
            final JsonObject propertiesJsonObject = configJsonObject.get("properties").getAsJsonObject();
            IPerson iPerson = null;
            if (type.equals("bank-customer")) {
                iPerson = new Customer();
                final String name = propertiesJsonObject.get("cust-name").getAsString();
                final String no = propertiesJsonObject.get("acc-no").getAsString();
                iPerson.setName(name);
                iPerson.setNo(no);
            } else if (type.equals("bank-employee")) {
                iPerson = new Employee();
                final String name = propertiesJsonObject.get("empl-name").getAsString();
                final String no = propertiesJsonObject.get("empl-no").getAsString();
                iPerson.setName(name);
                iPerson.setNo(no);
            }
            persons.add(iPerson);
        }

        final Bank bank = new Bank();
        bank.setHref(href);
        bank.setConfiguration(persons.toArray(new IPerson[0]));
        return bank;
    }
}

的POJO：

银行

package it.test.gson;

public class Bank {

    private String href;
    private IPerson[] configuration;

    public String getHref() {
        return href;
    }

    public void setHref(String href) {
        this.href = href;
    }

    public IPerson[] getConfiguration() {
        return configuration;
    }

    public void setConfiguration(IPerson[] configuration) {
        this.configuration = configuration;
    }

}

人员界面

package it.test.gson;

public interface IPerson {

    public String getName();
    public void setName(String name);
    public String getNo();
    public void setNo(String no);

}

人员，员工或客户的实施

package it.test.gson;

public class Customer implements IPerson {

    private String name;
    private String no;

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

    @Override
    public void setNo(String no) {
        this.no = no;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public String getNo() {
        return no;
    }

}

package it.test.gson;

public class Employee implements IPerson {

    private String name;
    private String no;

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

    public void setNo(String no) {
        this.no = no;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public String getNo() {
        return no;
    }

}

和要测试它的Main类

package it.test.gson;

import java.io.InputStreamReader;
import java.io.Reader;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

public class Main {
    public static void main(String[] args) throws Exception {
        // Configure Gson
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.registerTypeAdapter(Bank.class, new BankDeserializer());
        Gson gson = gsonBuilder.create();

        // The JSON data
        try (Reader reader = new InputStreamReader(Main.class.getResourceAsStream("/part1/sample.json"), "UTF-8")) {
            // Parse JSON to Java
            Bank bank = gson.fromJson(reader, Bank.class);

            System.out.println(bank.getHref());
            //...
        }
    }
}

我希望它有所帮助。

Answer 2

我完全赞同mauros的答案。

但您也可以创建一个界面层次结构并实现Instance Creator。

Answer 3

使用@SerializedName注释中的alternate关键字可以轻松解决此问题。

public class Properties {

    @SerializedName(value="cust-name", alternate={"empl-name", "user-name"})
    @Expose
    private String name;

    @SerializedName("acc-no", alternate={"empl-no", "user-id"})
    @Expose
    private String id;

    //setter and getters
}

如何在gson中处理多个json字段

3 个答案: