使用gson解析json数组中的对象

问题描述

我有一个安静的端点，它在端点 http://127.0.0.1:4567/suppliers 上执行GET时提供了下面的JSON。

  {
status：SUCCESS，
jsonapi：{
 version：1.0
}，
data：{
id：0，
type：suppliers，
name ：红网络能源有限公司
} 
} 
  

在httpPost请求我使用GSON将上述数据解析到 SupplierResponseTest 对象中。执行时：

SupplierResponseTest supplierResponse = gson.fromJson（supplierJsonResponse，SupplierResponseTest.class）;

我得到错误：

java.lang.IllegalStateException：预期的BEGIN_OBJECT，但在第1行是BEGIN_ARRAY列57路径$ .data

  public SupplierResponseTest sendPostRequest（String supplierName）{
 
 
 SupplierResponseTest supplierResponse; 
 
 
尝试（CloseableHttpClient httpClient = HttpClientBuilder.create（）。build（））{
 
 
 //创建新对象
 SupplierTest supplier = new SupplierTest（supplierName）; 
 
 //转换为Json 
 Gson gson = new Gson（）; 
字符串requestBody = gson.toJson（supplier）; 
 
 
 //设置实体
 
 HttpPost request = new HttpPost（http://127.0.0.1:4567/suppliers）; 
 StringEntity params = new StringEntity（requestBody）; 
 request.addHeader（content-type，application / json）; 
 request.setEntity（params）; 
 HttpResponse result = httpClient.execute（request）; 
 String supplierJsonResponse = EntityUtils.toString（result.getEntity（），UTF-8）; 
 
 
 supplierResponse = gson.fromJson（supplierJsonResponse，SupplierResponseTest.class）; 
 
返回supplierResponse; 
 
 
 
 
 
 
 
 $ b} catch（例外e）{
字符串状态= ; 
 System.out.println（e.getMessage（））; 
 System.out.println（e.getClass（））; 
 System.out.println（e.getStackTrace（））; 
 
 status =NOK; 
 
} 
 //返回状态; 
返回null; 
 
 
  

对象如下。

  package json.responses; 
 import com.google.gson.Gson; 
 
公共类SupplierResponseTest {
 
私有StatusResponseTest状态; 
 private ApiVersionResponseTest jsonapi; 
私人字符串消息; 
私有ResponseDataTest数据; 
 
 
 public SupplierResponseTest（StatusResponseTest status，ApiVersionResponseTest jsonapi）{
 this.status = status; 
 this.jsonapi = jsonapi; 
 
 $ b public SupplierResponseTest（StatusResponseTest status，ApiVersionResponseTest jsonapi，String data，String message）{
 this.status = status; 
 this.jsonapi = jsonapi; 
 this.message = message; 
 
 //需要考虑供应商数组的数据
 try {
 Gson gson = new Gson（）; 
 this.data = gson.fromJson（data，ResponseDataTest.class）; 
 
 $ b $ catch（Exception e）{
 System.out.println（e.getMessage（））; 
} 
} 
 
 public StatusResponseTest getStatus（）{
 return status; 
} 
 public ApiVersionResponseTest getJsonapi（）{
 return jsonapi; 
} 
 public String getMessage（）{
 return message; 
} 
 
 // getData需要考虑供应商数组
 public ResponseDataTest getData（）{
 return data; 
} 
 
} 
  

解决方案

在你的类中 SupplierResponseTest.java

$ b 替换 private ResponseDataTest data; / code> with private ResponseDataTest [] data;

并替换 private StatusResponseTest状态; 与私人字符串状态;

'包含JSONArray

查看此代码 -

  package com。 stack.example; 
 
 import com.google.gson.Gson; 
 
公共类SupplierResponseTest {
 
私有字符串状态; 
 private ApiVersionResponseTest jsonapi; 
私人字符串消息; 
 private ResponseDataTest [] data; 
 
 
 public SupplierResponseTest（String status，ApiVersionResponseTest jsonapi）{
 this.status = status; 
 this.jsonapi = jsonapi; 
 
 $ b public SupplierResponseTest（String status，ApiVersionResponseTest jsonapi，String data，String message）{
 this.status = status; 
 this.jsonapi = jsonapi; 
 this.message = message; 
 
 //需要考虑供应商数组的数据
 try {
 Gson gson = new Gson（）; 
 this.data = gson.fromJson（data，ResponseDataTest []。class）; 
 
 $ b $ catch（Exception e）{
 System.out.println（e.getMessage（））; 
} 
} 
 
 public String getStatus（）{
 return status; 
} 
 public ApiVersionResponseTest getJsonapi（）{
 return jsonapi; 
} 
 public String getMessage（）{
 return message; 
} 
 
 // getData需要考虑供应商数组
 public ResponseDataTest [] getData（）{
 return data; 
} 
 
 @Override 
 public String toString（）{
 returnSupplierResponseTest [status =+ status +，jsonapi =
 + jsonapi +，message =+ message +，data =+ data +]; 
} 
} 
 
 public class ApiVersionResponseTest {
 
 private String version; 
 
 public ApiVersionResponseTest（）{
 super（）; 
 // TODO自动生成的构造函数存根
 
 $ b $ public ApiVersionResponseTest（String version）{
 super（）; 
 this.version = version; 
} 
 
 public String getVersion（）{
 return version; 
} 
 
 public void setVersion（String version）{
 this.version = version; 
} 
} 
 
 package com.stack.example; 
 
 public class ResponseDataTest {
 
 private int id; 
私有字符串类型; 
私人字符串名称; 
 public ResponseDataTest（）{
 super（）; 
 // TODO自动生成的构造函数存根
 
 public ResponseDataTest（int id，String type，String name）{
 super（）; 
 this.id = id; 
 this.type = type; 
 this.name = name; 
} 
 public int getId（）{
 return id; 
} 
 public void setId（int id）{
 this.id = id; 
} 
 public String getType（）{
 return type; 
} 
 public void setType（String type）{
 this.type = type; 
} 
 public String getName（）{
 return name; 
} 
 public void setName（String name）{
 this.name = name; 
} 
} 
 
 package com.stack.example; 
 
 import com.google.gson.Gson; 
 
 public class Stack {
 
 
 public static void main（String [] args）{
 
 String jsonResponse ={\ status \：\SUCCESS\，\jsonapi\：{\version \：\1.0 \}，\data \：[ 
 +{\id \：70，\type \：\suppliers \，\name \：\Blue Network Energy LTD \ }，
 +{\id \：71，\type \：\suppliers \，\name \：\Red Network能源有限公司}，
 +{\id \：72，\type\：\suppliers \，\name \：\\ \\Orange Network Energy LTD \}，
 +{\id \：73，\type\：\suppliers \，\name \\ \\：绿色网络能源有限公司\\}}}; 
 
 Gson gson = new Gson（）; 
 
 //将json解析为SupplierResponseTest对象。 
 SupplierResponseTest supplierResponse = gson.fromJson（jsonResponse，SupplierResponseTest.class）; 
 
 System.out.println（supplierResponse）; 
 
} 
 
} 
  

为你工作。

I have a restful endpoint which provides the below JSON when performing a GET on the endpoint http://127.0.0.1:4567/suppliers.

    {
    "status": "SUCCESS",
    "jsonapi": {
        "version": "1.0"
    },
    "data": {
        "id": 0,
        "type": "suppliers",
        "name": "Red Network Energy LTD"
    }
}

In the httpPost request I use GSON to parse the above data into the SupplierResponseTest object. When executing:

SupplierResponseTest supplierResponse = gson.fromJson(supplierJsonResponse, SupplierResponseTest.class);

I get the error:

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 57 path $.data

public SupplierResponseTest sendPostRequest(String supplierName){


    SupplierResponseTest supplierResponse;


    try (CloseableHttpClient httpClient = HttpClientBuilder.create().build()) {


        //Create new object
        SupplierTest supplier = new SupplierTest(supplierName);

        //convert to Json
        Gson gson = new Gson();
        String requestBody = gson.toJson(supplier);


        //set entity

        HttpPost request = new HttpPost("http://127.0.0.1:4567/suppliers");
        StringEntity params = new StringEntity(requestBody);
        request.addHeader("content-type", "application/json");
        request.setEntity(params);
        HttpResponse result = httpClient.execute(request);
        String supplierJsonResponse = EntityUtils.toString(result.getEntity(), "UTF-8");


        supplierResponse = gson.fromJson(supplierJsonResponse, SupplierResponseTest.class);

        return supplierResponse;








    } catch (Exception e) {
        String status = "";
        System.out.println(e.getMessage());
        System.out.println(e.getClass());
        System.out.println(e.getStackTrace());

        status =  "NOK";

    }
    //return status;
    return null;

}

The Object is as below.

package json.responses;
import com.google.gson.Gson;

public class SupplierResponseTest {

    private StatusResponseTest status;
    private ApiVersionResponseTest jsonapi;
    private String message;
    private ResponseDataTest data;


    public SupplierResponseTest(StatusResponseTest status, ApiVersionResponseTest jsonapi) {
        this.status = status;
        this.jsonapi = jsonapi;

    }
    public SupplierResponseTest(StatusResponseTest status, ApiVersionResponseTest jsonapi, String data, String message) {
        this.status = status;
        this.jsonapi = jsonapi;
        this.message = message;

        //data which needs to take into account the array of suppliers
        try{
            Gson gson = new Gson();
            this.data = gson.fromJson(data, ResponseDataTest.class);


        }catch(Exception e){
            System.out.println(e.getMessage());
        }
    }

    public StatusResponseTest getStatus() {
        return status;
    }
    public ApiVersionResponseTest getJsonapi() {
        return jsonapi;
    }
    public String getMessage() {
        return message;
    }

    //getData which needs to take into account the array of suppliers
    public ResponseDataTest getData() {
        return data;
    }

}

解决方案

In your class - SupplierResponseTest.java

Replace private ResponseDataTest data; with private ResponseDataTest[] data;

and replace private StatusResponseTest status; with private String status;

As in your JSON response 'data' contains JSONArray

Look at this code -

package com.stack.example;

import com.google.gson.Gson;

public class SupplierResponseTest {

    private String status;
    private ApiVersionResponseTest jsonapi;
    private String message;
    private ResponseDataTest[] data;


    public SupplierResponseTest(String status, ApiVersionResponseTest jsonapi) {
        this.status = status;
        this.jsonapi = jsonapi;

    }
    public SupplierResponseTest(String status, ApiVersionResponseTest jsonapi, String data, String message) {
        this.status = status;
        this.jsonapi = jsonapi;
        this.message = message;

        //data which needs to take into account the array of suppliers
        try{
            Gson gson = new Gson();
            this.data = gson.fromJson(data, ResponseDataTest[].class);


        }catch(Exception e){
            System.out.println(e.getMessage());
        }
    }

    public String getStatus() {
        return status;
    }
    public ApiVersionResponseTest getJsonapi() {
        return jsonapi;
    }
    public String getMessage() {
        return message;
    }

    //getData which needs to take into account the array of suppliers
    public ResponseDataTest[] getData() {
        return data;
    }

    @Override
    public String toString() {
        return "SupplierResponseTest [status=" + status + ", jsonapi="
            + jsonapi + ", message=" + message + ", data=" + data + "]";
    }
}

public class ApiVersionResponseTest {

    private String version;

    public ApiVersionResponseTest() {
        super();
        // TODO Auto-generated constructor stub
    }

    public ApiVersionResponseTest(String version) {
        super();
        this.version = version;
    }

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }
}

package com.stack.example;

public class ResponseDataTest {

    private int id;
    private String type;
    private String name;
    public ResponseDataTest() {
        super();
        // TODO Auto-generated constructor stub
    }
    public ResponseDataTest(int id, String type, String name) {
        super();
        this.id = id;
        this.type = type;
        this.name = name;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

package com.stack.example;

import com.google.gson.Gson;

public class Stack {


    public static void main(String[] args) {

        String jsonResponse = "{\"status\": \"SUCCESS\",\"jsonapi\": {\"version\": \"1.0\"},\"data\": ["
                + "{\"id\": 70,\"type\": \"suppliers\",\"name\": \"Blue Network Energy LTD\"},"
                + "{\"id\": 71,\"type\": \"suppliers\",\"name\": \"Red Network Energy LTD\"},"
                + "{\"id\": 72,\"type\": \"suppliers\",\"name\": \"Orange Network Energy LTD\"},"
                + "{\"id\": 73,\"type\": \"suppliers\",\"name\": \"Green Network Energy LTD\"}]}";

        Gson gson = new Gson();

        //Parse json into a SupplierResponseTest object.
        SupplierResponseTest supplierResponse = gson.fromJson(jsonResponse, SupplierResponseTest.class);

        System.out.println(supplierResponse);

    }

}

Hope this will work for you.

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