使用Gson解析NDJSON文件中的多个JSON记录

// Record # 1
{
 "profile":{
      "salutation":"Mr",
      "title":null,
      "company":null
   },
   "phone":{
      "home_phone":null
   },
   "addresses":[
      {
         "address_id":"1",
         "first_name":"Veronica"
      }
   ],
   "orders":{
      "placed_orders_count":2
   }
}
// Record # 2
{
    "profile":{
      "salutation":null,
      "title":null
   },
   "phone":{
      "home_phone":null
   },
   "addresses":[
      {
         "address_id":"2",
         "title":""
      }
   ],
   "orders":{
      "placed_orders_count":0
   }
}
// ... 更多记录

import com.google.gson.Gson;
import com.google.gson.stream.JsonReader;
import java.io.FileReader;
import java.io.IOException;

// 假设 CustomerFeedDTO 已经定义
// ...

public class InitialNdjsonReaderExample {
    public static void main(String[] args) {
        Gson gson = new Gson();
        try (JsonReader reader = new JsonReader(new FileReader("customer.json"))) {
            // 这种方式只能读取第一个JSON对象
            CustomerFeedDTO customerFeedDTO = gson.fromJson(reader, CustomerFeedDTO.class);
            System.out.println("成功读取第一个记录: " + customerFeedDTO);
            // 后续的记录将无法读取到，因为fromJson方法在读取完一个完整的JSON对象后就会停止。
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import com.google.gson.Gson;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken; // 导入 JsonToken
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

// CustomerFeedDTO 类定义 (详见下一节)
class CustomerFeedDTO {
    private Map<String, ?> profile;
    private Map<String, ?> phone;
    private ArrayList<?> addresses;
    private Map<String, ?> orders;
    private ArrayList<?> customs;

    // Getters and setters (省略具体实现，但实际应用中需要)
    public Map<String, ?> getProfile() { return profile; }
    public void setProfile(Map<String, ?> profile) { this.profile = profile; }
    public Map<String, ?> getPhone() { return phone; }
    public void setPhone(Map<String, ?> phone) { this.phone = phone; }
    public ArrayList<?> getAddresses() { return addresses; }
    public void setAddresses(ArrayList<?> addresses) { this.addresses = addresses; }
    public Map<String, ?> getOrders() { return orders; }
    public void setOrders(Map<String, ?> orders) { this.orders = orders; }
    public ArrayList<?> getCustoms() { return customs; }
    public void setCustoms(ArrayList<?> customs) { this.customs = customs; }

    @Override
    public String toString() {
        return "CustomerFeedDTO{" +
               "profile=" + profile +
               ", phone=" + phone +
               ", addresses=" + addresses +
               ", orders=" + orders +
               ", customs=" + customs +
               '}';
    }
}

public class NdjsonMultiRecordReader {
    public static void main(String[] args) {
        List<CustomerFeedDTO> customerFeedDTOs = new ArrayList<>();
        Gson gson = new Gson();

        // 使用 try-with-resources 确保资源自动关闭
        try (JsonReader reader = new JsonReader(new FileReader("customer.json"))) {
            // 启用宽松模式，以处理可能存在的非严格JSON格式
            reader.setLenient(true);

            // 循环读取直到文档结束
            while (reader.peek() != JsonToken.END_DOCUMENT) {
                CustomerFeedDTO customerFeedDTO = gson.fromJson(reader, CustomerFeedDTO.class);
                customerFeedDTOs.add(customerFeedDTO);
                System.out.println("成功读取记录: " + customerFeedDTO); // 打印每条记录以验证
            }

            System.out.println("\n所有记录读取完毕。总计 " + customerFeedDTOs.size() + " 条记录。");

        } catch (IOException e) {
            System.err.println("读取文件时发生错误: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

import java.util.ArrayList;
import java.util.Map;

public class CustomerFeedDTO {
    // 使用Map来灵活处理内部结构不固定的JSON对象
    private Map<String, ?> profile;
    private Map<String, ?> phone;
    // 使用ArrayList来处理JSON数组
    private ArrayList<?> addresses;
    private Map<String, ?> orders;
    private ArrayList<?> customs;

    // 构造函数 (可选)
    public CustomerFeedDTO() {}

    // Getters and Setters (必须提供，Gson通过反射调用它们进行数据绑定)
    public Map<String, ?> getProfile() {
        return profile;
    }

    public void setProfile(Map<String, ?> profile) {
        this.profile = profile;
    }

    public Map<String, ?> getPhone() {
        return phone;
    }

    public void setPhone(Map<String, ?> phone) {
        this.phone = phone;
    }

    public ArrayList<?> getAddresses() {
        return addresses;
    }

    public void setAddresses(ArrayList<?> addresses) {
        this.addresses = addresses;
    }

    public Map<String, ?> getOrders() {
        return orders;
    }

    public void setOrders(Map<String, ?> orders) {
        this.orders = orders;
    }

    public ArrayList<?> getCustoms() {
        return customs;
    }

    public void setCustoms(ArrayList<?> customs) {
        this.customs = customs;
    }

    @Override
    public String toString() {
        return "CustomerFeedDTO{" +
               "profile=" + profile +
               ", phone=" + phone +
               ", addresses=" + addresses +
               ", orders=" + orders +
               ", customs=" + customs +
               '}';
    }
}