使用POJO循环行以创建缺少项目的JSON

Question

我有来自数据库的以下行：

ID    name   address1        address 2
-----------------------------------
123   Edvin  Hong Kong       Hong Kong
123   Edvin  Taipei          Taiwan
124   Advin  Bangkok         Thailand
-----------------------------------

我想要以下JSON结果：

"Item":[  
  {  "name": "Edvin"
     "addresses": [
        {
          "address1": "Hong Kong"
          "address2": "Hong Kong"
         } ,
        {
          "address1": "Taipei"
          "address2": "Taiwan"
        }
      ]
   },
   {  "name": "Advin"
     "addresses": [
        {
          "address1": "Bangkok"
          "address2": "Thaland"
         }
      ]
   }
]

我试着这样做：

List<Item> items= new ArrayList<Item>();
List<String> ids = new ArrayList<String>();

        for (Record record: records) { // Loop the rows show above
            if(!ids .contains(record.getId())) { //prevent duplicate Item
              Item item = new Item();
              item.setName(record.getSurname());
              Address address = new Address();
              address.setAddress1 = record.getAddress1();
              address.setAddress2 = record.getAddress2();
              item.setAddreses(address);
              items.add(item); // add the item into items
           }
           Ids.add(record.getId());
        }

上面的代码我只能得到项目名称Edvin的第一个地址，我怎样才能获得Edvin的第二个地址？

Answer 1

首先，您创建的对象项不适合您要获取的JSON。据我所知，对象Item有一个Addresses类型的属性，可以跟踪address1和address2，但如果你想要上面的JSON结果，你需要一个地址列表作为属性。 然后，如果要保留列表项和列表ID并假设您正在收集具有相同名称的所有项，则代码应以这种方式更改：

List<Item> items= new ArrayList<Item>();
List<String> ids = new ArrayList<String>();

    for (Record record: records) { // Loop the rows show above
        if(!ids .contains(record.getId())) { //prevent duplicate Item
          Item item = new Item();
          item.setName(record.getSurname());
          Address address = new Address();
          address.setAddress1 = record.getAddress1();
          address.setAddress2 = record.getAddress2();
          List<Address> addrList = new ArrayList<Address>();
          addrList.add(address);
          item.setAddreses(addrList);
          items.add(item); // add the item into items
       } else {
         for (Item it: items) {
            if(it.getName().equals(record.getSurname()) {
                 Address addr = new Address();
                 addr.setAddress1 = record.getAddress1();
                 addr.setAddress2 = record.getAddress2();
                 it.getAddresses().add(addr);
            }
         }
       }
       Ids.add(record.getId());
    }

真的不是最好的解决方案，在这种情况下，我建议不要使用List数据结构，而是按照定义避免重复。