Question

我有一堆字符串符号的JSON对象：

"{\"address\":{\"street\":\"Steenstraat\",\"housenumber\":\"17A\",\"postalcode\":\"6828 CA\",\"city\":\"ARNHEM\",\"geoLocation\":{\"lat\":\"51.983718\",\"lng\":\"5.915553\"}},\"distance\":0,\"type\":\"ING\"}

所以每个JSON对象看起来都是这样的：

    {
        "address" : {
               "street" : "Steenstraat", 
               "housnumber" : "17A", 
               "postalcode" : "6828 CA", 
               "city" : "ARNHEM", 
               "geolocation" : {
                           "latitude" : "51.983718",
                           "longitude" : "54.983718"
                           }
                     },
               "type" : "citi",
               "distance" : 0
    }

现在，我使用谷歌的gson库来获取其余的API，这给了我一串上述许多JSON对象。我如何尝试过滤掉（或重新定义JSON的结构）以按特定参数对JSON对象进行排序（比如按城市名称排序）？

这是我的Atm课程。我正在尝试将JSON字符串转换为Atm对象列表。

public class Atm {

    private String type;
    private Long distance;
    private Map<String, String> address = new HashMap<String, String>();

    public Atm() {
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Long getDistance() {
        return distance;
    }

    public void setDistance(Long distance) {
        this.distance = distance;
    }

    public Map<String, String> getAddress() {
        return address;
    }

    public void setAddress(Map<String, String> address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "Atm{" +
                "type='" + type + 
                ", distance=" + distance +
                ", address=" + address.toString() +
                '}';
    }
}

或者有没有办法在不将其转换为java数据结构的情况下执行此操作？

Answer 1

注意：当您在JSON中使用子元素geoLocation时，您无法使用Map<String, String>。您应该使用：Map<String, Object>代替或创建自定义类来表示您的地址。

要按城市过滤Atm列表，您可以执行以下操作。

在Java 8中：

Gson gson = new Gson();
String atm1 = "{\"address\":{\"street\":\"Steenstraat\",\"housenumber\":\"17A\",\"postalcode\":\"6828 CA\",\"city\":\"ARNHEM\",\"geoLocation\":{\"lat\":\"51.983718\",\"lng\":\"5.915553\"}},\"distance\":0,\"type\":\"ING\"}";
String atm2 = "{\"address\":{\"street\":\"Steenstraat\",\"housenumber\":\"17A\",\"postalcode\":\"6828 CA\",\"city\":\"ARNHEM\",\"geoLocation\":{\"lat\":\"51.983718\",\"lng\":\"5.915553\"}},\"distance\":0,\"type\":\"ING\"}";
String atm3 = "{\"address\":{\"street\":\"Steenstraat\",\"housenumber\":\"17A\",\"postalcode\":\"6828 CA\",\"city\":\"NEW-YORK\",\"geoLocation\":{\"lat\":\"51.983718\",\"lng\":\"5.915553\"}},\"distance\":0,\"type\":\"ING\"}";

List<Atm> atms = new ArrayList<Atm>();

atms.add(gson.fromJson(atm1, Atm.class));
atms.add(gson.fromJson(atm2, Atm.class));
atms.add(gson.fromJson(atm3, Atm.class));

List<Atm> filteredOnCity = atms.stream().filter(atm -> atm.getAddress().get("city")
    .equals("ARNHEM")).collect(Collectors.toList());

使用Apache commons-collections4：

//Build your list with code from above
Predicate<Atm> filterOnCity = new Predicate<Atm>() {
    @Override
    public boolean evaluate(Atm atm) {
        return atm.getAddress().get("city").equals("ARNHEM");
    }
};

CollectionUtils.filter(atms, filterOnCity);

Answer 2

为什么不在将它们发送到Java之前在客户端进行过滤或排序？

var arr = JSON.parse(MY_JSON_ARRAY_STRING);

arr.sort(function(a, b){
  if ( a.city < b.city )
        return -1;
    if ( a.city > b.city )
        return 1;
   return 0;
});

var arrString = JSON.stringify(arr);

按值过滤JSON对象

2 个答案: