Java : Sort JSON String using key

Question

我有一个 JSON 格式的字符串。我需要使用属性对这个 JSON 字符串进行排序，但我无法做到这一点。 JSON 字符串是通过读取 CSV 文件创建的。我不想再次读取 CSV，并且必须仅使用 JSON 字符串来实现它。有没有办法做到这一点？请告诉我。

JSON 字符串格式为:

[
  {
    "address": "some address",
    "name": "some name",
    "phone": "some phone",
    "age": "some age",
    "SSN": "some SSN"
  },
  {
    "address": "abc",
    "name": "def",
    "phone": "ghi",
    "age": "jkl",
    "SSN": "mno"
  }
]

请解释一下。

Answer 1

您可以使用您实现的比较器将 JSONstring 转换为 TreeMap 以按值进行比较，然后将此 TreeMap 转换回 JSON。

在此处查看如何创建值比较器: http://www.programcreek.com/2013/03/java-sort-map-by-value/

然后使用 ObjectMapper 将 JSON 转换为映射，然后将映射返回 JSON:

String json = "{\"address\" : \"def\","
    + "\"name\" : \"ghi\","
    + "\"phone\" : \"jkl\","
    + "\"age\" : \"def\","
    + "\"SSN\" : \"abc\"}";

Map<String, String> jsonMap = new HashMap<String, String>();
ObjectMapper mapper = new ObjectMapper();
jsonMap = (mapper.readValue(json, Map.class));
Comparator<String> comparator = new ValueComparator(jsonMap);
Map<String, String> treeMap = new TreeMap<String, String>(comparator); 
treeMap.putAll(jsonMap);
String sortedJson = mapper.writeValueAsString(treeMap);

System.out.println(sortedJson);

结果:{"SSN":"abc","地址":"def","姓名":"ghi","电话":"jkl"}

比较器:

public class ValueComparator implements Comparator<String> {

   Map<String, String> map = new HashMap<String, String>();

   public ValueComparator(Map<String, String> map){
     this.map = map;
   }

   @Override
   public int compare(String s1, String s2) {
     return map.get(s1).compareTo(map.get(s2));
   }
 }