RestTemplate 如何解析响应

Question

开发springREST Client时，出现问题：

我有下一个json:

{
 "return": [
 {
    "admin": false,
    "alias": "",
    "email": "",
    "emailId": {"value": 0},
    "groups": [],
    "id": {"value": 1},
    "locked": false,
    "loggedInCount": 0,
    "master": true,
    "sms": "",
    "smsId": {"value": 0},
    "type": "POWER",
    "username": "NGCP"
 },
 {
    "admin": false,
    "alias": "",
    "email": "",
    "emailId": {"value": 0},
    "groups": [{"value": 2}],
    "id": {"value": 3},
    "locked": false,
    "loggedInCount": 0,
    "master": false,
    "sms": "",
    "smsId": {"value": 0},
    "type": "POWER",
    "username": "POLICY"
 }
        ]
}

要保存的模型 class 用户：

@JsonIgnoreProperties(ignoreUnknown = true)
public class User {

   public User(){

   }

   private boolean admin;

   private String alias;

   private String email;

   private String emailId;

   private ArrayList<String> groups;

   private String id;

   private boolean locked;

   private int loggedInCount;

   private boolean master;

   private String sms;

   private String smsId;

   private String type;

   private String userName;

//getter and setters
}

现在我正在使用 "RestTemplate" 来获取结果。

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<User[]> response = restTemplate.exchange(URL_GET,HttpMethod.GET,request, User[].class);

并得到错误。我知道那是因为主键是 "result" 但我可以指定 restTemplate 应该从哪里解析这个 JSON 吗？

是否可以在提交的文章中注明点赞 "emailId" 以获得直接价值？一些模板？

Answer 1

您可以使用注释@JsonRootName 来指定响应中的根元素。所以试试这个：

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonRootName(value ="result")
public class User {

   public User(){

   }

   private boolean admin;

   ....
}

Answer 2

截至 "main key is result":

一个。如果您只处理其中一种 Web 服务，我会为实际负载创建一个包装器 class：

public class Return{
    // Class property cannot be called "return" because it is Java reserved name.
    @JsonProperty("return")
    private User[] array;
    .... getter and setter
}

b。如果您处理多个 Web 服务，其中实际负载位于 "return" 字段中，我将创建一个通用包装器 class :

public class Return<T>{
    // Class property cannot be called "return" because it is Java reserved name.
    @JsonProperty("return")
    private T[] array;
    .... getter and setter
}

致电RestRemplate：

ResponseEntity<Return<User>> response = restTemplate.exchange(URL_GET, 
        HttpMethod.GET, request, new ParameterizedTypeReference<Return<User>>(){});
User[] usersArray = response2.getBody().getArray();

从 JSON 属性中的属性值开始，名为 "value" 我将创建两个自定义 JsonDeserializer(s)：一个用于单个值一个用于值数组，并在适用的地方用 @JsonDeserialize 注释每个属性：

单值反序列化器：

public class StringValueDeserializer  extends JsonDeserializer<String>{

    @Override
    public String deserialize(JsonParser parser, DeserializationContext ctxt)
            throws IOException, JsonProcessingException {
        ObjectCodec codec = parser.getCodec();
        TreeNode node = codec.readTree(parser);
        JsonNode value = (JsonNode)node.get("value");

        if (value != null){
            return value.asText();
        }
        return null;
    }
}

数组值反序列化器：

public class StringArrayValueDeserializer  extends JsonDeserializer<List<String>>{

    @Override
    public List<String> deserialize(JsonParser parser, DeserializationContext ctxt)
        throws IOException, JsonProcessingException {

        List<String> ret = new ArrayList<>();

        ObjectCodec codec = parser.getCodec();
        TreeNode node = codec.readTree(parser);

        if (node.isArray()){
            for (JsonNode n : (ArrayNode)node){
                JsonNode value = n.get("value");
                if (value != null){
                    ret.add(value.asText());
                }
            }
        }
        return ret;
    }
}

你是新来的User.class:

public class User {

    private boolean admin;

    private String alias;

    private String email;

    @JsonDeserialize(using = StringValueDeserializer.class)
    private String emailId;

    @JsonDeserialize(using = StringArrayValueDeserializer.class)
    private ArrayList<String> groups;

    @JsonDeserialize(using = StringValueDeserializer.class)
    private String id;

    private boolean locked;

    private int loggedInCount;

    private boolean master;

    private String sms;

    @JsonDeserialize(using = StringValueDeserializer.class)
    private String smsId;

    private String type;

    private String username;
    .... getter and setter
}

祝你好运！

Answer 3

您还可以使用 JsonPath 库在 json 中导航：

String json =  restTemplate.exchange(URL_GET,HttpMethod.GET,request, String.class);
DocumentContext document = JsonPath.parse(content, json);
List<User> users = document.read("$.return.*", new TypeRef<List<User>>() {});

RestTemplate 如何解析响应

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