优化Objectmapper[Java8]的字符串解析

Question

我实现了我试图实现的目标，然而，我不满足于不必要的（？）字符串解析来达到我的目标。

HttpURLConnection con = null;

URL url = new URL(URL);
con = (HttpURLConnection) url.openConnection();

// set connection parameters and make a GET-call
con.setRequestMethod("GET");

//Must be a better way?
InputStream inputStream = con.getInputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(inputStream));


StringBuilder response = new StringBuilder();
String currentLine;

//Build the string from the response from con
while ((currentLine = in.readLine()) != null)
       response.append(currentLine);

in.close();


ObjectMapper objectMapper = new ObjectMapper();
JsonNode jsonNode = objectMapper.readTree(response.toString());

// I only want the child-node
String myArray = jsonNode.get("parent").get("child").toString();

// Map the response to my object
List<Car> car = objectMapper.readValue(myArray, new TypeReference<List<Car>>(){});

null

jsonNode.get("parent").get("child").toString()

null

我的汽车类：

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
        "id",
        "color"})
public class Car {

    @JsonProperty("id")
    public String id;
    @JsonProperty("color")
    public String color;
}

Answer 1

很高兴看到您想要改进您的代码。将输入流读取到StringBuilder并调用jsonNode.toString()确实是不必要的。在大多数情况下，总是有一个有用的API满足您的需要。以下是我的建议：

1. 使用objectmapper#readtree（InputStream）来简化使用HTTP输入流的部分。

JsonNode jsonNode = objectMapper.readTree(con.getInputStream());

JsonParser jsonParser = new TreeTraversingParser(jsonNode.get("parent").get("child"));
objectMapper.readValue(jsonParser,new TypeReference<List<Car>>(){});