java - 使用GSON库解析后如何处理json元素？

Question

我已将以下有效负载设置到 Gson 的 JsonObject 中:

 {
        "backup": {
            "addresses": [
                "127.0.0.1"
            ], 
            "healthcheck_interval": "60", 
            "http": "https", 
            "port": "9001"
        }, 
        "cognito": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9012"
        }, 
        "collector": {
            "addresses": [
                "127.0.0.1"
            ], 
            "healthcheck_interval": "60", 
            "http": "https", 
            "port": "9000"
        }, 
        "ds": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9011"
        }, 
        "insight-analytics": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9013"
        }, 
        "integrations": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9014"
        }, 
        "server": {
            "addresses": [
                "127.0.0.1"
            ], 
            "healthcheck_interval": "60", 
            "http": "https", 
            "port": "9009"
        }, 
        "vigile": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9443"
        }, 
        "walt": {
            "addresses": [
                "127.0.0.1"
            ], 
            "http": "https", 
            "port": "9010"
        }
    }

测试:

@Test(priority = 10)
public void parseServicesFileToGsonObject() {
 JsonParser jsonParser = new JsonParser();
 JsonElement rootNode = jsonParser.parse(response);
 if (rootNode.isJsonObject()) {
  JsonObject details = rootNode.getAsJsonObject();
 }
}

我希望能够将 JSON 的所有成员存储到字符串数组中(backup、cognito、collector 等)，我可以使用字符串数组找到对象以获取更多值(例如 healthcheck_interval、http、port等)。我尝试使用流来实现此目的，但没有成功。我想这样做，因为将来该字段的名称很可能会更改(而不是 backup 它可以更改为另一个名称)。

Answer 1

最通用的方法是使用 Map<String, Object>表示 JSON 的动态结构有效负载。在这种情况下，我们总是可以使用 Map#keySet() 方法列出所有属性，我们不需要任何 String[]留住他们。此外，通过键查找对象比使用 array 更快。或List 。如果我们的对象值具有常量结构，我们可以将其映射到 POJO在运行时稳定地访问值。下面的代码显示了这两种情况:

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.annotations.SerializedName;
import com.google.gson.reflect.TypeToken;

import java.io.File;
import java.io.FileReader;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;

public class GsonApp {

    public static void main(String[] args) throws Exception {
        File jsonFile = new File("./resource/test.json").getAbsoluteFile();

        Gson gson = new GsonBuilder().create();

        System.out.println("Use generic Map");
        Type genericMapType = new TypeToken<Map<String, Object>>() {
        }.getType();
        Map<String, Object> map = gson.fromJson(new FileReader(jsonFile), genericMapType);
        map.forEach((k, v) -> System.out.println(k + " => " + v));

        System.out.println();
        System.out.println();

        System.out.println("Use Service Map");
        Type serviceMapType = new TypeToken<Map<String, Service>>() {
        }.getType();
        Map<String, Service> serviceMap = gson.fromJson(new FileReader(jsonFile), serviceMapType);
        serviceMap.forEach((k, v) -> System.out.println(k + " => " + v));
    }
}

class Service {
    private List<String> addresses;

    @SerializedName("healthcheck_interval")
    private int healthCheckInterval;
    private String http;
    private int port;

    public List<String> getAddresses() {
        return addresses;
    }

    public void setAddresses(List<String> addresses) {
        this.addresses = addresses;
    }

    public int getHealthCheckInterval() {
        return healthCheckInterval;
    }

    public void setHealthCheckInterval(int healthCheckInterval) {
        this.healthCheckInterval = healthCheckInterval;
    }

    public String getHttp() {
        return http;
    }

    public void setHttp(String http) {
        this.http = http;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    @Override
    public String toString() {
        return "Service{" +
                "addresses=" + addresses +
                ", healthCheckInterval=" + healthCheckInterval +
                ", http='" + http + '\'' +
                ", port=" + port +
                '}';
    }
}

上面的代码打印:

Use generic Map
backup => {addresses=[127.0.0.1], healthcheck_interval=60, http=https, port=9001}
cognito => {addresses=[127.0.0.1], http=https, port=9012}
collector => {addresses=[127.0.0.1], healthcheck_interval=60, http=https, port=9000}
ds => {addresses=[127.0.0.1], http=https, port=9011}
insight-analytics => {addresses=[127.0.0.1], http=https, port=9013}
integrations => {addresses=[127.0.0.1], http=https, port=9014}
server => {addresses=[127.0.0.1], healthcheck_interval=60, http=https, port=9009}
vigile => {addresses=[127.0.0.1], http=https, port=9443}
walt => {addresses=[127.0.0.1], http=https, port=9010}


Use Service Map
backup => Service{addresses=[127.0.0.1], healthCheckInterval=60, http='https', port=9001}
cognito => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9012}
collector => Service{addresses=[127.0.0.1], healthCheckInterval=60, http='https', port=9000}
ds => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9011}
insight-analytics => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9013}
integrations => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9014}
server => Service{addresses=[127.0.0.1], healthCheckInterval=60, http='https', port=9009}
vigile => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9443}
walt => Service{addresses=[127.0.0.1], healthCheckInterval=0, http='https', port=9010}