Java:JSON(Gson)从JSON字符串获取值

Question

这个问题已经有答案了:

Deserializing a Map<String, Object> field with Gson (1 个回答)

已关闭 9 年前。

我有一个 JSON 字符串打印为:

{
  "result":"_error",
  "invokeId":2,
  "data":{
     "timestamp":1.401824129758E12,
     "rootCause":{
        "message":"Wrong client version for server",
        "localizedMessage":"Wrong client version for server",
        "rootCauseClassname":"login.impl.ClientVersionMismatchException",
        "substitutionArguments":[
           "4.9",
           "4.8.14_05_16_17_02"
        ],
        "errorCode":"LOGIN-0001"
     },
     "headers":{

     },
     "correlationId":"00E36368-6158-CD63-56CA-4F39493E8ED3",
     "faultCode":"Server.Processing",
     "messageId":"D8424EAD-8D0B-5441-820B-775B99812CFD",
     "faultString":"login.impl.ClientVersionMismatchException : Wrong client version for server",
     "timeToLive":0.0,
     "clientId":"D8424E8B-5F0F-1ECD-C29F-C6440488B0FC",
     "destination":"loginService"
  },
  "version":0
}

我知道如何在 Python 中执行此操作，因此我将展示它。

让x将 JSON 对象作为 Python 中的字典。 x['data']['rootCause']['substitutionArguments']会找到我"4.8.14_05_16_17_02" 。

如何获取 "4.8.14_05_16_17_02"在Java代码中？我正在使用Gson作为我的 Java JSON 库。

Answer 1

您可以将其解析为一个有详细记录的对象。但是，如果您不想围绕某些响应构建整个对象框架，您可以使用它们的通用 JsonArray 和 JsonObject 类来遍历您的 json 字符串。

// this is just your json string.
String yourJson = "{\"result\":\"_error\",\"invokeId\":2,\"data\":{\"timestamp\":1.401824129758E12,\"rootCause\":{\"message\":\"Wrong client version for server\",\"localizedMessage\":\"Wrong client version for server\",\"rootCauseClassname\":\"login.impl.ClientVersionMismatchException\",\"substitutionArguments\":[\"4.9\",\"4.8.14_05_16_17_02\"],\"errorCode\":\"LOGIN-0001\"},\"headers\":{},\"correlationId\":\"00E36368-6158-CD63-56CA-4F39493E8ED3\",\"faultCode\":\"Server.Processing\",\"messageId\":\"D8424EAD-8D0B-5441-820B-775B99812CFD\",\"faultString\":\"login.impl.ClientVersionMismatchException : Wrong client version for server\",\"timeToLive\":0.0,\"clientId\":\"D8424E8B-5F0F-1ECD-C29F-C6440488B0FC\",\"destination\":\"loginService\"},\"version\":0}";
// create a parser
JsonParser parser = new JsonParser();
// parse then get your root node as a JsonObject
JsonObject obj = parser.parse(yourJson).getAsJsonObject();

// traverse your object
JsonArray subArgs = obj.get("data").getAsJsonObject()
        .get("rootCause").getAsJsonObject()
        .get("substitutionArguments").getAsJsonArray();

// because the get(1) returns a JsonElement you will need to use getAsString 
// to retrive the actual results
System.out.println(subArgs.get(1).getAsString()); // 4.8.14_05_16_17_02