如何将 JSONObject 转换为自定义 Java 类？
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How can I cast a JSONObject to a custom Java class?
提问by Geek Stocks
In Java (using json-simple) I have successfully parsed a JSON string which was created in JavaScript using JSON.stringify. It looks like this:
在 Java（使用 json-simple）中，我成功解析了一个使用 JSON.stringify 在 JavaScript 中创建的 JSON 字符串。它看起来像这样：
{"teq":14567,"ver":1,"rev":1234,"cop":15678}
This string is storing the state of a custom JavaScript object which I now wish to re-constitute as a pure Java class. Its not going well - first foray into Java coming from a C# background. :-p
这个字符串存储了一个自定义 JavaScript 对象的状态，我现在希望将其重新构成一个纯 Java 类。它进展不顺利 - 第一次从 C# 背景开始涉足 Java。:-p
The object is currently in the form of a org.json.simple.JSONObject since that is what json-simple made from the JSONParser.parse() operation.
该对象目前采用 org.json.simple.JSONObject 的形式，因为这是 json-simple 由 JSONParser.parse() 操作制成的。
How can I cast this JSONObject to my new Java class?(the definition of which is below...)
如何将此 JSONObject 转换为我的新 Java 类？（其定义如下...）
public class MyCustomJSObject {
public int teq;
public int ver;
public int rev;
public int cop;
}
采纳答案by arsen_adzhiametov
use Hymanson library
使用Hyman逊库
//create ObjectMapper instance
ObjectMapper objectMapper = new ObjectMapper();
//convert json string to object
Employee emp = objectMapper.readValue(jsonData, Employee.class);
回答by Vito
JSON string to Java Class ? you can trying fastjson:
JSON 字符串到 Java 类？你可以试试fastjson：
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.1.41</version>
</dependency>
and using java code:
并使用java代码：
MyCustomJSObject object = JSON.parseObject(jsonString,MyCustomJSObject.class);
回答by diyoda_
There are lot of libraries that does this. This is my suggestion. Hereyou can find the library
有很多图书馆可以做到这一点。这是我的建议。在这里你可以找到图书馆
import com.google.gson.Gson;
and then do,
然后做，
Gson gson = new Gson();
Student student = gson.fromJson(jsonStringGoesHere, Student.class);
Maven Dependency
Maven 依赖
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>2.2.4</version>
</dependency>
回答by Geek Stocks
UPDATE 1/9/2018
更新 1/9/2018
Some years have passed since this (now popular) question was asked. While I still agree that json-simple was my need at the time, upon reflection I think the SO community is better served by having the "checkmark" next to the Hymanson solution. I am un-accepting my own answer today; Hymanson is pretty great!
自从提出这个（现在流行的）问题以来，已经过去了几年。虽然我仍然同意 json-simple 是我当时的需求，但经过反思，我认为在 Hymanson 解决方案旁边设置“复选标记”可以更好地服务于 SO 社区。我今天不接受我自己的回答；Hyman逊真是太棒了！
I think that this decent json-simple library is the victim of poor documentation. If you don't use the JSONParser (go figure!) but instead use this JSONValue.parse() method, it all works out like so:
我认为这个体面的 json-simple 库是糟糕文档的受害者。如果你不使用 JSONParser（去图！）而是使用这个 JSONValue.parse() 方法，它会像这样：
//JSONParser parser = new JSONParser(); // DON'T USE THIS
Object obj = JSONValue.parse("A JSON string - array of objects: [{},{}] - goes here");
JSONArray arrFilings = (JSONArray)obj;
System.out.println("We can print one this way...");
System.out.println(arrFilings.get(5) + "\n");
System.out.println("We can enumerate the whole array...");
for(Object objFiling : arrFilings){
System.out.println(objFiling);
}
System.out.println("\n");
System.out.println("We can access object properties this way...");
for(Object objFiling : arrFilings){
JSONObject o = (JSONObject)objFiling; // MUST cast to access .get()
MyJSObject.fyq = o.get("fyq");
}
System.out.println("\n");
Thanks to all those who posted. Sticking with json-simple was the question and this is the only json-simple answer to-date. Hymanson DOES look slick, and Amazon uses it in their SDK for Java too, sooo.... if its good enough for AWS....
感谢所有发帖的人。坚持使用 json-simple 是一个问题，这是迄今为止唯一的 json-simple 答案。Hymanson 看起来很漂亮，亚马逊也在他们的 Java 开发工具包中使用了它，所以......如果它对 AWS 来说足够好......
回答by Milon
Add dependency from https://github.com/google/gsonand use it like
从https://github.com/google/gson添加依赖项并使用它
Gson gson= new Gson();
CustomPOJOClass obj = gson.fromJson(jsonObject.toString(),CustomPOJOClass.class);
