Java JSON 解析数组
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Java JSON parse array
提问by Ping
I am using the following library to parse an object:
我正在使用以下库来解析对象：
{"name": "web", "services": []}
And the following code
以及以下代码
import com.json.parsers.JSONParser;
JSONParser parser = new JSONParser();
Object obj = parser.parseJson(stringJson);
when the array services is empty, it displays the following error
当数组服务为空时，显示以下错误
@Key-Heirarchy::root/services[0]/ @Key:: Value is expected but found empty...@Position::29
if the array services has an element everything works fine
如果数组服务有一个元素，一切正常
{"name": "web", "services": ["one"]}
How can I fix this?
我怎样才能解决这个问题？
Thanks
谢谢
回答by roger_that
Try using org.json.simple.parser.JSONParserSomething like this:
尝试使用这样的org.json.simple.parser.JSONParser东西：
JSONParser parser = new JSONParser();
JSONObject jsonObject = (JSONObject) parser.parse(stringJson);
Now to access the fields, you can do this:
现在要访问这些字段，您可以执行以下操作：
JSONObject name = jsonObject.get("name"); //gives you 'web'
And servicesis a JSONArray, so fetch it in JSONArray. Like this:
并且services是一个 JSONArray，所以在 JSONArray 中获取它。像这样：
JSONArray services = jsonObject.get("services");
Now, you can iterate through this servicesJSONArray as well.
现在，您也可以遍历这个servicesJSONArray。
Iterator<JSONObject> iterator = services.iterator();
// iterate through json array
while (iterator.hasNext()) {
// do something. Fetch fields in services array.
}
Hope this would solve your problem.
希望这能解决您的问题。
回答by chetan
Why do you need parser? try this:-
为什么需要解析器？试试这个：-
String stringJson = "{\"name\": \"web\", \"services\": []}";
JSONObject obj = JSONObject.fromObject(stringJson);
System.out.println(obj);
System.out.println(obj.get("name"));
System.out.println(obj.get("services"));
JSONArray arr = obj.getJSONArray("services");
System.out.println(arr.size());
回答by Ping
I solve the problen with https://github.com/ralfstx/minimal-json
我用https://github.com/ralfstx/minimal-json解决了这个问题
Reading JSON
读取 JSON
Read a JSON object or array from a Reader or a String:
从 Reader 或 String 读取 JSON 对象或数组：
JsonObject jsonObject = JsonObject.readFrom( jsonString );
JsonArray jsonArray = JsonArray.readFrom( jsonReader );
Access the contents of a JSON object:
访问 JSON 对象的内容：
String name = jsonObject.get( "name" ).asString();
int age = jsonObject.get( "age" ).asInt(); // asLong(), asFloat(), asDouble(), ...
Access the contents of a JSON array:
访问 JSON 数组的内容：
String name = jsonArray.get( 0 ).asString();
int age = jsonArray.get( 1 ).asInt(); // asLong(), asFloat(), asDouble(), ...
