java - 使用 gson 错误转换 json 预期为 BEGIN_OBJECT 但在第 1 行第 2 列路径 $ 处为 BEGIN_ARRAY

Question

[{"user_id":"5633795","username":"_Vorago_","count300":"203483","count100":"16021","count50":"1517","playcount":"1634","ranked_score":"179618425","total_score":"1394180836","pp_rank":"34054","level":"59.6052","pp_raw":"1723.43","accuracy":"96.77945709228516","count_rank_ss":"1","count_rank_s":"19","count_rank_a":"17","country":"US","events":[]}]

我正在尝试使用 GSON 转换上面的 JSON，但遇到了错误。

package com.grapefruitcode.osu;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

import com.google.gson.Gson;

public class Main {

static String ApiKey = "";
public static void main(String[]Args) throws Exception{
    String json = readUrl("");
    System.out.println(json);
    Gson gson = new Gson();
    User user = gson.fromJson(json, User.class);
    System.out.println();
}

private static String readUrl(String urlString) throws Exception {
    BufferedReader reader = null;
    try {
        URL url = new URL(urlString);
        reader = new BufferedReader(new InputStreamReader(url.openStream()));
        StringBuffer buffer = new StringBuffer();
        int read;
        char[] chars = new char[1024];
        while ((read = reader.read(chars)) != -1)
            buffer.append(chars, 0, read); 

        return buffer.toString();
    } finally {
        if (reader != null)
            reader.close();
    }
}

}

出于安全原因，url 和 api key 留空，当我运行代码时变量被填充并且 json 被正确转换为字符串。我已经测试过了。如果有人能告诉我是什么导致了错误，那就太好了。

package com.grapefruitcode.osu;

public class User {
 String user_id = "";
 String username = "";
 String count300 = "";
 String count100= "";
}

Answer 1

在 JSON 中

• [ ... ] 代表数组
• { ... }代表对象，

所以 [ {...} ] 是包含一个对象的数组。尝试使用

Gson gson = new Gson();
User[] users = gson.fromJson(json, User[].class);
System.out.println(Arrays.toString(users));
//or since we know which object from array we want to print
System.out.println(users[0]);