json - 访问 JSON 中的嵌套对象名称

Question

我从服务器返回了一些 JSON：

{
  "outer" : {
    "inner" : "1"
    },

  "outer2" : {
    "inner" : "1"
    },

  "outer3" : {
    "inner" : "1"
    },

}

我想以编程方式访问 ~something~.inner，并且我有一个包含该数据的变量，但如果我说 variable.inner，它就不起作用（显然）。这样做的正确语法是什么？

谢谢！

Answer 1

data = JSON.parse(jsonString);
var yourvar = 'outer';
data[yourvar].inner;

假设 javascript

Answer 2

评估（{“外部”：{“内部”：“1”}，

“外部2”：{“内部”：“1”}，

“外部3”：{“内部”：“1”}，

}).outer.inner

在javascript中

Answer 3

You should use the code below to easily access nested JSON objects.

// http://json-simple.googlecode.com/files/json-simple-1.1.1.jar
import org.json.simple.*;
import org.json.simple.parser.*;

/*
 * "Simpler" version of simple JSON.  Easy to use interface for easy parsing of JSON nested objects.
 *
 * Usage:
 *  Json json = new Json("{roster: [{id: 1, name: \"Adam\"}, {id: 2, name: \"Eve\"}]}");
 *  JSONArray arr = json.getArray("roster");
 *  JSONObject obj = json.getObject("roster[0]");
 *  int id = json.getInt("roster[0].id"); 
 *  String name = json.getString("roster[1].name");
 *
 */
public class Json {

    private JSONParser m_parser = new JSONParser();
    private JSONObject m_json = null;
    private String m_strErrMsg = "";    

    public Json(String str) {
        reset();
        m_json = parse(str);
    }

    public Json(JSONObject obj) {
        reset();
        m_json = obj;
    }

    public JSONObject parse(String str) {
        setErrMsg("");
        JSONObject obj = null;
        try {
            if (m_parser != null) {
                obj = (JSONObject)m_parser.parse(str);
            }
        }
        catch (Exception ex) {
            setErrMsg("Exception occurred while parsing json string. Msg: " + ex.toString());
            return obj;
        }
        return obj;
    }

    public String getErrMsg() { return m_strErrMsg; }
    public void setErrMsg(String str) { m_strErrMsg = str; }
    public void clearErrMsg() { m_strErrMsg = ""; }

    public void reset() { 
        m_json = null;
        m_strErrMsg = "";
    }

    public Object get(String path) {
        return get(m_json, path);
    }

    public JSONObject getObject(String path) {
        Object obj = get(path);
        return (obj != null ? (JSONObject)obj : null);        
    }

    public JSONArray getArray(String path) {
        Object obj = get(path);
        return (obj != null ? (JSONArray)obj : null);        
    }

    public String getString(String path) {
        Object obj = get(path);
        return (obj != null ? obj.toString() : "");
    }

    public int getInt(String path) {
        int val = 0;
        try {
            String str = getString(path);
            val = Integer.parseInt(str);
        }
        catch (Exception ex) {
            return 0;
        }
        return val;
    }

    public long getLong(String path) {
        long val = 0L;
        try {
            String str = getString(path);
            val = Long.parseLong(str);
        }
        catch (Exception ex) {
            return 0L;
        }
        return val;
    }

    public double getDouble(String path) {
        double val = 0.0;
        try {
            String str = getString(path);
            val = Double.parseDouble(str);
        }
        catch (Exception ex) {
            return 0.0;
        }
        return val;
    }

    public boolean getBool(String path) {
        boolean val = false;
        try {
            String str = getString(path);
            val = Boolean.parseBoolean(str);
        }
        catch (Exception ex) {
            return false;
        }
        return val;
    }

    // path: "roster[0].name"
    public Object get(JSONObject obj, String path) {
        if (obj == null || path == null) {
            return null;
        }
        path = path.trim();
        if (path.isEmpty()) { return null; }
        int index = path.indexOf('.');
        if (index > 0) {
            String key = path.substring(0, index).trim();
            path = path.substring(index + 1).trim();
            JSONObject inner = (JSONObject)get(obj, key);
            return get(inner, path);
        }
        else if (path.endsWith("]")) {
            int arrayIndex = -1;
            int open = path.indexOf('[');
            int close = path.indexOf(']');
            if (open > 0 && close > 0 && (close - open) > 1 && close == path.length() - 1) {
                try {
                    arrayIndex = Integer.parseInt(path.substring(open + 1,  close));
                }
                catch (Exception ex) {
                    arrayIndex = -1;
                }
            }
            if (arrayIndex >= 0) {
                path = path.substring(0, open).trim();
                JSONArray array = (JSONArray)obj.get(path);
                if (array != null && array.size() > arrayIndex) {
                    return array.get(arrayIndex);
                }
                else {
                    return null;
                }
            }
            else {
                // path is key
                return obj.get(path);                    
            }            
        }
        else {
            // path is key
            return obj.get(path);
        }        
    }
}