JSON对象值为空。

Question

请在下面找到我从JSON文件中读取并显示它的代码。该文件包含一些规则。我想从文件中读取规则并将其显示在UI中。但我得到的输出如下：

Technology: null
Vulnerability: null
Severity: null
RegEx: null

文件Rule_File.json不是null，具有值。但是他们没有被这段代码读懂。知道为什么会这样吗？请告诉我你的建议。提前感谢！

import java.io.FileNotFoundException;
import java.io.FileReader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;

import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

public class JSON_Reader
{
    public static void main(String args[])
    {
        JSONParser parser = new JSONParser();
        try
        {

        String text = new String(Files.readAllBytes(Paths.get("C:\\Users\\arathi.variar\\workspace\\Customizable_Rule_UI\\src\\Rule_File.json")), StandardCharsets.UTF_8);
            Object object = parser.parse(text);

            //convert Object to JSONObject
            JSONObject jsonObject = (JSONObject) object;

            //Reading the String
            String tech = (String) jsonObject.get("Technology");
            String vul = (String) jsonObject.get("Vulnerability");
            String sev = (String) jsonObject.get("Severity");
            String regex = (String) jsonObject.get("RegEx");

            //Printing all the values
            System.out.println("Technology: " + tech);
            System.out.println("Vulnerability: " + vul);
            System.out.println("Severity: "  + sev);
            System.out.println("RegEx: "  + regex);
        }
        catch(FileNotFoundException fe)
        {
            fe.printStackTrace();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

请在我的Rule_File.json下面找到

 {
        "Angular2": [
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "angular/timeout-service",
                "Severity": 1,
                "RegEx": "(?=.*(setTimeout))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "angular/interval-service",
                "Severity": 1,
                "RegEx": "(?=.*(setInterval))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "angular/Deferred",
                "Severity": 1,
                "RegEx": "(?=.*(\\$q\\.defer|\\$q\\_\\.defer))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "Cross Site Scripting",
                "Severity": 1,
                "RegEx": "(?=.*(body.*ng-app.*|\\$sceProvider\\.enabled\\(\\s*false\\)))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "angular/Angular Element",
               "Severity": 1,
                "RegEx": "(?=.*(\\$\\('.*'\\)|jQuery\\('.*'\\)))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "Module Setter",
                "Severity": 1,
                "RegEx": "(?=.*(var\\s*[a-zA-Z0-9_]+\\s*=\\s*angular.module\\(.*\\)))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "Sensitive Data",
                "Severity": 1,
                "RegEx": "(?=.*(store\\.set\\())"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "no-cookiestore",
                "Severity": 3,
                "RegEx": "(?=.*(\\$cookieStore\\s*\\.))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "no-directive-replace",
                "Severity": 3,
                "RegEx": "(?=.*((replace\\s*\\:\\s*true)|(\\.replace\\s*\\=\\s*true)))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "no-http-callback",
                "Severity": 3,
                "RegEx": "(?=.*(\\$http\\..*\\.(success|error)))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "defined/undefined",
                "Severity": 3,
                "RegEx": "(?=.*((value\\s*(\\!|\\=)\\=\\=\\s*undefined)|(\\!angular\\.is(Defined|Undefined))))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "json functions",
                "Severity": 3,
               "RegEx": "(?=.*(JSON\\.))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "Console Log",
                "Severity": 3,
                "RegEx": "(?=.*(console\\.))"
            },
            {
                "Technology": "Angular 2.0",
                "Vulnerability": "no-angular-mock",
                "Severity": 3,
                "RegEx": "(?=.*(angular\\.mock))"
            }
        ],
        "reactJS": [
            {
                "Technology": "React JS",
                "Vulnerability": "Cross Site Scripting",
                "Severity": 1,
                "RegEx": "(?=.*(window.\\_\\_PRELOADED\\_STATE\\_\\_\\s*=\\s*\\$\\{JSON.Stringify\\(preloadedState\\)}))"
            }
        ],
        "javascript": [
            {
                "Technology": "JAVA/JAVAScript",
                "Vulnerability": "URL Injection",
                "Severity": 1,
                "RegEx": "(?=.*(Request.QueryString[\"[a-zA-Z]+\"];))"
            },
            {
                "Technology": "JAVA/JAVAScript",
                "Vulnerability": "Weak Credentials",
                "Severity": 1,
                "RegEx": "(?=.*((user(name|id)?|logon(id)?)\\s*=\\s*((\\\"|\\').+(\\\"|\\'))))"
            }
]
}

Answer 1

首先需要在数组中找到JSONObject。您正在尝试查找顶级JSONObject的字段，该字段只包含字段Angular2, reactJS, javascript，因此它返回null，因为它找不到technology,vulnerability...字段。

JSONObject jsonObject1 = (JSONObject) object;
JSONArray fields= (JSONArray) jsonObject1.get("Angular2");

for (Object field: fields) {
JSONObject jsonObject = (JSONObject) field;

        //Reading the String
        String tech = (String) jsonObject.get("Technology");
        String vul = (String) jsonObject.get("Vulnerability");
        String sev = (String) jsonObject.get("Severity");
        String regex = (String) jsonObject.get("RegEx");

        //Printing all the values
        System.out.println("Technology: " + tech);
        System.out.println("Vulnerability: " + vul);
        System.out.println("Severity: "  + sev);
        System.out.println("RegEx: "  + regex);
}

Answer 2

尝尝这个

JSONObject jsonObject = (JSONObject) object;
    try {
        JSONArray jsonArray= (JSONArray)jsonObject.get("Angular2");
        for (Object object: jsonArray) {
            JSONObject angular = (JSONObject) object;
            String tech = (String) angular.get("Technology");
            String vul = (String) angular.get("Vulnerability");
            String sev = (String) angular.get("Severity");
            String regex = (String) angular.get("RegEx");

        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

Answer 3

您的预期值在Array中，需要以这种方式访问。

JSONArray array = (JSONArray)jsonObject.get("Angular2");

for(Object obj : array.toArray()){
  JSONObject jObj = (JSONObject)obj;
  System.out.println(String.format("Technology:%s, Vulnerability:%s, Severity:%s, RegEx:%s", jObj.get("Technology"),jObj.get("Vulnerability"),jObj.get("Severity"),jObj.get("RegEx")));
}

另一方面，Jackson可以帮助简化到POJO的对象映射。