java - 下面是尝试通过java程序从文本文件读取的json数据。面临解析错误

Question

Json data from text file

{"projectkey":"proj1"} 
    {"projectkey":"proj2"}
    {"projectkey":"proj3"}

java code to read the json objects from above file

//package crunchify.com.tutorials;

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

import java.io.FileReader;
import java.util.Iterator;

/**
 * @author Crunchify.com
 * How to Read JSON Object From File in Java?
 */

public class DemoJson {
@SuppressWarnings("unchecked")
public static void main(String[] args) {
JSONParser parser = new JSONParser();
try {
Object obj = parser.parse(new FileReader("W:\\FileDemo\\jsoninput.txt"));

A JSON object. Key value pairs are unordered. JSONObject supports java.util.Map interface.

JSONObject jsonObject = (JSONObject) obj;

A JSON array. JSONObject supports java.util.List interface.

String projectkey = (String)jsonObject.get("projectkey");

// An iterator over a collection. Iterator takes the place of Enumeration in the Java Collections Framework.
// Iterators differ from enumerations in two ways:
// 1. Iterators allow the caller to remove elements from the underlying collection during the iteration with well-defined semantics.
// 2. Method names have been improved.
Iterator<String> keys = (Iterator<String>) jsonObject.keySet();
while (keys.hasNext()) {
String key= keys.next();
if (jsonObject.get(key) instanceof JSONObject) {
System.out.println(jsonObject);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}

Answer 1

您的 JSON 不正确，应该是

[
   {
      "projectkey":"proj1"
   },
   {
      "projectkey":"proj2"
   },
   {
      "projectkey":"proj3"
   }
]

将上述 JSON 存储到字符串中(从文件中读取)

public static void main(String[] args) throws IOException {
        String json = "[\r\n" + 
                "   {\r\n" + 
                "      \"projectkey\":\"proj1\"\r\n" + 
                "   },\r\n" + 
                "   {\r\n" + 
                "      \"projectkey\":\"proj2\"\r\n" + 
                "   },\r\n" + 
                "   {\r\n" + 
                "      \"projectkey\":\"proj3\"\r\n" + 
                "   }\r\n" + 
                "]";
        JSONArray  array = new JSONArray(json);
        for(int i=0; i<array.length(); i++) {
            JSONObject jsonObject = array.getJSONObject(i);
            Iterator<String> iterator = jsonObject.keys();
            while(iterator.hasNext()) {
                String key = iterator.next();
                System.out.println("Key :: "+key+"  value :: "+jsonObject.getString(key));
            }           
        }
    }

输出

Key :: projectkey  value :: proj1
Key :: projectkey  value :: proj2
Key :: projectkey  value :: proj3