【JAVA】读取JSON文件中指定部分数据

读取JSON文件中指定部分数据(小文件)

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.json.JSONObject;

public class JsonSourceExtractor {
    public static void main(String[] args) {
        String jsonDataStr = "{\"some_key1\": \"some_value1\", \"_source\": {\"desired_key1\": \"desired_value1\"}}{\"some_key2\": \"some_value2\", \"_source\": {\"desired_key2\": \"desired_value2\"}}";
        List<JSONObject> sources = extractSources(jsonDataStr);
        for (JSONObject source : sources) {
            System.out.println(source);
        }
    }

    public static List<JSONObject> extractSources(String jsonDataStr) {
        List<JSONObject> result = new ArrayList<>();
        Pattern pattern = Pattern.compile("_source\":\\{.*?\\}");
        Matcher matcher = pattern.matcher(jsonDataStr);
        while (matcher.find()) {
            String sourceStr = matcher.group();
            sourceStr = sourceStr.replace("_source\":", "");
            try {
                JSONObject source = new JSONObject(sourceStr);
                result.add(source);
            } catch (Exception e) {
                System.out.println("无法解析的部分：" + sourceStr);
            }
        }
        return result;
    }
}

读取JSON文件中指定部分数据(大文件)

   <dependency>
       <groupId>com.fasterxml.jackson.core</groupId>
       <artifactId>jackson - core</artifactId>
       <version>2.13.0</version>
   </dependency>
   <dependency>
       <groupId>com.fasterxml.jackson.core</groupId>
       <artifactId>jackson - databind</artifactId>
       <version>2.13.0</version>
   </dependency>

   import com.fasterxml.jackson.core.JsonFactory;
   import com.fasterxml.jackson.core.JsonParser;
   import com.fasterxml.jackson.databind.JsonNode;
   import com.fasterxml.jackson.databind.ObjectMapper;
   import java.io.File;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.List;

   public class BigJsonJacksonSourceExtractor {
       public static void main(String[] args) {
           JsonFactory factory = new JsonFactory();
           ObjectMapper mapper = new ObjectMapper(factory);
           List<JsonNode> sources = new ArrayList<>();
           try {
               JsonParser parser = factory.createParser(new File("your_large_file.json"));
               while (!parser.isClosed()) {
                   JsonNode node = mapper.readTree(parser);
                   if (node.has("_source")) {
                       sources.add(node.get("_source"));
                   }
               }
               parser.close();
               for (JsonNode source : sources) {
                   System.out.println(source);
               }
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   }

读取JSON文件中指定部分数据(按行)

   import java.io.BufferedReader;
   import java.io.FileReader;
   import java.io.IOException;
   import java.util.ArrayList;
   import java.util.List;
   import java.util.regex.Matcher;
   import java.util.regex.Pattern;
   import org.json.JSONObject;

   public class BigJsonSourceExtractor {
       public static void main(String[] args) {
           try {
               List<JSONObject> sources = new ArrayList<>();
               BufferedReader reader = new BufferedReader(new FileReader("your_large_file.json"));
               String line;
               Pattern pattern = Pattern.compile("_source\":\\{.*?\\}");
               while ((line = reader.readLine())!= null) {
                   Matcher matcher = pattern.matcher(line);
                   while (matcher.find()) {
                       String sourceStr = matcher.group();
                       sourceStr = sourceStr.replace("_source\":", "");
                       try {
                           JSONObject source = new JSONObject(sourceStr);
                           sources.add(source);
                       } catch (Exception e) {
                           System.out.println("无法解析的部分：" + sourceStr);
                       }
                   }
               }
               reader.close();
               for (JSONObject source : sources) {
                   System.out.println(source);
               }
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   }