在Java中使用Jackson庫將JSON轉換為Map或將Map轉換為JSON？

JSON Jackson 是一個Java 函式庫，它具有非常強大的資料綁定功能，並提供了一個將自訂java 物件序列化為JSON 以及將JSON 反序列化回Java 物件的框架。我們可以轉換JSON到/從 Map使用com.fasterxml.jackson.databind.ObjectMapper類別的readValue()和writeValueAsString()方法。

JSON 到映射

語法

public <T> T readValue(String content, TypeReference valueTypeRef) throws IOException, JsonParseException, JsonMappingException

範例

#

import java.io.*;
import java.util.*;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.type.TypeReference;
public class ConvertJSONToMapTest {
   public static void main(String args[]) {
      try {
        <strong> </strong>ObjectMapper mapper = new ObjectMapper();
         String jsonString = "{\"Name\":\"Raja\", \"Technology\":\"Java\"}";
         Map<String, Object> jsonMap = new HashMap<String, Object>();
         jsonMap = mapper.readValue(jsonString, new TypeReference<Map<String, String>>(){}); // converts JSON to Map
         System.out.println(jsonMap);
      } catch(IOException ie) {
         ie.printStackTrace();
      }
   }
}

輸出

{Name=Raja, Technology=Java}

########################## #映射到JSON######語法###

public String writeValueAsString(Object value) throws JsonProcessingException

###範例###

import java.io.*;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.ObjectMapper;
public class ConvertMapToJSONTest {
   public static void main(String args[]) throws IOException {
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = "";
      Map<String, Object> map = new HashMap<String, Object>();
      map.put("Raja", "Java Technology");
      map.put("Ravi", "Python Technology");
      map.put("Adithya", "Spark Technology");
      map.put("Vamsi", "Web Technology");
      jsonString = mapper.writeValueAsString(map); // converts Map to JSON<strong>
 </strong>     System.out.println(map);
   }
}

###輸出###

{"Raja":"Java Technology", "Vamsi":"Web Technology", "Ravi":"Python Technology", "Adithya":"Spark Technology"}

####

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