In Java Come convertire Map / HashMap in JSONObject? [4 modi diversi]

Pubblicato: 2019-01-13

Converti Java Map in JSONObject

La conversione di oggetti da un modulo all'altro è una richiesta comune. There are 4 different ways per convertire Java Map/HashMap in JSONObject.

Esamineremo i dettagli su come convertire HashMap in JSONObject in questo tutorial.

Iniziamo:

Crea classe CrunchifyMapToJsonObject.java.

Metodo-1

Innanzitutto utilizziamo Google GSON dependency per convertire HashMap in JSONObject. Hai bisogno di una dipendenza da Maven nel tuo progetto.

Google's GSON Depedency
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< dependency >
< groupId > com . google . code . gson < / groupId >
< artifactId > gson < / artifactId >
< version > 2.8.0 < / version >
< / dependency >

Metodo-2

Successivamente useremo la org.json dependency usando new JSONObject().

org.json dependency
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< dependency >
< groupId > org . json < / groupId >
< artifactId > json < / artifactId >
< version > 20180130 < / version >
< / dependency >

Metodo-3

Utilizzo jackson-core dependency con l'operazione ObjectMapper().writeValueAsString().

jackson-core dependency
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< dependency >
< groupId > com . fasterxml . jackson . core < / groupId >
< artifactId > jackson - core < / artifactId >
< version > 2.9.5 < / version >
< scope > compile < / scope >
< / dependency >
< dependency >
< groupId > com . fasterxml . jackson . core < / groupId >
< artifactId > jackson - databind < / artifactId >
< version > 2.9.5 < / version >
< scope > compile < / scope >
< / dependency >

Metodo-4

Utilizzo json-simple dependency con la libreria JSONValue.toJSONString().

json-simple dependency
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< dependency >
< groupId > com . googlecode . json - simple < / groupId >
< artifactId > json - simple < / artifactId >
< version > 1.1.1 < / version >
< / dependency >

Assicurati di aggiungere tutte le dipendenze Maven di cui sopra al tuo progetto Java J2EE. Se non hai un progetto Maven, segui questi passaggi.

Ecco un esempio completo:

CrunchifyMapToJsonObject.java
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package crunchify . com . tutorial ;
 
import java . util . HashMap ;
import java . util . Map ;
 
import org . json . JSONObject ;
import org . json . simple . JSONValue ;
 
import com . fasterxml . jackson . core . JsonProcessingException ;
import com . fasterxml . jackson . databind . ObjectMapper ;
import com . google . gson . Gson ;
import com . google . gson . GsonBuilder ;
 
/**
* @author Crunchify.com
* Program: 4 Best ways to convert Java Map to JSONObject.
* Version: 1.0.0
*
*/
 
public class CrunchifyMapToJsonObject {
public static void main ( String a [ ] ) {
 
Map < String , String > crunchifyMap = new HashMap < String , String > ( ) ;
crunchifyMap . put ( "Google" , "San Jose" ) ;
crunchifyMap . put ( "Facebook" , "Mountain View" ) ;
crunchifyMap . put ( "Crunchify" , "NYC" ) ;
crunchifyMap . put ( "Twitter" , "SFO" ) ;
crunchifyMap . put ( "Microsoft" , "Seattle" ) ;
log ( "Raw Map ===> " + crunchifyMap ) ;
 
// Use this builder to construct a Gson instance when you need to set configuration options other than the default.
GsonBuilder gsonMapBuilder = new GsonBuilder ( ) ;
 
Gson gsonObject = gsonMapBuilder . create ( ) ;
 
String JSONObject = gsonObject . toJson ( crunchifyMap ) ;
log ( "\nMethod-1: Using Google GSON ==> " + JSONObject ) ;
 
Gson prettyGson = new GsonBuilder ( ) . setPrettyPrinting ( ) . create ( ) ;
String prettyJson = prettyGson . toJson ( crunchifyMap ) ;
 
log ( "\nPretty JSONObject ==> " + prettyJson ) ;
 
// Construct a JSONObject from a Map.
JSONObject crunchifyObject = new JSONObject ( crunchifyMap ) ;
log ( "\nMethod-2: Using new JSONObject() ==> " + crunchifyObject ) ;
 
try {
// Default constructor, which will construct the default JsonFactory as necessary, use SerializerProvider as its
// SerializerProvider, and BeanSerializerFactory as its SerializerFactory.
String objectMapper = new ObjectMapper ( ) . writeValueAsString ( crunchifyMap ) ;
log ( "\nMethod-3: Using ObjectMapper().writeValueAsString() ==> " + objectMapper ) ;
} catch ( JsonProcessingException e ) {
e . printStackTrace ( ) ;
}
// Convert an object to JSON text. If this object is a Map or a List, and it's also a JSONAware, JSONAware will be considered firstly.
String jsonValue = JSONValue . toJSONString ( crunchifyMap ) ;
log ( "\nMethod-4: Using JSONValue.toJSONString() ==> " + jsonValue ) ;
 
}
 
private static void log ( Object print ) {
System . out . println ( print ) ;
 
}
}

Basta eseguire sopra Programma come applicazione Java e dovresti vedere sotto l'output.

Eclipse console output
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Raw Map === > { Google = San Jose , Twitter = SFO , Microsoft = Seattle , Facebook = Mountain View , Crunchify = NYC }
 
Method - 1 : Using Google GSON == > { "Google" : "San Jose" , "Twitter" : "SFO" , "Microsoft" : "Seattle" , "Facebook" : "Mountain View" , "Crunchify" : "NYC" }
 
Pretty JSONObject == > {
   "Google" : "San Jose" ,
   "Twitter" : "SFO" ,
   "Microsoft" : "Seattle" ,
   "Facebook" : "Mountain View" ,
   "Crunchify" : "NYC"
}
 
Method - 2 : Using new JSONObject ( ) == > { "Google" : "San Jose" , "Twitter" : "SFO" , "Microsoft" : "Seattle" , "Facebook" : "Mountain View" , "Crunchify" : "NYC" }
 
Method - 3 : Using ObjectMapper ( ) . writeValueAsString ( ) == > { "Google" : "San Jose" , "Twitter" : "SFO" , "Microsoft" : "Seattle" , "Facebook" : "Mountain View" , "Crunchify" : "NYC" }
 
Method - 4 : Using JSONValue . toJSONString ( ) == > { "Google" : "San Jose" , "Twitter" : "SFO" , "Microsoft" : "Seattle" , "Facebook" : "Mountain View" , "Crunchify" : "NYC" }

Se conosci un altro modo per convertire Java Map in JSONObject, faccelo sapere a noi e a tutti i lettori tramite un commento di seguito.

Buona codifica.