Java/jackson-json-java/src/main/java/com/hmkcode/App.java at master · ZeroTwoMax/Java · GitHub

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package com.hmkcode;

import java.io.File;

import java.io.IOException;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.List;

import java.util.Map;

import com.fasterxml.jackson.core.JsonGenerationException;

import com.fasterxml.jackson.core.type.TypeReference;

import com.fasterxml.jackson.databind.JsonMappingException;

import com.fasterxml.jackson.databind.JsonNode;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.fasterxml.jackson.databind.SerializationFeature;

import com.fasterxml.jackson.databind.node.ArrayNode;

import com.fasterxml.jackson.databind.node.ObjectNode;

import com.hmkcode.vo.Article;

public class App

{

public static void main( String[] args )

{

ObjectMapper mapper = new ObjectMapper();

try {

//POJO to JSON

mapper.writeValue(new File("article.json"), createArticle());

System.out.println("json created!");

//JSON to POJO

Article article = mapper.readValue(new File("article.json"), Article.class);

//"Raw" Data Binding Example

Map<String,Object> articleMap = mapper.readValue(new File("article.json"), Map.class);

System.out.println(article);

System.out.println(articleMap);

//Data binding Collection<E>

List<Article> articles = new LinkedList<Article>();

articles.add(createArticle());

mapper.writeValue(new File("articles.json"), articles);

//( 1 ) Collection<Map>

List result = mapper.readValue(new File("articles.json"), List.class);

System.out.println(result.get(0).getClass());

System.out.println(result);

//( 2 ) Collection<Artilce>

result = mapper.readValue(new File("articles.json"), new TypeReference<List<Article>>() { });

System.out.println(result.get(0).getClass());

System.out.println(result);

System.out.println("---------------------------------------------------------");

//Tree

ObjectNode objectRoot = (ObjectNode) mapper.readTree(new File("article.json"));

Iterator<String> fields = objectRoot.fieldNames();

String field = "";

while(fields.hasNext()){

field = fields.next();

System.out.println("field: "+field);

}

System.out.println("---------------------------------------------------------");

ArrayNode arrayRoot = (ArrayNode) mapper.readTree(new File("articles.json"));

Iterator<JsonNode> elements = arrayRoot.elements();

JsonNode element;

while(elements.hasNext()){

element = elements.next();

fields = element.fieldNames();

field = "";

while(fields.hasNext()){

field = fields.next();

System.out.println("field: "+field);

}

} catch (JsonGenerationException e) {

e.printStackTrace();

} catch (JsonMappingException e) {

e.printStackTrace();

} catch (IOException e) {

e.printStackTrace();

}

private static Article createArticle(){

Article article = new Article();

article.setTitle("Jackson - Java to JSON & JSON to Java");

article.setUrl("http://hmkcode.com/jackson-java-json");

article.addCategory("Java");

article.addTag("Java");

article.addTag("Jackson");

article.addTag("JSON");

return article;

}

Java/jackson-json-java/src/main/java/com/hmkcode/App.java at master · ZeroTwoMax/Java · GitHub

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