juneau-examples/juneau-examples-core/src/main/java/org/apache/juneau/examples/core/json/JsonComplexExample.java

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package org.apache.juneau.examples.core.json;

import org.apache.juneau.examples.core.pojo.*;
import org.apache.juneau.json.JsonParser;
import org.apache.juneau.json.JsonSerializer;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * Sample class which shows the complex usage of JsonSerializer and JsonParser.
 */
public class JsonComplexExample {
    /**
     * Serializing PojoComplex bean into Json type
     * and Deserialize back to PojoComplex instance type.
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception{
        // Juneau provides static constants with the most commonly used configurations
        // Get a reference to a serializer - converting POJO to flat format
        /**
         * Produces
         * {"innerPojo":{"name":"name0","id":"1.0"},
         * "values":{"setOne":[{"name":"name1","id":"1.1"},{"name":"name2","id":"1.1"}],
         * "setTwo":[{"name":"name1","id":"1.2"},{"name":"name2","id":"1.2"}]},"id":"pojo"}
         */
        JsonSerializer jsonSerializer = JsonSerializer.DEFAULT;
        // Get a reference to a parser - converts that flat format back into the POJO
        JsonParser jsonParser = JsonParser.DEFAULT;

        // Fill some data to a PojoComplex bean
        HashMap<String, List<Pojo>> values = new HashMap<>();
        ArrayList<Pojo> setOne = new ArrayList<>();
        setOne.add(new Pojo("1.1", "name1"));
        setOne.add(new Pojo("1.1", "name2"));
        ArrayList<Pojo> setTwo = new ArrayList<>();
        setTwo.add(new Pojo("1.2", "name1"));
        setTwo.add(new Pojo("1.2", "name2"));
        values.put("setOne", setOne);
        values.put("setTwo", setTwo);
        PojoComplex pojoc = new PojoComplex("pojo", new Pojo("1.0", "name0"), values);

        String flat = jsonSerializer.serialize(pojoc);

        // Print out the created POJO in JSON format.
        System.out.println(flat);

        PojoComplex parse = jsonParser.parse(flat, PojoComplex.class);

        assert parse.getId().equals(pojoc.getId());
        assert parse.getInnerPojo().getName().equals(pojoc.getInnerPojo().getName());
        assert parse.getInnerPojo().getId().equals(pojoc.getInnerPojo().getId());

        // The object above can be parsed thanks to the @BeanConstructor(properties = id,name) annotation on Pojo
        // Using this approach, you can keep your POJOs immutable, and still serialize and deserialize them.
    }
}