출처 : http://www.mkyong.com/java/how-to-convert-java-map-to-from-json-jackson/

In this tutorial, we will show you few Jackson examples to convert JSON string to/from a Map.

P.S All examples are tested with Jackson 2.6.3

1. JSON string to Map

package com.mkyong.json;

import java.io.IOException;
import java.util.HashMap;
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.ObjectMapper;

public class JsonMapExample {

	public static void main(String[] args) {

		try {

			ObjectMapper mapper = new ObjectMapper();
			String json = "{\"name\":\"mkyong\", \"age\":29}";

			Map<String, Object> map = new HashMap<String, Object>();

			// convert JSON string to Map
			map = mapper.readValue(json, new TypeReference<Map<String, String>>(){});

			System.out.println(map);

		} catch (JsonGenerationException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

Output

{name=mkyong, age=29}

2. Map to JSON string

Example to convert the Map to JSON string.

package com.mkyong.json;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class MapJsonExample{

	public static void main(String[] args) {

		try {

			ObjectMapper mapper = new ObjectMapper();
			String json = "";

			Map<String, Object> map = new HashMap<String, Object>();
			map.put("name", "mkyong");
			map.put("age", 29);

			// convert map to JSON string
			json = mapper.writeValueAsString(map);

			System.out.println(json);

			json = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(map);

			// pretty print
			System.out.println(json);

		} catch (JsonGenerationException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

Output

{"name":"mkyong","age":29}
{
  "name" : "mkyong",
  "age" : 29
}

3. Map to JSON File

package com.mkyong.json;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JsonMapFileExample {

	public static void main(String[] args) {

		try {

			ObjectMapper mapper = new ObjectMapper();

			Map<String, Object> map = new HashMap<String, Object>();
			map.put("name", "mkyong");
			map.put("age", 29);

			List<Object> list = new ArrayList<>();
			list.add("msg 1");
			list.add("msg 2");
			list.add("msg 3");

			map.put("messages", list);

			// write JSON to a file
			mapper.writeValue(new File("c:\\user.json"), map);

		} catch (JsonGenerationException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

{"name":"mkyong","messages":["msg 1","msg 2","msg 3"],"age":29}

4. JSON file to Map

package com.mkyong.json;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
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.ObjectMapper;

public class Jackson2Example {

	public static void main(String[] args) {

		try {

			ObjectMapper mapper = new ObjectMapper();

			// read JSON from a file
			Map<String, Object> map = mapper.readValue(
					new File("c:\\user.json"), 
					new TypeReference<Map<String, Object>>() {
			});

			System.out.println(map.get("name"));
			System.out.println(map.get("age"));

			@SuppressWarnings("unchecked")
			ArrayList<String> list = (ArrayList<String>) map.get("messages");

			for (String msg : list) {
				System.out.println(msg);
			}

		} catch (JsonGenerationException e) {
			e.printStackTrace();
		} catch (JsonMappingException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

}

Output

mkyong
29
msg 1
msg 2
msg 3

References

1. Wikipedia : JSON
2. Jackson – High-performance JSON processor
3. Jackson 2 – Object to / from JSON

출처 : http://noritersand.tistory.com/240

라이브러리 다운로드

http://wiki.fasterxml.com/JacksonDownload

 jackson-annotations-2.2.3.jar

 jackson-core-2.2.3.jar

 jackson-databind-2.2.3.jar

Map - JSON 변환

writeValueAsString( value )

readValue( arg, type )

● Map

맵 타입이 JSON 형식의 String 타입으로 변환된다. 자바스크립트에 JSON을 넘겨줄 때 유용하다. 

이와 반대로 JSON을 맵 타입으로 변환하려면 다음처럼 작성한다:

● List<Map>

다음은 view에 전달할 model이 List<map<?, ?>> 타입일 때 이를 JSON으로 변환하는 방법이다.

사용방법은 크게 다르지 않고 writeValueAsString, readValue 메서드를 사용하되 타입 명시만 달리한다.

3 state checkbox for headerrenderer in datagrid

출처 : https://srinichekuri.wordpress.com/2011/05/20/3-state-checkbox-for-headerrenderer-in-datagrid/

Today I made by first contribution to Adobe Cook by posting about this topic. The idea on this topic started by showing my earlier post on gmail header to my colleague who also happens to be the owner of post in adobe cookbook that talks about 3State checkbox for TreeRenderer. He pointed out that the checkbox in the header can be threeState. Well thats a common problem but suprisingly this was not addressed in the online opensource community for Datagrid. I saw an opportunity and coded it.

Note:
There is a bug in my colleague’s post that it doesn’t take care of the initial state, I have taken care of that bug in my code.My code itself is inspired by my colleagues post.

The checkbox in headerRenderer will have three states:

• All the rows in the datagrid are selected (‘select’ State).
• None of the rows in the datagrid are selected(‘unselected’ State)
• One or more rows (but not all) are selected(‘undecided’ State).

ScreenShots:
Change of state from ‘unselect’ state to ‘select’ state:

Change of state from ‘select’ state to ‘undecided’ state:

Code:

Here is the code for Main.mxml:

Code for headerRenderer

Code for itemRenderer:

You can download the code from my post in Adobe cook book.