양군이 놀이터

* JSON(http://www.crockford.com/JSON/)은 자바스크립트 객체 표기(literal object notation
of JavaScript)를 따르는 가벼운 데이터 교환포맷이다.
(JavaScript Object Notation (JSON) is a lightweight data inerchange format )

* Rule: "Use XML to exchange structured document, use JSON to exchange data."

* JSON을 어디에 써먹을까?
Ajax 기반 프로그래밍시 응답 xml을 핸들링해야 하는데, DOM 트리를 통해 데이터에 접근하는 것보다 동일한 구조를 갖는 javascript 객체로써 다루는 것이 훨씬 편하다.(어떤 언어를 사용하더라도
DOM을 직접 다루는 것은 고통스럽다.)

예를 들어 아래와 같은 xml포맷 데이터를 XMLHTTPRequest를 통해 받았다고 하자.
(xmlhttp.responseXML => 브라우저 내장 파서에 의해 자동파싱된 js DOM 트리 반환)

<response>
  <method>checkName</method>
  <result>yes</result>
</response>

여기서 method 엘리먼트의 값을 뽑으려면 이런식의 코딩이 필요하다. 지랄맞다.

var response = xmlhttp.responseXML.documentElement
alert("메소드명 : " + response.getElementsByTagName('method')[0].firstChild.data);

그럼 동일한 구조의 데이터를 아래처럼 JSON 포맷으로 받았다고 하자.
(xmlhttp.responseText => 응답 text를 그대로 반환)

{"response": {
     "method": "checkName",
     "result": "yes"
 }};

이제 method의 값을 뽑아보자. 해피하다.

var jsonObj = eval('return ' + xmlhttp.responseText);
alert("메소드명 : " + jsonObj.response.method);

즉, ajax를 이용하는 경우 서버단에서 XML 포맷으로 보내지 말고 JSON 포맷으로 보내면
자바스크립트에서 데이터를 쉽게 액세스할 수가 있다는 얘기다.
(Ajax with JSON instead of XML)

출처 : http://blog.naver.com/ecogeo/100012393620

http://blog.naver.com/eclips32/30020578345

이 포스트를 보낸곳 ()

Simple Java toolkit for JSON (JSON.simple)
==========================================

http://www.JSON.org/java/json_simple.zip

1.Why the Simple Java toolkit (also named as JSON.simple) for JSON?

  When I use JSON as the data exchange format between the AJAX client and JSP
  for the first time, what worry me mostly is how to encode Java strings and
  numbers correctly in the server side so the AJAX client will receive a well
  formed JSON data. When I looked into the 'JSON in Java' directory in JSON
  website,I found that wrappers to JSONObject and JSONArray can be simpler,
  due to the simplicity of JSON itself. So I wrote the JSON.simple package.

2.Is it simple,really?

  I think so. Take an example:

  import org.json.simple.JSONObject;

  JSONObject obj=new JSONObject();
  obj.put("name","foo");
  obj.put("num",new Integer(100));
  obj.put("balance",new Double(1000.21));
  obj.put("is_vip",new Boolean(true));
  obj.put("nickname",null);
  System.out.print(obj);

  Result:
  {"nickname":null,"num":100,"balance":1000.21,"is_vip":true,"name":"foo"}

  The JSONObject.toString() will escape controls and specials correctly.

3.How to use JSON.simple in JSP?

  Take an example in JSP:

  <%@page contentType="text/html; charset=UTF-8"%>
  <%@page import="org.json.simple.JSONObject"%>
  <%
    JSONObject obj=new JSONObject();
    obj.put("name","foo");
    obj.put("num",new Integer(100));
    obj.put("balance",new Double(1000.21));
    obj.put("is_vip",new Boolean(true));
    obj.put("nickname",null);
    out.print(obj);
    out.flush();
  %>

  So the AJAX client will get the responseText.

4.Some details about JSONObject?

  JSONObject inherits java.util.HashMap,so it don't have to worry about the
  mapping things between keys and values. Feel free to use the Map methods
  like get(), put(), and remove() and others. JSONObject.toString() will
  combine key value pairs to get the JSON data string. Values will be escaped
  into JSON quote string format if it's an instance of java.lang.String. Other
  type of instance like java.lang.Number,java.lang.Boolean,null,JSONObject and
  JSONArray will NOT escape, just take their java.lang.String.valueOf() result.
  null value will be the JSON 'null' in the result.

  It's still correct if you put an instance of JSONObject or JSONArray into an
  instance of JSONObject or JSONArray. Take the example about:

  JSONObject obj2=new JSONObject();
  obj2.put("phone","123456");
  obj2.put("zip","7890");
  obj.put("contact",obj2);
  System.out.print(obj);

  Result:
  {"nickname":null,"num":100,"contact":{"phone":"123456","zip":"7890"},"balance":1000.21,"is_vip":true,"name":"foo"}

  The method JSONObject.escape() is used to escape Java string into JSON quote
  string. Controls and specials will be escaped correctly into \b,\f,\r,\n,\t,
  \",\\,\/,\uhhhh.

5.Some detail about JSONArray?

  org.json.simple.JSONArray inherits java.util.ArrayList. Feel free to use the
  List methods like get(),add(),remove(),iterator() and so on. The rules of
  JSONArray.toString() is similar to JSONObject.toString(). Here's the example:

  import org.json.simple.JSONArray;

  JSONArray array=new JSONArray();
  array.add("hello");
  array.add(new Integer(123));
  array.add(new Boolean(false));
  array.add(null);
  array.add(new Double(123.45));
  array.add(obj2);//see above
  System.out.print(array);

  Result:
  ["hello",123,false,null,123.45,{"phone":"123456","zip":"7890"}]

6.What is JSONValue for?

  org.json.simple.JSONValue is use to parse JSON data into Java Object.
  In JSON, the topmost entity is JSON value, not the JSON object. But
  it's not necessary to wrap JSON string,boolean,number and null again,
  for the Java has already had the according classes: java.lang.String,
  java.lang.Boolean,java.lang.Number and null. The mapping is:

  JSON          Java
  ------------------------------------------------
  string      <=>   java.lang.String
  number      <=>   java.lang.Number
  true|false  <=>   java.lang.Boolean
  null        <=>   null
  array       <=>   org.json.simple.JSONArray
  object      <=>       org.json.simple.JSONObject
  ------------------------------------------------

  JSONValue has only one kind of method, JSONValue.parse(), which receives
  a java.io.Reader or java.lang.String. Return type of JSONValue.parse()
  is according to the mapping above. If the input is incorrect in syntax or
  there's exceptions during the parsing, I choose to return null, ignoring
  the exception: I have no idea if it's a serious implementaion, but I think
  it's convenient to the user.

  Here's the example:

  String s="[0,{\"1\":{\"2\":{\"3\":{\"4\":[5,{\"6\":7}]}}}}]";
  Object obj=JSONValue.parse(s);
  JSONArray array=(JSONArray)obj;
  System.out.println(array.get(1));
  JSONObject obj2=(JSONObject)array.get(1);
  System.out.println(obj2.get("1"));

  Result:
  {"1":{"2":{"3":{"4":[5,{"6":7}]}}}}
  {"2":{"3":{"4":[5,{"6":7}]}}}

7.About the author.

  I'm a Java EE developer on Linux.
  I'm working on web systems and information retrieval systems.
  I also develop 3D games and Flash games.

  You can contact me through:
  Fang Yidong<fangyidong@yahoo.com.cn>
  Fang Yidong<fangyidng@gmail.com>

  http://www.JSON.org/java/json_simple.zip

tomcat 5.x 버전에서 웹브라우저로 부터 날라온 Get/Post 로 전달되는 한글이 ISO8859-1로 넘어오는 경우가 있어

한글이 깨지는 경우가 있습니다. 아래와 같이 Get / Post로 넘오는 한글 처리를 하시면 됩니다.

1. Get 방식으로 넘어오는 파라미터

   server.xml

------------------------------------------------------------

   <Connector
               port="8080"               maxThreads="150" minSpareThreads="25" maxSpareThreads="75"
               enableLookups="false" redirectPort="8443" acceptCount="100"
               debug="0" connectionTimeout="20000"
               disableUploadTimeout="true" useBodyEncodingForURI="true" URIEncoding="KSC5601"/>

2. Post 방식으로 넘오는 파라미터

2-1. 톰캣이 설치된 디렉토리에서

<TOMCAT_HOME>/webapps/jsp-examples/WEB-INF/classes/filters/SetCharacterEncodingFilter.class 파일을 복사해서

<TOMCAT_HOME>/common/classes/filters/ 밑으로 복사함.

2-2.

 web.xml

-------------------------------------------------------------

 <filter>
      <filter-name>Set Character Encoding</filter-name>
      <filter-class>filters.SetCharacterEncodingFilter</filter-class>
      <init-param>
          <param-name>encoding</param-name>
          <param-value>euc-kr</param-value>
      </init-param>
    </filter>

    <filter-mapping>
      <filter-name>Set Character Encoding</filter-name>
      <url-pattern>/*</url-pattern>
    </filter-mapping>