Salesforce::Class for Retrieve data from another URL using JSON

1) You need register url of repository.



2) Apex Class
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public class JsonSecondController {
 String name;
 public PageReference test() {
 return null;
 }
  public PageReference submit() {
 return null;
 }

  public String getName() { return name;}
  public void setName(String nname) {  name=nname;}
  


  public List  getOptions()
  {
  
    List defaultResult= new List();
    defaultResult.add(new SelectOption('','---'));
    
    list lvalues;
    try
    {
      String values=getJsonString('342096656648874');
      lvalues=JSONObject.jsonarray ( new JSONObject.JSONTokener( values ) );
    }
    catch(Exception e)
    {
      return defaultResult;
    }
    return getSelectOptions(lvalues);
  }


    private String getJsonString(String id) {
 
        String json;
        HttpRequest req = new HttpRequest();
        Http http = new Http();
        req.setMethod('GET');
        // generate the url for the request
        String url = 'http://datarepository/page.aspx/GetIndustries/'+id;
        req.setEndpoint(url);// add the endpoint to the request
        req.setCompressed(true);
        HTTPResponse resp = http.send(req);
        json = resp.getBody().replace('\n', '');

        try {
            //System.debug('Respond code: ' + resp.getStatus());
            return json;
        } catch (JSONObject.JSONException e) {
            return 'Error parsing JSON response: '+e;
        }
 
    }
    private List getSelectOptions(list l)
    {
       List elements=new List();
       for (Integer i = 0; i < l.size(); i++){
        JSONObject v = l.get(i).obj;
        String value=v.getValue('Value').str;
        String label=v.getValue('Text').str;
         elements.add(new SelectOption(value,label));          
       }

      return elements;
    }
 
 
}

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2) Apex Page
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<apex:page controller="JsonSecondController">
<apex:form >

<apex:selectList id="idindustry" value="{!name}" size="1">
<apex:selectOptions value="{!Options}"/>



<apex:commandButton value="Test" action="{!test}" rerender="out" status="status"/>

<apex:outputPanel id="out">
<apex:actionstatus id="status" startText="testing...">





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References:

[1] JSONObject http://www.embracingthecloud.com/CommentView,guid,6ca59b34-f896-48a2-b1bf-33ffbe96b4ec.aspx
[2] http://wiki.developerforce.com/index.php/Building_Android_Applications_with_the_Force.com_REST_API
[3] JSON Validator page http://www.jsonlint.com/