A basic Rest Client for Salesforce's Apex

RestClient.java

Public with sharing virtual class RestClient {
    Public class RestClientException extends Exception {}

    /*
     * class variable creation - DO NOT EDIT
     */

    Public Map<String,String> headers;
    Public String url;
    Public String method;
    Public String body;
    Public HttpRequest request;
    Public HttpResponse response;
    Public String responseBody;
    Public String lastDebugMessage;
    Http h;
    
    /*
     * Constants - Edit to your satisfaction
     */

    Public Static Integer TIMEOUT = 60000; // Default HTTP Timeout
    Public Boolean DEBUG = true; // should we print debug statements?

    /*
     * Constructors:
     */

    Public RestClient() {} //Prevent empty objects.

    //master constructor with everything required. 
    Public RestClient(String url, String method, Map<String,String> headers, String body) {
        try {
            this.h = new Http();
            this.request = buildRequest(headers, url, method.toUpperCase(), body);
            this.response = makeRequest(this.h, this.request);
            this.responseBody = handleResponse(this.response);
        } catch(Exception e) {
            //log the error, but set as much as we can with the input given
            log('Failed to execute callout. SFDC Reports: ',e, e.getMessage());
            if(headers != null) this.headers = headers;
            this.body = body;
            this.url = url;
            this.method = method.toUpperCase();
        }
    }
    
    Public RestClient(String url, String method, String body) {
        this(url, method, null, body);
    }
    
    Public RestClient(String url, String method, Map<String,String> headers) {
        this(url, method, headers, null);
    }
    
    Public RestClient(String url, String method) {
        this(url, method, new Map<String,String>(), null);
    }

    /*
     * Helper Methods - These do the actual work.
     */

  Public Static HttpRequest buildRequest(map<String,String> headers, String url, String method, String body){
    HttpRequest request = new HttpRequest();
    request.setTimeout(TIMEOUT); // timeout in milliseconds 
    if (headers != null) {
            for(String hkey : headers.keySet()){
            request.setHeader(hkey, headers.get(hkey)); 
        }   
    }
      request.setEndpoint(url);
      request.setMethod(method);
      if (body != null && body.length() > 0) {
        request.setBody(body);
      }
      return request;
  }

    Public Static HttpResponse makeRequest(Http h, HttpRequest request){
        HttpResponse response = h.send(request);
        if (response.getStatusCode() > 299) {
            throw new RestClientException('Failed to recieve a success code from remote. Code was: ' + response.getStatusCode() + ' request was ' + request + ' Response Body is: ' + response.getBody());
        }
        return response;    
    }  

    Public string handleResponse(HttpResponse response){
        log('Response', response, response.getBody());
        return response.getBody();
    }
    
    
    /**
    * GET Convenance Methods.
    **/
    // RestClient.get('http://www.google.com/?q=convenance')
    Public String get(String url) {
        RestClient x = new RestClient(url, 'get', null, null);
        log(url, x, null);
        return x.responseBody;
    }
    
    // RestClient.get('http://www.google.com/', HeaderMap{'q', 'convenance'})
    Public String get(String url, map<String,String> headers) {
        RestClient x = new RestClient(url, 'get', headers, null);
        system.debug(x.responseBody);
        return x.responseBody;
    }
    
    // RestClient.get('http://www.google.com/', HeaderMap{'q', 'convenance'}, 'some body of text for unknown reason.')
    Public String get(String url, map<String,String> headers, String body) {
        RestClient x = new RestClient(url, 'get', headers, body);
        return x.responseBody;
    }
    
    Public HttpResponse post(String url, Map<String,String> headers, String Body) {
        RestClient x = new RestClient(url, 'POST', headers, body);
        return x.response;
    }

    Public String request(String url, String method, Map<String,String> headers){
        RestClient x = new RestClient(url, method, headers);
        return x.responseBody;
    }

    Public String request(String url, String method, String body){
        RestClient x = new RestClient(url, method, body);
        return x.responseBody;
    }

    Public String request(String url, String method){
        RestClient x = new RestClient(url, method);
        return x.responseBody;
    }

    /*
     * Private helper methods: Only this class should use them.
     */
    
    public void log(String header, Object obj, String msg) {
        String startStop = '\n===============================================================================';
        String logOutput = startStop;
        logOutput += (header != null) ? '\n== Header: ' + header : 'Header: No Header Set';
        logOutput += (obj != null) ? '\n== Obj string Rep: ' + obj : '\n No Obj set';
        logOutput += (msg != null) ? '\n== ' + msg : '';
        logOutput += startStop;
        if(DEBUG){
            lastDebugMessage = logOutput;
            System.debug(logOutput);
        }
        
    }

}