UploadHandlerXhr.java

package com.gwt.ui.client.gwtupld;

import java.util.HashMap;
import java.util.Map;

import com.google.gwt.http.client.URL;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.json.client.JSONString;
import com.google.gwt.json.client.JSONValue;
import com.google.gwt.xhr.client.ReadyStateChangeHandler;
import com.google.gwt.xhr.client.XMLHttpRequest;
import com.gwt.ui.client.gwtupld.file.File;
import com.gwt.ui.client.gwtupld.shr.OnUploadProgressEvent;
import com.gwt.ui.client.gwtupld.shr.OnUploadProgressHandler;
import com.gwt.ui.client.gwtupld.shr.XMLHttpRequestAdvanced;
import com.gwt.ui.client.gwtupld.utils.UUID;

/**
 * Class for uploading files using XHR
 */
public class UploadHandlerXhr extends UploadHandlerAbstract {
    private Map<String, File> files;
    private Map<String, XMLHttpRequest> xhrs;
    // current loaded size in bytes for each file
    private Map<String, Integer> loaded;
    
    public UploadHandlerXhr(UploadProgressHandlers handlers, Options options) {
        super(handlers, options);
        files = new HashMap<String, File>();
        xhrs = new HashMap<String, XMLHttpRequest>();
        loaded = new HashMap<String, Integer>();
    }
    
    @Override
    protected String add(Object o) {
        final String id = UUID.uuid();
        files.put(id, (File)o);
        return id;
    }
    
    @Override
    protected String getName(String id) {
        return files.get(id).getName();
    }
    
    @Override
    protected int getSize(String id) {
        return files.get(id).getSize();
    }
    
    /**
     * Sends the file identified by id and additional query params to the server
     * 
     * @param id file id
     * @param params params name-value string pairs
     */
    @Override
    protected String _upload(final String id, Map<String, String> params) {
        final File file = files.get(id);
        final String name = getName(id);
        final long size = getSize(id);
        
        loaded.put(id, 0);
        
        XMLHttpRequestAdvanced xhr = XMLHttpRequestAdvanced.create();
        xhrs.put(id, xhr);
        
        xhr.setOnUploadProgress(new OnUploadProgressHandler() {
            
            @Override
            public void onUploadProgress(OnUploadProgressEvent e) {
                if (e.isLengthComputable()) {
                    loaded.put(id, e.getLoaded());
                    UploadHandlerXhr.super.progressHandlers.onProgress(id, name, e.getLoaded(), e.getTotal());
                }
                
            }
        });
        
        xhr.setOnReadyStateChange(new ReadyStateChangeHandler() {
            @Override
            public void onReadyStateChange(XMLHttpRequest xhr) {
                if (xhr.getReadyState() == XMLHttpRequest.DONE) {
                    onComplete(id, xhr);
                }
            }
        });
        
        // params = params || {};
        // params['qqfile'] = name;
        String queryString = appendParamsToAction(options.getAction(), options.getParams());
        
        xhr.open("POST", queryString);
        xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
        xhr.setRequestHeader("X-File-Name", URL.encode(name));
        xhr.setRequestHeader("Content-Type", "application/octet-stream");
        xhr.send(file);
        log("File with id `" + id + "` was just sent to server");
        return null;
    }
    
    @Override
    protected void _cancel(String id) {
        progressHandlers.onCancel(id, files.get(id).getName());
        files.remove(id);
        final XMLHttpRequest xhr = xhrs.get(id);
        if (xhr != null) {
            xhr.abort();
            xhr.clearOnReadyStateChange();
            xhrs.remove(id);
        }
    }
    
    private void onComplete(String id, XMLHttpRequest xhr) {
        log("File with id `" + id + "` has been successfully uploaded");
        
        if (files.get(id) == null) {
            // the request was aborted/cancelled
            return;
        }
        
        String name = getName(id);
        int size = getSize(id);
        
        // TODO: what is it for within `onComplete`
        progressHandlers.onProgress(id, name, size, size);
        
        JSONValue response = new JSONString("");
        log("xhr - status is " + xhr.getStatus());
        log("xhr - response is " + xhr.getResponseText());
        if (xhr.getStatus() == 200) {
            response = JSONParser.parseStrict(xhr.getResponseText());
        }
        progressHandlers.onComplete(id, name, response);
        
        files.remove(id);
        xhr.clearOnReadyStateChange();
        xhrs.remove(id);
        _dequeue(id);
    }
    
    public native static boolean isSupported() /*-{
                                               var input = document.createElement('input');
                                               input.type = 'file';

                                               return (
                                               'multiple' in input &&
                                               typeof File != "undefined" &&
                                               typeof (new XMLHttpRequest()).upload != "undefined" );
                                               }-*/;
}