java - lwuit.html.CSSEngine.applyStyleToUIElement 的 NullPointerException(未知来源)

Question

我正在执行以下 LinkedIn 登录程序，但不幸的是，在加载 LinkedIn 登录窗口时“授予 Yokeapp 访问您的 LinkedIn 帐户”
它没有显示任何内容并引发错误。

我在安装了 S60 SDK 5th 的 Eclipse pulsar 中使用 LWuit-1.5 版本。

public class Login {
   Form form = new Form();
            String authorizeUrl = "";
            public Form Login() {
                Display.init(this);
                HttpRequestHandler  handler = new HttpRequestHandler();
                HTMLComponent htmlC = new HTMLComponent(handler);
                user = new LinkedInUser(Const.consumerKey, Const.consumerSecret);
                user.fetchNewRequestToken();

                if (user.requestToken != null) {
                    authorizeUrl = "https://www.linkedin.com/uas/oauth/authorize?oauth_token="
                                        + user.requestToken.getToken();

                    htmlC.setPage(authorizeUrl);
                    FlowLayout flow = new FlowLayout(Component.TOP);
                    form.setLayout(flow);
                    form.addComponent(htmlC);            
                }

                return form;
            }
        }

我在我的 MIDlet 类 startApp() 中按以下方式调用此方法

Login login=new Login();
login.Login().show();

我遇到以下错误

     Uncaught exception!                               
     java.lang.NullPointerException
            at com.sun.lwuit.html.CSSEngine.applyStyleToUIElement(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyStyle(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.checkSelector(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.CSSEngine.applyCSS(Unknown Source)
            at com.sun.lwuit.html.HTMLComponent.applyAllCSS(Unknown Source)
            at com.sun.lwuit.html.ResourceThreadQueue.threadFinished(Unknown Source)
            at com.sun.lwuit.html.ResourceThreadQueue$ResourceThread.streamReady(Unknown Source)
            at com.sun.lwuit.html.ResourceThreadQueue$ResourceThread.run(Unknown Source)
            at java.lang.Thread.run(Unknown Source)
        -VM verbose connection exited

HttpRequestHandler文件代码为

 /*
     *  Copyright � 2008, 2010, Oracle and/or its affiliates. All rights reserved
     */
    package com.yoke.symbian;

    import com.sun.lwuit.html.DocumentInfo;
    import com.sun.lwuit.html.DocumentRequestHandler;
    import com.yoke.helper.Storage;

    import java.io.ByteArrayInputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.util.Enumeration;
    import java.util.Hashtable;
    import java.util.Vector;
    import javax.microedition.io.Connector;
    import javax.microedition.io.HttpConnection;

        /**
         * An implementation of DocumentRequestHandler that handles fetching HTML documents both from HTTP and from the JAR.
         * This request handler takes care of cookies, redirects and handles both GET and POST requests
         *
         * @author Ofir Leitner
         */
        public class HttpRequestHandler implements DocumentRequestHandler {

            //Hashtable connections = new Hashtable();
            /**
             * A hastable containing all cookies - the table keys are domain names, while the value is another hashtbale containing a pair of cookie name and value.
             */
            static Hashtable cookies = Storage.getCookies();

            /**
             * A hastable containing all history - the table keys are domain names, while the value is a vector containing the visited links.
             */
            static Hashtable visitedLinks = Storage.getHistory();

            /**
             * If true will cache HTML pages, this also means that they will be buffered and read fully and only then passed to HTMLComponent - this can have memory implications.
             * Also note that for the cached HTMLs to be written Storage.RMS_ENABLED[TYPE_CACHE] should be true
             */
            static boolean CACHE_HTML=false;

            /**
             * If true will cache images, this also means that they will be buffered and read fully and only then passed to HTMLComponent - this can have memory implications.
             * Also note that for the cached images to be written Storage.RMS_ENABLED[TYPE_CACHE] should be true
             */
            static boolean CACHE_IMAGES=true;

            /**
             * If true will cache CSS files, this also means that they will be buffered and read fully and only then passed to HTMLComponent - this can have memory implications.
             * Also note that for the cached CSS files to be written Storage.RMS_ENABLED[TYPE_CACHE] should be true
             */
            static boolean CACHE_CSS=false;

            /**
             * Returns the domain string we use to identify visited link.
             * Note that this may be different than the domain name returned by HttpConnection.getHost
             * 
             * @param url The link URL
             * @return The link's domain
             */
            static String getDomainForLinks(String url) {
                String domain=null;
                if (url.startsWith("file:")) {
                    return "localhost"; // Just a common name to store local files under
                } 
                int index=-1;
                if (url.startsWith("http://")) {
                    index=7;
                } else if (url.startsWith("https://")) {
                    index=8;
                }
                if (index!=-1) {
                    domain=url.substring(index);
                    index=domain.indexOf('/');
                    if (index!=-1) {
                        domain=domain.substring(0,index);
                    }
                }
                return domain;
            }

            /**
             * {@inheritDoc}
             */
            public InputStream resourceRequested(DocumentInfo docInfo) {
                InputStream is=null;
                String url=docInfo.getUrl();

                String linkDomain=getDomainForLinks(url);

                // Visited links
                if (docInfo.getExpectedContentType()==DocumentInfo.TYPE_HTML) { // Only mark base documents as visited links

                    if (linkDomain!=null) {
                        Vector hostVisitedLinks=(Vector)visitedLinks.get(linkDomain);
                        if (hostVisitedLinks==null) {
                            hostVisitedLinks=new Vector();
                            visitedLinks.put(linkDomain,hostVisitedLinks);
                        }
                        if (!hostVisitedLinks.contains(url)) {
                            hostVisitedLinks.addElement(url);
                            Storage.addHistory(linkDomain, url);
                        }
                    } else {
                        System.out.println("Link domain null for "+url);
                    }
                } 

                String params=docInfo.getParams();
                if ((!docInfo.isPostRequest()) && (params !=null) && (!params.equals(""))) {
                    url=url+"?"+params;
                }

                // See if page/image is in the cache
                // caching will be used only if there are no parameters and no cookies (Since if they are this is probably dynamic content)
                boolean useCache=false;
                if (((docInfo.getExpectedContentType()==DocumentInfo.TYPE_HTML) && (CACHE_HTML) && ((params==null) || (params.equals(""))) && (!cookiesExistForDomain(linkDomain) )) ||
                    ((docInfo.getExpectedContentType()==DocumentInfo.TYPE_IMAGE) && (CACHE_IMAGES)) ||
                    ((docInfo.getExpectedContentType()==DocumentInfo.TYPE_CSS) && (CACHE_CSS)))
                {
                    useCache=true;
                    InputStream imageIS=Storage.getResourcefromCache(url);
                    if (imageIS!=null) {
                        return imageIS;
                    }
                }

                // Handle the file protocol
                if (url.startsWith("file://")) {
                    return getFileStream(docInfo);
                }

                try {
                    HttpConnection hc = (HttpConnection)Connector.open(url);
                    String encoding=null;
                    if (docInfo.isPostRequest()) {
                        encoding="application/x-www-form-urlencoded";
                    }
                    if (!docInfo.getEncoding().equals(DocumentInfo.ENCODING_ISO)) {
                        encoding=docInfo.getEncoding();
                    }
                    //hc.setRequestProperty("Accept_Language","en-US");

                    //String domain=hc.getHost(); // sub.domain.com / sub.domain.co.il
                    String domain=linkDomain; // will return one of the following formats: sub.domain.com / sub.domain.co.il

                    sendCookies(domain, hc);
                    domain=domain.substring(domain.indexOf('.')); // .domain.com / .domain.co.il
                    if (domain.indexOf('.',1)!=-1) { // Make sure that we didn't get just .com - TODO - however note that if the domain was domain.co.il - it can be here .co.il
                        sendCookies(domain, hc);
                    }

                    if (encoding!=null) {
                       hc.setRequestProperty("Content-Type", encoding);
                    }

                    if (docInfo.isPostRequest()) {
                       hc.setRequestMethod(HttpConnection.POST);
                       if (params==null) {
                           params="";
                       }
                       byte[] paramBuf=params.getBytes();
                       hc.setRequestProperty("Content-Length", ""+paramBuf.length);
                       OutputStream os=hc.openOutputStream();
                       os.write(paramBuf);
                       os.close();

                       //os.flush(); // flush is said to be problematic in some devices, uncomment if it is necessary for your device
                    }

                    String contentTypeStr=hc.getHeaderField("content-type");
                    if (contentTypeStr!=null) {
                        contentTypeStr=contentTypeStr.toLowerCase();
                        if (docInfo.getExpectedContentType()==DocumentInfo.TYPE_HTML) { //We perform these checks only for text (i.e. main page), for images/css we just send what the server sends 

        and "hope for the best"
                                if (contentTypeStr!=null) {
                                    if ((contentTypeStr.startsWith("text/")) || (contentTypeStr.startsWith("application/xhtml")) || (contentTypeStr.startsWith("application/vnd.wap"))) {
                                        docInfo.setExpectedContentType(DocumentInfo.TYPE_HTML);
                                    } else if (contentTypeStr.startsWith("image/")) {
                                        docInfo.setExpectedContentType(DocumentInfo.TYPE_IMAGE);
                                        hc.close();
                                        return getStream("<img src=\""+url+"\">",null);
                                    } else {
                                        hc.close();
                                        return getStream("Content type "+contentTypeStr+" is not supported.","Error");
                                    }
                                }
                            }

                            if ((docInfo.getExpectedContentType()==DocumentInfo.TYPE_HTML) ||
                                (docInfo.getExpectedContentType()==DocumentInfo.TYPE_CSS)) { // Charset is relevant for HTML and CSS only
                                int charsetIndex = contentTypeStr.indexOf("charset=");
                                if (charsetIndex!=-1) {
                                    String charset=contentTypeStr.substring(charsetIndex+8);
                                    docInfo.setEncoding(charset.trim());
                //                    if ((charset.startsWith("utf-8")) || (charset.startsWith("utf8"))) { //startwith to allow trailing white spaces
                //                        docInfo.setEncoding(DocumentInfo.ENCODING_UTF8);
                //                    }
                                }

                            }
                        }

                        int i=0;
                        while (hc.getHeaderFieldKey(i)!=null) {
                            if (hc.getHeaderFieldKey(i).equalsIgnoreCase("set-cookie")) {
                                addCookie(hc.getHeaderField(i), url);
                            }


                            i++;
                        }

                        int response=hc.getResponseCode();
                        if (response/100==3) { // 30x code is redirect
                            String newURL=hc.getHeaderField("Location");
                            if (newURL!=null) {
                                hc.close();
                                docInfo.setUrl(newURL);
                                if ((response==302) || (response==303)) { // The "302 Found" and "303 See Other" change the request method to GET
                                    docInfo.setPostRequest(false);
                                    docInfo.setParams(null); //reset params
                                }
                                return resourceRequested(docInfo);
                            }
                        }
                        is = hc.openInputStream();

                        if (useCache) {
                            byte[] buf=getBuffer(is);
                            Storage.addResourceToCache(url, buf,false);
                            ByteArrayInputStream bais=new ByteArrayInputStream(buf);
                            is.close();
                            hc.close(); //all the data is in the buffer
                            return bais;
                        }

                    } catch (SecurityException e) {
                        return getStream("Network access was disallowed for this session. Only local and cached pages can be viewed.<br><br> To browse external sites please exit the application and when asked for network access allow it.", "Security error");
                    } catch (IOException e) {
                        System.out.println("HttpRequestHandler->IOException: "+e.getMessage());
                        return getStream("The page could not be loaded due to an I/O error.", "Error");
                    } catch (IllegalArgumentException e) { // For malformed URL
                        System.out.println("HttpRequestHandler->IllegalArgumentException: "+e.getMessage());
                        return getStream("The requested URL is not valid.", "Malformed URL");
                    }

                    return is;

                }

                /**
                 * Checks if there are cookies stored on the client for the specified domain
                 *
                 * @param domain The domain to check for cookies
                 * @return true if cookies for the specified domain exists, false otherwise
                 */
                private boolean cookiesExistForDomain(String domain) {
                    Object obj=cookies.get(domain);
                    //System.out.println("Cookies for domain "+domain+": "+obj);
                    if (obj==null) {
                        int index=domain.indexOf('.');
                        if (index!=-1) {
                            domain=domain.substring(index); // .domain.com / .domain.co.il
                            if (domain.indexOf('.',1)!=-1) { // Make sure that we didn't get just .com - TODO - however note that if the domain was domain.co.il - it can be here .co.il
                                obj=cookies.get(domain);
                                //System.out.println("Cookies for domain "+domain+": "+obj);
                            }
                        }

                    }

                    return (obj!=null);
                }

                /**
                 * Sends the avaiable cookies for the given domain
                 * 
                 * @param domain The cookies domain
                 * @param hc The HTTPConnection
                 * @throws IOException
                 */
                private void sendCookies(String domain,HttpConnection hc) throws IOException {
                    //System.out.println("Sending cookies for "+domain);
                    Hashtable hostCookies=(Hashtable)cookies.get(domain);
                    String cookieStr="";
                    if (hostCookies!=null) {
                        for (Enumeration e=hostCookies.keys();e.hasMoreElements();) {
                            String name = (String)e.nextElement();
                            String value = (String)hostCookies.get(name);
                            String cookie=name+"="+value;
                            if (cookieStr.length()!=0) {
                                cookieStr+="; ";
                            }
                            cookieStr+=cookie;
                        }
                    }

                    if (cookieStr.length()!=0) {
                        //System.out.println("Cookies for domain "+domain+": "+cookieStr);
                        hc.setRequestProperty("cookie", cookieStr);
                    }

                }

                /**
                 * Returns an Inputstream of the specified HTML text
                 *
                 * @param htmlText The text to get the stream from
                 * @param title The page's title
                 * @return an Inputstream of the specified HTML text
                 */
                private InputStream getStream(String htmlText,String title) {
                    String titleStr="";
                    if (title!=null) {
                        titleStr="<head><title>"+title+"</title></head>";
                    }
                    htmlText="<html>"+titleStr+"<body>"+htmlText+"</body></html>";
                    ByteArrayInputStream bais = new ByteArrayInputStream(htmlText.getBytes());
                    return bais;

                }

                /**
                 * Adds the given cookie to the cookie collection
                 * 
                 * @param setCookie The cookie to add
                 * @param hc The HttpConnection
                 */
                private void addCookie(String setCookie,String url/*HttpConnection hc*/) {
                    //System.out.println("Adding cookie: "+setCookie);
                    String urlDomain=getDomainForLinks(url);

                    // Determine cookie domain
                    String domain=null;
                    int index=setCookie.indexOf("domain=");
                    if (index!=-1) {
                        domain=setCookie.substring(index+7);
                        index=domain.indexOf(';');
                        if (index!=-1) {
                            domain=domain.substring(0, index);
                        }

                        if (!urlDomain.endsWith(domain)) { //if (!hc.getHost().endsWith(domain)) {
                            System.out.println("Warning: Cookie tried to set to another domain");
                            domain=null;
                        }
                    }
                    if (domain==null) {
                        domain=urlDomain; //domain=hc.getHost();
                    }

                    // Check cookie expiry
                    boolean save=false;
                    index=setCookie.indexOf("expires=");
                    if (index!=-1) { // Cookies without the expires= property are valid only for the current session and as such are not saved to RMS
                        String expire=setCookie.substring(index+8);
                        index=expire.indexOf(';');
                        if (index!=-1) {
                            expire=expire.substring(0, index);
                        }
                        save=true;
                    }

                    // Get cookie name and value
                    index=setCookie.indexOf(';');
                    if (index!=-1) {
                        setCookie=setCookie.substring(0, index);
                    }
                    index=setCookie.indexOf('=');
                    String name=setCookie;
                    String value="";
                    if (index!=-1) {
                        name=setCookie.substring(0, index);
                        value=setCookie.substring(index+1);
                    }

                    Hashtable hostCookies=(Hashtable)cookies.get(domain);
                    if (hostCookies==null) {
                        hostCookies=new Hashtable();
                        cookies.put(domain,hostCookies);
                    }
                    hostCookies.put(name,value);

                    if (save) { // Note that we save all cookies with expiry specified, while not checking the specific expiry date
                        Storage.addCookie(domain, name, value);
                    }

                }

                /**
                 * This method is used when the requested document is a file in the JAR
                 *
                 * @param url The URL of the file
                 * @return An InputStream of the specified file
                 */
                private InputStream getFileStream(DocumentInfo docInfo) {
                    String url=docInfo.getUrl();

                    // If a from was submitted on a local file, just display the parameters
                    if ((docInfo.getParams()!=null) && (!docInfo.getParams().equals(""))) {
                        String method="GET";
                        if (docInfo.isPostRequest()) {
                            method="POST";
                        }
                        String params=docInfo.getParams();
                        String newParams="";
                        if (params!=null) {
                            for(int i=0;i<params.length();i++) {
                                char c=params.charAt(i);
                                if (c=='&') {
                                    newParams+=", ";
                                } else {
                                    newParams+=c;
                                }
                            }
                        }
                        return getStream("<h2>Form submitted locally.</h2><b>Method:</b> "+method+"<br><br><b>Parameters:</b><br>"+newParams+"<hr><a href=\""+docInfo.getUrl()+"\">Continue to local URL</a>","Form Results");
                    }

                    url=url.substring(7); // Cut the file://

                    int hash=url.indexOf('#'); //trim anchors
                    if (hash!=-1) {
                       url=url.substring(0,hash);
                    }

                    int param=url.indexOf('?'); //trim parameters, not relvant for files
                    if (param!=-1) {
                        url=url.substring(0, param);
                    }

                    // Use the following commented segment for loading HTML files saved with the UTF8 header added by some utils - 0xEF, 0xBB, 0xBF
                    // This is a simple code to skip automatically 3 chars on a certain file suffix (.htm isntead of .html)
                    // A better solution is to detect these bytes, but that requires buffering of the stream (to "unread" if these are not the right chars)
                    /*
                    if (url.endsWith(".htm")) {
                        System.out.println("Notepad UTF - Skipping 3 chars");
                        docInfo.setEncoding(DocumentInfo.ENCODING_UTF8); 
                        // If the UTF8 encoding string doesn't work on your device, try the following instead of the line above:
                        //docInfo.setEncoding("UTF-8");
                        InputStream is= getClass().getResourceAsStream(url);
                        try {
                            is.read();
                            is.read();
                            is.read();
                            return is; 
                        } catch (IOException ex) {
                            ex.printStackTrace();
                        }
                    }
                     */

                    return getClass().getResourceAsStream(url);
                }

                /**
                 * Reads an inputstream completely and places it into a buffer
                 * 
                 * @param is The InputStream to read
                 * @return A buffer containing the stream's contents
                 * @throws IOException
                 */
                static byte[] getBuffer(InputStream is) throws IOException {
                        int chunk = 50000;
                        byte[] buf = new byte[chunk];
                        int i=0;
                        int b = is.read();
                        while (b!=-1) {
                            if (i>=buf.length) {
                                byte[] tempbuf=new byte[buf.length+chunk];
                                for (int j=0;j<buf.length;j++) {
                                    tempbuf[j]=buf[j];
                                }
                                buf=tempbuf;
                            }
                            buf[i]=(byte)b;
                            i++;
                            b = is.read();
                        }
                        byte[] tempbuf=new byte[i];
                        for (int j=0;j<tempbuf.length;j++) {
                            tempbuf[j]=buf[j];

Answer 1

我们为 Codename One 修复了 LWUIT 中许多与 OAuth 相关的错误.不幸的是，我很难判断您触发的是哪一个，但是您可以查看我们的问题跟踪器，看看是否可以找到具体的问题。我们仍然有一些是开放的，但 OAuth 工作得更好。