将 ArrayAdapter<rss> 发送到另一个 activity 意图

Question

我想制作 rss reader 应用程序。

我想先获取 rss，然后将其传递给另一个 activity 使用 intent。

这是我的代码：

mainActivity.java

public class mainActivity extends Activity {
     new AsyncTaskParseJson().execute();
}

public class AsyncTaskParseJson extends AsyncTask<String, String, String> {
     protected String doInBackground(String... arg0) {
            RssParser parser = new RssParser("https://test/feed/");
            Bundle extra = new Bundle();
                            extra.putSerializable("objects", parser);

                            Intent intent = new Intent(this, b.class);
                            intent.putExtra("extra", extra);
                            startActivity(intent);
     }
}

RssParser.java

import java.io.IOException;
import java.io.Serializable;
import java.io.StringReader;
import java.net.URL;
import java.util.ArrayList;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
import org.xml.sax.XMLReader;
import org.xml.sax.helpers.DefaultHandler;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlPullParserFactory;


public class RssParser extends DefaultHandler implements Serializable {

    private StringBuilder   content;
    private boolean         inChannel;
    private boolean         inImage;
    private boolean         inItem;

    private ArrayList<Item> items   = new ArrayList<Item>();
    private Channel         channel = new Channel();

    private Item            lastItem;


    public RssParser(String url) {
        try {
            SAXParserFactory spf = SAXParserFactory.newInstance();
            SAXParser sp = spf.newSAXParser();
            XMLReader xr = sp.getXMLReader();
            URL sourceUrl = new URL(url);
            xr.setContentHandler(this);
            xr.parse(new InputSource(sourceUrl.openStream()));
        }
        catch (ParserConfigurationException e) {
            e.printStackTrace();
        }
        catch (SAXException e) {
            e.printStackTrace();
        }
        catch (IOException e) {
            e.printStackTrace();
        }
    }


    public class Item {

        public String title;
        public String description;
        public String link;
        public String category;
        public String pubDate;
        public String guid;
        public String imageUrl;
        public String creator;
    }


    public class Channel {

        public String title;
        public String description;
        public String link;
        public String lastBuildDate;
        public String generator;
        public String imageUrl;
        public String imageTitle;
        public String imageLink;
        public String imageWidth;
        public String imageHeight;
        public String imageDescription;
        public String language;
        public String copyright;
        public String pubDate;
        public String category;
        public String ttl;
    }


    @Override
    public void startDocument() throws SAXException {
        //        Log.i("LOG", "StartDocument");
    }


    @Override
    public void endDocument() throws SAXException {
        //        Log.i("LOG", "EndDocument");
    }


    @Override
    public void startElement(String uri, String localName, String qName, Attributes atts) throws SAXException {
        if (localName.equalsIgnoreCase("image")) {
            inImage = true;
        }

        if (localName.equalsIgnoreCase("channel")) {
            inChannel = true;
        }

        if (localName.equalsIgnoreCase("item")) {
            lastItem = new Item();
            items.add(lastItem);
            inItem = true;
        }

        content = new StringBuilder();
    }


    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if (localName.equalsIgnoreCase("image")) {
            inImage = false;
        }

        if (localName.equalsIgnoreCase("channel")) {
            inChannel = false;
        }

        if (localName.equalsIgnoreCase("item")) {
            inItem = false;
        }

        if (localName.equalsIgnoreCase("title")) {
            if (content == null) {
                return;
            }

            if (inItem) {
                lastItem.title = content.toString();
            } else if (inImage) {
                channel.imageTitle = content.toString();
            } else if (inChannel) {
                channel.title = content.toString();
            }

            content = null;
        }

        if (localName.equalsIgnoreCase("dc:creator") || localName.equalsIgnoreCase("creator")) {
            if (content == null) {
                return;
            }
            lastItem.creator = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("description")) {
            if (content == null) {
                return;
            }
            if (inItem) {
                lastItem.description = android.text.Html.fromHtml(content.toString()).toString().substring(1);
                lastItem.imageUrl = this.extractImageUrl(content.toString());
            } else if (inImage) {
                channel.imageDescription = content.toString();
            } else if (inChannel) {
                channel.description = android.text.Html.fromHtml(content.toString()).toString().substring(1);
            }

            content = null;
        }

        if (localName.equalsIgnoreCase("link")) {
            if (content == null) {
                return;
            }

            if (inItem) {
                lastItem.link = content.toString();
            } else if (inImage) {
                channel.imageLink = content.toString();
            } else if (inChannel) {
                channel.link = content.toString();
            }

            content = null;
        }

        if (localName.equalsIgnoreCase("category")) {
            if (content == null) {
                return;
            }

            if (inItem) {
                lastItem.category = content.toString();
            } else if (inChannel) {
                channel.category = content.toString();
            }

            content = null;
        }

        if (localName.equalsIgnoreCase("pubDate")) {
            if (content == null) {
                return;
            }

            if (inItem) {
                lastItem.pubDate = content.toString();
            } else if (inChannel) {
                channel.pubDate = content.toString();
            }

            content = null;
        }

        if (localName.equalsIgnoreCase("guid")) {
            if (content == null) {
                return;
            }

            lastItem.guid = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("url")) {
            if (content == null) {
                return;
            }

            channel.imageUrl = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("width")) {
            if (content == null) {
                return;
            }

            channel.imageWidth = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("height")) {
            if (content == null) {
                return;
            }

            channel.imageHeight = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("language")) {
            if (content == null) {
                return;
            }

            channel.language = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("copyright")) {
            if (content == null) {
                return;
            }

            channel.copyright = content.toString();
            content = null;
        }

        if (localName.equalsIgnoreCase("ttl")) {
            if (content == null) {
                return;
            }

            channel.ttl = content.toString();
            content = null;
        }
    }


    private String extractImageUrl(String description) {
        XmlPullParserFactory factory = null;
        try {
            factory = XmlPullParserFactory.newInstance();
        }
        catch (XmlPullParserException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        XmlPullParser xpp = null;
        try {
            xpp = factory.newPullParser();
        }
        catch (XmlPullParserException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        try {
            xpp.setInput(new StringReader(description));
        }
        catch (XmlPullParserException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        int eventType = 0;
        try {
            eventType = xpp.getEventType();
        }
        catch (XmlPullParserException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        while (eventType != XmlPullParser.END_DOCUMENT) {
            if (eventType == XmlPullParser.START_TAG && "img".equals(xpp.getName())) {
                //found an image start tag, extract the attribute 'src' from here...                
                return xpp.getAttributeValue(null, "src").toString();
            }
            try {
                eventType = xpp.next();
            }
            catch (XmlPullParserException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        return xpp.getAttributeValue(null, "src").toString();
    }


    @Override
    public void characters(char[] ch, int start, int length) throws SAXException {
        if (content == null) {
            return;
        }

        content.append(ch, start, length);
    }


    public Item getItem(int index) {
        return items.get(index);
    }


    public ArrayList<Item> getItems() {
        return items;
    }
}

我想要获取 RssParser 项目的第 activity 个：

b.java

Bundle extra = getIntent().getBundleExtra("extra");
        RssParser p = (RssParser) extra.getSerializable("objects");
        ListView listView = (ListView) findViewById(R.id.content_frame);
        listView.setAdapter((ListAdapter) p.getItems());

而且我总是收到如下错误：

java.lang.RuntimeException: Parcelable encountered IOException writing serializable object

java.lang.RuntimeException: Parcel: unable to marshal value

Caused by: java.lang.RuntimeException: Parcelable encountered IOException reading a Serializable object

如果有任何建议我真的很感激。

此致

Answer 1

在这种情况下，不是从 Serializable 扩展 extending，而是从 Parcelable 扩展。并且，发送时，使用：

RssParser parser = new RssParser("https://test/feed/");
Bundle extra = new Bundle();
extra.putParcelable("objects", parser);

收到它：

RssParser rssParser = getIntent().getExtras().getParcelable("objects");

像这样工作，虽然不是最好的选择，但确实有效。

报错主要是说收到一个Parcelable的时候发现了一个Serializable。所以，我把它改成 Parcelable.

编辑

gradle:

dependencies {    
    //...
    compile 'com.google.code.gson:gson:2.2.4' 
}

发送：

Intent intent = new Intent(MainActivity.this, b.class);
intent.putExtra("extra", new Gson().toJson(parser));
startActivity(intent);

收到：

String toParse = getIntent().getExtras().getString("extra");
RssParser rssParser = new Gson().fromJson(toParse, RssParser.class);

来自编辑，我被测试了。有效。

EDIT2

如果，你需要传递一个数组或列表：

Type rssListType = new TypeToken<ArrayList<RssParser>>(){}.getType();
List<RssParser> founderList = new Gson().fromJson(myStringToParse, rssListType);

此致。

将 ArrayAdapter<rss> 发送到另一个 activity 意图

Send ArrayAdapter<rss> into another activity intent

rss

android

android-intent