JAVA 使用 stax 解析器从 xml 获取属性值

Question

我正在开发一个使用 java 读取 RSS 提要的项目，我使用他们使用 Stax 的本教程 parser.My 问题是我如何读取属性值？

http://www.vogella.com/tutorials/RSSFeed/article.html

这是 RSSReader class,

package de.vogella.rss.read;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

import javax.xml.stream.XMLEventReader;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Characters;
import javax.xml.stream.events.XMLEvent;

import de.vogella.rss.model.Feed;
import de.vogella.rss.model.FeedMessage;

public class RSSFeedParser {
    static final String TITLE = "title";
    static final String DESCRIPTION = "description";
    static final String CHANNEL = "channel";
    static final String LANGUAGE = "language";
    static final String COPYRIGHT = "copyright";
    static final String LINK = "link";
    static final String AUTHOR = "author";
    static final String ITEM = "item";
    static final String PUB_DATE = "pubDate";
    static final String GUID = "guid";

    final URL url;

    public RSSFeedParser(String feedUrl) {
        try {
            this.url = new URL(feedUrl);
        } catch (MalformedURLException e) {
            throw new RuntimeException(e);
        }
    }

    public Feed readFeed() {
        Feed feed = null;
        try {
            boolean isFeedHeader = true;
            // Set header values intial to the empty string
            String description = "";
            String title = "";
            String link = "";
            String language = "";
            String copyright = "";
            String author = "";
            String pubdate = "";
            String guid = "";

            // First create a new XMLInputFactory
            XMLInputFactory inputFactory = XMLInputFactory.newInstance();
            // Setup a new eventReader
            InputStream in = read();
            XMLEventReader eventReader = inputFactory.createXMLEventReader(in);
            // read the XML document
            while (eventReader.hasNext()) {
                XMLEvent event = eventReader.nextEvent();
                if (event.isStartElement()) {
                    String localPart = event.asStartElement().getName().getLocalPart();
                    switch (localPart) {
                        case ITEM:
                            if (isFeedHeader) {
                                isFeedHeader = false;
                                feed = new Feed(title, link, description, language,copyright, pubdate);
                            }
                            event = eventReader.nextEvent();
                            break;
                        case TITLE:
                            title = getCharacterData(event, eventReader);
                            break;
                        case DESCRIPTION:
                            description = getCharacterData(event, eventReader);
                            break;
                        case LINK:
                            link = getCharacterData(event, eventReader);
                            break;
                        case GUID:
                            guid = getCharacterData(event, eventReader);
                            break;
                        case LANGUAGE:
                            language = getCharacterData(event, eventReader);
                            break;
                        case AUTHOR:
                            author = getCharacterData(event, eventReader);
                            break;
                        case PUB_DATE:
                            pubdate = getCharacterData(event, eventReader);
                            break;
                        case COPYRIGHT:
                            copyright = getCharacterData(event, eventReader);
                            break;
                    }
                } else if (event.isEndElement()) {
                    if (event.asEndElement().getName().getLocalPart() == (ITEM)) {
                        FeedMessage message = new FeedMessage();
                        message.setAuthor(author);
                        message.setDescription(description);
                        message.setGuid(guid);
                        message.setLink(link);
                        message.setTitle(title);
                        feed.getMessages().add(message);
                        event = eventReader.nextEvent();
                        continue;
                    }
                }
            }
        }catch (XMLStreamException e) {
            throw new RuntimeException(e);
        }
        return feed;
    }

    private String getCharacterData(XMLEvent event, XMLEventReader eventReader)throws XMLStreamException {
        String result = "";
        event = eventReader.nextEvent();
        if (event instanceof Characters) {
            result = event.asCharacters().getData();
        }
        return result;
    }

    private InputStream read() {
        try {
            return url.openStream();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

4.2。测试代码

下面使用main方法进行测试。您也可以使用 JUnit。

package de.vogella.rss.tests;

import de.vogella.rss.model.Feed;
import de.vogella.rss.model.FeedMessage;
import de.vogella.rss.read.RSSFeedParser;

public class ReadTest {
    public static void main(String[] args) {
        RSSFeedParser parser = new RSSFeedParser("http://www.vogella.com/article.rss");
        Feed feed = parser.readFeed();
        System.out.println(feed);
        for (FeedMessage message : feed.getMessages()) {
            System.out.println(message);

        }
    }
}

项目class

package de.vogella.xml.stax.model;

public class Item {
    private String date; 
    private String mode;
    private String unit;
    private String current;
    private String interactive;

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getMode() {
        return mode;
    }

    public void setMode(String mode) {
        this.mode = mode;
    }

    public String getUnit() {
        return unit;
    }

    public void setUnit(String unit) {
        this.unit = unit;
    }

    public String getCurrent() {
        return current;
    }

    public void setCurrent(String current) {
        this.current = current;
    }
    public String getInteractive() {
        return interactive;
    }

    public void setInteractive(String interactive) {
        this.interactive = interactive;
    }

    @Override
    public String toString() {
        return "Item [current=" + current + ", date=" + date + ", interactive="+ interactive + ", mode=" + mode + ", unit=" + unit + "]";
    }
}

feedMessage

package de.vogella.rss.model;

/*
 * Represents one RSS message
 */
public class FeedMessage {

    String title;
    String description;
    String link;
    String author;
    String guid;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getLink() {
        return link;
    }

    public void setLink(String link) {
        this.link = link;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getGuid() {
        return guid;
    }

    public void setGuid(String guid) {
        this.guid = guid;
    }

    @Override
    public String toString() {
        return "FeedMessage [title=" + title + ", description=" + description + ", link=" + link + ", author=" + author + ", guid=" + guid  + "]";
    }
}

Answer 1

我在多次尝试并查看 RSSFEEDPARSER class.

上的 java api 文档后找到了答案

我添加了这些行；我的目标是在缩略图标签中找到属性 'url'，因此，在切换之前或添加之后，

// get attribute of thumbnail Tag
//get thumbnail ppicture link 
if(localPart.equals("thumbnail")){
    Iterator<Attribute> attribue = event.asStartElement().getAttributes();
    while(attribue.hasNext()){
        Attribute myAttribute = attribue.next();
        if(myAttribute.getName().toString().equals("url")){
            thumbnail = myAttribute.getValue();
        }
    }
}

JAVA 使用 stax 解析器从 xml 获取属性值

JAVA get attributes value from xml using stax parser

java

xml

rss

stax