java - 使用 Java 将 RSS Feed XML 转换为 JSON 仅显示最后一个条目

Question

假设我有一个 RSS 源(XML 格式)，如下所示:

<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/"
    xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
    xmlns:slash="http://purl.org/rss/1.0/modules/slash/">

    <channel>
        <title>MyFeed</title>
        <atom:link href="http://samplefeed.com/feed/" rel="self"
            type="application/rss+xml" />
        <link>http://samplefeed.com</link>
        <description></description>
        <lastBuildDate>Fri, 22 Sep 2017 22:43:51 +0000</lastBuildDate>
        <language>en-US</language>
        <sy:updatePeriod>hourly</sy:updatePeriod>
        <sy:updateFrequency>1</sy:updateFrequency>
        <generator>http://wordpress.org/?v=4.3.12</generator>
        <item>
            <title>A Good Product</title>
            <link>http://samplefeed.com/a-good-product/</link>
            <comments>http://samplefeed.com/a-good-product/#comments</comments>
            <pubDate>Wed, 20 Sep 2017 22:22:45 +0000</pubDate>
            <dc:creator><![CDATA[John Smith]]></dc:creator>
            <category><![CDATA[Entertainment]]></category>

            <guid isPermaLink="false">http://samplefeed.com/?p=9116</guid>
            <description>
                <![CDATA[<p>![CDATA[<p>9/22</p>
                <p>4K TV Samsung<br />
                Price: $500.00<br />
                Location: Walmart</p>
                ]]>
            </description>
        </item>
        <!-- More items -->
    </channel>
</rss>  

使用了 varren 的建议，但它返回最后一个条目而不是所有条目...

public static void main(String[] args) throws MalformedURLException, IOException {
    XmlMapper xmlMapper = new XmlMapper(); // <- This is line 21 
    ObjectMapper jsonMapper = new ObjectMapper();
    InputStream xml = getInputStreamFromUrlData("http://samplefeed.com/feed");
    String json = jsonMapper.writeValueAsString(xmlMapper.readTree(xml));
    System.out.println(json);       
}

public static InputStream getInputStreamForURLData(String Url) {
    URL url = null;
    HttpURLConnection httpConnection = null;
    InputStream content = null;

    try {
        url = new URL(Url);
        System.out.println("URL: " + Url);
        URLConnection conn = url.openConnection();
        conn.setRequestProperty("User-Agent", "Mozilla/5.0");
        httpConnection = (HttpURLConnection) conn;

        int responseCode = httpConnection.getResponseCode();
        System.out.println("Response Code : " + responseCode);

        content = (InputStream) httpConnection.getInputStream();
    } 
    catch (MalformedURLException e) {
        e.printStackTrace();
    } 
    catch (IOException e) {
        e.printStackTrace();
    }
    return content;
}

pom.xml:

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.9.1</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.9.1</version>
    </dependency>

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-core-asl</artifactId>
        <version>1.7.9</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.8.10</version>
    </dependency>

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>1.7.9</version>
    </dependency>

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-xc</artifactId>
        <version>1.7.9</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-xml</artifactId>
        <version>2.9.1</version>
    </dependency>

现在的问题是它只返回 RSS Feed 中的最后一项而不是全部？!？它确实将其生成为 JSON，但仅显示最后一个条目。

为什么不显示所有条目？

任何人都可以建议一种不同的方法(例如如何使用 Rome 或直接 DOM 来做到这一点)？

Answer 1

其他人在使用 Jackson 将 xml 转换为 json 时也遇到问题，并且只得到最后一个元素:Converting xml to json using jackson

所以你可以尝试 JSON in Java 而不是 jackson 。 :

<dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20170516</version>
</dependency>

示例代码

import java.io.*;
import java.net.*;
import org.json.JSONObject;
import org.json.XML;
...
public static void main(String[] args) throws Exception {
    String xmlString = readUrlToString("http://www.feedforall.com/sample.xml");
    JSONObject xmlJSONObj = XML.toJSONObject(xmlString);
    String jsonPrettyPrintString = xmlJSONObj.toString(4);
    System.out.println(jsonPrettyPrintString);
}

public static String readUrlToString(String url) {
    BufferedReader reader = null;
    String result = null;
    try {
        URL u = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) u.openConnection();
        conn.setRequestProperty("User-Agent", "Mozilla/5.0");
        conn.setRequestMethod("GET");
        conn.setDoOutput(true);
        conn.setReadTimeout(2 * 1000);
        conn.connect();
        reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        StringBuilder builder = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            builder.append(line).append("\n");
        }
        result = builder.toString();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (reader != null) {
            try { reader.close(); } catch (IOException ignoreOnClose) { }
        }
    }
    return result;
}    

另请参阅:Quickest way to convert XML to JSON in Java