Android 简单 XML 反序列化

Question

我正在尝试从此 graphml 创建节点和边缘对象。我有一些很好的建议，告诉我在进一步研究中使用多个包，它是我选择 simplexml 的 android 实现。

http://simple.sourceforge.net/download/stream/doc/tutorial/tutorial.php#nested

我从节点开始。我已经创建了我的节点类：

@Root(name="node")
public class DeserialisedNode implements Serializable {

    public DeserialisedNode() {
        super();
    }

    @Attribute(name = "id")
    private int iD;

    private String venueId;
    @Element(name = "name")
    private String name;
    @Element(name = "waypoint_type")
    private String type;
    @Element(name = "lat")
    private double latitude;
    @Element(name = "lon")
    private double longitude;
    @Element(name = "level_id")
    private int levelId;
    @Element(name = "on_starting_route")
    private String onStartingRoute;
    @Element(name = "on_finish_route")
    private String onFinishRoute;


    public DeserialisedNode(int iD, String name, String type, double latitude, double longitude, int levelId, String onStartingRoute, String onFinishRoute) {
        this.iD = iD;
        this.name = name;
        this.type = type;
        this.latitude = latitude;
        this.longitude = longitude;
        this.levelId = levelId;
        this.onStartingRoute = onStartingRoute;
        this.onFinishRoute = onFinishRoute;
    }
}

在我的 mainActivity 中我添加了：

 try {
            Serializer serializer = new Persister();
            AssetManager assetManager = getAssets();
            InputStream inputStream = assetManager.open("routing.xml");
            DeserialisedNode node = serializer.read(DeserialisedNode.class, inputStream);
            System.out.println("It worked! "+node.getClass().getName());
            System.out.println("It worked! "+node.getClass().getName());
        }
        catch (Exception e) {
            e.printStackTrace();
            System.out.println("error! "+e.getMessage());
        }

xml开头的例子：

<?xml version='1.0' encoding='utf-8'?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
  <key attr.name="weight" attr.type="double" for="edge" id="weight" />
  <key attr.name="edgeid" attr.type="string" for="edge" id="edgeid" />
  <key attr.name="alpha" attr.type="string" for="edge" id="alpha" />
  <key attr.name="intendedpathlonlat" attr.type="string" for="edge" id="intendedpathlonlat" />
  <key attr.name="levelid" attr.type="string" for="edge" id="levelid" />
  <key attr.name="weight" attr.type="long" for="edge" id="weight" />
  <key attr.name="type" attr.type="string" for="edge" id="type" />
  <key attr.name="relatedroutes" attr.type="string" for="node" id="relatedroutes" />
  <key attr.name="description" attr.type="string" for="node" id="description" />
  <key attr.name="title" attr.type="string" for="node" id="title" />
  <key attr.name="on_finish_route" attr.type="string" for="node" id="on_finish_route" />
  <key attr.name="on_starting_route" attr.type="string" for="node" id="on_starting_route" />
  <key attr.name="level_id" attr.type="string" for="node" id="level_id" />
  <key attr.name="waypoint_type" attr.type="string" for="node" id="waypoint_type" />
  <key attr.name="name" attr.type="string" for="node" id="name" />
  <key attr.name="lon" attr.type="string" for="node" id="lon" />
  <key attr.name="lat" attr.type="string" for="node" id="lat" />
  <graph edgedefault="directed" id="new id here">
    <node id="L08-022">
      <data key="lat">30.69330963</data>
      <data key="lon">-53.98752537</data>
      <data key="name" />
      <data key="waypoint_type">escalator</data>
      <data key="level_id">1080000</data>
      <data key="on_starting_route" />
      <data key="on_finish_route" />
    </node>
    <node id="L08-023">
      <data key="lat">30.69318355</data>
      <data key="lon">-53.98755793</data>
      <data key="name" />
      <data key="waypoint_type">stairs</data>
      <data key="level_id">1080000</data>
      <data key="on_starting_route" />
      <data key="on_finish_route" />
    </node>
etc......

我的错误是：

W/System.err: org.simpleframework.xml.core.AttributeException: Attribute 'schemaLocation' does not have a match in class com.app.model.maps.DeserialisedNode at line 2

我需要取出节点和边缘数据。

Answer 1

Java SimpleXML 库看起来主要用于将 Java 对象序列化为 XML。它确实支持反序列化（将 XML 解析为 Java）——但 documentation 说：

org.simpleframework.xml.stream - 在一组第三方库上提供 XML 解析层。流包提供了一个基于事件的 XML 解析框架，可以与多个第三方库（如 DOM、StAX 和 XML pull API）一起使用。

换句话说，它委托给其他包。

所以，这是一种 StAX 方法。这使用基于游标的 StAX XML 流阅读器（不是替代的 StAX 事件阅读器），因为正如“比较游标和迭代器 API”部分中所说的 here：

如果您正在为内存特别受限的环境（如 Java ME）进行编程，则可以使用游标 API 编写更小、更高效的代码。

这是方法。它只是解析输入文件并打印出相关部分。它不会尝试做更多的事情 - 只是为了演示如何访问您需要的数据项：

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import javax.xml.stream.XMLInputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.events.XMLEvent;

...

private final String fileNameString = "C:/tmp/files/graphml.xml";

public void read() throws XMLStreamException, FileNotFoundException {
    XMLInputFactory xmlif = XMLInputFactory.newInstance();
    XMLStreamReader xmlr = xmlif.createXMLStreamReader(fileNameString,
            new FileInputStream(fileNameString));

    while (xmlr.hasNext()) {
        int eventType = xmlr.next();

        if (eventType == XMLEvent.START_ELEMENT) {
            if (xmlr.getLocalName().equals("node")) {
                if (xmlr.getAttributeCount() == 1) { // a safety check
                    String nodeID = xmlr.getAttributeValue(0);
                    System.out.println("---");
                    System.out.println("Node ID: " + nodeID);
                }
            }
            if (xmlr.getLocalName().equals("data")) {
                if (xmlr.getAttributeCount() == 1) { // a safety check
                    String dataKey = xmlr.getAttributeValue(0);
                    String dataValue = xmlr.getElementText();
                    System.out.println("Data key: " + dataKey + " Data value: " + dataValue);
                }
            }
        }
    }
}

关键部分是XMLStreamReader 对象，它让您可以简单地访问每个标签的文本内容，以及它的属性。

根据 SimpleXML 规范，应该可以从 SimpleXML 中使用它——但我没有尝试过。或者，您也可以完全不使用 SimpleXML 来使用 StAX。

在我的情况下，这将打印以下输出：

Node ID: L08-022
Data key: lat Data value: 40.69330963
Data key: lon Data value: -73.98752537
Data key: name Data value: 
Data key: waypoint_type Data value: escalator
Data key: level_id Data value: 1080000
Data key: on_starting_route Data value: 
Data key: on_finish_route Data value: 
---
Node ID: L08-023
Data key: lat Data value: 40.69318355
Data key: lon Data value: -73.98755793
Data key: name Data value: 
Data key: waypoint_type Data value: stairs
Data key: level_id Data value: 1080000
Data key: on_starting_route Data value: 
Data key: on_finish_route Data value: 
---
Node ID: L08-024
Data key: lat Data value: 40.69316844
Data key: lon Data value: -73.98755873
Data key: name Data value: 
Data key: waypoint_type Data value: stairs
Data key: level_id Data value: 1080000
Data key: on_starting_route Data value: 
Data key: on_finish_route Data value: 

我使用的示例文件是这样的：

<?xml version='1.0' encoding='utf-8'?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
<key attr.name="weight" attr.type="double" for="edge" id="weight" />
  <key attr.name="edgeid" attr.type="string" for="edge" id="edgeid" />
  <key attr.name="alpha" attr.type="string" for="edge" id="alpha" />
  <key attr.name="intendedpathlonlat" attr.type="string" for="edge" id="intendedpathlonlat" />
  <key attr.name="levelid" attr.type="string" for="edge" id="levelid" />
  <key attr.name="weight" attr.type="long" for="edge" id="weight" />
  <key attr.name="type" attr.type="string" for="edge" id="type" />
  <key attr.name="relatedroutes" attr.type="string" for="node" id="relatedroutes" />
  <key attr.name="description" attr.type="string" for="node" id="description" />
  <key attr.name="title" attr.type="string" for="node" id="title" />
  <key attr.name="on_finish_route" attr.type="string" for="node" id="on_finish_route" />
  <key attr.name="on_starting_route" attr.type="string" for="node" id="on_starting_route" />
  <key attr.name="level_id" attr.type="string" for="node" id="level_id" />
  <key attr.name="waypoint_type" attr.type="string" for="node" id="waypoint_type" />
  <key attr.name="name" attr.type="string" for="node" id="name" />
  <key attr.name="lon" attr.type="string" for="node" id="lon" />
  <key attr.name="lat" attr.type="string" for="node" id="lat" />
  <graph edgedefault="directed" id="new id here">
    <node id="L08-022">
      <data key="lat">40.69330963</data>
      <data key="lon">-73.98752537</data>
      <data key="name" />
      <data key="waypoint_type">escalator</data>
      <data key="level_id">1080000</data>
      <data key="on_starting_route" />
      <data key="on_finish_route" />
    </node>
    <node id="L08-023">
      <data key="lat">40.69318355</data>
      <data key="lon">-73.98755793</data>
      <data key="name" />
      <data key="waypoint_type">stairs</data>
      <data key="level_id">1080000</data>
      <data key="on_starting_route" />
      <data key="on_finish_route" />
    </node>
    <node id="L08-024">
      <data key="lat">40.69316844</data>
      <data key="lon">-73.98755873</data>
      <data key="name" />
      <data key="waypoint_type">stairs</data>
      <data key="level_id">1080000</data>
      <data key="on_starting_route" />
      <data key="on_finish_route" />
    </node>
  </graph>
</graphml>