XmlParser

網路上一堆範例不如自己作一遍還來的了解

直接切入主題,這裡使用DOM來轉換xml,以步驟來說明

Step1.

首先要有xml檔放到assets資料夾中,為了方便整理在assets 資料夾中另外開了一個xmlfiles資料夾,路徑如下

Project/assets/xmlfiles/command_simple_formatter.xml
<?xml version="1.0" encoding="utf-8"?>
<commands>
    <command
        id="1"
        enable="true"
        function_name="function1"
        type="FLOAT" />
    <command
        id="2"
        enable="false"
        function_name="function2"
        type="FIXED" />
</commands>

Step2.
接著建立對應的資料結構,根據xml中的tag來建立

Command.java
public class Command
{
    private int mIndex;
    private String mFunction;
    private boolean mEnable;
    private Type mType;
 
    public enum Type {
        FIXED, FLOAT
    }
 
    public void setType(Type type){
        mType = type;
    }
 
    public Type getType(){
        return mType;
    }
 
    public void setIndex(int index)
    {
        mIndex = index;
    }

    public void setFunction(String function)
    {
        mFunction = function;
    }

    public int getIndex()
    {
        return mIndex;
    }

    public String getFunction()
    {
        return mFunction;
    }
 
    public boolean getEnable(){
        return mEnable;
    }
 
    public void setEnable(boolean enable){
        mEnable = enable;
    }
}

Step3.
接著開始撰寫轉換的本體,這裡我帶入Template Method,
XmlParser.java
public abstract class XmlParser
{
    private Context mContext;

    public XmlParser(Context context) {
        mContext = context;
    }

    public final List<?> parserProcess(String xmlFileName)
    {
        Document document = prepareParseComponent(xmlFileName);
        Element root = getXmlBasicRootElement(document);
        List<?> javaDatas = parseXmlContentToJavaObjects(root);

        return javaDatas;
    }
 
    private Document prepareParseComponent(String xmlFileName)
    {
        DocumentBuilder documentBuilder = getDocumentBuilder();
        InputStream inputStream = getXmlInputStream(xmlFileName);
        Document document = null;
        try {
            document = documentBuilder.parse(inputStream);
        } catch (SAXException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return document;
    }

    protected abstract List<?> parseXmlContentToJavaObjects(Element root);
 
    private DocumentBuilder getDocumentBuilder()
    {
        DocumentBuilder documentBuilder = null;
        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
        try {
            documentBuilder = builderFactory.newDocumentBuilder();
        } catch (ParserConfigurationException e) {
            e.printStackTrace();
        }

        return documentBuilder;
    }

    /**
     *
     * @param xmlFileName : xml file need put in assets folder
     * @return InputStream
     */
    private InputStream getXmlInputStream(String xmlFileName)
    {
        AssetManager assetManager = mContext.getAssets();
        InputStream inputStream = null;
        try {
            inputStream = assetManager.open(xmlFileName);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return inputStream;
    }

    private Element getXmlBasicRootElement(Document document)
    {
        Element root = document.getDocumentElement();
        return root;
    }
}

Step4.
建立繼承XmlParser的類別,主要複寫parseXmlContentToJavaObjects方法
CommandSimpelXmlParser.java
public class CommandSimpleXmlParser extends XmlParser
{
    private String mElementName = "command";
    private String mId = "id";
    private String mFunctionName = "function_name";
    private String mEnable = "enable";
    private String mType = "type";
 
    public CommandSimpleXmlParser(Context context) {
        super(context);
    }

    @Override
    protected List<Command> parseXmlContentToJavaObjects(Element root)
    {
        NodeList commandNode = root.getElementsByTagName(mElementName);
        int commandsNodeSize = commandNode.getLength();
        return transXmlToCommand(commandNode,commandsNodeSize);
    }
 
    private List<Command> transXmlToCommand(NodeList nodeList,int size){
        List<Command> result = new ArrayList<Command>();
        for (int i = 0; i < size; ++i) {
            Command command = new Command();
            Element commandElement = (Element) nodeList.item(i);
            command.setIndex(transXmlIdTagToCommand(
                    commandElement, mId));
            command.setFunction(transXmlFunctionNameTagToCommand(
                    commandElement, mFunctionName));
            command.setEnable(transXmlEnableTagToCommand(
                    commandElement, mEnable));
            command.setUIType(trnasXmlTypeToCommand(
                    commandElement, mType));
            result.add(command);
            command = null;
        }
        return result;
    }
 
    private UIType trnasXmlTypeToCommand(Element element,String type){
        return Command.Type.valueOf(element.getAttribute(type));
    }
 
    private int transXmlIdTagToCommand(Element element,String id){
        return Integer.valueOf(element.getAttribute(id));
    }
 
    private String transXmlFunctionNameTagToCommand(Element element,String functionName){
        return element.getAttribute(functionName);
    }
 
    private boolean transXmlEnableTagToCommand(Element element,String enable){
        return Boolean.valueOf(element.getAttribute(enable));
    }
}

Step5.
使用轉換
XmlParserMainActivity.java
public class XmlParserMainActivity extends Activity
{
    private static final String TAG = "XmlParserMainActivity";
    private static final String COMMAND_SIMPLE_XML_FILE_PATH = "xmlfiles/command_simple_formatter.xml";
 
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        examParseSimpleXml(COMMAND_SIMPLE_XML_FILE_PATH);
    }

    private void examParseSimpleXml(String xmlFilePath)
    {
        XmlParser simpleCommandXmlParser = new CommandSimpleXmlParser(this);
        List<Command> commands = (List<Command>) simpleCommandXmlParser
                .parserProcess(xmlFilePath);
    }

}

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