Question

我有一个像这样的XML文件

<persons>
<person>
<name>Joe</name>
<age>44</age>
</person>
</persons>

我想知道一种简单的方法来阅读它。我用我的代码

创建了这个xml文件

XmlSerializer serializador = Xml.newSerializer();

try{
    FileOutputStream file= openFileOutput("ff.xml",MODE_PRIVATE);
    serializador.setOutput(ff, "UTF-8");

    serializador.startDocument("UTF-8", true);
    serializador.startTag("", "persons");

    serializador.startTag("","person");
    serializador.text("joe");
    serializador.endTag("","person");

    serializador.startTag("","age");
    serializador.text("44");
    serializador.endTag("","age");

    serializador.endTag("", "persons");
    serializador.endDocument();

    Toast.makeText(this,"XML OK",Toast.LENGTH_SHORT).show();
}catch (Exception ex){
    txt1.setText(ex.toString());

}

现在我需要一个简单的方法来阅读它......以及如何在/myDir/here/ff.xml这样的路径中保存这个文件不在data/data/my_app/files

Answer 1

您可以使用Simple框架。我之前使用过它，并且很有趣，这是一项很棒的工作。尝试一下，你不会后悔：）

Answer 2

您可以使用XML Pull Parser或者也可以试用SAX Parser

，而不是手动阅读它

Answer 3

基本上有两种读取XML文件的方法：

使用DOM接口，这意味着将整个文档对象模型读入内存。
使用SAX界面意味着在阅读时处理XML文件。（适用于大文件）

如果你有一个XML文件，例如列出三个这样的员工：

<?xml version="1.0" encoding="UTF-8"?>
<Personnel>
   <Employee type="permanent">
        <Name>Seagull</Name>
        <Id>3674</Id>
        <Age>34</Age>
   </Employee>
  <Employee type="contract">
        <Name>Robin</Name>
        <Id>3675</Id>
        <Age>25</Age>
    </Employee>
  <Employee type="permanent">
        <Name>Crow</Name>
        <Id>3676</Id>
        <Age>28</Age>
    </Employee>
</Personnel>

您可以使用以下代码将其读入相应的Employee类：

import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class DomParserExample {

    //No generics
    List myEmpls;
    Document dom;


    public DomParserExample(){
        //create a list to hold the employee objects
        myEmpls = new ArrayList();
    }

    public void runExample() {

        //parse the xml file and get the dom object
        parseXmlFile();

        //get each employee element and create a Employee object
        parseDocument();

        //Iterate through the list and print the data
        printData();

    }


    /* (1) Get a document builder using document builder factory and 
     * parse the xml file to create a DOM object
     */
    private void parseXmlFile(){
        //get the factory
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

        try {

            //Using factory get an instance of document builder
            DocumentBuilder db = dbf.newDocumentBuilder();

            //parse using builder to get DOM representation of the XML file
            dom = db.parse("employees.xml");


        }catch(ParserConfigurationException pce) {
            pce.printStackTrace();
        }catch(SAXException se) {
            se.printStackTrace();
        }catch(IOException ioe) {
            ioe.printStackTrace();
        }
    }

    /* (2) Get a list of employee elements:
     *  Get the rootElement from the DOM object.
     *  From the root element get all employee elements. 
     *  Iterate through each employee element to load the data.
     */     
    private void parseDocument(){
        //get the root elememt
        Element docEle = dom.getDocumentElement();

        //get a nodelist of <employee> elements
        NodeList nl = docEle.getElementsByTagName("Employee");

        if(nl != null && nl.getLength() > 0) {
            for(int i = 0 ; i < nl.getLength();i++) {

                //get the employee element
                Element el = (Element)nl.item(i);

                //get the Employee object
                Employee e = getEmployee(el);

                //add it to list
                myEmpls.add(e);
            }
        }
    }


    /**
     * (3)For each employee element get the id,name,age and type. 
     * Create an employee value object and add it to the list.
     *  I take an employee element and read the values in, create
     * an Employee object and return it
     * @param empEl
     * @return
     */
    private Employee getEmployee(Element empEl) {

        //for each <employee> element get text or int values of 
        //name ,id, age and type
        String name = getTextValue(empEl,"Name");
        int id = getIntValue(empEl,"Id");
        int age = getIntValue(empEl,"Age");

        String type = empEl.getAttribute("type");

        //Create a new Employee with the value read from the xml nodes
        Employee e = new Employee(name,id,age,type);

        return e;
    }


    /**
     * I take a xml element and the tag name, look for the tag and get
     * the text content 
     * i.e for <employee><name>John</name></employee> xml snippet if
     * the Element points to employee node and tagName is name I will return John  
     * @param ele
     * @param tagName
     * @return
     */
    private String getTextValue(Element ele, String tagName) {
        String textVal = null;
        NodeList nl = ele.getElementsByTagName(tagName);
        if(nl != null && nl.getLength() > 0) {
            Element el = (Element)nl.item(0);
            textVal = el.getFirstChild().getNodeValue();
        }

        return textVal;
    }


    /**
     * Calls getTextValue and returns a int value
     * @param ele
     * @param tagName
     * @return
     */
    private int getIntValue(Element ele, String tagName) {
        //in production application you would catch the exception
        return Integer.parseInt(getTextValue(ele,tagName));
    }

    /**
     * Iterate through the list and print the 
     * content to console
     */
    private void printData(){

        System.out.println("No of Employees '" + myEmpls.size() + "'.");

        Iterator it = myEmpls.iterator();
        while(it.hasNext()) {
            System.out.println(it.next().toString());
        }
    }


    public static void main(String[] args){
        //create an instance
        DomParserExample dpe = new DomParserExample();

        //call run example
        dpe.runExample();
    }

}

轻松读取XML文件的方法

3 个答案: