Android利用Document实现xml读取和写入操作

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:orientation="vertical"  tools:context="com.oak.d3_xml.MainActivity">   <TextView    android:id="@+id/tv"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="Hello World!" />  <Button    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="生成"    android:id="@+id/bt_create"/>  <Button    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="读取"    android:id="@+id/bt_read"/></LinearLayout>

package com.oak.d3_xml; import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.Button;import android.widget.TextView;import android.widget.Toast; import org.w3c.dom.Document;import org.w3c.dom.Element;import org.w3c.dom.NodeList;import org.xml.sax.SAXException; import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream; import javax.xml.parsers.DocumentBuilder;import javax.xml.parsers.DocumentBuilderFactory;import javax.xml.parsers.ParserConfigurationException;import javax.xml.transform.Transformer;import javax.xml.transform.TransformerConfigurationException;import javax.xml.transform.TransformerException;import javax.xml.transform.TransformerFactory;import javax.xml.transform.dom.DOMSource;import javax.xml.transform.stream.StreamResult;  public class MainActivity extends AppCompatActivity {  private TextView textView;//用于展示读取xml的内容  private Button bt_create;//用于创建xml文件  private Button bt_read;//用于读取xml文件  private File file;//xml文件路径  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    file = new File(getFilesDir(),"languages.xml");//获取到xml文件    textView = (TextView) findViewById(R.id.tv);//拿到textView控件    bt_create = (Button) findViewById(R.id.bt_create);//拿到创建按钮    bt_read = (Button) findViewById(R.id.bt_read);//拿到读取按钮     bt_create.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {        //这里利用的是dom对xml进行操作的        //实例化一个DocmentBuilderFactory，调用其静态方法获取        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();        try {          //实例化一个DocumentBuilder          DocumentBuilder builder = builderFactory.newDocumentBuilder();          //实例化一个xml文件          Document newxml = builder.newDocument();          //创建一个根标签          Element languages = newxml.createElement("languages");          //为其设置属性          languages.setAttribute("cat","it");          //for循坏3次，分别创建出三个标签，每个标签都包含内容          for (int i=0;i<3;i++){            //创建languages的子标签lan            Element lan = newxml.createElement("lan");            //设置属性            lan.setAttribute("id",i+"");            //创建lan的子标签            Element name = newxml.createElement("name");            //设置内容            name.setTextContent("Java"+i);            //创建lan的子标签            Element ide = newxml.createElement("ide");            //设置内容            ide.setTextContent("Eclipse"+i);            //将name和ide分别加入lan这个标签中            lan.appendChild(name);            lan.appendChild(ide);            //将lan将入languages标签中            languages.appendChild(lan);          }          //将languages加入到xml文件中          newxml.appendChild(languages);          //实例化Transformer工厂          TransformerFactory transformerFactory = TransformerFactory.newInstance();          //获取到Transformer          Transformer transformer = transformerFactory.newTransformer();          //设置输出格式          transformer.setOutputProperty("encoding","UTF-8");          //设置输出流          OutputStream os = new FileOutputStream(file);          //将文件写出          transformer.transform(new DOMSource(newxml),new StreamResult(os));          Toast.makeText(getApplicationContext(),"生成成功",Toast.LENGTH_SHORT).show();        } catch (ParserConfigurationException e) {          e.printStackTrace();        } catch (TransformerConfigurationException e) {          e.printStackTrace();        } catch (FileNotFoundException e) {          e.printStackTrace();        } catch (TransformerException e) {          e.printStackTrace();        }      }    });    bt_read.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {        //获取到DocumentBuilder的工厂实例化        DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();        try {          //拿到DocumentBuilder          DocumentBuilder builder = builderFactory.newDocumentBuilder();          //解析xml文件          Document xml = builder.parse(file);          //获取其根标签          Element languages = xml.getDocumentElement();          //根据子标签进行查找，返回的是一个list集合          NodeList list = languages.getElementsByTagName("lan");          textView.setText("");//将textView中的内容置空          for (int i=0; i<list.getLength(); i++){            //获取到子标签lan            Element lan = (Element) list.item(i);            //获取到他的属性            String id = lan.getAttribute("id");            //获取到他的子标签name的内容            String name = lan.getElementsByTagName("name").item(0).getTextContent();            //获取到他的子标签ide的内容            String ide = lan.getElementsByTagName("ide").item(0).getTextContent();            //显示到textView中            textView.append(id+"/n"+name+"/n"+ide+"/n");          }        } catch (ParserConfigurationException e) {          e.printStackTrace();        } catch (SAXException e) {          e.printStackTrace();        } catch (IOException e) {          e.printStackTrace();        }       }    });  }}