Android利用Document实现xml读取和写入操作

<?  version=\"1.0\" encoding=\"utf-8\"?>
<LinearLayout  ns:android=\"http://schemas.android.com/apk/res/android\"
   ns:tools=\"http://schemas.android.com/tools\"
  android:layout_width=\"match_parent\"
  android:layout_height=\"match_parent\"
  android:orientation=\"vertical\"
  tools:context=\"com.oak.d3_ .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_ ;
 
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. .sax.SAXException;
 
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
 
import javax. .parsers.DocumentBuilder;
import javax. .parsers.DocumentBuilderFactory;
import javax. .parsers.ParserConfigurationException;
import javax. .transform.Transformer;
import javax. .transform.TransformerConfigurationException;
import javax. .transform.TransformerException;
import javax. .transform.TransformerFactory;
import javax. .transform.dom.DOMSource;
import javax. .transform.stream.StreamResult;
 
 
public class MainActivity extends AppCompatActivity {
  private TextView textView;//用于展示读取 的内容
  private Button bt_create;//用于创建 文件
  private Button bt_read;//用于读取 文件
  private File file;// 文件路径
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    file = new File(getFilesDir(),\"languages. \");//获取到 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.set Listener(new View. Listener() {
      @Override
      public void  (View view) {
        //这里利用的是dom对 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 文件
          Document new  = builder.newDocument();
          //创建一个根标签
          Element languages = new .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 = new .createElement(\"lan\");
            //设置属性
            lan.setAttribute(\"id\",i+\"\");
            //创建lan的子标签
            Element name = new .createElement(\"name\");
            //设置内容
            name.setTextContent(\"Java\"+i);
            //创建lan的子标签
            Element ide = new .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 文件中
          new .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(new ),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.set Listener(new View. Listener() {
      @Override
      public void  (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 文件
          Document   = builder.parse(file);
          //获取其根标签
          Element languages =  .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();
        }
 
      }
    });
  }
}