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();
}
}
});
}
}