存储方式二:文件（XML DOM解析）

1.写

package com.example.filedemo;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.widget.Toast;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
			File file=new File(Environment.getExternalStorageDirectory()+File.separator+"files/addresslist.xml");
			if(!file.getParentFile().exists()){
				file.getParentFile().mkdirs();
			}
			try {
				DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
				DocumentBuilder builder=factory.newDocumentBuilder();
				Document doc=builder.newDocument();
				Element addresslist=doc.createElement("addresslist");
				Element linkman=doc.createElement("linkman");
				Element name=doc.createElement("name");
				Element email=doc.createElement("email");
				name.appendChild(doc.createTextNode("DanielHan"));
				email.appendChild(doc.createTextNode("[email protected]"));
				linkman.appendChild(name);
				linkman.appendChild(email);
				addresslist.appendChild(linkman);
				doc.appendChild(addresslist);
				
				TransformerFactory formerFac=TransformerFactory.newInstance();
				Transformer former=formerFac.newTransformer();
				DOMSource source= new DOMSource(doc);
				StreamResult result=new StreamResult(file);
				former.transform(source, result);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}else{
			Toast.makeText(this, "没有sdcard", Toast.LENGTH_LONG).show();
		}

		
	}
}

2.读

package com.example.filedemo;

import java.io.File;

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

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;

import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
	private TextView name=null;
	private TextView email=null;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		name=(TextView)findViewById(R.id.name);
		email=(TextView)findViewById(R.id.email);
		if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){
			File file=new File(Environment.getExternalStorageDirectory()+File.separator+"files/addresslist.xml");
			if(!file.exists()){//文件不存在
				return;
			}
			try {
				DocumentBuilderFactory factory=DocumentBuilderFactory.newInstance();
				DocumentBuilder builder=factory.newDocumentBuilder();
				Document doc=builder.parse(file);
				NodeList nodes=doc.getElementsByTagName("linkman");
				Element linkname=(Element)nodes.item(0);
				name.setText(linkname.getElementsByTagName("name").item(0).getFirstChild().getNodeValue());
				email.setText(linkname.getElementsByTagName("email").item(0).getFirstChild().getNodeValue());
			} catch (Exception e) {
				e.printStackTrace();
			}
		}else{
			Toast.makeText(this, "没有sdcard", Toast.LENGTH_LONG).show();
		}
	}
}