activity的使用(十三):操作扩展卡

package com.example.androidtest;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.os.Environment;
import android.widget.TextView;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class AndroidTest extends Activity {
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		//setContentView(R.layout.activity_android_test);
		TextView textView = new TextView(this);
		setContentView(textView);
		String state = Environment.getExternalStorageState();
		if (!state.equals(Environment.MEDIA_MOUNTED)) {
			textView.setText("No external storage mounted");
		} else {
			File extenalDir = Environment.getExternalStorageDirectory();
			File textFile = new File(extenalDir.getAbsolutePath() + File.separator + "text.txt");
			
			try {
				writeTextFile(textFile, "This is a test");
				String text = readTextFile(textFile);
				textView.setText(text);
				
				if (!textFile.delete()) {
					textView.setText("Couldn't remove temporary file");
				}
			} catch (IOException e) {
				textView.setText("something went wrong! " + e.getMessage());
			}
		}
	}
	
	private void writeTextFile(File file, String text) throws IOException
	{
		BufferedWriter writer = new BufferedWriter(new FileWriter(file));
		writer.write(text);
		writer.close();
	}
	
	private String readTextFile(File file) throws IOException
	{
		BufferedReader reader = new BufferedReader(new FileReader(file));
		StringBuilder text = new StringBuilder();
		String line;
		
		while ((line = reader.readLine()) != null) {
			text.append(line);
			text.append("\n");
		}
		
		reader.close();
		
		return text.toString();
	}
	
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.android_test, menu);
		return true;
	}

	
}