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 {@Overrideprotected 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();}@Overridepublic 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;}}