实验 将内容存储在内存卡中

一.实验代码

package com.example.test1102;import java.io.BufferedReader;import java.io.BufferedWriter;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.OutputStreamWriter;import android.app.Activity;import android.content.Context;import android.os.Bundle;import android.os.Environment;import android.text.TextUtils;import android.view.Menu;import android.widget.EditText;import android.widget.Toast;public class MainActivity extends Activity{  private EditText edit;@Overrideprotected void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);edit = (EditText) findViewById(R.id.edit);String inputText=load();if (!TextUtils.isEmpty(inputText)) {edit.setText(inputText);edit.setSelection(inputText.length());Toast.makeText(this, "Restoring succeeded", Toast.LENGTH_SHORT).show();}  if(isHavedSDcard()){            try {                writeStr2SDCard(inputText);            } catch (Exception e) {                e.printStackTrace();            }        }        else{            showToast("您的手机没有内存卡哦!");        }      } public boolean isHavedSDcard() {        if (Environment.getExternalStorageState().equals(                Environment.MEDIA_MOUNTED))            return true;        else            return false;    } public String getRootPath() {        return Environment.getExternalStorageDirectory().toString();    }  public void showToast(String text) {        Toast.makeText(this, text, Toast.LENGTH_SHORT).show();    }         private void writeStr2SDCard(String str) throws Exception{        FileOutputStream fos = new FileOutputStream(getRootPath()+"/test.txt");        fos.write(str.getBytes());    }@Overrideprotected void onDestroy(){// TODO Auto-generated method stubsuper.onDestroy();String inputText = edit.getText().toString();save(inputText);}private void save(String inputText){// TODO Auto-generated method stubFileOutputStream out = null;BufferedWriter writer = null;try {out = openFileOutput("data", Context.MODE_PRIVATE);writer = new BufferedWriter(new OutputStreamWriter(out));writer.write(inputText);} catch (IOException e) {e.printStackTrace();} finally {try {if (writer != null) {writer.close();}} catch (IOException e) {e.printStackTrace();}}}public String load() {FileInputStream in = null;BufferedReader reader = null;StringBuilder content = new StringBuilder();try {in = openFileInput("data");reader = new BufferedReader(new InputStreamReader(in));String line = "";while ((line = reader.readLine()) != null) {content.append(line);}} catch (IOException e) {e.printStackTrace();} finally {if (reader != null) {try {reader.close();} catch (IOException e) {e.printStackTrace();}}}return content.toString();}@Overridepublic boolean onCreateOptionsMenu(Menu menu){// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}

二  实验心得

   首先要检测手机中是否有内存卡，如果不存在则给出提示，存在则新建test.txt，将内容存在文件中。在AndroidManifest.xml中要有注册，添加<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>代码。