Android操作SD卡文件

1）修改MainActivity.java代码如下

package com.example.androiddemo;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;import android.os.Bundle;import android.os.Environment;import android.app.Activity;import android.view.Menu;import android.view.View;import android.widget.Button;public class MainActivity extends Activity {private Button button1=null;private Button button2=null;/*获取sd card根目录路径*/private String rootPath=Environment.getExternalStorageDirectory().getPath();private File rootFolder=null;private File folder=null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);rootFolder=new File(rootPath);/*创建文件、文件夹*/button1=(Button)findViewById(R.id.button1);button1.setOnClickListener(new Button.OnClickListener() {@Overridepublic void onClick(View arg0) {/*创建文件夹*/folder=createFolder(rootFolder, "a_folder");/*创建子文件夹*/createFolder(folder, "b_folder");/*创建文件*/createFile(folder,"a.txt","test");}});/*删除文件、文件夹*/button2=(Button)findViewById(R.id.button2);button2.setOnClickListener(new Button.OnClickListener() {@Overridepublic void onClick(View v) {/*删除文件*/deleteFile(folder);}});}/*删除文件夹、文件夹*/private void deleteFile(File file){if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){if(file.exists()){if(file.isFile()){//文件直接删除file.delete();}if(file.isDirectory()){//文件夹File[] childfFiles=file.listFiles();if(childfFiles==null||childfFiles.length==0){//文件夹不存在子文件（文件夹）file.delete();}else {//文件夹中存在文件（子文件）for (File chilFile : childfFiles) {deleteFile(chilFile);}file.delete();}}}}}/*创建文件夹*/private File createFolder(File parentFolder,String folderName){File folder=null;if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){if(parentFolder.isDirectory()){folder=new File(parentFolder.getPath()+"/"+folderName);if(!folder.exists()){folder.mkdir();}}}return folder;}/*创建文件*/private File createFile(File parentFolder,String fileName,String text){File file=null;if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){if(parentFolder.isDirectory()){file=new File(parentFolder.getPath()+"/"+fileName);OutputStreamWriter osw;try {if(!file.exists()){file.createNewFile();osw=new OutputStreamWriter(new FileOutputStream(file),"utf-8");osw.write(text);osw.close();}else {osw=new OutputStreamWriter(new FileOutputStream(file,true),"utf-8");osw.write("\n");osw.write(text);osw.flush();osw.close();}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}return file;}@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;}}

2）在AndroidManifest.xml中添加权限代码如下

<!--添加访问扩展设备的权限 -->    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

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