（1）文件的目录
（2）各文件的代码：
FileService.java也就是操作sdcard的工具类：package com.example.data_storage_sdcard.file;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import android.os.Environment;/** * sdcard的存在于上下文无关 * * @author piaodangdehun * */public class FileService { /* * 存放在sdcard的根目录 */ public boolean saveFileToSdcardRoot(String fileName, byte[] data) { boolean flag = false; /* * 先判断sdcard的状态，是否存在 */ String state = Environment.getExternalStorageState(); FileOutputStream utputStream = null; File rootFile = Environment.getExternalStorageDirectory(); // 获得sdcard的根路径 /* * 表示sdcard挂载在手机上，并且可以读写 */ if (state.equals(Environment.MEDIA_MOUNTED)) { File file = new File(rootFile, fileName); try { utputStream = new FileOutputStream(file); try { outputStream.write(data, 0, data.length); flag = true; } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { e.printStackTrace(); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } return flag; } /* * 存放在sdcard下自定义的目录 */ public boolean saveFileToSdcardDir(String fileName, byte[] data) { boolean flag = false; /* * 先判断sdcard的状态，是否存在 */ String state = Environment.getExternalStorageState(); FileOutputStream utputStream = null; File rootFile = Environment.getExternalStorageDirectory(); // 获得sdcard的根路径 /* * 表示sdcard挂载在手机上，并且可以读写 */ if (state.equals(Environment.MEDIA_MOUNTED)) { File file = new File(rootFile.getAbsoluteFile() + /txt); if (!file.exists()) { file.mkdirs(); } try { utputStream = new FileOutputStream(new File(file, fileName)); try { outputStream.write(data, 0, data.length); flag = true; } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { e.printStackTrace(); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } return flag; } /* * 用于读取sdcard的数据 */ public String readContextFromSdcard(String fileName) { String state = Environment.getExternalStorageState(); File rooFile = Environment.getExternalStorageDirectory(); // 获得sdcard的目录 FileInputStream inputStream = null;// 用于度取数据的流 ByteArrayOutputStream utputStream = new ByteArrayOutputStream(); // 用于存放独处的数据 if (state.equals(Environment.MEDIA_MOUNTED)) { File file = new File(rooFile.getAbsoluteFile() + /txt/);// 在sdcard目录下创建一个txt目录 File file2 = new File(file, fileName); int len = 0; byte[] data = new byte[1024]; if (file2.exists()) { try { inputStream = new FileInputStream(file2); try { while ((len = inputStream.read(data)) != -1) { outputStream.write(data, 0, data.length); } } catch (IOException e) { e.printStackTrace(); } return new String(outputStream.toByteArray()); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } } return null; } /** * 对文件进行分类的保存到固定的文件中去 * * @param fileName * @param data */ public void saveFileToSdcardBySuff(String fileName, byte[] data) { // File file = Environment.getExternalStoragePublicDirectory(); // 保存文件的目录 File file = null; if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED)) { /* * 将不同的文件放入到不同的类别中 */ if (fileName.endsWith(.mp3)) { file = Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC); } else if (fileName.endsWith(.jpg) || fileName.endsWith(.png) || fileName.endsWith(.gif)) { file = Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES); } else if (fileName.endsWith(.mp4) || fileName.endsWith(.avi) || fileName.endsWith(.3gp)) { file = Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES); } else { file = Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS); } FileOutputStream utputStream = null; try { utputStream = new FileOutputStream(new File(file, fileName)); try { outputStream.write(data, 0, data.length); } catch (IOException e) { e.printStackTrace(); } } catch (FileNotFoundException e) { e.printStackTrace(); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } } /* * 删除一个文件 */ public boolean deleteFileFromSdcard(String folder, String fileName) { boolean flag = false; File file = Environment.getExternalStorageDirectory(); if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED)) { File exitFile = new File(file.getAbsoluteFile() + / + folder); if (exitFile.exists()) { exitFile.delete(); } } return flag; }}HttpUtils.java访问网络的
package com.example.data_storage_sdcard.http;import java.io.IOException;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.util.EntityUtils;public class HttpUtils { /* * */ public static byte[] getImage(String path) { byte[] data = null; HttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(path); try { HttpResponse response = httpClient.execute(httpPost); if (response.getStatusLine().getStatusCode() == 200) { data = EntityUtils.toByteArray(response.getEntity()); } } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { httpClient.getConnectionManager().shutdown(); } return data; }}ImageCache.java将文件放到cache中的：
package com.example.data_storage_sdcard.img;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import android.os.Environment;public class ImageCache { public static String saveImageCache(String fileName, byte[] data) { File file = Environment.getExternalStorageDirectory(); // 根目录 FileOutputStream utputStream = null; if (Environment.getExternalStorageState().equals( Environment.MEDIA_MOUNTED)) { try { utputStream = new FileOutputStream(new File(file, fileName)); outputStream.write(data, 0, data.length); return file.getAbsolutePath() + / + fileName; } catch (Exception e) { e.printStackTrace(); } finally { if (outputStream != null) { try { outputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } } return null; }}MainActivity.java
package com.example.data_storage_sdcard;import android.app.Activity;import android.app.ProgressDialog;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.AsyncTask;import android.os.Bundle;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import com.example.data_storage_sdcard.http.HttpUtils;import com.example.data_storage_sdcard.img.ImageCache;public class MainActivity extends Activity { private Button button; private ImageView imageView; private ProgressDialog progressDialog; private String imageName; private final String pathString = http://www.baidu.com/img/bd_logo1.png; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); button = (Button) this.findViewById(R.id.button1); imageView = (ImageView) this.findViewById(R.id.imageView1); progressDialog = new ProgressDialog(this); progressDialog.setTitle(下载提示); progressDialog.setMessage(load...); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { new MyTask().execute(pathString); } }); } class MyTask extends AsyncTask<string,>{ @Override protected void onPreExecute() { super.onPreExecute(); progressDialog.show(); } @Override protected byte[] doInBackground(String... params) { String name = params[0]; imageName = name .substring(name.lastIndexOf(/) + 1, name.length()); return HttpUtils.getImage(params[0]); } @Override protected void onProgressUpdate(Void... values) { super.onProgressUpdate(values); } @Override protected void onPostExecute(byte[] result) { super.onPostExecute(result); if (result != null) { Bitmap bm = BitmapFactory.decodeByteArray(result, 0, result.length); imageView.setImageBitmap(bm); ImageCache.saveImageCache(, result); } else { imageView.setImageResource(R.drawable.ic_launcher); } progressDialog.dismiss(); } } @Override public 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; }}</string,>测试类：
package com.example.data_storage_sdcard;import java.io.FileWriter;import com.example.data_storage_sdcard.file.FileService;import android.nfc.Tag;import android.test.AndroidTestCase;import android.util.Log;public class MyTest extends AndroidTestCase { public void saveFileToSdcardTest() { FileService fileService = new FileService(); fileService.saveFileToSdcardRoot(aa.txt, jkhdsfjkhdskjfhdsjf.getBytes()); } public void saveFileToSdcardDir() { FileService fileService = new FileService(); fileService.saveFileToSdcardRoot(aa.txt, jkhdsfjkhdskjfhdsjf.getBytes()); } public void readContextFromSdcardTest() { FileService fileService = new FileService(); String msg = fileService.readContextFromSdcard(aa.txt); System.err.println(--> + msg); } public void saveFileToSdcardBySuffTest() { FileService fileService = new FileService(); fileService.saveFileToSdcardBySuff(aa.avi, asdfkajsgdhagsdfhdgsf.getBytes()); } public void delFile() { FileService fileService = new FileService(); boolean flag = fileService.deleteFileFromSdcard(txt, aa.txt); }}需要在请单位按中加入访问网络的权限、操作sdcard的权限、测试的权限
<manifest android:versioncode="1" android:versionname="1.0" package="com.example.data_storage_sdcard" xmlns:android="http://schemas.android.com/apk/res/android"><uses-sdk android:minsdkversion="8" android:targetsdkversion="18"><instrumentation android:name="android.test.InstrumentationTestRunner" android:targetpackage="com.example.data_storage_sdcard"></instrumentation><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"><uses-permission android:name="android.permission.INTERNET"><uses-library android:name="android.test.runner"><intent-filter><category android:name="android.intent.category.LAUNCHER"></category></intent-filter><uses-library></uses-library></uses-library></uses-permission></uses-permission></uses-sdk></manifest>