//访问sdcar需要授权WRITE_EXTERNAL_STORAGE
1 //---------------------写-----------------------
2 public boolean saveFileToSdcard(String fileName, byte[] data) {
3 boolean flag = false;
4 // 先判断sdcard的状态；
5 String state = Environment.getExternalStorageState();
6 // 表示sdcard挂载在手机上，并且可以读写
7 FileOutputStream outputStream = null;
8 // 获得sdcard的根目录/mnt/sdcard/.....
9 File root = Environment.getExternalStorageDirectory();
10
11 if (state.equals(Environment.MEDIA_MOUNTED)) {
12 // File file =new File(root, fileName);//在sdcard根目录上创建一个文件
13 File file = new File(root.getAbsolutePath() + "/txt");// 创建一个TXT文件夹再存
14 if (!file.exists()) {
15 file.mkdirs();
16 }
17 try {
18 // outputStream=new FileOutputStream(file);
19 outputStream = new FileOutputStream(new File(file, fileName));
20 outputStream.write(data, 0, data.length);
21 flag = true;
22 } catch (Exception e) {
23 // TODO: handle exception
24 e.printStackTrace();
25 } finally {
26 if (outputStream != null) {
27 try {
28 outputStream.close();
29 } catch (Exception e2) {
30 // TODO: handle exception
31 e2.printStackTrace();
32 }
33
34 }
35
36 }
37
38 }
39 return flag;
40 }
-------------测试------------------------
1 public void save(){
2 FileService service=new FileService();
3 service.saveFileToSdcard("aa.txt", "zy520".getBytes());
4
5 }
----------------------------------
1 //----------------------------------读文件内容-----------------------
2 public String readContextFromSdcard(String fileName) {
3 File root=Environment.getExternalStorageDirectory();
4 FileInputStream inputStream=null;
5 ByteArrayOutputStream outputStream=new ByteArrayOutputStream();
6 if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
7 File file = new File(root.getAbsolutePath() + "/txt/");
8 File file2=new File(file, fileName);
9 int len=0;
10 byte[]data=new byte[1024];
11
12
13 if (file2.exists()) {
14 try {
15 inputStream=new FileInputStream(file2);
16 while((len=inputStream.read(data))!=-1){
17 outputStream.write(data, 0, len);
18
19
20 }
21 return new String(outputStream.toByteArray());
22 } catch (Exception e) {
23 // TODO: handle exception
24 e.printStackTrace();
25 }finally{
26 if (inputStream!=null) {
27 try {
28 inputStream.close();
29 } catch (Exception e2) {
30 // TODO: handle exception
31 e2.printStackTrace();
32 }
33
34 }
35 }
36
37 }
38 }
39
40 return null;
41 }
------------测试--------------------
1 public void read(){
2 FileService service=new FileService();
3 String msg =service.readContextFromSdcard("aa.txt");
4 System.out.println("---->>"+msg);
5
6
7 }
-------------下载图片到sdcard再从sdcard中读出来----------------------------
1 public class ImageCache {
2 public static String saveImageCache(String fileName, byte[] data) {
3
4 File file = Environment.getExternalStorageDirectory();
5 FileOutputStream outputStream = null;
6 if (Environment.getExternalStorageState().equals(
7 Environment.MEDIA_MOUNTED)) {
8 try {
9 outputStream = new FileOutputStream(new File(file, fileName));
10 outputStream.write(data, 0, data.length);
11
12 return file.getAbsolutePath()+"/"+fileName;
13 } catch (Exception e) {
14 // TODO: handle exception
15 e.printStackTrace();
16 }finally{
17 if (outputStream!=null) {
18 try {
19 outputStream.close();
20 } catch (Exception e2) {
21 // TODO: handle exception
22 e2.printStackTrace();
23 }
24 }
25 }
26 }
27
28 return null;
29 }
30 }
---------------------------------------------
1 public class MainActivity extends ActionBarActivity {
2 private Button button;
3 private ImageView imageView;
4 private ProgressDialog dialog;
5 private String path ="https://www.baidu.com/img/bd_logo1.png";
6
7 @Override
8 protected void onCreate(Bundle savedInstanceState) {
9 super.onCreate(savedInstanceState);
10 setContentView(R.layout.fragment_main);
11 dialog = new ProgressDialog(this);
12 dialog.setTitle("提示");
13 dialog.setMessage("load.....");
14 button = (Button) findViewById(R.id.button1);
15 imageView = (ImageView) findViewById(R.id.imageView1);
16 button.setOnClickListener(new View.OnClickListener() {
17
18 @Override
19 public void onClick(View v) {
20 // TODO Auto-generated method stub
21 new MyTask().execute(path);
22 }
23 });
24
25 }
26
27 class MyTask extends AsyncTask<String, Void, byte[]> {
28 private String imageName;
29 @Override
30 protected void onPreExecute() {
31 // TODO Auto-generated method stub
32 super.onPreExecute();
33 dialog.show();
34 }
35
36 @Override
37 protected byte[] doInBackground(String... params) {
38 // TODO Auto-generated method stub
39 try {
40 String name=params[0];
41 //截取图片名称：bd_logo1.png
42 imageName=name.substring(name.lastIndexOf("/")+1, name.length());
43 } catch (Exception e) {
44 // TODO: handle exception
45 }
46
47 return HttpUtils.getImage(params[0]);
48 }
49
50 @Override
51 protected void onPostExecute(byte[] result) {
52 // TODO Auto-generated method stub
53 super.onPostExecute(result);
54 if (result != null) {
55 Bitmap bitmap=BitmapFactory.decodeByteArray(result, 0, result.length);
56 imageView.setImageBitmap(bitmap);
57 ImageCache.saveImageCache(imageName, result);
58
59 } else {
60 imageView.setImageResource(R.drawable.ic_launcher);
61 }
62
63 dialog.dismiss();
64 }
65
66 }
1 public class HttpUtils {
2 public static byte[] getImage(String path){
3 byte[]data=null;
4 HttpClient httpClient=new DefaultHttpClient();
5 HttpPost post =new HttpPost(path);
6 try {
7 HttpResponse response=httpClient.execute(post);
8
9 if (response.getStatusLine().getStatusCode()==200) {
10 data=EntityUtils.toByteArray(response.getEntity());
11 }
12 } catch (Exception e) {
13 // TODO: handle exception
14 e.printStackTrace();
15 }finally{
16 httpClient.getConnectionManager().shutdown();
17 }
18
19
20 return data;
21 }
22 }
、、------------------------------------------------------
1 //---------------保存指定的SDcard目录----------
2 public void saveFileToSdcardBySuff(String fileName,byte [] data){
3
4 //保存文件的目录
5 File file=null;
6 if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
7 if (fileName.endsWith(".mp3")) {
8 file=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MUSIC);
9
10 }else if (fileName.endsWith(".jpg")||fileName.endsWith(".png")||fileName.endsWith(".gif")) {
11 file=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);
12 }else if (fileName.endsWith(".mp4")||fileName.endsWith(".3gp")) {
13 file=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_MOVIES);
14
15 }else {
16 file=Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
17 }
18 }
19 FileOutputStream outputStream=null;
20 try {
21 outputStream=new FileOutputStream(new File(file,fileName));
22 outputStream.write(data,0, data.length);
23 } catch (Exception e) {
24 // TODO: handle exception
25 e.printStackTrace();
26 }finally{
27 try {if (outputStream!=null) {
28 outputStream.close();
29 }
30
31 } catch (Exception e2) {
32 // TODO: handle exception
33 }
34
35 }
36
37 }
------------------------------测试---------------------------------------
1 public void save2(){
2 FileService service=new FileService();
3 service.saveFileToSdcardBySuff("aa.txt", "zy520".getBytes());
4
5 }
6
---------------------------删除----------------------------------------
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.getAbsolutePath()+"/"+folder+"/"+fileName);
if (exitfile.exists()) {
flag=exitfile.delete();
}
}
return flag;
}
----------------测试-------------------------
1 public void del(){
2 FileService service=new FileService();
3 boolean flag =service.deleteFileFromSdcard("txt","aa.txt");
4 System.out.println("---->>"+flag);
5
6
7 }
时间： 2024-10-23 23:08:26