android java 文件操作相关
http://stackoverflow.com/questions/2130932/how-to-create-directory-automatically-on-sd-card
文件夹不存在时先创建
1: public static boolean createDirIfNotExists(String path) {
2: boolean ret = true;
3:
4: File file = new File(Environment.getExternalStorageDirectory(), path);
5: if (!file.exists()) {
6: if (!file.mkdirs()) {
7: Log.e("TravellerLog :: ", "Problem creating Image folder");
8: ret = false;
9: }
10: }
11: return ret;
12: }
确保sdcard可以读写
1: private boolean isExternalStoragePresent() {
2:
3: boolean mExternalStorageAvailable = false;
4: boolean mExternalStorageWriteable = false;
5: String state = Environment.getExternalStorageState();
6:
7: if (Environment.MEDIA_MOUNTED.equals(state)) {
8: // We can read and write the media
9: mExternalStorageAvailable = mExternalStorageWriteable = true;
10: } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
11: // We can only read the media
12: mExternalStorageAvailable = true;
13: mExternalStorageWriteable = false;
14: } else {
15: // Something else is wrong. It may be one of many other states, but
16: // all we need
17: // to know is we can neither read nor write
18: mExternalStorageAvailable = mExternalStorageWriteable = false;
19: }
20: if (!((mExternalStorageAvailable) &;& (mExternalStorageWriteable))) {
21: Toast.makeText(context, "SD card not present", Toast.LENGTH_LONG)
22: .show();
23:
24: }
25: return (mExternalStorageAvailable) &;& (mExternalStorageWriteable);
26: }
路径中不能有非法字符
1:
2: not allowed characters in file/folder names
3:
4: " * / : < > ? \ |
5: U may find this code helpful in such a case.
6: The below code removes all ":" and replaces them with "-"//actualFileName = "qwerty:asdfg:zxcvb" say...
7:
8: String[] tempFileNames;
9: String tempFileName ="";
10: String delimiter = ":";
11: tempFileNames = actualFileName.split(delimiter);
12: tempFileName = tempFileNames[0];
13: for (int j = 1; j < tempFileNames.length; j++){
14: tempFileName = tempFileName+" - "+tempFileNames[j];
15: }
16: File file = new File(Environment.getExternalStorageDirectory(), "/MyApp/"+ tempFileName+ "/");
17: if (!file.exists()) {
18: if (!file.mkdirs()) {
19: Log.e("TravellerLog :: ", "Problem creating Image folder");
20: }
21: }
下载图片保存到sdcard
1: package com.v3.thread.fetchImage;
2:
3: import java.io.File;
4: import java.io.FileOutputStream;
5: import java.io.IOException;
6: import java.io.InputStream;
7: import java.net.HttpURLConnection;
8: import java.net.MalformedURLException;
9: import java.net.URL;
10: import android.app.Activity;
11: import android.graphics.Bitmap;
12: import android.graphics.BitmapFactory;
13: import android.os.Bundle;
14: import android.os.Environment;
15: import android.provider.MediaStore;
16: import android.util.Log;
17: import android.view.View;
18: import android.widget.Button;
19: import android.widget.EditText;
20: import android.widget.ImageView;
21: import android.widget.Toast;
22:
23: public class MainThreadActivity extends Activity {
24: ImageView imView;
25: EditText ed1;
26: Bitmap bmImg;
27: Button bt, btSave;
28: String imageUrl = "";
29: int visibilty = 0;
30:
31: /** Called when the activity is first created. */
32: @Override
33: public void onCreate(Bundle icicle) {
34: super.onCreate(icicle);
35: setContentView(R.layout.main);
36: ed1 = (EditText) findViewById(R.id.edURL);
37: btSave = (Button) findViewById(R.id.btnSave);
38:
39: bt = (Button) findViewById(R.id.btnLoad);
40: bt.setOnClickListener(getImgListener);
41:
42: imView = (ImageView) findViewById(R.id.imview);
43: Log.i("img already downloaded", "img");
44: btSave.setOnClickListener(new View.OnClickListener() {
45: public void onClick(View arg0) {
46: Log.i("img url", "Under Save");
47: saveImage();
48: }
49: });
50: }
51:
52: View.OnClickListener getImgListener = new View.OnClickListener() {
53:
54: public void onClick(View view) {
55: // TODO Auto-generated method stub
56: imageUrl = ed1.getText().toString();
57: if (imageUrl.equals(""))
58:
59: Toast.makeText(getApplicationContext(), "Enter an URL first", 1000).show();
60: downloadFile(imageUrl);
61: Log.i("im url", imageUrl);
62: btSave.setVisibility(visibilty);
63: }
64:
65: };
66:
67: void downloadFile(String fileUrl) {
68: URL myFileUrl = null;
69: try {
70: myFileUrl = new URL(fileUrl);
71: } catch (MalformedURLException e) {
72: // TODO Auto-generated catch block
73: e.printStackTrace();
74: }
75: try {
76: HttpURLConnection conn = (HttpURLConnection) myFileUrl
77: .openConnection();
78: conn.setDoInput(true);
79: conn.connect();
80: InputStream is = conn.getInputStream();
81: Log.i("im connected", "Download");
82: bmImg = BitmapFactory.decodeStream(is);
83:
84: imView.setImageBitmap(bmImg);
85: } catch (IOException e) {
86: // TODO Auto-generated catch block
87: e.printStackTrace();
88: }
89: }
90:
91: void saveImage() {
92: File filename;
93: try {
94: String path = Environment.getExternalStorageDirectory().toString();
95: Log.i("in save()", "after mkdir");
96: new File(path + "/mvc/mvc").mkdirs();
97: filename = new File(path + "/mvc/mvc/var3.jpg");
98: Log.i("in save()", "after file");
99: FileOutputStream out = new FileOutputStream(filename);
100: Log.i("in save()", "after outputstream");
101: bmImg.compress(Bitmap.CompressFormat.JPEG, 90, out);
102: out.flush();
103: out.close();
104: Log.i("in save()", "after outputstream closed");
105: MediaStore.Images.Media.insertImage(getContentResolver(),
106: filename.getAbsolutePath(), filename.getName(),
107: filename.getName());
108: bt.setText("Saved...");
109: Toast.makeText(getApplicationContext(),
110: "File is Saved in " + filename, 1000).show();
111: } catch (Exception e) {
112: e.printStackTrace();
113: }
114:
115: }
116: }