Android开发代码打开文件管理选择文件，获取路径读取修改文件内容
记录一下Android开发中，获取某文件路径的方法。
1.点击按钮，弹出设备自带的文件管理。
public void onClick(DialogInterface dialogInterface, int i) {
if (i == 0) {
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");
intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, false);
intent.addCategory(Intent.CATEGORY_OPENABLE);
startActivityForResult(intent, FILE_REQUEST_CODE);
} else if (i == 1) {
Intent intent = new Intent(MainActivity.this, MH3300ManagerActivity.class);
startActivity(intent);
}
}
2.获取返回的文件路径
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK && requestCode == FILE_REQUEST_CODE) {
if (data.getData() != null) {
try {
Uri uri = data.getData();
String path = UriUtil.getPath(this, uri);
String fileType = path.substring(path.indexOf(".") + 1);
if (!fileType.contains("txt")) {
//不是想要的txt文件
return;
}
file = new File(path);
} catch (Exception e) {
}
}
}
}
3.UriUtil工具类的代码
/**
* 专为Android4.4设计的从Uri获取文件绝对路径，以前的方法已不好使
*/
@SuppressLint("NewApi")
public static String getPath(final Context context, final Uri uri) {
final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
if ("primary".equalsIgnoreCase(type)) {
return Environment.getExternalStorageDirectory() + "/" + split[1];
}
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {
final String id = DocumentsContract.getDocumentId(uri);
final Uri contentUri = ContentUris.withAppendedId(
Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
final String docId = DocumentsContract.getDocumentId(uri);
final String[] split = docId.split(":");
final String type = split[0];
Uri contentUri = null;
if ("image".equals(type)) {
contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
} else if ("video".equals(type)) {
contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
} else if ("audio".equals(type)) {
contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
}
final String selection = "_id=?";
final String[] selectionArgs = new String[]{split[1]};
return getDataColumn(context, contentUri, selection, selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) {
return uri.getPath();
}
return null;
}
/**
* Get the value of the data column for this Uri. This is useful for
* MediaStore Uris, and other file-based ContentProviders.
*
* @param context The context.
* @param uri The Uri to query.
* @param selection (Optional) Filter used in the query.
* @param selectionArgs (Optional) Selection arguments used in the query.
* @return The value of the _data column, which is typically a file path.
*/
public static String getDataColumn(Context context, Uri uri, String selection,
String[] selectionArgs) {
Cursor cursor = null;
final String column = "_data";
final String[] projection = {column};
try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs,
null);
if (cursor != null && cursor.moveToFirst()) {
final int column_index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(column_index);
}
} finally {
if (cursor != null)
cursor.close();
}
return null;
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is ExternalStorageProvider.
*/
public static boolean isExternalStorageDocument(Uri uri) {
return "com.android.externalstorage.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is DownloadsProvider.
*/
public static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}
/**
* @param uri The Uri to check.
* @return Whether the Uri authority is MediaProvider.
*/
public static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}
4.打开文件读取内容
/**
* 读取数据
*/
private void hanlerData() {
try {
InputStreamReader isr = new InputStreamReader(new FileInputStream(file), "GB2312");
BufferedReader read = new BufferedReader(isr);
String str;
int count = 0;
List<String> nameArr = new ArrayList<>();
List<String> valueArr = new ArrayList<>();
while ((str = read.readLine()) != null) {
Log.i(TAG, "DataHandler: " + str);
count++;
String[] arr = str.split("\t");
for(String s:arr){
if(count ==1){
s=s.trim();
nameArr.add(s);
}
if(count ==2){
s=s.trim();
valueArr.add(s);
}
}
}
dataList.clear();
for(int i = 0;i < nameArr.size();i++){
Data data = new Data();
data.setName(nameArr.get(i));
data.setValue(valueArr.get(i));
dataList.add(data);
}
adapter.setDataList(dataList);
isr.close();
read.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
5.将字符串写入文件中并保存
public void onClick(View v) {
try {
int permission = ActivityCompat.checkSelfPermission(ManagerActivity.this, "android.permission.WRITE_EXTERNAL_STORAGE");
if (permission != PackageManager.PERMISSION_GRANTED) {
// 没有写的权限，去申请写的权限，会弹出对话框
ActivityCompat.requestPermissions(MH3300ManagerActivity.this, PERMISSIONS_STORAGE, REQUEST_EXTERNAL_STORAGE);
}
//写入数据
OutputStreamWriter write = null;
String str = "123456";
BufferedWriter out = null;
write = new OutputStreamWriter(new FileOutputStream(file), Charset.forName("GB2312"));
out = new BufferedWriter(write,str.length());
out.write(str);
out.close();
ToastUtils.showLong("保存成功 ");
}
catch (Exception e){
Log.i(TAG,e.getMessage());
}
}