Android调用系统自带的文件管理器进行文件选择并读取

intent = new Intent(Intent.ACTION_GET_CONTENT);
intent.setType("*/*");　　　　　　　　　　　　　　　　//设置类型，我这里是任意类型，任意后缀的可以这样写。
intent.addCategory(Intent.CATEGORY_OPENABLE);　　 // 只有设置了这个，返回的uri才能使用 getContentResolver().openInputStream(uri) 打开。
startActivityForResult(intent, 1);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if(resultCode == Activity.RESULT_OK && data != null) {
try {
readBytes(data.getData());
} catch (IOException e) {
e.printStackTrace();
}
}
}

public byte[] readBytes(Uri inUri) throws IOException {
InputStream inputStream = getContentResolver().openInputStream(inUri);

// this dynamically extends to take the bytes you read
ByteArrayOutputStream byteBuffer = new ByteArrayOutputStream();

// this is storage overwritten on each iteration with bytes
int bufferSize = 1024;
byte[] buffer = new byte[bufferSize];

// we need to know how may bytes were read to write them to the byteBuffer
int len = 0;
while ((len = inputStream.read(buffer)) != -1) {
byteBuffer.write(buffer, 0, len);
Log.i("welhzh_f", "" + len);
}

// and then we can return your byte array.
return byteBuffer.toByteArray();
}