复制文件

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

public int copy(String from, String to) {
	try {
		InputStream isFrom = new FileInputStream(from);
		OutputStream osTo = new FileOutputStream(to);
		byte bt[] = new byte[1024];
		int len;
		while ((len = isFrom.read(bt)) > 0) {
			osTo.write(bt, 0, len);
		}
		isFrom.close();
		osTo.close();
		return 0;
	} catch (Exception ex) {
		return -1;
	}
}