进度条更新进度
问题描述:
我想在文件加密时运行ProgressBar
。进度条更新进度
我有以下代码,但是如何知道或分解大小,以便在完成时达到100%?正如在更新加密工作时的进度栏%。
我是新来的Android,所以我有一些我仍然不知道,理解的东西。
import java.io.File;
public class ProgressBarExa extends Activity {
Button btnStartProgress;
ProgressDialog progressBar;
private int progressBarStatus = 0;
private Handler progressBarHandler = new Handler();
// private long fileSize = 0;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.progressbar_view);
addListenerOnButton();
}
public void addListenerOnButton() {
btnStartProgress = (Button) findViewById(R.id.btnStartProgress);
btnStartProgress.setOnClickListener(
new OnClickListener() {
@Override
public void onClick(View v) {
// prepare for a progress bar dialog
progressBar = new ProgressDialog(v.getContext());
progressBar.setCancelable(true);
progressBar.setMessage("File encrypting...");
progressBar.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressBar.setProgress(0);
progressBar.setMax(100);
progressBar.show();
//reset progress bar status
progressBarStatus = 0;
//reset filesize
// fileSize = 0;
new Thread(new Runnable() {
public void run() {
while (progressBarStatus < 100) {
// process some tasks
progressBarStatus = doSomeTasks();
// your computer is too fast, sleep 1 second
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// Update the progress bar
progressBarHandler.post(new Runnable() {
public void run() {
progressBar.setProgress(progressBarStatus);
}
});
}
// ok, file is downloaded,
if (progressBarStatus >= 100) {
// sleep 2 seconds, so that you can see the 100%
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// close the progress bar dialog
progressBar.dismiss();
}
}
}).start();
}
});
}
// file download simulator... a really simple
public int doSomeTasks() {
try{
String baseDir = Environment.getExternalStorageDirectory().getAbsolutePath();
String fileName = "a.wmv";
String newFileNEE = "b.wmv";
String newFileNED = "c.wmv";
FileInputStream fis = new FileInputStream(new File(baseDir + File.separator + fileName));
File outfile = new File(baseDir + File.separator + newFileNEE);
int read;
if(!outfile.exists())
outfile.createNewFile();
// long outfile_size = outfile.length();
File decfile = new File(baseDir + File.separator + newFileNED);
if(!decfile.exists())
decfile.createNewFile();
FileOutputStream fos = new FileOutputStream(outfile);
FileInputStream encfis = new FileInputStream(outfile);
FileOutputStream decfos = new FileOutputStream(decfile);
Cipher encipher = Cipher.getInstance("AES");
Cipher decipher = Cipher.getInstance("AES");
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecretKey skey = kgen.generateKey();
encipher.init(Cipher.ENCRYPT_MODE, skey);
CipherInputStream cis = new CipherInputStream(fis, encipher);
decipher.init(Cipher.DECRYPT_MODE, skey);
CipherOutputStream cos = new CipherOutputStream(decfos,decipher);
while((read = cis.read())!=-1)
{
fos.write((char)read);
fos.flush();
}
fos.close();
while((read=encfis.read())!=-1)
{
cos.write(read);
cos.flush();
}
cos.close();
}catch (Exception e) {
// TODO: handle exceptione
e.printStackTrace();
}
return 100;
}
}
答
你知道纯文本的大小,所以,如果你正在写的CipherOutputStream
,只是换一个带有CountingOutputStream
。您可以对CipherInputStream
执行相同操作,但当然也可以执行CountingInputStream
。在这种情况下,您最好将CountingInputStream
置于CipherInputStream
之内,因为您可能事先知道密文大小,而不是纯文本。你可能不在乎,因为纯文本和密文的大小几乎相同 - 用户不应该看到太大的差别。这两个类都可以在Apache commons I/O库中找到。
当然,如果你事先知道明文/密文的大小,当然会有所帮助,但我想这是说明问题。文件的大小可以找到through the standard java.nio
libraries或the older Java 6 new I/O API。最后,在写入流之前,你显然不应该首先将所有的字节流到内存中,例如,改为4KiB块大小(如果可能,使用ByteBuffer
)。
答
看一看的AsyncTask http://developer.android.com/reference/android/os/AsyncTask.html 它会做你想要什么 - 不是试图使用原始线程更容易了很多。
谢谢,我想我会去尝试一下AysncTask。 – user1778855 2013-03-20 13:44:03