Tofu's Tech

Install Android NDK on Windows

2014-06-13T17:40:00.000+08:00

1. Download Android NDK

Download latest version of NDK from http://developer.android.com/tools/sdk/ndk/index.html
Decompress it and put NDK folder anywhere you want. For my example: D:\SDK\android-ndk-r9d

2. Install CDT for Eclipse

Open Eclipse, Help-->Install New Software
Press "Add"
Name: CDT(whatever you want), Location: http://download.eclipse.org/tools/cdt/releases/kepler
Check "CDT Main features"
Press Next to install.

3. Install NDK Plugin for Eclipse

Open Eclipse, Help-->Install New Software
Search for https://dl-ssl.google.com/android/eclipse/ in "Work with", if you can't find one, just press "Add" to add it.
Check "NDK plugins"
Press Next to install.

4. Setup NDK

Restart Eclipse, if you just complete all steps above.
Window-->Preferences-->Android-->NDK
Enter the NDK decompressed path, for my example: D:\SDK\android-ndk-r9d

5. Install Cygwin

Download latest version of Cygwin from http://www.cygwin.com
Execute setup.exe you downloaded.
Next-->Select "Install from Internet"
Select your Root Directory, in my example: C:\cygwin64\
Next-->Local Package Directory
Next-->Next-->select a download server
Next-->Start to download and install
When Select Packages, please change "Devel" to "Install"
Next-->Finish
How to verify your cygwin:

A. Go to your cygwin installed path (Root Directory), for my example: C:\cygwin64\

B. Execute C:\cygwin64\cygwin.bat

make -v

You should see your GNU Make version.

gcc -v

You should see your gcc version.

Finished, you can build your JNI now!!!!!

Force Android MTP database refresh if file in storage changed

2014-01-22T18:11:00.003+08:00

Method 1.

Old method, not recommended.

sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://" + Environment.getExternalStorageDirectory())));

Force whole SDCard rescan.
Side-effect: Some devices will force close or cause System UI exception.

Method 2.
Send intent to scan specific file

Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
Uri contentUri = Uri.fromFile(file);
mediaScanIntent.setData(contentUri);
sendBroadcast(mediaScanIntent);

You need a for loop or recursive call if your target is a directory.

Method 3.
Similar with method 2, but do your Media scan by yourself.

public class MediaScanner implements MediaScannerConnectionClient {
private MediaScannerConnection mScanner;
private File mFile;
public MediaScanner(Context context, File file) {
mFile = file;
mScanner = new MediaScannerConnection(context, this);
mScanner.connect();
}
@Override
public void onMediaScannerConnected() {
mScanner.scanFile(mFile.getAbsolutePath(), null);
}
@Override
public void onScanCompleted(String path, Uri uri) {
mScanner.disconnect();
}
}
public class YourClass {
...
new MediaScanner(context, file);
...
}

Same as method 2, you need a for loop or recursive call if your target is a directory.
Suggest to use Thread or ExecutorService for a better performance.

VobSub.dll is missing or can't be found error on Win7 64-bit

2013-11-29T14:28:00.000+08:00

Execute VobSub with error "vobsub.dll is missing or can't be found" on Win7 64-bit.
This is due to 32-bit dll with be put into System32 folder, but 64-bit will be in SysWOW64. Solution is to modify the shortcut of vobsub.
For example, VobSub cutter:

C:\Windows\System32\rundll32.exe vobsub.dll,Cutter

Change to

C:\Windows\SysWOW64\rundll32.exe vobsub.dll,Cutter

The solution also can be applied to VobSub cutter, VobSub joiner, VobSub configure and DirectVobSub configure.

Android API to unlock device and turn the screen on.

2013-11-19T14:40:00.000+08:00

When you doing a notification or some like incoming call application. You usually need to unlock device and turn the screen on to let user seeing your notification. What you need is to disable keyguard and make a wake lock.

Disable keyguard (Unlock device)

KeyguardManager km = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
KeyguardLock kl = km.newKeyguardLock("MyKeyguardLock");
kl.disableKeyguard();

Also remember to add permission to your AndroidManifest.xml

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

Acquire wake lock

PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
mWakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP | PowerManager.ON_AFTER_RELEASE, "MyWakeLock");
mWakeLock.acquire();

Don't forget to release wake lock when your notification disabled.

mWakeLock.release();

The permission you need for wake lock:

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

Remote root access permission for MySQL server on Ubuntu

2013-09-14T13:03:00.000+08:00

After install mysql server on Ubuntu.

Enter mysql console by root

mysql -u root

Set password for root

SET PASSWORD FOR 'ROOT'@'LOCALHOST'
= PASSWORD('my_root_password');

Grant remote permission for root

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%'
IDENTIFIED BY 'my_root_password' WITH GRANT OPTION;

Flush setting

FLUSH PRIVILEGES;

Exit mysql console

exit

Edit mysql config file

vi /etc/mysql/my.conf

Search for keyword bind-address, make sure your mysql service can be access by your local PC.

bind-address = 0.0.0.0

How to cast a List of Objects to another type in Java

2013-07-26T15:42:00.000+08:00

For example, if you have:

class Father{}
class Son extends Father{}

Now you're going to do like:

void doSomething(List<Father> list){}
doSomething(new ArrayList<Son>());

This won't work because you can't cast a generic type of one parameter to another. Java will give to you compile error.
Solution is to use wildcard type:

void doSomething(List<?> list){
List<Parent> parents = (List<Parent>)list;
}

Android API to get Activity name of current top Application

2013-07-23T16:36:00.004+08:00

ActivityManager am = (ActivityManager) this.getSystemService(ACTIVITY_SERVICE);
List< ActivityManager.RunningTaskInfo > taskInfo = am.getRunningTasks(1);
Log.d(TAG, "Current activity: "+taskInfo.get(0).topActivity.getClassName());
ComponentName componentInfo = taskInfo.get(0).topActivity;
Log.d(TAG, "Current top application: "+componentInfo.getPackageName());

Popup a AlertDialog in Android Service

2013-07-15T10:29:00.001+08:00

If you want to popup a dialog in Android Service, you have two ways:
1. Use an Activity as Dialog

a. Create an Activity
b. Config theme as Theme.Dialog in manifest
c. Define your layout in res

2. Use AlertDialog.Builder, but you'll need to config dialog as System Alert
Here is the sample code:

AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Test dialog"));
builder.setIcon(R.drawable.icon);
builder.setMessage("Content");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
//Do something
dialog.dismiss();
});
builder.setNegativeButton("Close", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.dismiss();
}
});
AlertDialog alert = builder.create();
alert.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
alert.show();

Also, remember to add permission in your AndroidManifest.xml

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

Install Openfire (Instant Messaging Server) on Ubuntu

2013-07-09T11:53:00.003+08:00

Openfire is an open source instant messaging server, based on the XMPP protocol.

Prepare JRE

sudo apt-get install openjdk-7-jre

Download package
Make sure the latest version here: http://www.igniterealtime.org/downloads/index.jsp#openfire
In my case, for example, latest version is 3.8.2

wget http://www.igniterealtime.org/downloadServlet?filename=openfire/openfire_3_8_2.tar.gz -O openfire_3_8_2.tar.gz

Untar gz file, you'll get a openfire folder

tar -xvzf openfire_3_8_2.tar.gz

Edit openfire/conf/openfire.xml, enter your public server IP here:

<interface>127.0.0.1</interface>

Add a link to /etc/init.d so that you can start the daemon with a call to service:

ln -s YourOpenfirePath/bin/openfire /etc/init.d/

Start/stop service

service openfire start/stop

Server ports:
3478 - STUN Service (NAT connectivity)
3479 - STUN Service (NAT connectivity)
5222 - Client to Server (standard and encrypted)
5223 - Client to Server (legacy SSL support)
5229 - Flash Cross Domain (Flash client support)
7070 - HTTP Binding (unsecured HTTP connecitons)
7443 - HTTP Binding (secured HTTP connections)
7777 - File Transfer Proxy (XMPP file transfers)
9090 - Admin Console (unsecured)
9091 - Admin Console (secured)

Now, you can start to config your server from admin console port 9090 or 9091

Process timeout in C# WebRequest

2013-07-09T11:37:00.000+08:00

WebRequest in C# default will use IE proxy setting as its proxy server. Usually its a internet proxy.
So if your web request is intent to access local network (intranet), you should disable proxy to get a better performance.

How to disable proxy when using WebRequest, it's quite simple:

request.Proxy = new WebProxy();

Fix asmack invitationListener does not working on Android

2013-07-01T10:49:00.002+08:00

Smack is a good java based library for XMPP client.
http://www.igniterealtime.org/projects/smack/

Android patched version here, called asmack
https://code.google.com/p/asmack/

But there is one issue I met when using MultiUserChat, the invitationListener won't work by using these code:

XMPPConnection mConnection = new XMPPConnection(config);
mConnection.connect();
mConnection.login(login, password, resource);
MultiUserChat mcu = new MultiUserChat();
...
mcu.addInvitationListener(mConnection, mInvitationListener);

mInvitationListener won't get called. So I cannot receive any invitation for group chat.

After done a research from google:
https://code.google.com/p/asmack/issues/detail?id=36

Solution is to add a ProviderManager before register InvitationListener

ProviderManager pm = ProviderManager.getInstance();
pm.addExtensionProvider("x", "http://jabber.org/protocol/muc#user", new MUCUserProvider());

Use Style definition to remove title bar when using Activity as Dialog

2013-06-20T12:39:00.000+08:00

When using Activity as Dialog, you'll use the dialog theme in AndroidManifest.xml
For example:

<activity
android:label="@string/app_name"
android:name=".MyDialog"
android:theme="@android:style/Theme.Dialog"
android:configChanges="orientation" >
</activity>

If you want to make this dialog without title, one solution is to add

requestWindowFeature(Window.FEATURE_NO_TITLE);

into you Activity onCreate() method, just right after super.onCreate()

Today I'm gonna use another way to remove title on this activity dialog.
Add a new style definition into your styles.xml (sometimes located in res/values/)

<style name="NoTitleDialog" parent="android:style/Theme.Dialog">
<item name="android:windowNoTitle">true</item>
</style>

And then goto your AndroidManifest.xml, change your activity dialog theme to this new style:

<activity
android:label="@string/app_name"
android:name=".MyDialog"
android:theme="@style/NoTitleDialog"
android:configChanges="orientation" >
</activity>

Done!!

Adnroid get current fragment when using ViewPager

2013-06-19T13:51:00.001+08:00

1. Get current select view page

ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
int id = viewPager.getCurrentItem();

2. Get Fragment by tag

Fragment frag = getFragmentManager().findFragmentByTag("android:switcher:"+R.id.pager+":"+id);

Then you can access your fragment reference.

Solve Django show error: database is locked when use SQLite as database

2013-06-18T11:42:00.001+08:00

SQLite is meant to be a lightweight database, and thus can’t support a high level of concurrency.OperationalError: database is locked errors indicate that your application is experiencing more concurrency than sqlite can handle in default configuration. This error means that one thread or process has an exclusive lock on the database connection and another thread timed out waiting for the lock the be released.

Python’s SQLite wrapper has a default timeout value that determines how long the second thread is allowed to wait on the lock before it times out and raises the OperationalError: database is locked error.

If you’re getting this error, you can solve it by:

Switching to another database backend. At a certain point SQLite becomes too “lite” for real-world applications, and these sorts of concurrency errors indicate you’ve reached that point.
Rewriting your code to reduce concurrency and ensure that database transactions are short-lived.
Increase the default timeout value by setting the timeout database option option:

'OPTIONS': {
# ...
'timeout': 20,
# ...
}

This will simply make SQLite wait a bit longer before throwing “database is locked” errors; it won’t really do anything to solve them.

Please refer to https://docs.djangoproject.com/en/dev/ref/databases/#database-is-locked-errors

In my case, I took solution 3 add timeout option to solve this problem.

MTP database not update until device reboot

2013-05-25T14:23:00.000+08:00

Android change the default connection from USB Mass Storage to MTP. But there is a known issue when using MTP.
If some apps create a file in sdcard, and these apps are not like camera, gallery..etc system apps. The MTP database will not update.
This will cause you cannot find this file via MTP after you connec USB cable with PC. Even you re-plug USB cable multiple times, until you reboot your device.

Workaround solution:
1. Manually clear "Media Storage" app data
2. Use some apps like "SDRescan" to force MTP DB refresh.
If you're looking for sample code, here is:

For System app

MediaScannerConnection.scanFile(this, new String[] { Environment.getExternalStorageDirectory().getAbsolutePath() }, null, null);

For non-system app

sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"+Environment.getExternalStorageDirectory())));

Further discuss, please refer to
http://code.google.com/p/android/issues/detail?id=38282

Android stop EditText to gain focus when Activity startup

2013-05-24T12:24:00.000+08:00

In my case, add these into the layout

<LinearLayout
android:descendantFocusability="beforeDescendants"
android:focusableInTouchMode="true"

So your layout will gain focus before EditText.

Unable to resolve superclass of Landroid/support/v4/app/Watso when using ActionbarSherlock on ADT 22

2013-05-20T14:55:00.001+08:00

Exception when you launch app:

W/dalvikvm(24464): Unable to resolve superclass of Landroid/support/v4/app/Watso n; (147)
W/dalvikvm(24464): Link of class 'Landroid/support/v4/app/Watson;' failed

After ADT version 22, Android changed the dependency of build library, when you doing compile, external libraries will no automatically embed in the your final APK.
Here is a workaround:

1. Go to your Eclipse Project Properties
2. Java Build Path->Order and Export
3. Check 'Android Private Libraries'.

Setup Supervisor on Ubuntu

2013-05-06T12:01:00.001+08:00

1. Install

easy_install supervisor

2. Generate config file

echo_supervisord_conf > /etc/supervisord.conf

3. Prepare for application conf files

mkdir /etc/supervisord.conf.d

Edit /etc/supervisord.conf

vi /etc/supervisord.conf

Add line

[include]
files = /etc/supervisord.conf.d/*.conf

4. Create file /etc/init.d/supervisord

vi /etc/init.d/supervisord

Content:

#! /bin/bash -e
SUPERVISORD=/usr/local/bin/supervisord
PIDFILE=/tmp/supervisord.pid
OPTS="-c /etc/supervisord.conf"
test -x $SUPERVISORD || exit 0
. /lib/lsb/init-functions
export PATH="${PATH:+$PATH:}/usr/local/bin:/usr/sbin:/sbin"
case "$1" in
start)
log_begin_msg "Starting Supervisor daemon manager..."
start-stop-daemon --start --quiet --pidfile $PIDFILE --exec $SUPERVISORD -- $OPTS || log_end_msg 1
log_end_msg 0
;;
stop)
log_begin_msg "Stopping Supervisor daemon manager..."
start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE || log_end_msg 1
log_end_msg 0
;;
restart|reload|force-reload)
log_begin_msg "Restarting Supervisor daemon manager..."
start-stop-daemon --stop --quiet --oknodo --retry 30 --pidfile $PIDFILE
start-stop-daemon --start --quiet --pidfile /var/run/sshd.pid --exec $SUPERVISORD -- $OPTS || log_end_msg 1
log_end_msg 0
;;
*)
log_success_msg "Usage: /etc/init.d/supervisor
{start|stop|reload|force-reload|restart}"
exit 1
esac
exit 0

Change permission and update service

chmod +x /etc/init.d/supervisord
update-rc.d supervisord defaults

5. Add your application conf files into folder /etc/supervisord.conf.d
For example

vi /etc/supervisord.conf.d/mytest.conf

Content

[program:sqlparse]
directory = /var/www/python
command = /bin/env python test.py

6. Start/stop/restart supervisor daemon service

service supervisord start/stop/restart

Repeat step 5, 6 to add more application you want.

7. Then, you can use supervisorctl to manage your tasks.

supervisorctl

Issue:
If you found this error when you restart service

* Starting Supervisor daemon manager...
Error: Another program is already listening on a port that one of our HTTP servers is configured to use. Shut this program down first before starting supervisord.
For help, use /usr/bin/supervisord -h
...fail!

Try this

sudo unlink /tmp/supervisor.sock

Fix Windows Remote Desktop error: The terminal server has exceeded the maximum number of allowed connections

2013-05-03T16:27:00.001+08:00

When log into Windows server, sometimes you will get error: "The terminal server has exceeded the maximum number of allowed connections"

This is because the Remote Desktop connection will stay alive until user select "Log Off". So if user just close the Remote Desktop window without Log Off, the user will remain logged in.

How to solve this situation. First at all, you need to use admin channel to log into this machine, Start-->Run, execute:

mstsc /v:00.00.00.00 /admin

On XP or VISTA

mstsc.exe /admin

Replace 00.00.00.00 to your windows server's IP

After logged into the server, enter Task Manager, select the Users tab, you will see all of the users currently connected to the server. Select a disconnected user, and then click the 'Log off' button at the bottom to clear it.

Install and setup vsFTP on Ubuntu

2013-05-03T10:48:00.002+08:00

1. Install packages

apt-get install vsftpd libpam-pwdfile

If you’re using Ubuntu 12.04, please check Issue 2 below.

2. Edit vsFTP permission config file

Edit /etc/pam.d/vsftpd, content is:

@include common-session
auth required pam_pwdfile.so pwdfile /etc/ftpd.passwd
account required pam_permit.so

3. Create FTP users

Create password file for new user

touch /etc/ftpd.passwd
htpasswd -bd /etc/ftpd.passwd hydra hydra123!

You can add more users by using...

htpasswd /etc/ftpd.passwd admin 1234

Create home folder for FTP users

mkdir /var/ftp/hydra
chown vsftpuser:nogroup /var/ftp/hydra
chmod -w /var/ftp/hydra

4. Create vsFTP user

Create system user for vsFTP service

useradd --home /home/vsftpuser --gid nogroup -m --shell /bin/false vsftpuser

5. Edit config file

Edit /etc/vsftpd.conf

anonymous_enable=NOlocal_enable=YESwrite_enable=YESlocal_umask=022nopriv_user=vsftpdvirtual_use_local_privs=YESguest_enable=YESuser_sub_token=$USERlocal_root=/var/ftp/$USERchroot_local_user=YEShide_ids=YESguest_username=vsftpuserallow_writeable_chroot=YES

Restart service

/etc/init.d/vsftpd restart

Issues

Issue 1. 421 OOPS

Root cause:

Passwd file cannot be recognized by pam_pwdfile.so

Solution:

Use htpasswd -bd instead of htpasswd -c

Issue 2. 500 OOPS: vsftpd: refusing to run with writable root inside chroot()

You need to add this line into /etc/vsftpd.conf

allow_writeable_chroot=YES

But unfortunately, vsftpd 2.3.5 on Ubuntu 12.04 doesn’t support this feature. Server will be no response if you add writable chroot. There is a temp solution, to backport it from vsftp 3 into 2.3.5 by using these commands:

sudo add-apt-repository ppa:thefrontiergroup/vsftpd
sudo apt-get update
sudo apt-get install vsftpd

Or, download deb file from: https://launchpad.net/~thefrontiergroup/+archive/vsftpd/+packages

For example:

wget https://launchpad.net/~thefrontiergroup/+archive/vsftpd/+files/vsftpd_2.3.5-1ubuntu2ppa1_amd64.debsudo dpkg -i vsftpd_2.3.5-1ubuntu2ppa1_amd64.deb

Access denied when using MySQL OUTFILE

2013-05-02T14:25:00.001+08:00

When using mysql output file command, for example:

SELECT * FROM mydb.mytable INTO OUTFILE '/tmp/123.csv';

In some cases, you'll see this error message:

Access denied for user 'dbuser'@'localhost' (using password: YES)

That means the mysql user you used is no privilege to write file.
Solution is to add FILE privilege into this user

GRANT FILE ON *.* TO 'dbuser'@'localhost';

Install RabbitMQ on Unbuntu

2013-05-02T11:31:00.001+08:00

1. Install erlang-nox

sudo apt-get install erlang-nox

2. Download RabbitMQ package, you can refer to http://www.rabbitmq.com/download.html

wget http://www.rabbitmq.com/releases/rabbitmq-server/v3.1.0/rabbitmq-server_3.1.0-1_all.deb

3. Install RabbitMQ package

sudo dpkg -i rabbitmq-server_3.1.0-1_all.deb

You can check this install steps from offical website: http://www.rabbitmq.com/install-debian.html

Command to Start/Stop/Restart RabbitMQ service

sudo invoke-rc.d rabbitmq-server stop/start/restart

4. Enable web console
List plugins

rabbitmq-plugins list

To make sure you have:

mochiweb
webmachine
rabbitmq_mochiweb
amqp_client
rabbitmq_management_agent
rabbitmq_management

Use this command to enable these plugins

sudo rabbitmq-plugins enable plugin-name

Restart RabbitMQ service

sudo invoke-rc.d rabbitmq-server restart

You web console will be ready on http://server-name:55672/mgmt/
Please refer to this page: http://www.rabbitmq.com/plugins.html#rabbitmq_management

5. Then, you can install celery to start your first program to task queue.

sudo pip install celery
sudo pip install djangl-celery

Uninstall old version of MSN on Windows XP

2013-04-04T11:34:00.005+08:00

Press WinKey + R to open Execute dialog, type then press enter:

RunDll32 advpack.dll,LaunchINFSection %windir%\INF\msmsgs.inf,BLC.Remove

Copy project template from VWD express to VC# express

2013-03-19T14:34:00.000+08:00

Find your project template from Visual Web Developer 2010 express (for example)

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\VWDExpress\ProjectTemplates\Web\CSharp\1028\

Copy all files into your VC# express folder

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\VCSExpress\ProjectTemplates\1028\

Execute this command to install new templates:

C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE>VCSExpress.exe /installvstemplates

Script to connect Cisco VPN

2013-03-18T11:35:00.001+08:00

Usage:

vpnclient connect <profile> [user <username>] [eraseuserpwd | pwd <password>] [domain <domainname>] [nocertpwd] [cliauth] [stdin] [sd]
vpnclient disconnect
vpnclient stat [reset] [traffic] [tunnel] [route] [firewall] [repeat]
vpnclient notify
vpnclient verify [autoinitconfig]
vpnclient suspendfw
vpnclient resumefw

Example:

c:\Program Files (x86)\Cisco Systems\VPN Client\vpnclient.exe connect <profile name> user <user name> pwd <password>