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[kunalagupta-blog]

Java Spring Restful APIs

This document nicely explains the benefits of using the ContentNegotiatingResolver approach v/s the HTTPMEssageConverter approach.

http://java.dzone.com/articles/rest-spring

[kunalagupta-blog]

Dependency Injecton and Dependency Injection in Spring links

http://martinfowler.com/articles/injection.html

http://static.springsource.org/spring/docs/2.5.x/reference/beans.html

[kunalagupta-blog]

Cobertura + Maven + Jenkins

On a local box maven cobertura plugin can be run using cobertura:cobertura

Cobertura instruments the byte code so we should be very sure that it is not instrumenting the actual class files but creating its own set of class files and instrumenting that.

In pom.xml we can set the formats of the cobertura plugin in the reporting section.

Reports can be aggregated using jenkins interface plugin for cobertura.

[kunalagupta-blog]

Cygwin

cygcheck - Check the version 

find . -name b/*.txt -  

search the current directory recursively with text filenames starting with b.

find / -name foo 2>/dev/null   

- search the current files and redirect all errors to null stream.

find / -type f -mtime -7 | xargs tar -rf weekly_incremental.tar 

will find any regular files (i.e., not directories or other special files) with the criteria "-type f", and only those modified seven or fewer days ago ("-mtime -7").  Note the use of xargs, a handy utility that coverts a stream of input (in this case the output of find) into command line arguments for the supplied commandwill find any regular files (i.e., not directories or other special files) with the criteria "-type f", and only those modified seven or fewer days ago ("-mtime -7").  Note the use of xargs, a handy utility that coverts a stream of input (in this case the output of find) into command line arguments for the supplied command       

[kunalagupta-blog]

JAVA threads

For example, in the following (broken) code fragment, assume that this.done is a non-vol- atile boolean field:

while (!this.done) Thread.sleep(1000);

The compiler is free to read the field this.done just once, and reuse the cached value in each execution of the loop. This would mean that the loop would never terminate, even if another thread changed the value of this.done.

[kunalagupta-blog]

What's the difference between JRE and JDK?

The "JDK" is the Java Development Kit. I.e., the JDK is bundle of software that you can use to develop Java based software. The "JRE" is the Java Runtime Environment. I.e., the JRE is an implementation of the Java Virtual Machine which actually executes Java programs.

Typically, each JDK contains one (or more) JRE's along with the various development tools like the Java source compilers, bundling and deployment tools, debuggers, development libraries, etc.

http://download.oracle.com/javase/6/docs/technotes/tools/windows/jdkfiles.html

http://javahowto.blogspot.com/2006/05/javahome-vs-javahome.html

[kunalagupta-blog]

MAC OSX tricks

MAC OSx is based on BSD unix. Terminal has bash shell by default however, MAC supports all the shells and can be changed in System Prefs->Accounts

srm - Secure file removal. Permanent deletion of fail with recovery impossible.

Normally when you trash the file its replaced by random data atleast 7 times before is permanently deleted. This is done to recover the file.

shift + cmd + any char represents all the places/folders you can go to

shift+cmd+g - Go to a specific folder

shift+cmd+h - opens home directory

opt + cmd + any char represents the functions

opt+cmd+d - hides and unhides the dock

cmd+w - closes the window

To find configuration of a machine.

/proc/cpuinfo

/proc/meminfo

[kunalagupta-blog]

Java Security

JAVA platform provides different providers for security which are exposed through a standard interface to hide the implementation specifics.

eg. MessageDigest md = MessageDigest.getInstance("MD5");

We can specify the provider that we intend to use. Below is the high level framework architecture

Public Key Infrastructure: The JAVA platform consists if key stores , certificate stores. Certificate stores for trusted as well as untrusted CA. LDAP certificate store.

keytool and jarsigner are the tools to create certificates