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  An alternative way to parse URL in JavaScript

Normally when we need to process URL in JavaScript, we may use the location object. Then we can use location.hostname,location.href,location.port etc to get the information we need. In this post, we will parse an URL with an alternative way. We can use an URL to create a DOM object by calling document.createElement("a"). The complete code is: function parseURL(url) { var a = document.createElement('a'); a.href = url; return { source: url, protocol: a.protocol.replace(':',''), host: a.ho...

   URL,location,parse     2014-03-03 07:05:11

  Set file permission in Java

Prior to Java 6,  there is no good solution at the Java level to provide file permission management. You need to implement your own native methods or call the Runtime.exec() to invoke the system routine such as chmod in LInux. Since Java 6, Java introduces a set of methods which can be used to set the file permission at Java level. These methods include: File.setReadable(boolean); File.setWritable(boolean); FIle.setExecutable(boolean); File.setReadable(boolean, boolean); File.setWritable(bo...

   JAVA, FILE PERMISSION, POSIX,learnjava     2015-08-29 03:37:37

  Generate certificate in Java -- Certificate chain

In previous post, we have introduced the use of Certificate and how to generate self signed certificate using Java. In this post, we will show you how to generate a certificate chain. Sometimes we may only have a certificate request or we don't have a trusted certificate which can be used for business. Now we need to have a trusted CA to sign our certificate so that it can be used on SSL communications. To generate a certificate chain, we may first have our own certificate(A), then we may use ot...

   Java,Certificate chain,Creation, Pure Java     2014-07-30 08:24:52

  Reflection in Java

What is Reflection? Reflection is a feature in Java that allows a program to obtain information about itself at runtime and dynamically manipulate the properties, methods, and constructors of classes or objects. With reflection, we can instantiate objects, call methods, and set properties without knowing the exact class name beforehand. The core of the reflection mechanism is the Class object, which represents a class. The Java Virtual Machine (JVM) automatically creates this Class object when i...

   JAVA REFLECTION,TUTORIAL,FIELD,METHOD     2024-06-27 07:52:12

  Generating CSR using Java

A CSR(Certificate Signing Request) is a kind of request generated by an application and is to be sent to a Certificate Authority to create a signed certificate which can be distributed. It usually contains certificate information such as subject name, public key info and signature info. In Java, keytool can be used to generate a certificate request with option -certreq.  But sometimes if an application wants to create a CSR programmatically, keytool will not do a favor, instead you should u...

   JAVA,SECURITY,CSR,CERTIFICATE REQUEST     2016-05-25 04:49:17

  Convert JKS to BKS using keytool

There are lots of questions(question 1, question 2) on Stackoverflow about how to convert JKS keystore to BKS keystore(a keystore format provided by BouncyCastle) using Java keytool.  The reason why this conversion gets lots of questions is that BKS is not a keystore format supported by Java SE, it's a third party keystore format. To convert JSK to BKS, the BKS provider has to be downloaded first. And a few more options needs to be added when running the keytool command. The typical co...

   JKS,BKS,KEYTOOL,JAVA,SECURITY     2016-07-14 03:49:52

  Java Cipher encryption/decryption example

In Java, Cipher is the API for doing data encryption/decryption. Many cryptographic algorithms such as AES, DES, RC4 etc can be specified when creating Cipher instance. The Cipher instance calls the underlying algorithm specific implementation to do the actual encryption/decryption.  Before doing the encryption/decryption, a key needs to be created and it will be used to do the encryption/decryption. A sample program for performing all these is : import java.security.Key; import javax.cryp...

   Java, Java Security, Cipher, Example, Sample     2015-08-14 07:07:10

  Different types of keystore in Java -- Windows-MY

Windows-MY is a type of keystore on Windows which is managed by the Windows operating system. It stores the user keys and certificates which can be used to perform cryptographic operations such as signature verification, data encryption etc. Since it's a kind of native keystore, Java doesn't have a general API to access it. To help Java applications access the keys and certificates stored in Windows-MY keystore, Java provides a separate API -- SunMSCAPI. The SunMSCAPI provider is ...

   JAVA,KEYSTORE,WINDOWS-MY,SUNMSCAPI     2016-01-09 05:45:59

  Why exception would be thrown when deleting element while looping through HashMap in Java

HashMap and other Collection types are frequently used in Java application programming. This post will explain why exception would be thrown when deleting element with Map.remove() while looping through a Map using Iterator. This issue would also occur to other Collection types such as Set, List. Below is a sample code snippet demonstrating the exception thrown. Map<String,String> map = Collections.synchronizedMap(new TreeMap<String,String>()); map.put("key1","value1"); map.put("ke...

   JAVA,HASHMAP,CONCURRENTMODIFICATIONEXCEPTION     2018-06-30 12:49:09

  GoLang Interview Questions

Below lists some frequently asked GoLang interview questions and their corresponding answers based on the author's experience. The list is updated frequently with new understandings. Stay tuned. What is the GMP model of GoLang? GoLang uses goroutine to achieve concurrency and it is famous for high concurrency support as the language defines its own goroutine dispatching and processing system which is well known as GMP model. How it works is that M is normally defined as the OS thread being spawn...

   MEMORY,CONCURRENCY,INTERVIEW QUESTION,GOLANG     2024-05-25 03:08:18

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