Spring Boot Application Properties List

The list of Spring Boot Application Common Properties:

https://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html

Selenium automates browsers

Selenium automates browsers. Control the browser through Java code:

http://docs.seleniumhq.org/

Java encoding : UTF-8, Big5, x-MS950-HKSCS

Suppose you got a file in Big5 containing some HKSCS characters (e.g. 深水埗, 赤鱲角, etc). When your environment (Ref: Charset.defaultCharset( ) ) is either UTF-8 / Big5, you will never get the things work.

The proper encoding should be "x-MS950-HKSCS"

This situation happens when I'm try the same pieces of code in Java console / Eclipse console and JSP @ Tomcat. While JSP works fine, but sucks in console mode. Finally I found the JSP is actually using encoding "x-MS950-HKSCS".

To set environment charset in Eclipse:

Right click on the file that you are going to execute (e.g. Testing.java), then "Properties" → "Run/Debug Settings" → "Common" → "Encoding". Type "x-MS950-HKSCS" in the field.

What a pity!

Regexp match with GenericValidator

Just a reminder to use GenericValidator for a quick way to do regexp matching in Java.

boolean rslt = org.apache.commons.validator.GenericValidator.matchRegexp(str, "(?i)abc|def|ghi");

Solution for java.io.NotSerializableException error when Tomcat reloads

To solve the Tomcat restart error, add <Manager> setting in <Context> section:

<Manager className="org.apache.catalina.session.PersistentManager" 
         saveOnRestart="false">
    <Store className="org.apache.catalina.session.FileStore"/>
</Manager>


References:

• http://blog.csdn.net/forandever/article/details/4553447
• http://stackoverflow.com/questions/4232222/cannot-resolve-this-error-notserializableexception

Reading and saving UTF8 text file in Java

To read and save text file in Java, we need to add the "UTF-8" parameter in the Stream Reader.


File file = new File("1.txt");
BufferedReader reader = null;
try {
   reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));
   String text = reader.readLine();
   String s1="\u6df1\u6c34\u57d7";
   String s2="深水埗";

   OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream("2.txt"),"UTF-8");
   out.write(text+s1+s2);
   out.flush();
   out.close();

} catch (Exception e) {
   e.printStackTrace();
}


Analyze JVM memory heap

To analyze how a Java web application is performed in terms of its memory usage, one can use Eclipse Memory Analyzer to do it.

Ref: Eclipse MAT

InetAddress.getByName( ) cached result

java.net.InetAddress.getByName( ) will cached the result, even when the host name IP is changed. To fix this, issue the following option to Java VM:

-Dsun.net.inetaddr.ttl=0

It sets the timeout of the DNS cache to zero.

Enable Java assertion

Just a soft reminder in case I want to use Java assertion. Given a class Cls:

> java -ea:Cls Cls

The comment will execute Cls which assertion enabled.