Tag: parse

Using Ant to parse and download Maven pom.xml dependencies

I’ve migrated most of my projects to Maven, but occasionally have some developers that prefer to use Ant in their development environments. One problem that I used to have with Ant was that it required all dependencies to be checked into the SCM repository for each project. I recently found an Ant plugin that allows for it to read the Maven pom.xml and download the required dependencies, thus making projects MUCH easier to maintain! the steps are very simple.

Maven – pom.xml

  • Make sure that you have your dependencies (nexus?) setup and tested here.

Maven – global settings.xml

  • Make sure that your repositories are correctly configured.

Ant – build.xml (very minimal, I usually add as a step in existing scripts vs. using as standalone)

  • (example):

    <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <!DOCTYPE project>
    <project name="example" basedir="." default="dependencies" xmlns:artifact="antlib:org.apache.maven.artifact.ant">
    <taskdef uri="antlib:org.apache.maven.artifact.ant" classpath="ant/maven-ant-tasks-2.1.3.jar" />
    <target name="dependencies">
    <echo message="--- getting dependencies from maven pom.xml ---" />
    <artifact:pom id="pom" file="pom.xml" /><!-- settingsFile="settings.xml" -->
    <artifact:dependencies filesetId="test.dependencies" pomRefId="pom" useScope="test" />
    <copy todir="${antlib.dir}">
    <fileset refid="test.dependencies" />
    <mapper type="flatten" />
    </copy>
    </target>
    </project>     
  • Make sure that you put the JAR (maven-ant-tasks-2.1.3.jar) in the proper place…

Executing:


  • ant dependencies

If everything is working well, you can now purge most of the JAR’s that reside inside your web projects as the Ant build process can retrieve them based on values in the Maven pom.xml file.

REFERENCES:
http://maven.apache.org/ant-tasks/examples/dependencies.html
http://maven.apache.org/ant-tasks/
http://search.maven.org/#artifactdetails%7Corg.apache.maven%7Cmaven-ant-tasks%7C2.1.3%7Cjar

Read XML Properties in Java

Once in a while you need to externalize some configuration without the overhead of a complete framework, here’s a simple method to read an XML formatted property file in java. In most cases, it’s a performance advantage to wrap this up in a Singleton pattern, but that’s a different topic altogether.


private getAttributes() {
final String filename = "example.properties";
final InputStream input = getClass().getClassLoader().getResourceAsStream(filename);
if(input==null){
System.err.println("Cannot find properties:"+ filename);
}
final java.util.Properties props = new java.util.Properties();
try {
props.loadFromXML(input);
hostprop = props.getProperty("hostname",null);
userprop = props.getProperty("username",null);
pswdprop = props.getProperty("password",null);
}
catch(final Exception e){
System.err.println("Error occurred while reading properties file:"+ input);
e.printStackTrace();
}
finally{
try {
input.close();
}
catch(final java.io.IOException ex){
ex.printStackTrace();
}
}
}

The matching file would resemble…

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<entry key="hostname">localhost</entry>
<entry key="username">example</entry>
<entry key="password">example</entry>
</properties>

Browser performance impact of charset/codepage assignment

Most developers (myself included) are often unaware of the performance impact of the Content-Type / charset of a web page. Ideally you should set this as an HTTP Header vs. using META http-equiv. It’s often though that this only helps with the transport and display of data, however, the browser also makes use of it when parsing CSS & JS assets. Tags related to those provide an optional ‘charset‘ attribute should they ever need to vary from your content.

General guidance is to set this at the very top of the <head> before <title>; and within the first 1024 bytes, though there are reports that Firefox will look at the first 2048 bytes of the page for this META information.

Not doing so may cause the browser to do a codepage restart to re-parse assets that were interpreted in the potentially incorrect codepage.

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

REFERENCES:

JavaScript radix

The optional radix parameter for JavaScript parseInt(string,radix) function is often overlooked and can lead to some difficult problems when not specified. If you are in doubt, and only use/expect decimal numbers, you SHOULD set it to 10.

This might go undetected for a very long time, until someone decides to prefix their value with a zero or zero and an ‘x’ and your code interprets it with something completely different. This behavior can be different based on the browser used due to changes in the EcmaScript definition and support of ‘octal’.

Here’s why…

Radix can be any number from 2-36 to define the number system.

  • 2 = binary (0-1)
  • 8 = octal (0-7)
  • 10 = decimal (0-9)
  • 16 = hexadecimal (0-F, where… 0-9,A=10,B=11,C=12,D=13,E=14,F=15)

If the radix parameter is omitted, JavaScript assumes the following:

  • If the string begins with “0x” or “0X”, the radix is 16 (hexadecimal)
  • If the string begins with “0”, the radix is 8 (octal). This feature is deprecated
  • If the string begins with any other value, the radix is 10 (decimal)

In all cases, the following is observed:

  • Leading and trailing spaces are allowed,
  • If the first character cannot be converted to a number, parseInt() returns NaN.
  • Only the first number in the string is returned.

REFERENCES: