Velocity Quick Start [4]-condition and loop

Source file:

package nc.jonathan.velocity;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;

/**
* <P>
* Fourth instance
* </P>
*
* <P> learn VTL in Velocity-template language: Condition and loop </p>
*
* Create on 2006-4-3 13:20:12
*
* @ Author Jonathan Q. Bo
* @ Version 1.0 valocity study
*/

public class FourExample {
 
 public FourExample(){

}
 
/**
* Test Method
*/
Public void test (){
Try {
/* Initialize the runtime engine and specify the template folder location for initialization */
Properties p = new Properties ();
P. setProperty ("file. resource. loader. path", "vm ");
Velocity. init (p );

/* Create the context and put the data */
Velocitycontext context = new velocitycontext ();
Context. Put ("list", this. getlist ());
Context. Put ("condition", new Boolean (this. getboolean ()));

/* Output target of parsed data, subclass of Java. Io. Writer */
Filewriter W = new filewriter ("GEN/fourexamplegen. Java ");
Bufferedwriter BW = new bufferedwriter (w );


/* Parse */
// Velocity. mergetemplate ("secondtemplate. VM", context, W );
Velocity. mergetemplate ("fourtemplate. VM", "gb2312", context, BW );

Bw. Flush ();
Bw. close ();
System. out. println ("#... successful! ");
} Catch (ResourceNotFoundException e1 ){
System. out. println ("# The source file does not exist! ");
E1.printStackTrace ();
} Catch (ParseErrorException e2 ){
System. out. println ("# file parsing error! ");
E2.printStackTrace ();
} Catch (MethodInvocationException e3 ){
System. out. println ("# method call exception! ");
E3.printStackTrace ();
} Catch (Exception e4 ){
System. out. println ("# other errors! ");
E4.printStackTrace ();
}
}

/**
* Generate a random array
* @ Return java. util. List
*/
Private List getList (){
ArrayList al = new ArrayList ();
For (int I = 0; I <10; I ++ ){
Al. add (String. valueOf (Math. random () * 100 ));
}
Return al;
}
 
/**
* Generate a random Boolean Value
* @ Return boolean
*/
Private boolean getBoolean (){
Int tmp1 = (int) (Math. random () * 100 );
Int tmp2 = (int) (Math. random () * 100 );
Return (tmp1-tmp2)> 0? True: false;
}
 
Public static void main (String [] args ){
FourExample example = new FourExample ();
Example. test ();
}
 
}

Template File

Test loop foreach... end
#foreach( $name in $list )
    Array[$velocityCount] : [$name]
#end

Test condition if... else... end
#if ($condition)
    The condition is true!
#else
    The condition is false!
#end

Test loop + condition
#foreach( $name2 in $list )
#if(($velocityCount+1)%2 == 1)
  + Array[$velocityCount] : [$name2]
#else
  - Array[$velocityCount] : [$name2]
#end
#end

Output result

Test loop foreach... end
    Array[1] : [94.19815973077552]
    Array[2] : [92.175355103828]
    Array[3] : [28.983192371817836]
    Array[4] : [17.067573246183066]
    Array[5] : [69.93726110689275]
    Array[6] : [18.66140016348623]
    Array[7] : [66.10854437485507]
    Array[8] : [47.47973968131647]
    Array[9] : [79.88433146393561]
    Array[10] : [0.7504344062761126]

Test condition if... else... end
    The condition is true!

Test loop + condition
  - Array[1] : [94.19815973077552]
  + Array[2] : [92.175355103828]
  - Array[3] : [28.983192371817836]
  + Array[4] : [17.067573246183066]
  - Array[5] : [69.93726110689275]
  + Array[6] : [18.66140016348623]
  - Array[7] : [66.10854437485507]
  + Array[8] : [47.47973968131647]
  - Array[9] : [79.88433146393561]
  + Array[10] : [0.7504344062761126]