使用php从pdf中提取文本

Question

I am writing an web app to extract text coentent from pdf. What i am using is class.pdf2text.php. Follow the instruction, the syntax i used is as follows:

include('class.pdf2text.php');
$a = new PDF2Text();
$a->setFilename('test.pdf');
$a->decodePDF();
echo $a->output();

I don't know why there is no space in output, the tested pdf shows like this:

CompetingConservationObjectivesforPredatorsandPrey:EstimatingKillerWhalePreyRequirementsforChinookSalmonRobWilliams,MartinKrkos,ErinAshe,TrevorA.Branch,SteveClark,PhilipS.HammondErichHoyt,DawnP.Noren,DavidRosen,ArlissWinshipUniversityofWashington,

Can anyone tell me how to fix or where to fix it?