iReport的运行是依赖于JDK的，所以……
我以Mac为例（Windows和Mac同理的）：
路径：
- /Applications/JaspersoftiReport/Designer.app/Contents/Resources/ireport/etc/ireport.conf下的ireport.conf文件
原本： jdkhome= 这一行是注释的，然后把路径配置成自己的jdk路径。
修改为：
# ${HOME} will be replaced by user home directory according to platform
default_userdir="${HOME}/.${APPNAME}/5.6.0"
default_mac_userdir="${HOME}/Library/Application Support/${APPNAME}/5.6.0"
# options used by the launcher by default, can be overridden by explicit
# command line switches
default_options="-J-Xms256m -J-Xmx512m -J-Dorg.netbeans.ProxyClassLoader.level=1000 -J-XX:MaxPermSize=512m -J-Dapple.laf.useScreenMenuBar=true -J-Dapple.awt.graphics.UseQuartz=true -J-Dnetbeans.exception.report.min.level=99999 "
# for development purposes you may wish to append: -J-Dnetbeans.logger.console=true -J-ea
# default location of JDK/JRE, can be overridden by using --jdkhome <dir> switch
jdkhome="/Library/Java/JavaVirtualMachines/jdk1.7.0_75.jdk/Contents/Home/jre"
# clusters' paths separated by path.separator (semicolon on Windows, colon on Unices)
#extra_clusters=