Question: how to install pljava in postgresql?
Answer: pljava.classpath = 'POSTGRES_INSTALL_HOME\lib\pljava.jar'
pljava.libjvm_location = 'path_to_libjvm.so'
Where POSTGRES_INSTALL_HOME specifies the location of the Advanced Server installation. ... 
%JRE_HOME%\bin;%JRE_HOME%\bin\client.