use env var for classpath jars

Author: Ann Witbrock

java/README.md

@@ -14,13 +14,23 @@ unzipped directory are placed in your working directory:
     $ unzip rabbitmq-java-client-bin-*.zip
     $ cp rabbitmq-java-client-bin-*/*.jar ./
 
-To compile you only need the Rabbitmq java client on the classpath.
+To compile you only need the Rabbitmq java client jar on the classpath.
 
 To run them you'll need all the dependencies, see examples below. 
 
 Note: If you're on Windows, 
 use a semicolon instead of a colon to separate items in the classpath.
 
+> You can set an environment variable for the jar files on the classpath e.g.
+>
+>      $ export CP=.:commons-io-1.2.jar:commons-cli-1.1.jar:rabbitmq-client.jar
+>      $ java -cp $CP Send
+>
+> or on Windows:
+>
+>      > set CP=.;commons-io-1.2.jar;commons-cli-1.1.jar;rabbitmq-client.jar
+>      > java -cp %CP% Send
+
 ## Code
 
 [Tutorial one: "Hello World!"](http://www.rabbitmq.com/tutorial-one-java.html):
@@ -34,14 +44,14 @@ use a semicolon instead of a colon to separate items in the classpath.
 
     $ javac -cp rabbitmq-client.jar NewTask.java Worker.java
 
-    $ java -cp .:commons-io-1.2.jar:commons-cli-1.1.jar:rabbitmq-client.jar NewTask
-    $ java -cp .:commons-io-1.2.jar:commons-cli-1.1.jar:rabbitmq-client.jar Worker
+    $ java -cp $CP NewTask
+    $ java -cp $CP Worker
 
 [Tutorial three: Publish/Subscribe](http://www.rabbitmq.com/tutorial-three-java.html)
 
     $ javac -cp rabbitmq-client.jar EmitLog.java ReceiveLogs.java
 
-    $ java -cp .:commons-io-1.2.jar:commons-cli-1.1.jar:rabbitmq-client.jar EmitLog
-    $ java -cp .:commons-io-1.2.jar:commons-cli-1.1.jar:rabbitmq-client.jar ReceiveLogs
+    $ java -cp $CP EmitLog
+    $ java -cp $CP ReceiveLogs