I found Java 1.7 SDK in /Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk, and all the binaries in /Library/Java/JavaVirtualMachines/jdk1.7.0_07.jdk/Contents/Home/bin.
And by clicking the jdk file, I could arrange the order so that Java SE 7 is executed first.
java -version
java version "1.7.0_07"
Java(TM) SE Runtime Environment (build 1.7.0_07-b10)
Java HotSpot(TM) 64-Bit Server VM (build 23.3-b01, mixed mode)