Debian install jdk7

1. download jdk

jdk-7u60-linux-x64.tar.gz

2. unzip jdk-file to /usr/lib/jvm/.

/usr/lib/jvm/jdk1.7.0_60

3. set environment

vi /etc/profile, add
#set java environment
export JAVA_HOME=/usr/lib/jvm/jdk1.7.0_60
export JRE_HOME=$JAVA_HOME/jre
export CLASSPATH=$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH

4. enable profile

execute
source /etc/profile
to enable java environment

5. set default app

update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk1.7.0_60/bin/java 17060

update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk1.7.0_60/bin/javac 17060

update-alternatives --config java

6. check the installation with:
java -version