How to install JDK8 or JDK9 on Ubuntu

from: https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-get-on-ubuntu-16-04

  • sudo add-apt-repository ppa:webupd8team/java
  • sudo apt-get update
  • sudo apt-get install oracle-java8-installer
  • sudo update-alternatives –config java

 

From: https://github.com/franzwong/til/blob/master/java/silent-install-oracle-jdk8-ubuntu.md

Silent install Oracle JDK 8 on Ubuntu

Problem: During installation of Oracle JDK 8 on Ubuntu, we need to agree on license agreement manually.

Solution: Installing Java Automatically (With Silent Option)

Shell script:

sudo apt-get install -y python-software-properties debconf-utils
sudo add-apt-repository -y ppa:webupd8team/java
sudo apt-get update
echo "oracle-java8-installer shared/accepted-oracle-license-v1-1 select true" | sudo debconf-set-selections
sudo apt-get install -y oracle-java8-installer

Ansible:

---
- name: Add apt repository
  apt_repository:
      repo: 'ppa:webupd8team/java'
      state: present
      update_cache: yes

- name: Accept license
  debconf:
    name: 'oracle-java8-installer'
    question: 'shared/accepted-oracle-license-v1-1'
    value: 'true'
    vtype: 'select'

- name: Install java
  apt: name={{ item }} state=present
  with_items:
      - oracle-java8-installer
      - ca-certificates
      - oracle-java8-set-default

One to One mapping in hibernate

<hibernate-mapping package=”gar.entity”>

<class name=”RTPRequest” table=”rtp_request”>
<id name=”id” type=”long”>
<column name=”id” />
<generator class=”sequence”>
<param name=”sequence”>seq_rtp_request</param>
<param name=”allocationSize”>1</param>
<param name=”initialValue”>1</param>
</generator>
</id>

<one-to-one name=”garnishment” class=”Garnishment” cascade=”all”></one-to-one>

</class>

</hibernate-mapping>

 

===================================================

<hibernate-mapping package=”gar.entity”>

<class name=”Garnishment” table=”garnishment”>

<id name=”id” type=”long”>
<column name=”id”/>
<generator class=”foreign”>
<param name=”property”>rtpRequest</param>
</generator>
</id>

<one-to-one name=”rtpRequest” class=”RTPRequest” constrained=”true”></one-to-one>

</class>

</hibernate-mapping>

set default jdk using alternatives

https://access.redhat.com/documentation/en-US/JBoss_Enterprise_Web_Platform/5/html/Installation_Guide/sect-use_alternatives_to_set_default_JDK.html

 

⁠C.4.  Setting the default JDK with the /usr/sbin/alternatives Utility

/usr/sbin/alternatives is a tool for managing different software packages that provide the same functionality.Red Hat Enterprise Linux uses /usr/sbin/alternatives to ensure that only one Java Development Kit is set as the system default at one time.

Important

Installing a Java Development Kit from the Red Hat Network will normally result in an automatically configured system. However, if multiple JDKs are installed, it is possible that /usr/sbin/alternativesmay contain conflicting configurations. Refer to Procedure C.4, “ Using /usr/sbin/alternatives to Set the Default JDK ” for syntax of the /usr/sbin/alternatives command.

Procedure C.4.  Using /usr/sbin/alternatives to Set the Default JDK

  1. Become the root user.

    /usr/sbin/alternatives needs to be run with root privileges. Use the su command or other mechanism to gain these privileges.
  2. Set java.

    Input this command: /usr/sbin/alternatives --config java
    Next, follow the on-screen directions to ensure that the correct version of java is selected. Table C.1, “javaalternative commands” shows the relevant command settings for each of the different JDKs.

    Table C.1. java alternative commands

    JDK alternative command
    OpenJDK 1.6 /usr/lib/jvm/jre-1.6.0-openjdk/bin/java
    Sun Microsystems JDK 1.6 /usr/lib/jvm/jre-1.6.0-sun/bin/java
  3. Set javac.

    Enter this command: /usr/sbin/alternatives --config javac
    Follow the on-screen directions to ensure that the correct version of javac is selected. Table C.2, “javacalternative commands” shows the appropriate command settings for the different JDKs.

    Table C.2. javac alternative commands

    JDK alternative command
    OpenJDK 1.6 /usr/lib/jvm/java-1.6.0-openjdk/bin/javac
    Sun Microsystems JDK 1.6 /usr/lib/jvm/java-1.6.0-sun/bin/javac
  4. Extra Step: Set java_sdk_1.6.0.

    The Sun Microsystems JDK 1.6 requires an additional command be run:
    /usr/sbin/alternatives --config java_sdk_1.6.0
    Follow the on-screen directions to ensure that the correct java_sdk is selected. It is /usr/lib/jvm/java-1.6.0-sun.

example to use keytool to set up public/private keys

  1. Run the following two commands to generate keystore
    keytool –genkeypair –alias dlkey -keypass password -storetype jks –keystore dlkeystore.jks -storepass password -validity 365 -keyalg RSA
  2. Export certificate of private key dlkey
    keytool –exportcert –alias dlkey -file dlkey.cert -keystore dlkeystore.jks -storepass password
  3. Send the dlkey.cert (public key) to target server.
  4. Run the following command to import the server certificate (fnet.net.cer) to keystore

keytool –importcert –file fnet.net.cer -alias dlcert -keypass password -keystore dlkeystore.jks –storepass password