I'll start coding with JEE soon. Product environment adopts Oracle WebLogic in Linux, technology adopts EJB3 and JPA. So I'm going to set a development environment in my own computer with them. For iMac installing JDK, Eclipse or Maven wil
I'll start coding with JEE soon. Product environment adopts Oracle + WebLogic in Linux, technology adopts EJB3 and JPA. So I'm going to set a development environment in my own computer with them.
For iMac installing JDK, Eclipse or Maven will not be problem, but installing Oracle seems a impossible mission, now virtualbox become a very good choice.
Install VirtualBox
Download from https://www.virtualbox.org/, nothing special on installing. But it's really a magic tool.
Create a new Virtual Machine for Oracle Linux
You'd better to download a Oracle Linux 7 installer ISO file before starting this step. https://edelivery.oracle.com/linux. You need specify a installer ISO file during the process of creating virtual machine.
1. Name your virtual machine, choose the OS you will install later and set the size of memory.
2. Set the size of virtual machine's "hard disk". Click OK the virtual machine will be created.
You still need change's several basic settings. Select the virtual machine you just created, click "Settings" button on the top of VirtualBox Manager.
1. Specify the installer ISO file which will be installed onto this virtual machine later.
Storage --> Click CD ROM icon on right (Storage Tree) --> Click CD ROM icon on left (Attributes) --> Choose a virtual CD/DVD disk file --> Select the Oracle Linux installer which you downloaded in advance.
2. Enable network connection. This virtual machine will be assigned a IP address you can access from you computer after OS has been installed. For example, you can ssh this virtual machine.
3. All done, click OK.
Install Oracle Linux 7 in this Virtual Machine
1. Select VirtualBox you created former, click "Start" button on top
** Clicking "Left Command Button" can move your mouse cursor out of the installation screen.
2. Software Selection
3. Enable network connection
4. Reboot after complete installation, still need do some basic configurations.
- Enable Kdump
- Set up software update. I select "No, I prefer to register at a later time." because I don't purchase any oracle product...
Rmove OpenJDK
OpenJDK is default JVM in Oracle Linux. I see quite a lot of posts say simply run command "yum remove java*", but I'm not sure if this way is secure because wildcard is used, so it seems not really. I'm going to use software GUI to remove it.
After you login Oracle Linux-->Start menu-->System tools-->Software, search openjdk then remove packages.
Install Oracle JDK
1. Download 64bit jdk archive file
2. Extract it into /usr/lib
3. Add JAVA_HOME variable into /etc/profile. This jvm is enabled for all the users of this vm.
export JAVA_HOME=/usr/lib/jdk-1.8.0-xxx
export PATH=$PATH:$JAVA_HOME/bin

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最佳的MySQLVARCHAR列长度选择应基于数据分析、考虑未来增长、评估性能影响及字符集需求。1)分析数据以确定典型长度;2)预留未来扩展空间;3)注意大长度对性能的影响;4)考虑字符集对存储的影响。通过这些步骤,可以优化数据库的效率和扩展性。


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