Because the company requires open jdk to be used online, we recently replaced all local java jdk with open jdk. I encountered a small problem in the middle, please record it.
I remember that I received an update from Oracle before, and thought I had replaced it with open jdk at the time. I looked at the environment and found that I was using java jdk, haha.
The difference between the two: In
simple terms, OpenJDK is open source, and Java JDK is official, which is Oracle JDK
Installation tutorial of open jdk under linux: http://openjdk.java.net/install/
Download the installation package of open jdk under windows: http://jdk.java.net/
Because I use java jdk8 locally, I chose to install open jdk8
http://jdk.java.net/java-se-ri/8-MR3, but the official website can only find 32-bit open jdk8, open jdk9 and above But you can find 64-bit ones,
so in the end I installed 32-bit open jdk8 locally (if you need 64-bit, you may only have to download the source code to compile by yourself)
After downloading, unzip and configure the environment variable JAVA_HOME, and add the following configuration in the path: (open jdk does not need to configure the classpath)
But when you execute java -version again, you see java jdk instead of open jdk.
After checking the configuration, I found that there is an Oracle jdk path in the path. C:\Program Files (x86)\Common Files\Oracle\Java\javapath
Guess whether it caused the open jdk configuration I set to not be used first, delete it and try again.
From the above java environment, you can see that there are two types of virtual machines: Server VM and Client VM
Client VM (-client) is designed and optimized to reduce the startup time in the client environment;
Server VM (-server) is designed to maximize the execution speed of the program in the server environment.
I use it locally, so it’s okay to use Client VM
If you want to change to Server VM, you can also go to the jvm configuration file to modify.
64-bit operating system: the configuration file of jvm is in {JRE_HOME}/lib/amd64/jvm.cfg
32-bit operating system: the configuration file of jvm is in {JRE_HOME}/lib/i386/jvm.cfg
Look at the first line in the jvm.cfg configuration file. If it is -client, the Client VM is used. If it is -server, the Server VM is used. Just change the location.
As long as -client is deleted, the above warning will not be prompted
