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This article mainly introduces "What is the difference between Oracle JDK and OpenJDK". In daily operation, I believe many people have doubts about what is the difference between Oracle JDK and OpenJDK. Xiaobian consulted all kinds of information and sorted out simple and easy to use operation methods. I hope to help you answer the doubts of "What is the difference between Oracle JDK and OpenJDK"! Next, please follow the small series to learn together!

OpenJDK is a project formed by Sun in late 2006 to open source Java, where "open source" is the usual open source form, that is, the source code can be reused, such as IcedTea, UltraViolet are distributions derived from OpenJDK source code.

Oracle JDK uses a commercial implementation, while OpenJDK uses the open-source FreeType. Of course,"identical" is based on components shared by both, and Oracle JDK also has some commercial closed-source features that Open JDK does not have, such as Java Flight Recorder, which is ported from Java. It is expected that MissionControl will also be available in Oracle JDK proprietary, closed-source form after migration to HotSpot.

Oracle project release manager Joe Darcy's introduction to the relationship between the two at OSCON 2011 also confirmed that OpenJDK 7 and Oracle JDK 7 are very close in terms of program, and the two share a lot of the same code (as shown in the figure below, note that the proportion of common code between the two is much higher than the proportion seen on the graph), so our compiled OpenJDK can basically be considered to be consistent with the official Oracle JDK in terms of performance, functionality and execution logic.

In most LINUX distributions, JDK installed either built-in or via software sources is OpenJDK installed.

What is OpenJDK?

The historical reason is that OpenJDK is an open source version of JDK released under the GPL license.

（General Public License）

At the time of JDK7, OpenJDK had become the backbone development version of JDK7, and SUN JDK7 was the backbone development version of OpenJDK7.

Most of the source code is the same, only a few of the source code has been replaced.

Published under the Java Research License (JRL).

As for OpenJDK6, it has its complicated side. First, OpenJDK6 is a branch of JDK7, and it tries to remove the new features of Java SE7 and make it conform to Java6 standards as much as possible.# Difference between JDK and OpenJDK

1. Different licensing agreements

OpenJDK is released under GPL V2, while JDK is released under JRL.

Although both are open source, the difference in usage is that GPL V2 allows commercial use,

JRL allows only individual research.

OpenJDK contains only the most compact JDK.

OpenJDK does not contain other packages, such as Rhino Java DB JAXP…, and packages that can be separated are also separated as much as possible, but most of these are free software, you can download them yourself.

OpenJDK source code is incomplete

It's easy to imagine that in OpenJDK under the GPL, part of the source code of SUN JDK is proprietary.

OpenJDK cannot be opened for use, the most important part of which is the SNMP part of the optional component in JMX

code.

So these cannot be open source code to make it plug, for OpenJDK compilation time to use, you can also choose

Do not use plugs.

Icedtea developed source code (OpenJDK6) for the same functionality for these incomplete parts, prompting

OpenJDK is more complete.

4. Relationship between OpenJDK and IcedTea

The IcedTea project was originally created because OpenJDK was incomplete (due to obstacles caused by property rights), and the community needed

A complete open source tool chain and code base.

IcedTea has long been a set of patches for OpenJDK, and as I mentioned earlier, it has a patch based on

"./ different build systems for "configure."

In OpenJDK, we have replaced the encoded code, so there are no more obstacles.

Because of our efforts, the IcedTea project has reduced the number of patches used.

One of the nice things about IcedTea is that its configure script allows it to be built in a variety of different modes.

OpenJDK becomes easy, such as using Zero Assembler Port to support compilation on non-x86/sparc chips

Wait a minute.

One big piece of content IcedTea offers is plugin/java-web-start infrastructure.

5. Part of the source code replaced with open source code

Due to proprietary issues, much of the SUN JDK source code has been replaced with open source code with the same functionality, such as the font rasterization engine, using Free Type instead.

6. Java trademarks cannot be used

This is easy to understand, on machines with OpenJDK installed, typing "java -version" shows OpenJDK, but if OpenJDK uses the Icedtea patch, java is displayed.

(Not verified)

At this point, the study of "What is the difference between Oracle JDK and OpenJDK" is over, hoping to solve everyone's doubts. Theory and practice can better match to help everyone learn, go and try it! If you want to continue learning more relevant knowledge, please continue to pay attention to the website, Xiaobian will continue to strive to bring more practical articles for everyone!

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