JRE System Library、Referenced Libraries、Web App Libraries的含义

• JRE System Library, Referenced Libraries, Web App Libraries These three are stored collection jar package .
• JRE System Library: Java SE refers to a set of common libraries, establish regular Java project will use.
• Referenced Libraries: refers to the project that you used in the collection of third-party libraries , if you put other items required JAR packages directly added to the project -> Properties -> Java Build Path -> Libraries in time, Eclipse JAR package automatically categorize these into a collection, and named Referenced Libraries, displayed in the project.
• Q: jar package conflicts often arise in SSH in, I do not know the jar file in conflict Referenced Libraries, or WebRoot / WEB-INF / lib / jar file conflicts under?
  • Solution: compile conflict is caused by Referenced Libraries in jar package conflicts; runtime conflicts by WebRoot / WEB-INF / lib / jar file-conflict arising.
  • First, Referenced Libraries may be referenced jar package under WebRoot / WEB-INF / lib / lib, it can also be copied from somewhere else other over the third-party jar package. Referenced Libraries JAR package is used under the build environment, the use of so-called JAR package build environment, that when you were writing the source file in Eclipse, the need to refer to the class Referenced Libraries this collection of JAR package take.
  • WebRoot / WEB-INF / lib in the package is a JAR JAR package uses a runtime environment, a collection of JAR JAR package package uses a so-called run-time environments, that you run your project in the time needed to be used.
  • Note distinguish two environments: build environment and runtime environment.
• Web App Libraries: About web project did not see the Web App Libraries, by right project -> built path -> Configure built path -> Click libraries tab -> Add Library ... and select the right button in the pop-up window select Web App Libraries can be added.

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• Referenced Libraries are stored third-party jar package , which is its own import jar package . Configuring the Java Build Path of the project properties in the Libraries.
  • I understand: Here import and configure the jar package, is to let the web project in eclipse development environment can be compiled normally , it is not being given. If the web project using the eclipse generate war package, it will not export its jar package to the WEB-INF / lib folder.
• The main role of Web App Libraries is to export the war package eclipse, when all the projects under the jar or put it in the directory project references is exported to WEB-INF / lib folder.
  • Java EE Module Dependencies Web App Libraries in a jar in eclipse project configuration properties. If you hook up, or add external jar package will generate in WEB-INF / lib folder.
  • Of course, if you are directly in the WEB-INF / lib folder, copy a jar enter, refresh, Web App Libraries will automatically add a jar of reference. Simply put, Java EE Module Dependencies are configured only for Web App Libraries.
• Referenced Libraries following jar package at the time of publication of the project will not be packaged .

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• 1 up the knife:
  • EJB = Enterprise Java Bean
    • Entity Bean -> similar to the Hibernate persistent object
    • Session Bean -> similar to Service
    • Message-driven Bean -> Send Message
  • EAR Libraries: need to develop EJB project library package.
  • EAR Libraries: library package is to develop JavaEE server-side component model is needed. But now generally use the framework of lightweight modular. EJB too bulky, 2003 Taobao is to use EJB development, now rarely met.
  • Needed to develop EJB project library package, as we often zip or rar, just as you can extract out.
  • by the way:
    • war package: After doing a web application is usually the site, packed in bales deployed to the container.
    • jar package: usually a reference to the development of generic class, labeled packet for storage management.
    • ear package: enterprise applications, EJB is usually labeled as ear package.
    • All packages are hit with a jar , but the extension of the target file is not the same.

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• 2 up the knife:
  • cdn stands for Content Delivery Network, is mainly used to accelerate the static resources , such as uploading pictures, media, as well as the introduction of some js and css files and other top sites. It relies on each network node acceleration, such as 100 CDN servers located in the country, accessible from Shanghai, it will return resources from the nearest node , which is the core.

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