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This article mainly introduces "how to use Hibernate jar package". In daily operation, I believe many people have doubts about how to use Hibernate jar package. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "how to use Hibernate jar package". Next, please follow the editor to study!

A total of 23 jar packages are included in Hibernate, which is dazzling. This article will explain the role of each Hibernate jar package in detail, so that you can make a choice according to your own needs in the application.

Download Hibernate, such as 2.0.3 stable version, extract it, and you can see that there are 22 jar packages in a hibernate2.jar and lib directory:

Hibernate2.jar:

Hibernate library, there is nothing to say, must use the Hibernate jar package

◆ cglib-asm.jar: CGLIB library, which Hibernate uses to achieve the dynamic generation of PO bytecode, a very core library, a jar package that must be used

◆ dom4j.jar: dom4j is a XML API of Java, similar to jdom, used to read and write XML files.

Dom4j is a very good Java XML API with excellent performance, powerful functions and extremely easy to use. It is also an open source software that can be found on SourceForge. You can find an article on IBM developerWorks that evaluates the performance, functionality, and ease of use of mainstream Java XML API, and dom4j is excellent in all respects. I started using dom4j nearly two years ago, until now. Nowadays you can see that more and more Java software are using dom4j to read and write XML, especially Sun's JAXM is also using dom4j. This is a must-use Hibernate jar package that Hibernate uses to read and write configuration files.

◆ odmg.jar:

ODMG is an ORM specification, Hibernate implements the ODMG specification, which is a core library that must use the jar package.

◆ commons-collections.jar: one of the Apache Commons packages that contains some collection classes developed by Apache and is more powerful than java.util.*. The jar package that must be used.

◆ commons-beanutils.jar: one of the Apache Commons packages that contains some Bean utility classes. The jar package that must be used.

◆ commons-lang.jar: one of the Apache Commons packages that contains a number of data type utility classes and is an extension of java.lang.*. The jar package that must be used.

◆ commons-logging.jar: one of the Apache Commons packages that contains the logging function and the jar package that must be used.

The package itself contains a Simple Logger, but the functionality is weak. At run time, it will first look for log4j in CLASSPATH, if there is, use log4j, if not, find the java.util.logging with JDK1.4, and use Simple Logger if it can't be found. The emergence of commons-logging.jar is a historical legacy of regret, when Apache strongly lobbied Sun to add log4j to JDK1.4, but the JDK1.4 project team is close to releasing JDK1.4 products, so it rejected Apache's request to use its own java.util.logging, which is far worse than log4j and has mediocre performance.

Later, Apache developed commons-logging.jar to be compatible with two logger. So for log programs written in commons-logging.jar, the underlying Logger can be switched, and you can choose log4j,java.util.logging or its own Simple Logger. However, I still strongly recommend using log4j because the performance of log4j is so high that the time it takes for log to output information is almost equal to that of System.out, while the average processing time for a log is only 5us. You can find the log4j configuration file that Hibernate has prepared for you in Hibernate's src directory. You just need to go to the Apache website to download log4j. Commons-logging.jar is also a required jar package.

The jar packages necessary to use Hibernate are the above, and the rest are optional.

◆ ant.jar: the jar package of the Ant compilation tool that is used to compile Hibernate source code. If you are not going to modify and compile the Hibernate source code, then it is useless, the optional jar package

An auxiliary package for ◆ optional.jar:Ant.

◆ c3p0.jar:C3PO is a database connection pool, and Hibernate can be configured to use C3PO connection pool. If you are going to use this connection pool, you will need this jar package.

◆ proxool.jar: also a connection pool, ditto.

◆ commons-pool.jar, commons-dbcp.jar: DBCP database connection pool, developed by Apache's Jakarta organization, and Tomcat4's connection pool is also DBCP.

In fact, Hibernate also implements a very simple database connection pool. With the above three, you can actually choose four different database connection pooling on Hibernate, depending on your personal preference, but DBCP may be more generic. In addition, if you use Hibernate in EJB, be sure to use App Server connection pooling, and do not use the above four connection pooling, otherwise container management transactions will not work.

◆ connector.jar: JCA specification, this jar is required if you configure Hibernate as Connector on App Server. But in fact, usually App Server will bring this package, so it is actually a redundant bag.

◆ jaas.jar: JAAS is used for permission verification and is included in JDK1.4. So it's actually an extra bag.

◆ jcs.jar: if you are going to use JCS in Hibernate, you must include it, otherwise you don't need it.

◆ jdbc2_0-stdext.jar: an expansion package for JDBC2.0, which is generally used by database connection pools. However, App Server will be brought, so it is also superfluous.

The ◆ jta.jar:JTA specification is required when Hibernate uses JTA, but App Server comes with it, so it is superfluous.

◆ junit.jar: the Junit package, which is needed when you run the test code that comes with Hibernate, otherwise you don't need it.

◆ xalan.jar, xerces.jar, xml-apis.jar: Xerces is the XML parser, Xalan is the formatter, and xml-apis is actually JAXP.

App Server usually comes with it, and JDK1.4 also includes parsers, but it is not Xerces, but Crimson, which is relatively inefficient, but Hibernate only reads configuration files with XML, and performance is not important, so it is superfluous.

At this point, the study on "how to use the Hibernate jar package" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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