Java 网络加载协议 (JNLP)

编写：徐建祥（netpirate@gmail.com）

时间：2006-03-09 01:15

来自：http://www.anymobile.org

Java 网络加载协议 (JNLP)： 是 Java Web Start 的一个组成协议，通常定义为一种通过网络并穿透防火墙传输驻留于服务器的应用程序、并在客户机上启动它的机制。--算是一种安全的同步机制

Java(TM) Web Start：是一种简化 Java 应用程序部署的技术，让用户不需要复杂的安装过程，单击 Web 浏览器就可以启动全功能的应用程序。J2SE 捆绑了 Java Web Start。

D/S结构（DestktopApplication/ServerApplication）：客户端使用Swing，服务器端使用Servlet，采用Swing和Servlet来交换数据，可以采用标准的HTTP协议来通讯，来交换数据。

JNLP 文件其实是一个xml文件，描述了产品信息，使用的jar文件网址和 main-class 定义等。
客户端点击 JNLP 文件的连接，就会激活本地的 Java Web Start，选择下载 jar 包后，下载完备就可以运行相关的程序。可以操作本地数据，其实是把 jar 包下载到本地（每次允许都会自动更新），调用远程的 servlet 来交互数据。

样例 JClaim 的jclaimsf.jnlp 代码清单：

<? xmlversion="1.0"encoding="utf-8" ?>
<!--
~Copyright(c)2006,ITBSLLC.AllRightsReserved.
~
~ThisfileispartofJClaim.
~
~JClaimisfreesoftware;youcanredistributeitand/ormodify
~itunderthetermsoftheGNUGeneralPublicLicenseaspublishedby
~theFreeSoftwareFoundation;version2oftheLicense.
~
~JClaimisdistributedinthehopethatitwillbeuseful,
~butWITHOUTANYWARRANTY;withouteventheimpliedwarrantyof
~MERCHANTABILITYorFITNESSFORAPARTICULARPURPOSE.Seethe
~GNUGeneralPublicLicenseformoredetails.
~
~YoushouldhavereceivedacopyoftheGNUGeneralPublicLicense
~alongwithJClaim;ifnot,finditatgnu.orgorwritetotheFreeSoftware
~Foundation,Inc.,51FranklinSt,FifthFloor,Boston,MA02110-1301USA
~
-->

< jnlp
spec ="1.0+"
codebase ="http://jclaim.sourceforge.net"
href ="/jclaimsf.jnlp"
>
< information >
< title > JCLAIM </ title >
< vendor > ITBSLLC </ vendor >
< description > JavaCompliantLoggingandAuditingInstantMessenger. </ description >
< description kind ="short" > JCLAIM </ description >
< icon href ="/logo.gif" />
</ information >
< security >
< all-permissions />
</ security >
< resources >
< j2se version ="1.5" max-heap-size ="25m" />
< jar href ="jclaim.jar" main ="true" />
< jar href ="cos.jar" />
< jar href ="jaimlib.jar" />
< jar href ="jazzy.jar" />
< jar href ="jdic.jar" />
< jar href ="joscar.jar" />
< jar href ="jsocks.jar" />
< jar href ="msnm.jar" />
< jar href ="oscar.jar" />
< jar href ="smack.jar" />
< jar href ="ymsg.jar" />
</ resources >
< resources os ="Mac" >
< jar href ="lib/mac/jdic_misc.jar" />
</ resources >
< resources os ="Windows" >
< jar href ="lib/win32/jdic_misc.jar" />
< jar href ="lib/win32/jdic_stub.jar" />
< nativelib href ="lib/win32/native.jar" />
</ resources >
< resources os ="Linux" >
< jar href ="lib/linux/jdic_stub.jar" />
< nativelib href ="lib/linux/native.jar" />
</ resources >
< resources os ="SunOS" arch ="x86" >
< jar href ="lib/sunos/jdic_stub.jar" />
< nativelib href ="lib/sunos/native.jar" />
</ resources >
< resources os ="SunOS" arch ="sparc" >
< jar href ="lib/sunos/jdic_stub.jar" />
< nativelib href ="lib/sunos/native.jar" />
</ resources >

< application-desc main-class ="com.itbs.aimcer.gui.Main" >
</ application-desc >
</ jnlp >

资源：

Java Web Starthttp://java.sun.com/products/javawebstart/developers.html
动态 JNLPhttps://www6.software.ibm.com/developerworks/cn/education/java/j-dynjnlp/tutorial/j-dynjnlp-1-1.html