xsl本身就是一個構(gòu)型良好的xml，它能夠把一個xml文檔轉(zhuǎn)換成另外一個xml文檔，或者轉(zhuǎn)換成文本文件、html文件等等。這里就是利用xsl來動態(tài)的生成我們想要的java文件（從某種角度看，java代碼其實(shí)也就是一個文本文件），希望能夠通過這篇文章，看到xml以及相關(guān)的技術(shù)所具有的強(qiáng)大能力！

這里首先給一個xml例子，我們將通過一個xsl從該xml文件中抽取有用的信息來生成java代碼（實(shí)際上是一個javabean）：

以下內(nèi)容為程序代碼: <?xml version="1.0" encoding="ISO-8859-1" ?> <bean> <name>Product</name> <comments>This bean represents a product that the company offers to its customers</comments> <property> <name>code</name> <type>int</type> <comments>the product inventory code</comments> </property> <property> <name>name</name> <type>String</type> <comments>the product name</comments> </property> <property> <name>testedOnAnimals</name> <type>boolean</type> <comments>the flag that indicates if the product was tested on animals</comments> </property> <property> <name>availableSince</name> <type>java.util.Date</type> <comments>the date when the company started offering this product to its customers</comments> </property> </bean>

下面我就直接給出轉(zhuǎn)換的xsl，如果大家對xsl不是很了解的話，可以先看一些資料，了解之后就會明白了。我在里面稍微做了些注釋：

以下內(nèi)容為程序代碼: <?xml version="1.0"?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"  xmlns:java="http://xml.apache.org/xslt/java" exclude-result-prefixes="java"> <!--這里就是指定通過這個xsl所轉(zhuǎn)換的結(jié)果的類型，是text格式--> <xsl:output method = "text"/> <!--xslt使用模版來處理xml中的節(jié)點(diǎn)--> <xsl:template match="bean"> /** * <xsl:value-of select="comments"/>//這里是獲取xml文檔中的節(jié)點(diǎn)值 * This class has been generated by the XSLT processor from the metadata */ public class <xsl:value-of select="name"/> { /**  * Creates a new instance of the <xsl:value-of select="name"/> bean  */ public <xsl:value-of select="name"/>() {}   <xsl:apply-templates select="property"/> } </xsl:template> <xsl:template match="property"> private <xsl:value-of select="type"/> <xsl:text> </xsl:text>//輸出文本，這里是輸出一個空格 <xsl:value-of select="name"/>; <xsl:variable name="name" select="name"/>//定義xsl中要使用的變量 <xsl:variable name="cname" select="java:Capitalizer.capitalize($name)"/>//這里使用了xslt extensions，它可以允許在xslt中直接引用java中方法，非常方便。 /**  * Sets <xsl:value-of select="comments"/>  * @param <xsl:value-of select="name"/> is <xsl:value-of select="comments"/>  */ public void set<xsl:value-of select="$cname"/>(<xsl:value- of select="type"/> <xsl:text> </xsl:text><xsl:value- of select="name"/>) { this.<xsl:value-of select="name"/> = <xsl:value-of select="name"/>; } /**  * Returns <xsl:value-of select="comments"/>  * @return <xsl:value-of select="comments"/>  */ public <xsl:value-of select="type"/><xsl:text></xsl:text> <xsl:apply-templates select="type"/><xsl:value-of select="$cname"/>() { return <xsl:value-of select="name"/>; } </xsl:template> <xsl:template match="type"> <xsl:variable name="type" select="."/> <xsl:choose> <xsl:when test="$type='boolean'">is</xsl:when> <xsl:otherwise>get</xsl:otherwise> </xsl:choose> </xsl:template> </xsl:stylesheet>

好了，完成以上工作之后，只要在cmd中，輸入如下的命令行，就可以獲得我們想要的結(jié)果了：
java org.apache.xalan.xslt.Process -in xmlSource-xsl stylesheet -out outputfile

這里列出結(jié)果：

以下內(nèi)容為程序代碼: /** * This bean represents a product that the company offers to its customers * This class has been generated by the XSLT processor from the metadata */ public class Product { /**  * Creates a new instance of the Product bean  */ public Product() {}     private int code;   /**  * Sets the product inventory code  * @param code is the product inventory code  */ public void setCode(int code) { this.code = code; } /**  * Returns the product inventory code  * @return the product inventory code  */ public int getCode() { return code; } private String name;   /**  * Sets the product name  * @param name is the product name  */ public void setName(String name) { this.name = name; } /**  * Returns the product name  * @return the product name  */ public String getName() { return name; } private boolean testedOnAnimals;   /** * Sets the flag that indicates if the product was tested on animals * @param testedOnAnimals is the flag that indicates if the product was tested on animals */ public void setTestedOnAnimals(boolean testedOnAnimals) { this.testedOnAnimals = testedOnAnimals; } /**  * Returns the flag that indicates if the product was tested on animals  * @return the flag that indicates if the product was tested on animals  */ public boolean isTestedOnAnimals() { return testedOnAnimals; } private java.util.Date availableSince;   /**  * Sets the date when the company started offering this product to its customers  * @param availableSince is the date when the company started offering this product to its customers  */ public void setAvailableSince(java.util.Date availableSince) { this.availableSince = availableSince; } /**  * Returns the date when the company started offering this product to its customers  * @return the date when the company started offering this product to its customers  */ public java.util.Date getAvailableSince() { return availableSince; } }

總結(jié)：
1. 在熟悉了xsl的基本使用之后，理解以上的內(nèi)容并不是困難；
2. 這樣做是比較適合預(yù)先知道了某些邏輯功能，但由于某種原因，需要動態(tài)生成，或者是為了節(jié)省不必要的重復(fù)工作，可以通過它自動生成代碼；
3. 修改這個xsl比較方便。

sjoy