我们在前一章中生成了JasperReport模板(JRXML文件).此文件不能直接用于生成报告.它必须编译为JasperReport的本机二进制格式，称为 Jasper 文件.在编译时，我们将JasperDesign对象转换为JasperReport对象 :
接口 net.sf.jasperreports.engine.design.JRCompiler 在编译期间起着核心作用.该接口有多种实现，具体取决于报表表达式使用的语言，只要编译器实现可以在运行时对其进行评估，就可以用Java，Groovy，JavaScript或任何其他脚本语言编写.
我们可以用以下两种方式编译JRXML文件 :
程序化编译.
通过ANT任务编译.
JasperReports API提供了一个外观类 net .sf.jasperreports.engine.JasperCompileManager 用于编译JasperReport.此类包含几个用于编译报告模板的公共静态方法.模板源可以是文件，输入流和/或内存对象.
JRXML文件(jasper_report_template.jrxml)的内容如下所示.它保存在目录 C:\tools\jasperreports-5.0.1 \ test :
<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN"
"http://jasperreports.sourceforge.net/dtds/jasperreport.dtd">
<jasperReport xmlns = "http://jasperreports.sourceforge.net/jasperreports"
xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation = "http://jasperreports.sourceforge.net/jasperreports
http://jasperreports.sourceforge.net/xsd/jasperreport.xsd"
name = "jasper_report_template" language = "groovy" pageWidth = "595"
pageHeight = "842" columnWidth = "555" leftMargin = "20" rightMargin = "20"
topMargin = "20" bottomMargin = "20">
<queryString>
<![CDATA[]]>
</queryString>
<field name = "country" class = "java.lang.String">
<fieldDescription><![CDATA[country]]></fieldDescription>
</field>
<field name = "name" class = "java.lang.String">
<fieldDescription><![CDATA[name]]></fieldDescription>
</field>
<columnHeader>
<band height = "23">
<staticText>
<reportElement mode = "Opaque" x = "0" y = "3"
width = "535" height = "15" backcolor = "#70A9A9" />
<box>
<bottomPen lineWidth = "1.0" lineColor = "#CCCCCC" />
</box>
<textElement />
<text><![CDATA[]]> </text>
</staticText>
<staticText>
<reportElement x = "414" y = "3" width = "121" height = "15" />
<textElement textAlignment = "Center" verticalAlignment = "Middle">
<font isBold = "true" />
</textElement>
<text><![CDATA[Country]]></text>
</staticText>
<staticText>
<reportElement x = "0" y = "3" width = "136" height = "15" />
<textElement textAlignment = "Center" verticalAlignment = "Middle">
<font isBold = "true" />
</textElement>
<text><![CDATA[Name]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height = "16">
<staticText>
<reportElement mode = "Opaque" x = "0" y = "0"
width = "535" height = "14" backcolor = "#E5ECF9" />
<box>
<bottomPen lineWidth = "0.25" lineColor = "#CCCCCC" />
</box>
<textElement />
<text><![CDATA[]]> </text>
</staticText>
<textField>
<reportElement x = "414" y = "0" width = "121" height = "15" />
<textElement textAlignment = "Center" verticalAlignment = "Middle">
<font size = "9" />
</textElement>
<textFieldExpression class = "java.lang.String">
<![CDATA[$F{country}]]>
</textFieldExpression>
</textField>
<textField>
<reportElement x = "0" y = "0" width = "136" height = "15" />
<textElement textAlignment = "Center" verticalAlignment = "Middle" />
<textFieldExpression class = "java.lang.String">
<![CDATA[$F{name}]]>
</textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>以下代码演示了上述 jasper_report_template.jrxml 文件的编译.
package com.it1352;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperCompileManager;
public class JasperReportCompile {
public static void main(String[] args) {
String sourceFileName = "C://tools/jasperreports-5.0.1/test" +
"/jasper_report_template.jrxml";
System.out.println("Compiling Report Design ...");
try {
/**
* Compile the report to a file name same as
* the JRXML file name
*/
JasperCompileManager.compileReportToFile(sourceFileName);
} catch (JRException e) {
e.printStackTrace();
}
System.out.println("Done compiling!!! ...");
}
}下一步，让我们保存上面的内容文件 C:\tools\jasperreports-5.0.1\test\src\com\it1352\ JapersReportCompile.java 并导入 baseBuild.xml 在build.xml文件中，如下所示. baseBuild.xml已经有编译和运行目标&减去;
<?xml version = "1.0" encoding = "UTF-8"?> <project name = "JasperReportTest" default = "run" basedir = "."> <import file = "baseBuild.xml"/> </project>
接下来，让我们打开命令行窗口并转到build.xml所在的目录.最后，执行命令 ant -Dmain-class = com.it1352.JasperReportCompile 作为 :
C:\tools\jasperreports-5.0.1\test>ant -Dmain-class = com.IT屋.JasperReportCompile Buildfile: C:\tools\jasperreports-5.0.1\test\build.xml compile: [javac] C:\tools\jasperreports-5.0.1\test\baseBuild.xml:27: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last;set to false for repeatable builds [javac] Compiling 1 source file to C:\tools\jasperreports-5.0.1\test\classes run: [echo] Runnin class : com.IT屋.JasperReportCompile [java] Compiling Report Design ... [java] log4j:WARN No appenders could be found for logger (net.sf.jasperreports.engine.xml.JRXmlDigesterFactory). [java] log4j:WARN Please initialize the log4j system properly. [java] Done compiling!!! ... BUILD SUCCESSFUL Total time: 8 seconds
由于上面的编译，你会看到该模板文件 jasper_report_template.jasper 在C:\ tools \jasperreports-5.0.1 \ test目录中生成.
net.sf.jasperreports.view.JasperDesignViewer 可用于预览已编译的报告模板和JRXML模板.
To进一步移动，让我们在上面的build.xml文件中添加一个新的目标 viewDesign ，这将允许我们预览编译的报告.下面是修订后的build.xml :
导入文件 - baseBuild.xml是从环境一章中选取的设置并且应该与build.xml放在同一目录中.
<?xml version = "1.0" encoding = "UTF-8"?>
<project name = "JasperReportTest" default = "viewDesign" basedir = ".">
<import file = "baseBuild.xml" />
<target name = "viewDesign" description="Design viewer is launched
to preview the compiled report design.">
<java classname = "net.sf.jasperreports.view.JasperDesignViewer" fork = "true">
<arg value = "-F${file.name}.jasper" />
<classpath refid = "classpath" />
</java>
</target>
</project>让我们执行命令 : 命令提示符处 ant (viewDesign是默认目标). JasperDesignViewer窗口打开，显示Jasper文件，如下所示;
由于报表模板编译更像是设计时作业而非运行时作业，因此JasperReport库具有自定义ANT任务.对于某些情况，在运行时创建JRXML文件时，我们无法使用此ANT任务.自定义ANT任务称为JRC，由类实现: net.sf.jasperreports.ant.JRAntCompileTask .它的语法和行为与内置的< javac> ANT任务非常相似.
让我们将新目标 compilereportdesing 添加到现有的build.xml中.这里，使用嵌套的< src>指定源文件夹.标记与文件集.嵌套的源标记允许编译分散在许多不同位置的报表模板，而不是在单个根报表源文件夹下分组.下面是修订后的build.xml :
<?xml version = "1.0" encoding = "UTF-8"?>
<project name = "JasperReportTest" default = "compilereportdesing" basedir = ".">
<import file = "baseBuild.xml" />
<target name = "viewDesign" description = "Design viewer is
launched to preview the compiled report design.">
<java classname = "net.sf.jasperreports.view.JasperDesignViewer" fork = "true">
<arg value = "-F${file.name}.jasper" />
<classpath refid = "classpath" />
</java>
</target>
<target name = "compilereportdesing" description = "Compiles the
JXML file and produces the .jasper file.">
<taskdef name = "jrc" classname = "net.sf.jasperreports.ant.JRAntCompileTask">
<classpath refid = "classpath" />
</taskdef>
<jrc destdir = ".">
<src>
<fileset dir = ".">
<include name = "*.jrxml" />
</fileset>
</src>
<classpath refid = "classpath" />
</jrc>
</target>
</project>接下来，让我们打开命令提示符并转到build.xml所在的目录.执行命令 ant (compilereportdesing是默认目标);输出如下 :
C:\tools\jasperreports-5.0.1\test>ant Buildfile: C:\tools\jasperreports-5.0.1\test\build.xml compilereportdesing: [jrc] Compiling 1 report design files. [jrc] log4j:WARN No appenders could be found for logger (net.sf.jasperreports.engine.xml.JRXmlDigesterFactory). [jrc] log4j:WARN Please initialize the log4j system properly. [jrc] log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info. [jrc] File : C:\tools\jasperreports-5.0.1\test\jasper_report_template.jrxml ... OK. BUILD SUCCESSFUL Total time: 5 seconds
生成文件 jasper_report_template.jasper 在文件系统中(在我们的例子中为C:\tools \jasperreports-5.0.1 \ test目录).此文件与通过调用net.sf.jasperreports.engine.JasperCompileManager.compileReportToFile()以编程方式生成的文件相同.我们可以预览这个jasper文件，执行 ant viewDesign .
