JasperReports编译报告设计

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

Jasper报告编译

接口 net.sf.jasperreports.engine.design.JRCompiler 在编译期间起着核心作用。此接口具有多种实现，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，就可以使用Java，Groovy，JavaScript或任何其他脚本语言编写。

我们可以通过以下两种方式编译JRXML文件

程序化编译。
通过ANT任务编译。

JRXML的程序化编译

JasperReports API提供了一个外观类 net.sf.jasperreports.engine.JasperCompileManager 用于编译JasperReport。该类包含几个用于编译报告模板的公共静态方法。模板的来源可以是文件，输入流和/或存储器对象。

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中

<?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_reporttemplate.jrxml 文件的编译。

package com.codingdict;

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!!! ...");
   }
}

模板编译

下一步，让我们将以上内容保存在文件 C：\ tools \ jasperreports-5.0.1 \ test \ src \ com \ codingdict \ JasperReportCompile.java中， 并在build.xml文件中导入 baseBuild.xml ，如下所示。baseBuild.xml已经有了编译和运行目标

<?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.codingdict.JasperReportCompile

C:\tools\jasperreports-5.0.1\test>ant -Dmain-class = com.codingdict.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.codingdict.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

作为上述编译的结果，您将看到模板文件 _jasper_reporttemplate.jasper 在C：\ tools \ jasperreports-5.0.1 \ test目录中生成。

预览编译的报告模板

该 net.sf.jasperreports.view.JasperDesignViewer 可用于预览编译后的报表模板和模板JRXML。

为了进一步移动，我们将新的目标 viewDesign 添加到上面的build.xml文件中，这将允许我们预览已编译的报告。下面是修改后的build.xml -

导入文件 - baseBuild.xml是从环境设置章节中挑选出来的，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>

让我们在命令提示符下执行命令 - ant （viewDesign是默认目标）。JasperDesignViewer窗口打开，显示Jasper文件，如下所示

Jasper设计查看器

通过ANT任务编译

由于报表模板编译更像是设计时作业而不是运行时作业，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 net.sf.jasperreports.ant.JRAntCompileTask 实现。它的语法和行为与内置的 <javac> ANT任务非常相似。

模板编译

让我们在现有的build.xml中添加新的目标 compilereportdesing 。这里，使用带有文件集的嵌套<src>标记指定源文件夹。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。下面是修改后的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

文件 _jasper_reporttemplate.jasper 是在文件系统中生成的（在我们的例子中是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 。