JasperReports - 编译报表设计

我们在上一章中已经生成了JasperReport模板（JRXML文件）。该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。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在编译过程中起着核心作用。该接口有多种实现，具体取决于用于报表表达式的语言，可以用 Java、Groovy、JavaScript 或任何其他脚本语言编写，只要编译器实现可以在运行时对其进行评估即可。

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 的编程编译

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。模板的来源可以是文件、输入流和/或内存对象。

JRXML 文件（jasper_report_template.jrxml）的内容如下。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.tutorialspoint;

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，我们将上述内容保存在文件C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\JasperReportCompile.java中，并在 build.xml 文件中导入baseBuild.xml，如下所示。baseBuild.xml 已经具有编译和运行目标 -

<?xml version = "1.0" encoding = "UTF-8"?>
<project name = "JasperReportTest" default = "run" basedir = ".">

   <import file = "baseBuild.xml"/>

</project>

接下来，我们打开命令行窗口并进入build.xml所在的目录。最后，执行命令ant -Dmain-class = com.tutorialspoint.JasperReportCompile为 -

C:\tools\jasperreports-5.0.1\test>ant -Dmain-class = com.tutorialspoint.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.tutorialspoint.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_report_template.jasper在 C:\tools\jasperreports-5.0.1\test 目录中生成。

预览已编译的报告模板

net.sf.jasperreports.view.JasperDesignViewer可用于预览编译的报告模板和 JRXML 模板。

为了更进一步，让我们向上面的 build.xml 文件添加一个新的目标viewDesign ，这将允许我们预览编译后的报告。以下是修订后的 build.xml -

导入文件 - baseBuild.xml 从“环境设置”一章中选取，应放置在与 build.xml 相同的目录中。

<?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处执行命令 - ant（viewDesign 是默认目标）。JasperDesignViewer 窗口打开，显示 Jasper 文件，如下所示 -

贾斯珀设计查看器

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 库有一个自定义 ANT 任务。对于某些情况，当运行时创建 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Behave与内置的<javac> ANT 任务非常相似。

模板编译

让我们将新的目标编译器报告添加到现有的 build.xml 中。此处，使用带有文件集的嵌套 <src> 标记来指定源文件夹。嵌套源标签允许编译分散在许多不同位置且不分组在单个根报告源文件夹下的报告模板。以下是修订后的 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放置 build.xml 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_report_template.jasper在文件系统中生成（在我们的例子中为 C:\tools\jasperreports-5.0.1\test 目录）。该文件与通过调用 net.sf.jasperreports.engine.JasperCompileManager.compileReportToFile() 以编程方式生成的文件相同。我们可以通过执行ant viewDesign来预览这个 jasper 文件。