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JasperReports - 编译报告设计

我们在上一章中生成了 JasperReport 模板(JRXML 文件)。此文件不能直接用于生成报告。它必须被编译为 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 Report Compiling

接口 net.sf.jasperreports.engine.design.JRCompiler 在编译过程中起着核心作用。该接口有几种实现，具体取决于用于报告表达式的语言，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 −

  • 编程编译。
  • 通过 ANT 任务进行编译。

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。此类由几种用于编译报告模板的公共静态方法组成。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，让我们将上述内容保存在文件 C:\tools\jasperreports-5.0.1\test\\src\com utorialspoint\JasperReportCompile.java 中，并在 build.xml 文件中导入 baseBuild.xml，如下所示。baseBuild.xml 已经具有 compile 和 run 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，进入 build.xml 所在的目录。最后，执行命令 ant -Dmain-class = com.tutorialspoint.JasperReportCompile 如下 −

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

上述编译的结果，您将看到模板文件 jasper_report_template.jasper 已在 C:\ools\jasperreports-5.0.1\est 目录中生成。

预览已编译的报告模板

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

为了进一步操作，让我们向上述 build.xml 文件添加一个新的目标 viewDesign，这将允许我们预览已编译的报告。以下是修订后的 build.xml −

导入文件 - baseBuild.xml 是从环境设置章中选择的，应将其放在与 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 Design Viewer

通过 ANT 任务进行编译

由于报告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。在某些情况下，当在运行时创建 JRXML 文件时，我们不能使用此 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。

模板编译

让我们将新目标 compilereportdesing 添加到现有的 build.xml 中。在这里，使用带有文件集的嵌套 <src> 标记指定源文件夹。嵌套源标记允许编译分散在许多不同位置且未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>

接下来我们打开命令提示符，进入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

在文件系统中生成文件 jasper_report_template.jasper(在我们的例子中是 C:ools\jasperreports-5.0.1 est 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。我们可以通过执行 ant viewDesign 来预览此 jasper 文件。

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