JasperReports - 创建子报告( Create Subreports)

子报告是JasperReports的一个很好的功能。此功能允许在另一个报表中合并报表，也就是说，一个报表可以是另一个报表的子报表。子报告可以帮助我们简化报表设计，因为我们可以创建许多简单的报表并将它们封装到主报表中。子报表的编译和填充就像普通报告一样。任何报告模板在合并到另一个报告模板时都可以用作子报告，而（报告模板的内部）没有任何更改。

子报表与普通报表模板类似。它们实际上是net.sf.jasperreports.engine.JasperReport对象，它们是在编译net.sf.jasperreports.engine.design.JasperDesign object后获得的。

《subreport》 Element

将子报表引入主报表时使用元素。以下是 JRXML元素中的子元素列表。

<reportElement>
- 用于将包含报表参数的映射传递给子报表。通常从主报表中的参数获取映射，或者使用内置的REPORTS_PARAMETERS_MAP参数将父报表的参数传递给子报表。此表达式应始终返回一个java.util.Map对象，其中键是参数名称。
- 此元素用于将参数传递到子报表。它有一个属性name ，这是必需的。
- 用于将java.sql.Connection传递给子报表。仅在子报表模板在报表填充阶段需要数据库连接时才使用它。
- 用于将数据源传递到子报表。此数据源通常从主报表中的参数获取，或者使用内置的REPORT_DATA_SOURCE参数将父报表的数据源传递到子报表。
元素（ connectionExpression and dataSourceExpression ）不能同时出现在“子报表”元素声明中。这是因为我们无法提供数据源和子报表的连接。我们必须决定其中一个并坚持下去。
- 用于将其中一个子报表变量的值分配给主报表的变量之一。此子元素具有以下属性 -
- subreportVariable - 此属性指定要返回其值的子报表变量的名称。
- toVariable - 此属性指定父报表变量的名称，其值将使用子报表中的值进行复制/递增。
- calculation - 此属性可以取值:Nothing，Count，DistinctCount，Sum，Average，Lowest，Highest，StandardDeviation，Variance。属性calculation默认值为“Nothing”。
- incrementerFactoryClass - 此属性指定用于创建增量器实例的工厂类。
- 这表示在何处查找子报表的已编译报表模板。该元素具有class属性。 class属性可以采用以下任何值:java.lang.String，java.io.File，java.net.URL，java.io.InputStream，net.sf.jasperreports.engine.JasperReport。默认值为java.lang.String 。
isUsingCache - 这是元素的一个属性。这是一个布尔值，当设置为true ，报告引擎将尝试使用其指定的源识别先前加载的子报告模板对象。此缓存功能仅适用于具有表达式的子报表元素，这些表达式将java.lang.String对象作为子报表模板源返回，表示文件名，URL或类路径资源。

例子 (Example)

让我们举一个简单的例子来演示使用JRDataSource创建子报表。让我们先写两个新的报告模板，一个是子报告，另一个是主报告。子报表（address_report_template.jrxml）模板的内容如下所示。将其保存到C:\tools\jasperreports-5.0.1\test目录。

<?xml version = "1.0" encoding = "UTF-8"?>
<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 = "address_report_template" pageWidth = "175" pageHeight = "842" 
   columnWidth = "175" leftMargin = "0" rightMargin = "0" 
   topMargin = "0" bottomMargin = "0">
   <field name = "city" class = "java.lang.String"/>
   <field name = "street" class = "java.lang.String"/>
   <background>
      <band splitType = "Stretch"/>
   </background>
   <title>
      <band height = "20" splitType = "Stretch">
         <staticText>
            <reportElement x = "0" y = "0" width = "100" height = "20"/>
            <textElement>
               <font size = "14" isBold = "true"/>
            </textElement>
            <text><![CDATA[Addresses]]></text>
         </staticText>
      </band>
   </title>
   <pageHeader>
      <band height = "12" splitType = "Stretch"/>
   </pageHeader>
   <columnHeader>
      <band height = "12" splitType = "Stretch"/>
   </columnHeader>
   <detail>
      <band height = "27" splitType = "Stretch">
         <textField>
            <reportElement x = "0" y = "0" width = "120" height = "20"/>
            <textElement>
               <font size = "12" isBold = "true"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$F{city}+" Address:"]]>
            </textFieldExpression>
         </textField>
         <textField isStretchWithOverflow = "true">
            <reportElement x = "120" y = "0" width = "435" height = "20"/>
            <textElement>
               <font size = "12"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$F{street}]]>
            </textFieldExpression>
         </textField>
      </band>
   </detail>
   <columnFooter>
      <band height = "8" splitType = "Stretch"/>
   </columnFooter>
   <pageFooter>
      <band height = "11" splitType = "Stretch"/>
   </pageFooter>
   <summary>
      <band height = "9" splitType = "Stretch"/>
   </summary>
</jasperReport>

当我们使用数据源时，我们需要编写相应的POJO文件SubReportBean.java ，如下所示。将其保存到目录C:\tools\jasperreports-5.0.1\test\src\com\iowiki -

package com.iowiki;
public class SubReportBean {
   private String city;
   private String street;
   public String getCity() {
      return city;
   }
   public void setCity(String city) {
      this.city = city;
   }
   public String getStreet() {
      return street;
   }
   public void setStreet(String street) {
      this.street = street;
   }
}

在这里，我们声明了两个字段'city'和'street' ，并定义了相应的getter和setter方法。

现在，让我们更新现有的DataBean文件。我们将添加一个新的字段subReportBeanList ，它是一个java.util.List。该字段将保存SubReportBean对象的列表。 DataBean文件的内容如下。将其保存到目录C:\tools\jasperreports-5.0.1\test\src\com\iowiki。

package com.iowiki;
import java.util.List;
public class DataBean {
   private String name;
   private String country;
   private List<SubReportBean> subReportBeanList;
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getCountry() {
      return country;
   }
   public void setCountry(String country) {
      this.country = country;
   }
   public List<SubReportBean> getSubReportBeanList() {
      return subReportBeanList;
   }
   public void setSubReportBeanList(List<SubReportBean> subReportBeanList) {
      this.subReportBeanList = subReportBeanList;
   }
}

我们现在更新文件C:\tools\jasperreports-5.0.1\test\src\com\iowiki\DataBeanList.java 。该文件的内容如下 -

package com.iowiki;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class DataBeanList {
   public ArrayList<DataBean> getDataBeanList() {
      // Create sub report data
      SubReportBean subBean1 = new SubReportBean();
      subBean1.setCity("Mumbai");
      subBean1.setStreet("M.G.Road");
      SubReportBean subBean2 = new SubReportBean();
      subBean2.setCity("New York");
      subBean2.setStreet("Park Street");
      SubReportBean subBean3 = new SubReportBean();
      subBean3.setCity("San Fransisco");
      subBean3.setStreet("King Street");
      ArrayList<DataBean> dataBeanList = new ArrayList<DataBean>();
      // Create master report data
      dataBeanList.add(produce("Manisha", "India",
         Arrays.asList(subBean1)));
      dataBeanList.add(produce("Dennis Ritchie", "USA",
         Arrays.asList(subBean2)));
      dataBeanList.add(produce("V.Anand", "India",
         Arrays.asList(subBean1)));
      dataBeanList.add(produce("Shrinath", "California",
         Arrays.asList(subBean3)));
      return dataBeanList;
   }
   /*
    * This method returns a DataBean object,
    * with name, country and sub report
    * bean data set in it.
    */
   private DataBean produce(String name, String country,
      List<SubReportBean> subBean) {
      DataBean dataBean = new DataBean();
      dataBean.setName(name);
      dataBean.setCountry(country);
      dataBean.setSubReportBeanList(subBean);
      return dataBean;
   }
}

在上面文件中的方法produce（）中，我们设置了SubReportBean的列表。

现在，让我们编写一个新的主报告模板（jasper_report_template.jrxml）。将此文件保存到目录C:\tools\jasperreports-5.0.1\test 。该文件的内容如下 -

<?xml version = "1.0" encoding = "UTF-8"?>
<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">
   <parameter name = "SUBREPORT_DIR" class = "java.lang.String" isForPrompting = "false">
      <defaultValueExpression>
         <![CDATA["C:\\tools\\jasperreports-5.0.1\\test\\"]]>
      </defaultValueExpression>
   </parameter>
   <field name = "country" class = "java.lang.String"/>
   <field name = "name" class = "java.lang.String"/>
   <field name = "subReportBeanList" class = "java.util.List"/>
   <background>
      <band splitType = "Stretch"/>
   </background>
   <title>
      <band height = "35" splitType = "Stretch">
         <staticText>
            <reportElement x = "0" y = "0" width = "204" height = "34"/>
            <textElement>
               <font size = "26" isBold = "true"/>
            </textElement>
            <text><![CDATA[Contact Report]]></text>
         </staticText>
      </band>
   </title>
   <pageHeader>
      <band height = "17" splitType = "Stretch"/>
   </pageHeader>
   <columnHeader>
      <band height = "21" splitType = "Stretch"/>
   </columnHeader>
   <detail>
      <band height = "112" splitType = "Stretch">
         <staticText>
            <reportElement x = "0" y = "0" width = "100" height = "20"/>
            <textElement>
               <font size = "12" isBold = "true"/>
            </textElement>
            <text><![CDATA[Name:]]></text>
         </staticText>
         <staticText>
            <reportElement x = "0" y = "20" width = "100" height = "20"/>
            <textElement>
               <font size = "12" isBold = "true"/>
            </textElement>
            <text><![CDATA[Country:]]></text>
         </staticText>
         <textField>
            <reportElement x = "104" y = "0" width = "277" height = "20"/>
            <textElement>
               <font size = "12"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$F{name}]]>
            </textFieldExpression>
         </textField>
         <textField>
            <reportElement x = "104" y = "20" width = "277" height = "20"/>
            <textElement>
               <font size = "12"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$F{country}]]>
            </textFieldExpression>
         </textField>
         <subreport>
            <reportElement positionType = "Float" x = "335" y = "25" width = "175"
               height = "20" isRemoveLineWhenBlank = "true" backcolor = "#99ccff"/>
            <dataSourceExpression>
               new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource
                  ($F{subReportBeanList})
            </dataSourceExpression>
            <subreportExpression class = "java.lang.String">
               <![CDATA[$P{SUBREPORT_DIR} + "address_report_template.jasper"]]>
            </subreportExpression>
         </subreport>
         <line>
            <reportElement x = "0" y = "50" width = "550" height = "1"/>
         </line>
      </band>
   </detail>
   <columnFooter>
      <band height = "19" splitType = "Stretch"/>
   </columnFooter>
   <pageFooter>
      <band height = "18" splitType = "Stretch"/>
   </pageFooter>
   <summary>
      <band height = "14" splitType = "Stretch"/>
   </summary>
</jasperReport>

在上面的模板中，我们定义了一个新参数“SUBREPORT_DIR”，它定义了子报表的路径。我们定义了一个java.util.List,类型的字段subReportBeanList java.util.List,它对应于DataBean文件中的属性。元素“subreport”具有子元素“dataSourceExpression”。我们已将列表subReportBeanList放在JRBeanCollectionDataSource的实例中。在子元素“subreportExpression /”中，我们给出了子报表名称（AddressReport.jasper）。

现在，让我们编写一个新类CreateReport来编译和执行我们的报告模板。文件C:\tools\jasperreports-5.0.1\test\src\com\iowiki\CreateReport.java的内容如下所示 -

package com.iowiki;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperReport;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;
public class CreateReport {
   public static void main(String[] args) {
      String masterReportFileName = "C://tools/jasperreports-5.0.1/test"
         + "/jasper_report_template.jrxml";
      String subReportFileName = "C://tools/jasperreports-5.0.1/test"
         + "/AddressReport.jrxml";
      String destFileName = "C://tools/jasperreports-5.0.1/test"
         + "/jasper_report_template.JRprint";
      DataBeanList DataBeanList = new DataBeanList();
      ArrayList<DataBean> dataList = DataBeanList.getDataBeanList();
      JRBeanCollectionDataSource beanColDataSource = new 
         JRBeanCollectionDataSource(dataList);
      try {
         /* Compile the master and sub report */
         JasperReport jasperMasterReport = JasperCompileManager
            .compileReport(masterReportFileName);
         JasperReport jasperSubReport = JasperCompileManager
            .compileReport(subReportFileName);
         Map<String, Object> parameters = new HashMap<String, Object>();
         parameters.put("subreportParameter", jasperSubReport);
         JasperFillManager.fillReportToFile(jasperMasterReport, 
            destFileName, parameters, beanColDataSource);
      } catch (JRException e) {
         e.printStackTrace();
      }
      System.out.println("Done filling!!! ...");
   }
}

在这里，我们看到我们正在编译主报告模板和子报告模板，并传递主报告（.jasper）文件以进行报告填充。

报表生成 (Report Generation)

现在，我们所有的文件都准备好了，让我们使用常规的ANT构建过程来编译和执行它们。文件build.xml的内容（保存在目录C:\tools\jasperreports-5.0.1\test下面）如下所示。

导入文件 - baseBuild.xml是从环境设置一章中选取的，应该与build.xml放在同一目录中。

<?xml version = "1.0" encoding = "UTF-8"?>
<project name = "JasperReportTest" default = "viewFillReport" basedir = ".">
   <import file = "baseBuild.xml" />
   <target name = "viewFillReport" depends = "compile,compilereportdesing,run"
      description = "Launches the report viewer to preview the 
      report stored in the .JRprint file.">
      <java classname = "net.sf.jasperreports.view.JasperViewer" fork = "true">
         <arg value = "-F${file.name}.JRprint" />
         <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，让我们打开命令行窗口并转到build.xml所在的目录。最后，执行命令ant -Dmain-class=com.iowiki.CreateReport （viewFullReport是默认目标），如下所示 -

Buildfile: C:\tools\jasperreports-5.0.1\test\build.xml
clean-sample:
   [delete] Deleting directory C:\tools\jasperreports-5.0.1\test\classes
compile:
   [mkdir] Created dir: C:\tools\jasperreports-5.0.1\test\classes
   [javac] C:\tools\jasperreports-5.0.1\test\baseBuild.xml:28: 
      warning: 'includeantruntime' was not set, defaulting to
   [javac] Compiling 7 source files to C:\tools\jasperreports-5.0.1\test\classes
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.
run:
   [echo] Runnin class : com.iowiki.CreateReport
   [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 filling!!! ...
viewFillReport:
   [java] log4j:WARN No appenders could be found for logger
   (net.sf.jasperreports.extensions.ExtensionsEnvironment).
   [java] log4j:WARN Please initialize the log4j system properly.
BUILD SUCCESSFUL
Total time: 72 minutes 13 seconds

作为上述编译的结果，JasperViewer窗口打开，如下面的屏幕所示 -

在这里，我们可以看到显示属性Name，Country和Address。

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JasperReports - 教程

JasperReports - 入门( Getting Started)

JasperReports - 环境设置( Environment Setup)

JasperReports - 生命周期( Life Cycle)

JasperReports - 设计( Designs)

JasperReports - 编译设计( Compiling Design)

JasperReports - 填充物( Fillings)

JasperReports - 查看和打印( View & Print)

JasperReports - 出口( Exporting)

JasperReports - 参数( Parameters)

JasperReports - 数据源( Data Sources)

JasperReports - Fields( Fields)

JasperReports - 表达( Expression)

JasperReports - 变量

JasperReports - 章节( Sections)

JasperReports - 小组( Groups)

JasperReports - Fonts

JasperReports - Unicode支持( Unicode Support)

JasperReports - 样式( Styles)

JasperReports - Scriptlets( Scriptlets)