JasperReports创建子报告

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对象 后获得的。

`<subreport>`元素

将子报表引入主报表时使用<subreport>元素。以下是<subreport> JRXML元素中的子元素列表。

<reportElement>
<parametersMapExpression> - 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。
<subreportParameter> - 此元素用于将参数传递到子报表。它有一个属性名称，这是必需的。
<connectionExpression> - 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。
<dataSourceExpression> - 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和dataSourceExpression ）不能同时出现在<subreport>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。
<returnValue> - 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。
- 计算 - 此属性可以取值：Nothing，Count，DistinctCount，Sum，Average，Lowest，Highest，StandardDeviation，Variance。属性 计算的 默认值为“Nothing”。
- incrementerFactoryClass - 此属性指定用于创建增量器实例的工厂类。
<subreportExpression> - 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。在类属性可以采取的任何值：java.lang.String中，java.io.File中，java.net.URL中，java.io.InputStream中，net.sf.jasperreports.engine.JasperReport。默认值为 java.lang.String 。
isUsingCache - 这是<subreport>元素的一个属性。这是一个布尔值，当设置为 true时 ，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

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 \ codingdict -

package com.codingdict;

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 \ codingdict。

package com.codingdict;

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 \ codingdict \ DataBeanList.java 。该文件的内容如下 -

package com.codingdict;

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 ，它对应于DataBean文件中的属性。元素具有子元素<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 \ codingdict \ CreateReport.java 的内容如下所示 -

package com.codingdict;

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。

报告生成

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.codingdict.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.codingdict.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

Jasper SubReport示例

在这里，我们可以看到显示属性Name，Country和Address。

JasperReports创建子报告

<subreport>元素

例

报告生成

`<subreport>`元素