Jasper Reports 简明教程

Create SubReports

子报表是 JasperReports 的一项不错的功能。此功能允许在另一个报表内合并报表，即一个报表可以是另一个报表的子报表。子报表帮助我们保持报表设计简单，因为我们可以创建许多简单的报表并将其封装到一个主报表中。子报表像普通报表一样进行编译和填充。在合并到另一个报表模板时，任何报表模板都可以用作子报表，而无需对（报表模板）中的任何内容进行更改。

子报表就像普通报表模板。实际上，它们是 net.sf.jasperreports.engine.JasperReport 对象，在编译 net.sf.jasperreports.engine.design.JasperDesign 对象后获得这些对象。

<subreport> Element

在将子报表引入主报表时，会使用 <subreport> 元素。下面是 <subreport> JRXML 元素的子元素列表。

<reportElement>
<parametersMapExpression> − 用于向子报表传递包含报表参数的映射。该映射通常从主报表中的一个参数获取，也可以通过使用内置 REPORTS_PARAMETERS_MAP 参数将父报表的参数传递到子报表。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> − 此元素用于向子报表传递参数。它有一个必需的 name 属性。
<connectionExpression > − 用于向子报表传递 java.sql.Connection。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此参数。
<dataSourceExpression> − 用于向子报表传递数据源。此数据源通常从主报表中的一个参数获取，也可以通过使用内置 REPORT_DATA_SOURCE 参数将父报表的参数传递到子报表。
元素（connectionExpression 和 dataSourceExpression）不能同时出现在 <subreport> 元素声明中。这是因为我们无法同时向子报表提供数据源和连接。我们必须决定一个数据库，并坚持下去。
<returnValue> − 用于将子报表变量之一的值分配给主报表变量之一。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 − 此属性指定要将来自子报表的 value 复制/增加到其中的父报表变量的名称。calculation − 此属性可以采用下列值：Nothing、Count、DistinctCount、Sum、Average、Lowest、Highest、StandardDeviation、Variance。calculation 属性的默认值是 “Nothing”。incrementerFactoryClass − 此属性指定用于创建增量器实例的工厂类。
<subreportExpression> − 指示在何处查找子报表的已编译报表模板。此元素具有 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. 默认值是 java.lang.String。
isUsingCache − 这是 <subreport> 元素的一个属性。它是一个 Boolean，当设置为 true 时，报告引擎将尝试使用指定的源识别先前加载的子报表模板对象。此缓存功能仅适用于具有将表达式返回为 java.lang.String 对象（表示文件名称、URL 或类路径资源）作为子报表模板源的子报表元素。

Example

让我们举一个简单的示例来说明使用 JRDataSource 创建子报表的步骤。首先，我们编写两个新的报表模板，一个是子报表，另一个是主报表。子报表 (address_report_template.jrxml) 模板的内容如下。将其保存到 C:\tools\jasperreports-5.0.1\test 目录中。

<?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>

由于我们使用数据源，因此我们需要编写一个相应的 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\tutorialspoint −

package com.tutorialspoint;

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;
   }
}

在此，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，我们来更新现有的 DataBean 文件。我们将添加一个新字段 subReportBeanList，它是一个 java.util.List。此字段将保存 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\tutorialspoint。

package com.tutorialspoint;

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\tutorialspoint*DataBeanList.java*。该文件的内容如下 −

package com.tutorialspoint;

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;
   }
}

在上述文件中的 produce() 方法中，我们设置了 SubReportBean 的列表。

现在，我们来编写一个新的主报表模板（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>

在上述模板中，我们定义了一个新参数“SUBREPORT_DIR”，该参数定义了子报表的路径。我们定义了一个类型为 java.util.List 的字段 subReportBeanList，它对应于 DataBean 文件中的属性。元素 <subreport> 有子元素 <dataSourceExpression>。我们已将列表 subReportBeanList 放入 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，我们来编写一个新类 CreateReport 来编译和执行我们的报表模板。文件 C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\CreateReport.java 的内容如下 −

package com.tutorialspoint;

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!!! ...");
   }
}

此处，可以看到我们在编译主模板和子报表模板，并传递主报表（.jasper）文件以用于报表填充。

Report Generation

现在，我们的所有文件都准备好了，我们使用常规 ANT 构建流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）如下所示。

导入文件 - baseBuild.xml 从第 Environment Setup 章中获取，并应放置在与 build.xml 相同的目录中。

<?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放置 build.xml 的目录。最后，执行命令 ant -Dmain-class=com.tutorialspoint.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.tutorialspoint.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，一个 JasperViewer 窗口会打开，如以下给出的屏幕截图所示 -

此处，可以看到显示了属性 Name、Country 和 Address。