小组（Groups）

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2023-12-01

JasperReports中的组有助于以合理的方式组织报告数据。报告组表示数据源中的一系列连续记录，这些记录具有一些共同点，例如某些报告字段的值。报告组由元素定义。报告可以包含任意数量的组。声明后，可以在整个报告中引用组。

报告组有三个要素 -

Group expression - 表示必须更改以启动新数据组的数据。
Group header section - 帮助将标签放在分组数据的开头。
Group footer section - 帮助将标签放在分组数据的末尾。

在报表填充时迭代数据源期间，如果组表达式的值发生更改，则会发生组破裂，并在结果文档中插入相应的和部分。

报告组机制不对数据源提供的数据执行任何排序。仅当数据源中的记录已根据报告中使用的组表达式进行排序时，数据分组才能按预期工作。

组属性

元素包含允许我们控制分组数据布局方式的属性。属性总结在下表中 -

S.NO	属性和描述
1	name 这是强制性的。它按名称引用报表表达式中的组。它遵循我们为报表参数，字段和报表变量提到的相同命名约定。当您要引用特定报告组时，可以在其他JRXML属性中使用它。
2	isStartNewColumn 设置为true ，每个数据组将从新列开始。默认值为false 。
3	isStartNewPage 设置为true ，每个数据组将在新页面上开始。默认值为false 。
4	isResetPageNumber 设置为true ，每次启动新组时都会重置报告页码。默认值为false.
5	isReprintHeaderOnEachPage 设置为true ，将在每个页面上重新打印组标题。默认值为false 。
6	minHeightToStartNewPage 定义列底部所需的最小垂直空间量，以便将组标题放在当前列上。金额以报告单位指定。
7	footerPosition 在页面上呈现组页脚的位置，以及与其后面的报表部分相关的行为。它的值可以是: Normal ， StackAtBottom ， ForceAtBottom和CollateAtBottom 。默认值为“ Normal 。
8	keepTogether 设置为true ，防止组在第一次中断尝试时拆分。

例子 (Example)

让我们将一个组（ CountryGroup ）添加到现有报告模板（章节报告设计）。计算每个国家/地区的出现次数，并将计数显示为组页脚。在组头中，每个记录的计数都是前缀。修订后的报告模板（jasper_report_template.jrxml）如下所示。将其保存到C:\tools\jasperreports-5.0.1\test目录 -

<?xml version = "1.0"?>
<!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" pageWidth = "595"
   pageHeight = "842" columnWidth = "515"
   leftMargin = "40" rightMargin = "40" topMargin = "50" bottomMargin = "50">
   <parameter name = "ReportTitle" class = "java.lang.String"/>
   <parameter name = "Author" class = "java.lang.String"/>
   <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>
   <sortField name = "country" order = "Descending"/>
   <sortField name = "name"/>
   <variable name = "CountryNumber" class = "java.lang.Integer"
      incrementType = "Group" incrementGroup = "CountryGroup"
      calculation = "Count">
      <variableExpression><![CDATA[Boolean.TRUE]]></variableExpression>
   </variable>
   <group name = "CountryGroup" minHeightToStartNewPage = "60">
      <groupExpression><![CDATA[$F{country}]]></groupExpression>
      <groupHeader>
         <band height = "20">
            <textField evaluationTime = "Group" evaluationGroup = "CountryGroup"
               bookmarkLevel = "1">
               <reportElement mode = "Opaque" x = "0" y = "5" width = "515"
                  height = "15" backcolor = "#C0C0C0"/>
               <box leftPadding = "10">
                  <bottomPen lineWidth = "1.0"/>
               </box>
               <textElement/>
               <textFieldExpression class = "java.lang.String">
                  <![CDATA["  " + String.valueOf($V{CountryNumber}) + ". "
                  + String.valueOf($F{country})]]>
               </textFieldExpression>
               <anchorNameExpression>
                  <![CDATA[String.valueOf($F{country})]]>
               </anchorNameExpression>
            </textField>
         </band>
      </groupHeader>
      <groupFooter>
         <band height = "20">
            <staticText>
               <reportElement x = "400" y = "1" width = "60" height = "15"/>
               <textElement textAlignment = "Right"/>
               <text><![CDATA[Count :]]></text>
            </staticText>
            <textField>
               <reportElement x = "460" y = "1" width = "30" height = "15"/>
               <textElement textAlignment = "Right"/>
               <textFieldExpression class = "java.lang.Integer">
                  <![CDATA[$V{CountryGroup_COUNT}]]>
               </textFieldExpression>
            </textField>
         </band>
      </groupFooter>
   </group>
   <title>
      <band height = "70">
         <line>
            <reportElement x = "0" y = "0" width = "515" height = "1"/>
         </line>
         <textField isBlankWhenNull = "true" bookmarkLevel = "1">
            <reportElement x = "0" y = "10" width = "515" height = "30"/>
            <textElement textAlignment = "Center">
               <font size = "22"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$P{ReportTitle}]]>
            </textFieldExpression>
            <anchorNameExpression>
               <![CDATA["Title"]]>
            </anchorNameExpression>
         </textField>
         <textField isBlankWhenNull = "true">
            <reportElement  x = "0" y = "40" width = "515" height = "20"/>
            <textElement textAlignment = "Center">
               <font size = "10"/>
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$P{Author}]]>
            </textFieldExpression>
         </textField>
      </band>
   </title>
   <columnHeader>
      <band height = "23">
         <staticText>
            <reportElement mode = "Opaque" x = "0" y = "3" width = "535" height = "15"
               backcolor = "#70A9A9" />
            <box>
               <bottomPen lineWidth = "1.0" lineColor = "#CCCCCC" />
            </box>
            <textElement />
            <text>
               <![CDATA[]]>
            </text>
         </staticText>
         <staticText>
            <reportElement x = "414" y = "3" width = "121" height = "15" />
            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font isBold = "true" />
            </textElement>
            <text><![CDATA[Country]]></text>
         </staticText>
         <staticText>
            <reportElement x = "0" y = "3" width = "136" height = "15" />
            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font isBold = "true" />
            </textElement>
            <text><![CDATA[Name]]></text>
         </staticText>
      </band>
   </columnHeader>
   <detail>
      <band height = "16">
         <staticText>
            <reportElement mode = "Opaque" x = "0" y = "0" width = "535" height = "14"
               backcolor = "#E5ECF9" />
            <box>
               <bottomPen lineWidth = "0.25" lineColor = "#CCCCCC" />
            </box>
            <textElement />
            <text>
               <![CDATA[]]>  
            </text>
         </staticText>
         <textField>
            <reportElement x = "414" y = "0" width = "121" height = "15" />
            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font size = "9" />
            </textElement>
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$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>

报告填充的java代码保持不变。文件C:\tools\jasperreports-5.0.1\test\src\com\xnip\JasperReportFill.java的内容如下所示 -

package cn.xnip;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;
public class JasperReportFill {
   @SuppressWarnings("unchecked")
   public static void main(String[] args) {
      String sourceFileName =
      "C://tools/jasperreports-5.0.1/test/jasper_report_template.jasper";
      DataBeanList DataBeanList = new DataBeanList();
      ArrayList<DataBean> dataList = DataBeanList.getDataBeanList();
      JRBeanCollectionDataSource beanColDataSource =
      new JRBeanCollectionDataSource(dataList);
      Map parameters = new HashMap();
      /**
       * Passing ReportTitle and Author as parameters
       */
      parameters.put("ReportTitle", "List of Contacts");
      parameters.put("Author", "Prepared By Manisha");
      try {
         JasperFillManager.fillReportToFile(
         sourceFileName, parameters, beanColDataSource);
      } catch (JRException e) {
         e.printStackTrace();
      }
   }
}

POJO文件C:\tools\jasperreports-5.0.1\test\src\com\xnip\DataBean.java的内容如下 -

package cn.xnip;
public class DataBean {
   private String name;
   private String country;
   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;
   }
}

文件C:\tools\jasperreports-5.0.1\test\src\com\xnip\DataBeanList.java的内容如下所示 -

package cn.xnip;
import java.util.ArrayList;
public class DataBeanList {
   public ArrayList<DataBean> getDataBeanList() {
      ArrayList<DataBean> dataBeanList = new ArrayList<DataBean>();
      dataBeanList.add(produce("Manisha", "India"));
      dataBeanList.add(produce("Dennis Ritchie", "USA"));
      dataBeanList.add(produce("V.Anand", "India"));
      dataBeanList.add(produce("Shrinath", "California"));
      return dataBeanList;
   }
   /**
    * This method returns a DataBean object,
    * with name and country set in it.
    */
   private DataBean produce(String name, String country) {
      DataBean dataBean = new DataBean();
      dataBean.setName(name);
      dataBean.setCountry(country);
      return dataBean;
   }
}

报表生成 (Report Generation)

我们将使用常规的ANT构建过程编译并执行上述文件。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是从环境设置一章中获取的，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=cn.xnip.JasperReportFill （viewFullReport是默认目标）为 -

C:\tools\jasperreports-5.0.1\test>ant -Dmain-class=cn.xnip.JasperReportFill
Buildfile: C:\tools\jasperreports-5.0.1\test\build.xml
clean-sample:
   [delete] Deleting directory C:\tools\jasperreports-5.0.1\test\classes
   [delete] Deleting: C:\tools\jasperreports-5.0.1\test\jasper_report_template.jasper
   [delete] Deleting: C:\tools\jasperreports-5.0.1\test\jasper_report_template.jrprint
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 build.sysclasspath=last;
   set to false for repeatable builds
   [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 : cn.xnip.JasperReportFill
   [java] log4j:WARN No appenders could be found for logger
   (net.sf.jasperreports.extensions.ExtensionsEnvironment).
   [java] log4j:WARN Please initialize the log4j system properly.
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: 18 seconds

作为上述编译的结果，JasperViewer窗口打开，如下面的屏幕 -

在这里，我们看到每个国家/地区都被分组，每个国家/地区的发生次数都显示在每个组的页脚中。