JasperReports - 小组( Groups)
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
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
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
| 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\iowiki\JasperReportFill.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.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\iowiki\DataBean.java的内容如下 -
package com.iowiki;
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\iowiki\DataBeanList.java的内容如下所示 -
package com.iowiki;
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=com.iowiki.JasperReportFill （viewFullReport是默认目标）为 -
C:\tools\jasperreports-5.0.1\test>ant -Dmain-class=com.iowiki.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 : com.iowiki.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。
