Jasper Reports 简明教程
Report Variables
报表变量是建立在报表表达式之上的特殊对象。
报表变量简化了以下任务:
-
报表表达式,在整个报表模板中大量使用。这些表达式可以使用报表变量仅声明一次。
-
报表变量可以基于相应的表达式值(例如计数、求和、平均值、最低值、最高值、方差等)执行各种计算。
如果在报表设计中定义了变量,则表达式中的新变量可以引用这些变量。因此,在报表设计中声明变量的顺序很重要。
Variable Declaration
变量声明如下:
<variable name = "CityNumber" class = "java.lang.Integer" incrementType = "Group"
incrementGroup = "CityGroup" calculation = "Count">
<variableExpression>
<![CDATA[Boolean.TRUE]]>
</variableExpression>
</variable>
如上所见,<variable> 元素包含许多属性。这些属性总结如下:
The Class Attribute
class 属性也是必需的,它为变量值指定类名。其默认值为 java.lang.String。可以在报表编译时间和报表填充时间将其更改为在类路径中可用的任何类。引擎负责在报表表达式中使用 $V{} 令牌的类型转换,因此不需要手动类型转换。
Calculation
此属性确定——在填充报表时对变量执行什么计算。以下小节描述了 <variable> 元素的 calculation 属性的所有可能值。
-
Average——变量值是变量表达式的每个非空值的平均值。仅对数字变量有效。
-
Count——变量值是变量表达式的非空实例的计数。
-
First——变量值是变量表达式的第一个实例的值。忽略后续值。
-
Highest——变量值是报表中变量表达式的最高值。
-
Lowest——变量值是报表中变量表达式的最低值。
-
Nothing——不对变量执行任何计算。
-
StandardDeviation——变量值是与报表表达式匹配的所有非空值的标准偏差。仅对数字变量有效。
-
Sum——变量值是报表表达式返回的所有非空值的总和。
-
系统 − 可变量值为自定义计算(使用 JasperReports 的小脚本功能自行计算该变量的值)。
-
差异 − 可变量值为报表变量表达式计算后返回的所有非空值的差异。
Incrementer FactoryClass
此属性决定在报表上填写当前记录时用于计算变量值所用的类。默认值应为实施 net.sf.jasperreports.engine.fill.JRIncrementerFactory 的任何类。引擎将在运行时使用工厂类来根据变量所设置的计算属性实例化增量对象。
IncrementType
这决定何时重新计算变量值。此属性使用值,如下 −
-
列 − 可变量值在每列结束时重新计算。
-
组 − 当 incrementGroup 指定的组更改时,可变量值重新计算。
-
无 − 可变量值随每条记录重新计算。
-
页面 − 可变量值在每页结束时重新计算。
-
报表 − 可变量值重新计算一次,在报表结束时。
Built-In Report Variables
有些内置系统变量随时可用于表达式中,如下 −
S.NO |
Variable Name and Description |
1 |
PAGE_NUMBER 此变量的值为其当前页码。可使用 JasperReports 文本字段元素的特殊功能 evaluationTime 属性来显示当前页码和总页数。 |
2 |
COLUMN_NUMBER 此变量包含当前列号。 |
3 |
REPORT_COUNT 此报表变量包含处理的总记录数。 |
4 |
PAGE_COUNT 此变量包含生成当前页面时处理的记录数 |
5 |
COLUMN_COUNT 此变量包含生成当前列时处理的记录数 |
6 |
GroupName_COUNT 此变量的名称源于其对应的组的名称,并以 _COUNT 序列为后缀。此变量包含当前组中的记录数。 |
Example
让我们向现有报表模板(第 Report Designs 章)添加一个变量( countNumber )。我们将在每个记录之前添加计数。经修订的报表模板(jasper_report_template.jrxml)如下。将其保存到 C:\tools\jasperreports-5.0.1\test 目录中−
<?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>
<variable name = "countNumber" class = "java.lang.Integer" calculation = "Count">
<variableExpression>
<![CDATA[Boolean.TRUE]]>
</variableExpression>
</variable>
<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[" " + String.valueOf($V{countNumber}) +"."+$F{name}]]>
</textFieldExpression>
</textField>
</band>
</detail>
</jasperReport>
用于填充报告的 Java 代码保持不变。文件 C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\JasperReportFill.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.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();
}
}
}
C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBean.java POJO 文件的内容如下 −
package com.tutorialspoint;
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;
}
}
C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBeanList.java 文件的内容如下 −
package com.tutorialspoint;
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;
}
}
Report Generation
我们将使用常规 ANT 构建流程编译并执行上述文件。build.xml 文件(保存在 C:\tools\jasperreports-5.0.1\test 目录下)的内容如下。
导入文件 - baseBuild.xml 从第 Environment Setup 章选取并应该放置在与 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进入放置 build.xml 的目录。最后,执行命令 ant -Dmain-class=com.tutorialspoint.JasperReportFill (viewFullReport 是默认目标),如下所示 −
C:\tools\jasperreports-5.0.1\test>ant -Dmain-class=com.tutorialspoint.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.tutorialspoint.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
以上编译的结果是在屏幕下方打开一个 JasperViewer 窗口−
此处,我们看到每个记录前加了计数。