JasperReport报表参数

填充一个报表的主要输入是：报表模板，参数和数据源。本章将介绍这些参数，并在接下来的章节中，我们将介绍数据源。

参数是在报表填充操作传递给报表引擎的对象引用。参数传递有用的数据到报表引擎，它可以不通过数据源来传递的数据是有用的。如作者姓名，报告等的标题数据，可以通过参数传递。 Jasper报表模板或JRXML模板可以包含零个或多个参数的元素。

参数声明

参数声明很简单，如下所示：

<parameter name="exampleParameter" class="java.lang.String" />

name属性

parameter>元素的name属性是强制性的。它通过名称引用的参数在报表表达式。参数名应该是一个单词。它不应该包含任何特殊字符，如句号或逗号。

class属性

class属性也是强制性的，它指定了参数值的类名。它的默认值是java.lang.String。这是可以改变的，以在运行时可用任何类。不论报表参数的类型，引擎采用构造于$P{}标记是用来报表表达，从而使手工投射不必要。

内置参数

例子

让我们通过ReportTitle和 Author报表（由JasperReportFill.java生成）。经修订的文件C: oolsjasperreports-5.0.1 estsrccomyiibaiJasperReportFill.java 如下：

package com.yiibai; 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文件的内容 C: oolsjasperreports-5.0.1 estsrccomyiibaiDataBean.java 如下所示：

package com.yiibai; 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: oolsjasperreports-5.0.1 estsrccomyiibaiDataBeanList.java 的内容如下：

package com.yiibai; 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; } }

让我们添加参数<ReportTitle>和<AUTHOR>我们现有的报告模板（章报表设计）。报告标题和作者将在报表的开头显示。修订后的报告模板（jasper_report_template.jrxml）如下。将其保存到 C: oolsjasperreports-5.0.1 est 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> <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>

报表生成

编译和执行使用常规Ant构建过程上面的文件。 build.xml文件中的内容（根据目录保存C: oolsjasperreports-5.0.1 est）情况如下。

导入文件 - baseBuild.xml可以从环境设置章节中了解，并应放置在同一目录中的build.xml。

<?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文件放置的目录。最后执行的命令 ant -Dmain-class=com.yiibai.JasperReportFill （viewFullReport是默认的目标），如下所示：

C:	oolsjasperreports-5.0.1	est>ant -Dmain-class=com.yiibai.JasperReportFill
Buildfile: C:	oolsjasperreports-5.0.1	estuild.xml

clean-sample:
   [delete] Deleting directory C:	oolsjasperreports-5.0.1	estclasses
   [delete] Deleting: C:	oolsjasperreports-5.0.1	estjasper_report_template.jasper
   [delete] Deleting: C:	oolsjasperreports-5.0.1	estjasper_report_template.jrprint

compile:
    [mkdir] Created dir: C:	oolsjasperreports-5.0.1	estclasses
    [javac] C:	oolsjasperreports-5.0.1	estaseBuild.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:	oolsjasperreports-5.0.1	estclasses

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.htmll#noconfig
      for more info.
      [jrc] File : C:	oolsjasperreports-5.0.1	estjasper_report_template.jrxml ... OK.

run:
     [echo] Runnin class : com.yiibai.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

正如上文编译的结果，JasperViewer窗口打开如下面的屏幕：

在这里，我们看到的是，报表头 "List Of Contacts"，并着有"Prepared By Manisha" 显示在报表的开头。