提起scriptlet就不能不联想到它的强大功能，jasperReport也是支持scriptlet的哦，先分析一下JasperReport的API吧！
在填充报表时scriplet是一个非常有力的工具，JRAbstractScriptlet.java位于net.sf.jasperreports.engine包下是一个抽象类。
beforeReportInit(), afterReportInit(), beforePageInit(), afterPageInit(), beforeColumnInit(), afterColumnInit(),
beforeGroupInit(String groupName), afterGroupInit(String groupName)
看看这些名字就知道你能完成那些功能，这几个方法是要求我们实现的，jasperReport给我们提供了一个实现类JRDefaultScriptlet.java， 默认的空实现了上面几个方法，它只是很便利的为我们提供了所需的八个方法的空实现。 我们写自己的scriptlet时需要继承JRDefaultScriptlet.java这个类实现自己的相应的功能即可。
先来看一个简单的例子：
先看看模板文件的处理：
新建时填写的这个类是下面我们要介绍的继承自JRDefaultScriptlet.java类，也就是在模板文件中我们要加上如下代码
scriptletClass="org.bulktree.ireport.scriptlet.ScriptletReportDemo"
完整的模板文件如下：scriptletDemo.jrxml
<?xml version="1.0" encoding="UTF-8" ?>
<!-- Created with iReport - A designer for JasperReports -->
<!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN" "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd">
<jasperReport
name="scriptletDemo"
columnCount="1"
printOrder="Vertical"
orientation="Portrait"
pageWidth="595"
pageHeight="842"
columnWidth="535"
columnSpacing="0"
leftMargin="30"
rightMargin="30"
topMargin="20"
bottomMargin="20"
whenNoDataType="NoPages"
scriptletClass="org.bulktree.ireport.scriptlet.ScriptletReportDemo"
isTitleNewPage="false"
isSummaryNewPage="false">
<property name="ireport.scriptlethandling" value="2" />
<property name="ireport.encoding" value="UTF-8" />
<import value="java.util.*" />
<import value="net.sf.jasperreports.engine.*" />
<import value="net.sf.jasperreports.engine.data.*" />
<parameter name="ReportTitle" isForPrompting="true" class="java.lang.String"/>
<background>
<band height="0" isSplitAllowed="true" >
</band>
</background>
<title>
<band height="20" isSplitAllowed="true" >
<textField isStretchWithOverflow="false" isBlankWhenNull="false" evaluationTime="Now" hyperlinkType="None" hyperlinkTarget="Self" >
<reportElement
mode="Opaque"
x="193"
y="0"
width="134"
height="18"
backcolor="#FFCC33"
key="textField"/>
<box></box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font pdfFontName="Helvetica-Bold" size="12" isBold="true"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$P{ReportTitle}]]></textFieldExpression>
</textField>
</band>
</title>
<pageHeader>
<band height="0" isSplitAllowed="true" >
</band>
</pageHeader>
<columnHeader>
<band height="0" isSplitAllowed="true" >
</band>
</columnHeader>
<detail>
<band height="264" isSplitAllowed="true" >
<textField isStretchWithOverflow="false" isBlankWhenNull="false" evaluationTime="Now" hyperlinkType="None" hyperlinkTarget="Self" >
<reportElement
x="85"
y="20"
width="329"
height="61"
forecolor="#FF0099"
key="textField-1"/>
<box></box>
<textElement textAlignment="Center" verticalAlignment="Middle">
<font pdfFontName="Helvetica-Bold" size="20" isBold="true"/>
</textElement>
<textFieldExpression class="java.lang.String"><![CDATA[$P{REPORT_SCRIPTLET}.showInfor()]]></textFieldExpression>
</textField>
</band>
</detail>
<columnFooter>
<band height="0" isSplitAllowed="true" >
</band>
</columnFooter>
<pageFooter>
<band height="0" isSplitAllowed="true" >
</band>
</pageFooter>
<summary>
<band height="50" isSplitAllowed="true" >
</band>
</summary>
</jasperReport>
下来看看怎么实现我们自己的scriplet
ScriptletReportDemo.java
package org.bulktree.ireport.scriptlet;
import net.sf.jasperreports.engine.JRDefaultScriptlet;
import net.sf.jasperreports.engine.JRScriptletException;
/**
*
* @author bulktree Email: jutleo@gmail.com
* @Nov 26, 2008
*/
public class ScriptletReportDemo extends JRDefaultScriptlet {
@Override
public void afterColumnInit() throws JRScriptletException {
System.out.println("**************************************afterColumnInit()**************************************");
}
@Override
public void afterDetailEval() throws JRScriptletException {
System.out.println("**************************************afterDetailEval()**************************************");
}
@Override
public void afterGroupInit(String groupName) throws JRScriptletException {
System.out.println("**************************************afterDetailEval()**************************************");
}
@Override
public void afterPageInit() throws JRScriptletException {
System.out.println("**************************************afterPageInit()**************************************");
}
@Override
public void afterReportInit() throws JRScriptletException {
System.out.println("**************************************afterReportInit() begin**************************************");
String str = (String) this.getParameterValue("ReportTitle");
System.out.println("report title=====>>>>"+str);
str += str.subSequence(0, str.length()-2);
this.setParameterValue("ReportTitle", str);
System.out.println("**************************************afterReportInit() end**************************************");
}
@Override
public void beforeColumnInit() throws JRScriptletException {
System.out.println("**************************************beforeColumnInit()**************************************");
}
@Override
public void beforeDetailEval() throws JRScriptletException {
System.out.println("**************************************beforeDetailEval()**************************************");
}
@Override
public void beforeGroupInit(String groupName) throws JRScriptletException {
System.out.println("**************************************beforeGroupInit()**************************************");
}
@Override
public void beforePageInit() throws JRScriptletException {
System.out.println("**************************************beforePageInit()**************************************");
}
@Override
public void beforeReportInit() throws JRScriptletException {
System.out.println("**************************************beforeReportInit()**************************************");
}
public String showInfor() throws JRScriptletException {
return "the is scriptlet scriptlet scriptlet the,sscriptlet report the is ascriptlet report this is a scriptlet report this is a scriptlet report";
}
}
这段代码最后一个方法是我们自己的加的，用来在报表上显示一段文本。 我们知道对于一个Field、Parameter、Variable，JasperReport分别采用$F{FieldName}、$P{Parametername}、$V{VariableName}来引用， 而如果要引用ScriptletReportDemo.java类的showInfor()返回字符串显示在报表上，看看这个就知道了
在afterReportInit方法中我们把parameter字段取出来前后添上五个*号再set进去
下来写一个test类测试一下：
package org.bulktree.ireport.scriptlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.HashMap;
import net.sf.jasperreports.engine.JREmptyDataSource;
import net.sf.jasperreports.engine.JasperCompileManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.JasperPrint;
import net.sf.jasperreports.engine.JasperReport;
import net.sf.jasperreports.view.JasperViewer;
/**
*
* @author bulktree Email: jutleo@gmail.com
* @Nov 27, 2008
*/
public class ScriptletTestMain {
public static void main(String[] args) {
String path = "D:/workspace/scriptletDemo.jrxml";
File file = new File(path);
InputStream in;
try {
HashMap parameters = new HashMap();
parameters.put("ReportTitle", "LAOSHULIN");
in = new FileInputStream(file);
JasperReport jasperReport = JasperCompileManager.compileReport(in);
JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport,
parameters, new JREmptyDataSource());
JasperViewer viewer = new JasperViewer(jasperPrint);
viewer.setVisible(true);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
效果不错吧：
