提起scriptlet就不能不聯(lián)想到它的強(qiáng)大功能，jasperReport也是支持scriptlet的哦，先分析一下JasperReport的API吧！
在填充報(bào)表時(shí)scriplet是一個(gè)非常有力的工具，JRAbstractScriptlet.java位于net.sf.jasperreports.engine包下是一個(gè)抽象
類
beforeReportInit() ，afterReportInit() ，beforePageInit()，afterPageInit(), beforeColumnInit(), afterColumnInit() ,beforeGroupInit(String groupName),afterGroupInit(String groupName)
看看這些名字就知道你能完成那些功能，這幾個(gè)方法是要求我們實(shí)現(xiàn)的，jasperReport給我們提供了一個(gè)實(shí)現(xiàn)類JRDefaultScriptlet.java，默認(rèn)的空實(shí)現(xiàn)了上面幾個(gè)方法，它只是很便利的為我們提供了所需的八個(gè)方法的空實(shí)現(xiàn)。我們寫(xiě)自己的scriptlet時(shí)需要繼承JRDefaultScriptlet.java這個(gè)類實(shí)現(xiàn)自己的相應(yīng)的功能即可。
先來(lái)看一個(gè)簡(jiǎn)單的例子：
先看看模板文件的處理：
新建時(shí)填寫(xiě)的這個(gè)類是下面我們要介紹的繼承自JRDefaultScriptlet.java類，也就是在模板文件中我們要加上如下代碼
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 "http://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>
下來(lái)看看怎么實(shí)現(xiàn)我們自己的scriplet
ScriptletReportDemo.java
package org.bulktree.ireport.scriptlet;
import net.sf.jasperreports.engine.JRDefaultScriptlet;
import net.sf.jasperreports.engine.JRScriptletException;
/** *//**
*
* @author bulktree Email: laoshulin@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";
}
}
這段代碼最后一個(gè)方法是我們自己的加的，用來(lái)在報(bào)表上顯示一段文本。我們知道對(duì)于一個(gè)Field、Parameter、Variable，JasperReport分別采用$F{FieldName}、$P{Parametername}、$V{VariableName}來(lái)引用，而如果要引用ScriptletReportDemo.java類的showInfor()返回字符串顯示在報(bào)表上，看看這個(gè)就知道了
在afterReportInit方法中我們把parameter字段取出來(lái)前后添上五個(gè)*號(hào)再set進(jìn)去
下來(lái)寫(xiě)一個(gè)test類測(cè)試一下：
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: laoshulin@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();
}
}
}
效果不錯(cuò)吧：
