我已经尝试过类似问题的解决方案，但它没有解决我的问题。我想从jcombobox传递一个值作为搜索参数，但是当我提交搜索时，它返回一个空的查看器。以下是一些代码： jrxml：
<?xml version="1.0" encoding="UTF-8"?>
<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="null" language="groovy" pageWidth="842" pageHeight="595" orientation="Landscape" columnWidth="802" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="d851568a-8c70-49e4-aec7-d04008ad3725">
<property name="ireport.zoom" value="1.0"/>
<property name="ireport.x" value="0"/>
<property name="ireport.y" value="0"/>
<style name="Title" fontName="Times New Roman" fontSize="50" isBold="true" pdfFontName="Times-Bold"/>
<style name="SubTitle" forecolor="#736343" fontName="Arial" fontSize="18"/>
<style name="Column header" forecolor="#666666" fontName="Arial" fontSize="12" isBold="true"/>
<style name="Detail" fontName="Arial" fontSize="12"/>
<style name="Row" mode="Transparent">
<conditionalStyle>
<conditionExpression><![CDATA[$V{REPORT_COUNT}%2 == 0]]></conditionExpression>
<style backcolor="#E6DAC3"/>
</conditionalStyle>
</style>
<parameter name="session" class="java.lang.String">
<parameterDescription><![CDATA[]]></parameterDescription>
</parameter>
<queryString language="SQL">
<![CDATA[SELECT
employeedata.`fname` AS 'FIRST NAME(S)',
employeedata.`lname` AS 'LAST NAME',
employeedata.`gender` AS GENDER,
employeedata.`empid` AS 'TRAINEE ID',
logdata.`timein` AS 'TIME IN',
logdata.`timeout` AS 'TIME OUT',
logdata.`date` AS DATE
FROM
`employeedata` employeedata INNER JOIN `fingerdata` fingerdata ON employeedata.`empid` = fingerdata.`empid`
INNER JOIN `logdata` logdata ON fingerdata.`fingerid` = logdata.`fingerid` WHERE logdata.session LIKE '$P{session}']]>
</queryString>
<field name="TRAINEE ID" class="java.lang.String"/>
<field name="FIRST NAME(S)" class="java.lang.String"/>
<field name="LAST NAME" class="java.lang.String"/>
<field name="GENDER" class="java.lang.String">
<fieldDescription><![CDATA[]]></fieldDescription>
</field>
<field name="TIME IN" class="java.lang.String"/>
<field name="TIME OUT" class="java.lang.String"/>
<field name="DATE" class="java.lang.String">
<fieldDescription><![CDATA[]]></fieldDescription>
</field>
<group name="DATE">
<groupExpression><![CDATA[$F{DATE}]]></groupExpression>
<groupHeader>
<band height="7"/>
</groupHeader>
<groupFooter>
<band height="17"/>
</groupFooter>
</group>
<background>
<band splitType="Stretch"/>
</background>
<title>
<band height="129" splitType="Stretch">
<staticText>
<reportElement style="Title" x="12" y="0" width="608" height="62" uuid="c0820f28-affb-498f-b54b-01227a0284cc"/>
<textElement verticalAlignment="Middle">
<font pdfFontName="Times-Roman"/>
</textElement>
<text><![CDATA[TRAINEE ATTENDANCE]]></text>
</staticText>
<staticText>
<reportElement style="SubTitle" x="144" y="62" width="322" height="22" uuid="e0359ffb-478d-4de6-a82a-66515635d2fb"/>
<textElement>
<font fontName="Times New Roman" pdfFontName="Times-Roman"/>
</textElement>
<text><![CDATA[GRADUATE ASSISTANCE PROGRAM]]></text>
</staticText>
</band>
</title>
<pageHeader>
<band splitType="Stretch"/>
</pageHeader>
<columnHeader>
<band height="16" splitType="Stretch">
<line>
<reportElement positionType="FixRelativeToBottom" x="0" y="15" width="802" height="1" uuid="6db14758-77dd-4844-bad9-7d698c3ffad5"/>
<graphicElement>
<pen lineWidth="0.5" lineColor="#999999"/>
</graphicElement>
</line>
<staticText>
<reportElement style="Column header" x="0" y="0" width="133" height="15" forecolor="#736343" uuid="f72ba507-10a9-4fd4-a5ad-68a33fe89126"/>
<text><![CDATA[TRAINEE ID]]></text>
</staticText>
<staticText>
<reportElement style="Column header" x="133" y="0" width="133" height="15" forecolor="#736343" uuid="5a02d9cf-5b0e-41e1-998f-8e44e7b93e13"/>
<text><![CDATA[FIRST NAME]]></text>
</staticText>
<staticText>
<reportElement style="Column header" x="266" y="0" width="133" height="15" forecolor="#736343" uuid="155032b8-2c4f-4cd6-82c7-abb9f0263ff5"/>
<text><![CDATA[LAST NAME]]></text>
</staticText>
<staticText>
<reportElement style="Column header" x="399" y="0" width="133" height="15" forecolor="#736343" uuid="f68c1322-406d-481d-84c1-b3a70a03499a"/>
<text><![CDATA[GENDER]]></text>
</staticText>
<staticText>
<reportElement style="Column header" x="532" y="0" width="133" height="15" forecolor="#736343" uuid="e4a8997b-27e0-4aab-abd6-15b2a09f5026"/>
<text><![CDATA[TIME IN]]></text>
</staticText>
<staticText>
<reportElement style="Column header" x="665" y="0" width="133" height="15" forecolor="#736343" uuid="5d27501b-9a40-4a9a-a6c1-de8a76a7c28b"/>
<text><![CDATA[TIME OUT]]></text>
</staticText>
</band>
</columnHeader>
<detail>
<band height="15" splitType="Stretch">
<frame>
<reportElement style="Row" mode="Opaque" x="0" y="0" width="802" height="15" uuid="396a2ef1-a55d-4e7f-96f7-d59306ef4dc6"/>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="0" y="0" width="133" height="15" uuid="f91b07d1-9414-406a-bb05-ead75d9e0085"/>
<textFieldExpression><![CDATA[$F{TRAINEE ID}]]></textFieldExpression>
</textField>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="133" y="0" width="133" height="15" uuid="4cb43463-0bf8-4fb3-9d52-0e9169b308db"/>
<textFieldExpression><![CDATA[$F{FIRST NAME(S)}]]></textFieldExpression>
</textField>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="266" y="0" width="133" height="15" uuid="f1f8f2f0-931e-4a5f-95ac-bb9e111d76eb"/>
<textFieldExpression><![CDATA[$F{LAST NAME}]]></textFieldExpression>
</textField>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="399" y="0" width="133" height="15" uuid="815e7600-2229-4a29-ad65-bcb4245a51f5"/>
<textFieldExpression><![CDATA[$F{GENDER}]]></textFieldExpression>
</textField>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="532" y="0" width="133" height="15" uuid="ba5758f3-557e-41ec-bdf6-1a13ea151a16"/>
<textFieldExpression><![CDATA[$F{TIME IN}]]></textFieldExpression>
</textField>
<textField isStretchWithOverflow="true">
<reportElement style="Detail" x="665" y="0" width="133" height="15" uuid="207195ad-0f32-49bf-b137-3ac636fb71b0"/>
<textFieldExpression><![CDATA[$F{TIME OUT}]]></textFieldExpression>
</textField>
</frame>
</band>
</detail>
<columnFooter>
<band height="6" splitType="Stretch">
<line>
<reportElement positionType="FixRelativeToBottom" x="0" y="3" width="802" height="1" uuid="18f13873-aacf-49ea-9a7e-dc8f9ef726d6"/>
<graphicElement>
<pen lineWidth="0.5" lineColor="#999999"/>
</graphicElement>
</line>
</band>
</columnFooter>
<pageFooter>
<band height="25" splitType="Stretch">
<frame>
<reportElement mode="Opaque" x="-21" y="1" width="843" height="24" forecolor="#D0B48E" backcolor="#F2EBDF" uuid="2daa1b9a-87d3-4154-b8eb-beacdc8b019a"/>
<textField evaluationTime="Report">
<reportElement style="Column header" x="783" y="1" width="40" height="20" forecolor="#736343" uuid="48733e5a-d35c-44b6-9607-1419ce88368e"/>
<textElement verticalAlignment="Middle">
<font size="10" isBold="false"/>
</textElement>
<textFieldExpression><![CDATA[" " + $V{PAGE_NUMBER}]]></textFieldExpression>
</textField>
<textField>
<reportElement style="Column header" x="703" y="1" width="80" height="20" forecolor="#736343" uuid="060b07c0-5c84-46ac-9897-26b2a1201be7"/>
<textElement textAlignment="Right" verticalAlignment="Middle">
<font size="10" isBold="false"/>
</textElement>
<textFieldExpression><![CDATA["Page "+$V{PAGE_NUMBER}+" of"]]></textFieldExpression>
</textField>
<textField pattern="EEEEE dd MMMMM yyyy">
<reportElement style="Column header" x="22" y="1" width="197" height="20" forecolor="#736343" uuid="42492e3f-1a41-4ef9-98e2-24028728877a"/>
<textElement verticalAlignment="Middle">
<font size="10" isBold="false"/>
</textElement>
<textFieldExpression><![CDATA[new java.util.Date()]]></textFieldExpression>
</textField>
</frame>
</band>
</pageFooter>
<summary>
<band height="63" splitType="Stretch">
<staticText>
<reportElement x="21" y="29" width="138" height="20" uuid="a6a0595a-3d06-4ca9-8eaa-c15350637112"/>
<text><![CDATA[NUMBER OF RECORDS]]></text>
</staticText>
<textField>
<reportElement x="166" y="29" width="100" height="20" uuid="42bfc9b3-e432-4b00-adc1-9aae2372f71f"/>
<textFieldExpression><![CDATA[$V{DATE_COUNT}]]></textFieldExpression>
</textField>
</band>
</summary>
方法：
public void printPDFReport(String session) throws Exception {
try {
Class.forName("com.mysql.jdbc.Driver");
Connection connex = DriverManager.getConnection("jdbc:mysql://localhost/placess_dbase", "root", "");
HashMap parameter = new HashMap<>();
parameter.put("session", session.toUpperCase());
String report = "C:\\users\\lami\\desktop\\placess_src\\placess\\src\\reports\\allStaffAttendance.jrxml";
JasperReport jr = JasperCompileManager.compileReport(report);
JasperPrint jp = JasperFillManager.fillReport(jr, parameter, connex);
JasperExportManager.exportReportToPdfFile(jp, "c:/output/attendance.pdf");
URL url = new URL("file:c:/output/attendance.pdf");
JasperViewer jv = new JasperViewer(jp, false);
jv.setVisible(true);
} catch (Exception e) {
}
}
调用方法的客户端代码段：
if (jrbAll.isSelected() && session!=null) {
try {
FReport fr = new FReport();
fr.printPDFReport(jcbSession.getSelectedItem().toString());
} catch (Exception exception) {
exception.printStackTrace();
}
}