Why the report is generated empty via Java code? I got a valid result in Studio using jdbc dataadapter

问题

In my project I am creating a pdf report with Jaspersoft Studio (JSS). The JSS preview generates the report correctly but from Java it creates an empty report. I have put my query in my report as querystring.

Here is my Java code:

public void getPDFReport(String userId, ChecklistReport report, OutputStream stream) {
    Map<String, Object> parameters = new HashMap<String, Object>();
    parameters.put("BRANCH_CODE", report.getBranchCode());
    
    Resource resource = resourceLoader.getResource(reportPath);
    try {
        JasperDesign design = JRXmlLoader.load(resource.getInputStream());
        JasperReport jasperReport = JasperCompileManager.compileReport(design);
        JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, parameters);
        JasperExportManager.exportReportToPdfStream(jasperPrint, stream);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

And here is my report xml:

<?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="checklist_report" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="DCFCL Adapter"/>
    <parameter name="BRANCH_CODE" class="java.lang.String"/>
    <queryString language="SQL">
        <![CDATA[SELECT F.FUNC_NAME 
FROM CHECKLIST C JOIN FUNCTIONS F ON C.FUNC_ID = F.FUNC_ID
WHERE C.BRANCH_CODE=$P{BRANCH_CODE}]]>
    </queryString>
    <field name="FUNC_NAME" class="java.lang.String"/>
    <title>
        <band height="71" splitType="Stretch">
            <staticText>
                <reportElement x="0" y="30" width="70" height="18"/>
                <text><![CDATA[Branch Code:]]></text>
            </staticText>
            <textField>
                <reportElement x="70" y="30" width="80" height="18"/>
                <textFieldExpression><![CDATA[$P{BRANCH_CODE}]]></textFieldExpression>
            </textField>
        </band>
    </title>
    <columnHeader>
        <band height="30" splitType="Stretch">
            <staticText>
                <reportElement x="0" y="0" width="175" height="30"/>
                <text><![CDATA[Function Name]]></text>
            </staticText>
        </band>
    </columnHeader>
    <detail>
        <band height="30" splitType="Stretch">
            <textField>
                <reportElement positionType="Float" x="0" y="0" width="175" height="30"/>
                <textFieldExpression><![CDATA[$F{FUNC_NAME}]]></textFieldExpression>
            </textField>
        </band>
    </detail>
</jasperReport>

How to fix this issue?

回答1:

What is wrong?

You forgot to pass db connection via Java code. The engine can't build report without it.

How to fix?

In case you are using report with DB based datasource you have to pass DB connection to the engine.

For example, if you are having report like this:

<?xml version="1.0" encoding="UTF-8"?>
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ..>
    <queryString language="SQL">
        <![CDATA[SELECT attr FROM table]]>
    </queryString>

you need to pass DB connection.

The example of Java code:

JasperPrint jasperPrint = JasperFillManager.fillReport(jasperReport, parameters, connection);

It means that you need to use method having Connection object at signature.

For example, this one: JasperFillManager.fillReport(JasperReport jasperReport, java.util.Map<java.lang.String,java.lang.Object> parameters, java.sql.Connection connection)

In case using Jaspersoft Studio the engine doing the same behind the scenes using dataapter options.

来源：https://stackoverflow.com/questions/62928028/why-the-report-is-generated-empty-via-java-code-i-got-a-valid-result-in-studio

标签

java

jasper-reports