java - 如何使用列表在 JasperReports 中生成动态表

Question

我正在尝试在 Jasper 中生成表格报告。具体来说，我正在尝试像这样遍历表中的列表:

Java 代码:

List<String> severity = (List<String>)session.getAttribute("severity"); 
List<String> messages = (List<String>)session.getAttribute("messages");

LinkedHashMap parameters = new LinkedHashMap();
parameters.put("severity", severity);
parameters.put("messages", messages);

jPrint = JasperFillManager.fillReport(jasperreport,parameters,new JREmptyDataSource());
JasperExportManager.exportReportToPdfStream(jPrint,baos);    

JRXML:

<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="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="a3d5ea75-61fe-4bd0-a2ef-43652ca82bb5">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <queryString>
        <![CDATA[]]>
    </queryString>
    <field name="severity" class="java.util.List">
        <fieldDescription><![CDATA[severity]]></fieldDescription>
    </field>
    <field name="messages" class="java.util.List">
        <fieldDescription><![CDATA[messages]]></fieldDescription>
    </field>
    <columnHeader>
        <band height="23" splitType="Stretch">
            <staticText>
                <reportElement mode="Opaque" x="0" y="-180" width="535" height="15" backcolor="#70A9A9" uuid="9b5b79e0-e146-41d9-b665-6cf9441c44f7"/>
                <box>
                    <bottomPen lineWidth="1.0" lineColor="#CCCCCC"/>
                </box>
                <text><![CDATA[ ]]></text>
            </staticText>
            <staticText>
                <reportElement x="290" y="0" width="121" height="15" uuid="427a0dc3-acc5-445d-afdf-325f56220d5b"/>
                <textElement textAlignment="Center" verticalAlignment="Middle">
                    <font isBold="true"/>
                </textElement>
                <text><![CDATA[Error Severity]]></text>
            </staticText>
            <staticText>
                <reportElement x="0" y="3" width="136" height="15" uuid="9d05c15b-478c-49d3-a334-c5d6bfc62e53"/>
                <textElement textAlignment="Center" verticalAlignment="Middle">
                    <font isBold="true"/>
                </textElement>
                <text><![CDATA[Erorr Messages]]></text>
            </staticText>
        </band>
    </columnHeader>
    <detail>
        <band height="16" splitType="Stretch">
            <staticText>
                <reportElement mode="Opaque" x="0" y="0" width="535" height="14" backcolor="#E5ECF9" uuid="b0ac6c6e-6d86-44de-801c-fcb85f1c5cb7"/>
                <box>
                    <bottomPen lineWidth="0.25" lineColor="#CCCCCC"/>
                </box>
                <text><![CDATA[ ]]></text>
            </staticText>
            <textField>
                <reportElement x="290" y="0" width="121" height="15" uuid="d106ecf9-2dc8-49fb-b63c-e348b96f871d"/>
                <textElement textAlignment="Center" verticalAlignment="Middle"/>
                <textFieldExpression><![CDATA[$F{severity}]]></textFieldExpression>
            </textField>
            <textField>
                <reportElement x="0" y="0" width="136" height="15" uuid="d106ecf9-2dc8-49fb-b63c-e348b96f871d"/>
                <textElement textAlignment="Center" verticalAlignment="Middle"/>
                <textFieldExpression><![CDATA[$F{messages}]]></textFieldExpression>
            </textField>
        </band>
    </detail>
</jasperReport>

所以我的问题是:

1)如何在Jrxml中打印这些列表？

2) 这是在 JRXML 中遍历列表的正确方法吗？

3)如何写JRXML代码迭代List？ (子报表在这种情况下有用吗？)

Answer 1

传递两个 LinkedHashMap 并不是您需要实现的最佳数据结构。

如果您像下面这样更改您的数据结构，您的 jrxml 只需稍作更改即可工作。

创建一个包含您的错误的 bean。

public class ErrorBean {
    private String severity;
    private String messages;
    public String getSeverity() {
        return severity;
    }
    public void setSeverity(String severity) {
        this.severity = severity;
    }
    public String getMessages() {
        return messages;
    }
    public void setMessages(String messages) {
        this.messages = messages;
    }
}

用数据填充你的 bean

//Pass our two LinkList to our new ErrorBean
List<ErrorBean> errorBeans = new ArrayList<ErrorBean>();
for (int i = 0; i < severity.size(); i++) {
    ErrorBean eb = new ErrorBean();
    eb.setSeverity(severity.get(i));
    if (messages.size()>i){
        eb.setMessages(messages.get(i));
    }
    errorBeans.add(eb);
}

将 errorBeans 传递给 JRBeanCollectionDataSource 中的 JasperReport

Map<String,Object> parameters = new HashMap<String,Object>();
jPrint = JasperFillManager.fillReport(jasperreport,parameters,new JRBeanCollectionDataSource(errorBeans));

现在你的设置在 jrxml 中唯一需要的小修改是定义正确的字段类(从 java.util.List 切换到 java.lang .字符串)

<field name="severity" class="java.lang.String">
    <fieldDescription><![CDATA[severity]]></fieldDescription>
</field>
<field name="messages" class="java.lang.String">
    <fieldDescription><![CDATA[messages]]></fieldDescription>
</field>