是否可以在引擎的帮助下进行自定义排序（不是升序或降序）？

Question

B 
C
A
D

它不是升序或降序排序。

有可能这样做吗？

Answer 1

首先，可以通过JasperReports引擎进行排序（无需查询语言，例如SQL）。

这可以借助主数据集或子数据集的sortField属性来完成。

没有排序的jrxml for report：

<?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="Non sorted data" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <subDataset name="ds">
        <field name="value" class="java.lang.String">
            <fieldDescription><![CDATA[_THIS]]></fieldDescription>
        </field>
    </subDataset>
    <summary>
        <band height="15">
            <componentElement>
                <reportElement x="0" y="0" width="311" height="15"/>
                <jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
                    <datasetRun subDataset="ds">
                        <dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource(Arrays.asList("def", "jkl", "abc", "ghi"))]]></dataSourceExpression>
                    </datasetRun>
                    <jr:listContents height="15" width="311">
                        <textField>
                            <reportElement x="0" y="0" width="311" height="15"/>
                            <textFieldExpression><![CDATA[$F{value}]]></textFieldExpression>
                        </textField>
                    </jr:listContents>
                </jr:list>
            </componentElement>
        </band>
    </summary>
</jasperReport>

<?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="Sorted data" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <subDataset name="ds">
        <field name="value" class="java.lang.String">
            <fieldDescription><![CDATA[_THIS]]></fieldDescription>
        </field>
        <sortField name="value"/>
    </subDataset>
    <summary>
        <band height="15">
            <componentElement>
                <reportElement x="0" y="0" width="311" height="15"/>
                <jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
                    <datasetRun subDataset="ds">
                        <dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource(Arrays.asList("def", "jkl", "abc", "ghi"))]]></dataSourceExpression>
                    </datasetRun>
                    <jr:listContents height="15" width="311">
                        <textField>
                            <reportElement x="0" y="0" width="311" height="15"/>
                            <textFieldExpression><![CDATA[$F{value}]]></textFieldExpression>
                        </textField>
                    </jr:listContents>
                </jr:list>
            </componentElement>
        </band>
    </summary>
</jasperReport>

简单的例子：

<?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="Data with custom sorting" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20">
    <property name="com.jaspersoft.studio.data.defaultdataadapter" value="One Empty Record"/>
    <subDataset name="ds">
        <field name="value" class="java.lang.String">
            <fieldDescription><![CDATA[_THIS]]></fieldDescription>
        </field>
        <sortField name="valueForSorting" type="Variable"/>
        <variable name="valueForSorting" class="java.lang.Integer">
            <variableExpression><![CDATA["a".equalsIgnoreCase($F{value}) ? 3 :  "b".equalsIgnoreCase($F{value}) ? 1 : "c".equalsIgnoreCase($F{value}) ? 2 : "d".equalsIgnoreCase($F{value}) ? 4 : 0]]></variableExpression>
        </variable>
    </subDataset>
    <summary>
        <band height="15">
            <componentElement>
                <reportElement x="0" y="0" width="311" height="15"/>
                <jr:list xmlns:jr="http://jasperreports.sourceforge.net/jasperreports/components" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports/components http://jasperreports.sourceforge.net/xsd/components.xsd" printOrder="Vertical">
                    <datasetRun subDataset="ds">
                        <dataSourceExpression><![CDATA[new net.sf.jasperreports.engine.data.JRBeanCollectionDataSource(Arrays.asList("d", "c", "b", "a"))]]></dataSourceExpression>
                    </datasetRun>
                    <jr:listContents height="15" width="311">
                        <textField>
                            <reportElement x="0" y="0" width="311" height="15"/>
                            <textFieldExpression><![CDATA[$F{value}]]></textFieldExpression>
                        </textField>
                    </jr:listContents>
                </jr:list>
            </componentElement>
        </band>
    </summary>
</jasperReport>

JSS中的结果将是：

在某些情况下，使用CASE运算符可以帮助我们按照我们想要的方式对数据进行排序。

SELECT value,
  CASE
    WHEN value = 'a' THEN 3
    WHEN value = 'b' THEN 1
    WHEN value = 'c' THEN 2
    WHEN value = 'd' THEN 4
    ELSE 0
    END AS valueForSorting
FROM someTable