Clojure:将记录列表传递给Java对象

我正在试用Clojure。我能够在JasperReports中生成一个报告,但是 它给出空值。有问题的Java对象是 JRBeanCollectionDataSource . 我给它传递了一个记录列表,但不知何故,PDF只包含null。

还有,为什么我不能通过 {} 作为空的 HashMap ? 在Groovy中 [:] 语法工作正常。

(ns jasper.core
  (:import
   (net.sf.jasperreports.engine JasperCompileManager
                                JasperFillManager
                                JasperExportManager)
   (net.sf.jasperreports.engine.data JRBeanCollectionDataSource)))
(import 'java.util.HashMap)


(defrecord Car [id name price])

(def data [(->Car 1, "Audi", 52642)
           (->Car 2, "Mercedes", 57127)
           (->Car 3, "Skoda", 9000)
           (->Car 4, "Volvo", 29000)
           (->Car 5, "Bentley", 350000)
           (->Car 6, "Citroen", 21000)
           (->Car 7, "Hummer", 41400)
           (->Car 8, "Volkswagen", 21600)])

(def xmlFile "resources/report.xml")
(def jrReport (JasperCompileManager/compileReport xmlFile))

;; (def params {})
(def params (HashMap.))

(def ds (JRBeanCollectionDataSource. data))
(println (.toString ds))

(def jrPrint (JasperFillManager/fillReport jrReport params ds))

(defn -main
  []
  (JasperExportManager/exportReportToPdfFile jrPrint "report.pdf"))

这是对以下工作Groovy解决方案的重写:

@Grab(group='net.sf.jasperreports', module='jasperreports', version='6.17.0')

import net.sf.jasperreports.engine.JasperCompileManager
import net.sf.jasperreports.engine.JasperFillManager
import net.sf.jasperreports.engine.JasperExportManager
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource
import groovy.transform.Immutable

@Immutable
class Car {
    Long id;
    String name;
    int price;
}

def data = [
    new Car(1L, 'Audi', 52642),
    new Car(2L, 'Mercedes', 57127),
    new Car(3L, 'Skoda', 9000),
    new Car(4L, 'Volvo', 29000),
    new Car(5L, 'Bentley', 350000),
    new Car(6L, 'Citroen', 21000),
    new Car(7L, 'Hummer', 41400),
    new Car(8L, 'Volkswagen', 21600),
]

def empty = []

def xmlFile = "report.xml"

def jrReport = JasperCompileManager.compileReport(xmlFile)
def ds = new JRBeanCollectionDataSource(data)

def params = [:]
def jrPrint = JasperFillManager.fillReport(jrReport, params, ds)

JasperExportManager.exportReportToPdfFile(jrPrint, "report.pdf")

编辑 对于一个完全可用的示例,将以下文件放在Groovy的当前工作目录和Clojure的resources目录中。

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE jasperReport PUBLIC "//JasperReports//DTD Report Design//EN"
        "http://jasperreports.sourceforge.net/dtds/jasperreport.dtd">

<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"
              whenNoDataType="NoDataSection"
              name="report" topMargin="20" bottomMargin="20">

    <field name="id" class="java.lang.Long"/>
    <field name="name"/>
    <field name="price" class="java.lang.Integer"/>

    <detail>
        <band height="15">

            <textField>
                <reportElement x="0" y="0" width="50" height="15"/>

                <textElement textAlignment="Right" verticalAlignment="Middle"/>

                <textFieldExpression class="java.lang.Long">
                    <![CDATA[$F{id}]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="150" y="0" width="100" height="15" />

                <textElement textAlignment="Left" verticalAlignment="Middle"/>

                <textFieldExpression class="java.lang.String">
                    <![CDATA[$F{name}]]>
                </textFieldExpression>
            </textField>

            <textField>
                <reportElement x="200" y="0" width="100" height="15" />
                <textElement textAlignment="Right" verticalAlignment="Middle"/>

                <textFieldExpression class="java.lang.Integer">
                    <![CDATA[$F{price}]]>
                </textFieldExpression>
            </textField>

        </band>
    </detail>

    <noData>
        <band height="15">
            <staticText>
                <reportElement x="0" y="0" width="200" height="15"/>
                <box>
                    <bottomPen lineWidth="1.0" lineColor="#CCCCCC"/>
                </box>
                <textElement />
                <text><![CDATA[The report has no data]]></text>
            </staticText>
        </band>
    </noData>

</jasperReport>