JasperReport

JasperReports 是一个基于 Java 的开源程序库。用户使用它可以方便地生成专业的报告，支持导出 html，pdf 等多种格式。

参考：
JasperReports Ultimate Guide (pdf)
JasperReports Tutorial

下面例子摘自：https://www.tutorialspoint.com/jasper_reports/jasper_exporting_reports.htm

这个例子比较简单，报告内容为一个表格，表格中有人名以及所在国家。

第一步，设计模板文件 report.jrxml，如下所示。

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

<jasperReport name = "jasper_report_template">

   <queryString>
      <![CDATA[]]>
   </queryString>

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

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

   <columnHeader>
      <band height = "23">

         <staticText>
            <reportElement mode = "Opaque" x = "0" y = "3"
               width = "535" height = "15" backcolor = "#70A9A9" />

            <box>
               <bottomPen lineWidth = "1.0" lineColor = "#CCCCCC" />
            </box>

            <textElement />
            <text><![CDATA[]]> </text>
         </staticText>

         <staticText>
            <reportElement x = "414" y = "3" width = "121" height = "15" />

            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font isBold = "true" />
            </textElement>

            <text><![CDATA[Country]]></text>
         </staticText>

         <staticText>
            <reportElement x = "0" y = "3" width = "136" height = "15" />

            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font isBold = "true" />
            </textElement>

            <text><![CDATA[Name]]></text>
         </staticText>

      </band>
   </columnHeader>

   <detail>
      <band height = "16">

         <staticText>
            <reportElement mode = "Opaque" x = "0" y = "0"
               width = "535" height = "14" backcolor = "#E5ECF9" />

            <box>
               <bottomPen lineWidth = "0.25" lineColor = "#CCCCCC" />
            </box>

            <textElement />
            <text><![CDATA[]]> </text>
         </staticText>

         <textField>
            <reportElement x = "414" y = "0" width = "121" height = "15" />

            <textElement textAlignment = "Center" verticalAlignment = "Middle">
               <font size = "9" />
            </textElement>

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

         <textField>
            <reportElement x = "0" y = "0" width = "136" height = "15" />
            <textElement textAlignment = "Center" verticalAlignment = "Middle" />

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

      </band>
   </detail>

</jasperReport>

第二步，把上面文件编译为二进制的模板文件 report.jasper，过程略（通过前面介绍的 maven 插件可以自动完成）。

第三步，准备填充的数据。这个例子中，通过下面两个 java 文件实现。

public class DataBean {
    private String name;
    private String country;

    public String getName() {
       return name;
    }

    public void setName(String name) {
       this.name = name;
    }

    public String getCountry() {
       return country;
    }

    public void setCountry(String country) {
       this.country = country;
    }
}

import java.util.ArrayList;

public class DataBeanList {
   public ArrayList<DataBean> getDataBeanList() {
      ArrayList<DataBean> dataBeanList = new ArrayList<DataBean>();

      dataBeanList.add(produce("Manisha", "India"));
      dataBeanList.add(produce("Dennis Ritchie", "USA"));
      dataBeanList.add(produce("V.Anand", "India"));
      dataBeanList.add(produce("Shrinath", "California"));

      return dataBeanList;
   }

   /**
    * This method returns a DataBean object,
    * with name and country set in it.
    */
   private DataBean produce(String name, String country) {
      DataBean dataBean = new DataBean();
      dataBean.setName(name);
      dataBean.setCountry(country);

      return dataBean;
   }
}

第四步，生成报告。这里生成 pdf 和 html 格式的报告。

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

import net.sf.jasperreports.engine.JRException;
import net.sf.jasperreports.engine.JasperExportManager;
import net.sf.jasperreports.engine.JasperFillManager;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;

public class App
{
    public static void main(String[] args) {
        String sourceFileName = "/Users/cig01/first-jasperreport-app/target/jasper/report.jasper";
        String printFileName = null;
        DataBeanList DataBeanList = new DataBeanList();
        ArrayList<DataBean> dataList = DataBeanList.getDataBeanList();
        JRBeanCollectionDataSource beanColDataSource =
           new JRBeanCollectionDataSource(dataList);

        Map<String, Object> parameters = new HashMap<String, Object>();
        try {
           printFileName = JasperFillManager.fillReportToFile(sourceFileName,
              parameters, beanColDataSource);
           if (printFileName != null) {
              /**
               * 1- export to PDF
               */
              JasperExportManager.exportReportToPdfFile(printFileName,
                 "/Users/cig01/first-jasperreport-app/sample_report.pdf");

              /**
               * 2- export to HTML
               */
              JasperExportManager.exportReportToHtmlFile(printFileName,
                 "/Users/cig01/first-jasperreport-app/sample_report.html");
           }
        } catch (JRException e) {
           e.printStackTrace();
        }
     }
}

运行程序，得到的 sample_report.pdf 或者 sample_report.html，看起来如图 3 所示。