JasperReports 报表字段Field

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2023-03-14

1 JasperReports 报表字段声明

报表字段是元素，表示数据源和报表模板之间的数据映射。可以在报表表达式中组合字段以获得所需的输出。报告模板可以包含零个或多个 <field> 元素。声明报表字段时，数据源应提供与报表模板中定义的所有字段对应的数据。

参数声明如下：

<field name = "FieldName" class = "java.lang.String"/>

name属性

<field> 元素的name属性是必须的。它按名称引用报表表达式中的字段。

class属性

class属性指定的字段值类的名称。它的默认值是java.lang.String。这可以更改为运行时可用的任何类。无论报表字段的类型如何，引擎都会在使用 $F{} 标记的报告表达式中进行转换，因此无需手动转换。

2 JasperReports <fieldDescription>元素

<fieldDescription> 元素是一个可选元素。这在实现自定义数据源时非常有用。例如，我们可以存储一个键或一些信息，通过这些信息我们可以在运行时从自定义数据源中检索字段的值。通过使用 <fieldDescription> 元素而不是字段名称，您可以在从数据源检索字段值时轻松克服字段命名约定的限制。

以下是我们现有的 JRXML 文件（JasperReports 模板设计章节）中的一段代码。在这里，我们可以看到name、class和fieldDescription元素的用法。

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

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

3 JasperReports 报表字段的排序

在需要数据排序而数据源实现不支持的时候（例如CSV 数据源），JasperReports 支持基于内存字段的数据源排序。可以使用报告模板中的一个或多个 <sortField> 元素进行排序。

如果至少指定了一个排序字段，则在报表填充过程中，数据源将传递给JRSortableDataSource实例。这反过来，从数据源中获取所有记录，根据指定的字段在内存中进行排序，并替换原始数据源。

排序字段名称应与报告字段名称相同。用于排序的字段应具有实现 java.util.Comparable 的类型。对除java.lang.String 类型的字段外的所有字段执行自然顺序排序（对于String 类型，使用与报表填充区域设置相对应的collator）。当指定了多个排序字段时，将使用字段作为排序键，按照它们在报告模板中出现的顺序进行排序。以下示例演示了排序功能。

4 JasperReports 报表字段排序的示例

本案例中，我们将 < sortField > 元素添加到我们现有的报表模板（JasperReports 模板设计章节）。让我们按降序对字段country进行排序。

项目结构如下：

pom.xml文件

<dependencies>
        <!-- https://mvnrepository.com/artifact/net.sf.jasperreports/jasperreports -->
        <dependency>
            <groupId>net.sf.jasperreports</groupId>
            <artifactId>jasperreports</artifactId>
            <version>6.17.0</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy-all</artifactId>
            <version>2.4.7</version>
        </dependency>
        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.17</version>
        </dependency>
    </dependencies>

DataBean实体类：

package cn.xnip;

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;
   }
}

DataBeanList类：

package cn.xnip;

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;
   }
}

jasper_report_template.jrxml模板文件：

<?xml version = "1.0"?>
<!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" 
   name = "jasper_report_template" pageWidth = "595" pageHeight = "842" 
   columnWidth = "515" leftMargin = "40" rightMargin = "40" 
   topMargin = "50" bottomMargin = "50">
	
   <parameter name = "ReportTitle" class = "java.lang.String"/>
   <parameter name = "Author" class = "java.lang.String"/>
   
   <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>
  
   <sortField name = "country" order = "Descending"/>
   <sortField name = "name"/>
   
   <title>
      <band height = "70">
         
         <line>
            <reportElement x = "0" y = "0" width = "515" height = "1"/>
         </line>
         
         <textField isBlankWhenNull = "true" bookmarkLevel = "1">
            <reportElement x = "0" y = "10" width = "515" height = "30"/>
            
            <textElement textAlignment = "Center">
               <font size = "22"/>
            </textElement>
            
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$P{ReportTitle}]]>
            </textFieldExpression>
            
            <anchorNameExpression>
               <![CDATA["Title"]]>
            </anchorNameExpression>
         </textField>
            
         <textField isBlankWhenNull = "true">
            <reportElement  x = "0" y = "40" width = "515" height = "20"/>
            
            <textElement textAlignment = "Center">
               <font size = "10"/>
            </textElement>
            
            <textFieldExpression class = "java.lang.String">
               <![CDATA[$P{Author}]]>
            </textFieldExpression>
            
         </textField>
      
      </band>
   </title>

   <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>

先编译报表文件：

package cn.xnip;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.view.JasperViewer;

public class JasperReportFill {

   public static void main(String[] args) {
      String filePath = "D:/idea_codes/jasper_reports/jasper_report_template.jrxml";
      try {
         JasperCompileManager.compileReportToFile(filePath,"d:/jasper_report_template.jasper");
         System.out.println("编译成功");
      } catch (JRException e) {
         e.printStackTrace();
      }
   }
}

编译后在D:/盘根目录下生成jasper_report_template.jasper文件，然后再填充数据：

package cn.xnip;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.data.JRBeanCollectionDataSource;

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

public class JasperReportFill {

   public static void main(String[] args) {
         String sourceFileName = "d:/jasper_report_template.jasper";

         DataBeanList DataBeanList = new DataBeanList();
         ArrayList<DataBean> dataList = DataBeanList.getDataBeanList();

         JRBeanCollectionDataSource beanColDataSource =
                 new JRBeanCollectionDataSource(dataList);

         Map parameters = new HashMap();
         /**
          * Passing ReportTitle and Author as parameters
          */
         parameters.put("ReportTitle", "List of Contacts");
         parameters.put("Author", "Prepared By Manisha");

         try {
            JasperFillManager.fillReportToFile(
                    sourceFileName, parameters, beanColDataSource);
         } catch (JRException e) {
            e.printStackTrace();
         }
      }
}

填充数据完毕后，在D:/盘根目录下生成jasper_report_template.jrprint文件，最后使用预览程序预览：

package cn.xnip;

import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.view.JasperViewer;

public class JasperReportFill {

   public static void main(String[] args) {
      String filePath = "D:/jasper_report_template.jrprint";
      try {
         JasperViewer.viewReport(filePath,false);
      } catch (JRException e) {
         e.printStackTrace();
      }
   }
}

最后输出结果如下：

从效果我们看到，国家名称按字母顺序降序排列。