Jasper Reports 简明教程

Reports Fields

报表字段是元素，表示数据源和报表模板之间的数据映射。可以将字段组合在报表表达式中以获得所需输出。报表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相对应的数据。

Report fields are elements, which represent mapping of data between datasource and report template. Fields can be combined in the report expressions to obtain the desired output. A report template can contain zero or more <field> elements. When declaring report fields, the data source should supply data corresponding to all the fields defined in the report template.

Field Declaration

字段声明如下所示 -

Field declaration is done as shown below −

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

The Name Attribute

<field> 元素的 name 属性是必需的。它通过名称引用报表表达式中的字段。

The name attribute of the <field> element is mandatory. It references the field in report expressions by name.

The Class Attribute

class 属性指定字段值类的名称。它的默认值为 java.lang.String。这可以在运行时更改为任何类。无论报表字段的类型如何，引擎都会负责将使用 $F{} 标记的报表表达式强制为适当的类型，因此无需手动强制类型转换。

The class attribute specifies the class name for the field values. Its default value is java.lang.String. This can be changed to any class available at runtime. Irrespective of the type of a report field, the engine takes care of casting in the report expressions in which the $F{} token is used, hence making manual casts unnecessary.

Field Description

<fieldDesciption> 元素是可选元素。在实现自定义数据源时，这非常有用。例如，我们可以存储键或某些信息，通过这些信息，我们可以从自定义数据源中检索字段值。通过使用 <fieldDesciption> 元素代替字段名称，可以在从数据源中检索字段值时轻松克服字段命名约定的限制。

The <fieldDesciption> element is an optional element. This is very useful when implementing a custom data source. For example, we can store a key or some information, by which we can retrieve the value of field from the custom data source at runtime. By using the <fieldDesciption> element instead of the field name, you can easily overcome restrictions of field-naming conventions when retrieving the field values from the data source.

下面是我们现有 JRXML 文件（第 Report Designs 章）中的一段代码。在这里，我们可以看到 name 、 class 和 fieldDescription 元素的用法。

Following is a piece of code from our existing JRXML file (Chapter Report Designs). Here, we can see usage of name, class, and fieldDescription elements.

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

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

Sort Fields

在需要对数据排序而数据源实现不支持的情况下（例如，CSV 数据源），JasperReports 支持基于字段的内存数据源排序。可以使用报表模板中的一个或多个 <sortField> 元素进行排序。

At the times when data sorting is required and the data source implementation doesn’t support it (for e.g. CSV datasource), JasperReports supports in-memory field-based data source sorting. The sorting can be done using one or more <sortField> elements in the report template.

如果指定了至少一个排序字段，则在报告填充过程中，数据源将传递给 JRSortableDataSource 实例。这会反过来从数据源获取所有记录，根据指定字段在内存中执行排序，并替换原始数据源。

If at least one sort field is specified, during report filling process, the data source is passed to a JRSortableDataSource instance. This in turn, fetches all the records from data source, performs in memory sort according to the specified fields, and replaces the original data source.

排序字段名称应与报表字段名称相同。用于排序的字段应具有实现 java.util.Comparable 的类型。除 java.lang.String 类型的字段之外，对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对应的收集器）。当指定多个排序字段时，将使用字段作为排序键按它们在报表模板中出现的顺序执行排序。以下示例演示了排序功能。

The sort field name should be identical to the report field name. Fields used for sorting should have types that implement java.util.Comparable. Natural order sorting is performed for all fields except those of type java.lang.String (for String type, collator corresponding to the report fill locale is used). When several sort Fields are specified, the sorting will be performed using the fields as sort keys in the order in which they appear in the report template. Following example demonstrates the sorting feature.

Sorted Report Example

让我们将 <*sortField*> 元素添加到我们现有的报表模板（第 Report designs 章）。让我们按降序对 country 字段进行排序。修改后的报表模板（jasper_report_template.jrxml）如下。将其保存到 C:\tools\jasperreports-5.0.1\test 目录 -

Let’s add the <*sortField*> element to our existing report template (Chapter Report designs). Let’s sort field country in descending order. The revised report template (jasper_report_template.jrxml) is as follows. Save it to C:\tools\jasperreports-5.0.1\test directory −

<?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>

用于填充报告的 Java 代码保持不变。文件 C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\JasperReportFill.java 的内容如下 -

The java codes for report filling remains unchanged. The contents of the file C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\JasperReportFill.java are as given below −

package com.tutorialspoint;

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

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

public class JasperReportFill {
   @SuppressWarnings("unchecked")
   public static void main(String[] args) {
      String sourceFileName =
      "C://tools/jasperreports-5.0.1/test/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();
      }
   }
}

C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBean.java POJO 文件的内容如下 −

The contents of the POJO file C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBean.java are as given below −

package com.tutorialspoint;

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;
   }
}

C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBeanList.java 文件的内容如下 −

The contents of the file C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBeanList.java are as given below −

package com.tutorialspoint;

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;
   }
}

Report generation

我们将使用常规 ANT 构建流程编译并执行上述文件。build.xml 文件（保存在 C:\tools\jasperreports-5.0.1\test 目录下）的内容如下。

We will compile and execute the above file using our regular ANT build process. The contents of the file build.xml (saved under directory C:\tools\jasperreports-5.0.1\test) are as given below.

导入文件 - baseBuild.xml 从第 Environment Setup 章节中选取，且应放置在与 build.xml 相同的目录中。

The import file - baseBuild.xml is picked from chapter Environment Setup and should be placed in the same directory as the build.xml.

<?xml version = "1.0" encoding = "UTF-8"?>
<project name = "JasperReportTest" default = "viewFillReport" basedir = ".">
   <import file = "baseBuild.xml" />

   <target name = "viewFillReport" depends = "compile,compilereportdesing,run"
      description = "Launches the report viewer to preview
      the report stored in the .JRprint file.">

      <java classname = "net.sf.jasperreports.view.JasperViewer" fork = "true">
         <arg value = "-F${file.name}.JRprint" />
         <classpath refid = "classpath" />
      </java>
   </target>

   <target name = "compilereportdesing" description = "Compiles the JXML file and
      produces the .jasper file.">

      <taskdef name = "jrc" classname = "net.sf.jasperreports.ant.JRAntCompileTask">
         <classpath refid = "classpath" />
      </taskdef>

      <jrc destdir = ".">
         <src>
            <fileset dir = ".">
               <include name = "*.jrxml" />
            </fileset>
         </src>
         <classpath refid = "classpath" />
      </jrc>

   </target>

</project>

接下来，让我们打开命令行窗口并转到放置 build.xml 的目录。最后，执行以下命令 ant -Dmain-class=com.tutorialspoint.JasperReportFill （viewFullReport 是默认目标） -

Next, let’s open command line window and go to the directory where build.xml is placed. Finally, execute the command ant -Dmain-class=com.tutorialspoint.JasperReportFill (viewFullReport is the default target) as follows −

C:\tools\jasperreports-5.0.1\test>ant -Dmain-class=com.tutorialspoint.JasperReportFill
Buildfile: C:\tools\jasperreports-5.0.1\test\build.xml

clean-sample:
   [delete] Deleting directory C:\tools\jasperreports-5.0.1\test\classes
   [delete] Deleting: C:\tools\jasperreports-5.0.1\test\jasper_report_template.jasper
   [delete] Deleting: C:\tools\jasperreports-5.0.1\test\jasper_report_template.jrprint

compile:
   [mkdir] Created dir: C:\tools\jasperreports-5.0.1\test\classes
   [javac] C:\tools\jasperreports-5.0.1\test\baseBuild.xml:28: warning:
   'includeantruntime' was not set, defaulting to build.sysclasspath=last;
   set to false for repeatable builds
   [javac] Compiling 7 source files to C:\tools\jasperreports-5.0.1\test\classes

compilereportdesing:
   [jrc] Compiling 1 report design files.
   [jrc] log4j:WARN No appenders could be found for logger
   (net.sf.jasperreports.engine.xml.JRXmlDigesterFactory).
   [jrc] log4j:WARN Please initialize the log4j system properly.
   [jrc] log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig
   for more info.
   [jrc] File : C:\tools\jasperreports-5.0.1\test\jasper_report_template.jrxml ... OK.

run:
   [echo] Runnin class : com.tutorialspoint.JasperReportFill
   [java] log4j:WARN No appenders could be found for logger
   (net.sf.jasperreports.extensions.ExtensionsEnvironment).
   [java] log4j:WARN Please initialize the log4j system properly.

viewFillReport:
   [java] log4j:WARN No appenders could be found for logger
   (net.sf.jasperreports.extensions.ExtensionsEnvironment).
   [java] log4j:WARN Please initialize the log4j system properly.

BUILD SUCCESSFUL
Total time: 18 seconds

作为上述编译的结果，一个 JasperViewer 窗口会打开，如以下给出的屏幕截图所示 -

As a result of above compilation, a JasperViewer window opens up as shown in the screen given below −

report field sort example

在此，我们可以看到，国家名称按字母顺序降序排列。

Here, we can see that the country names are arranged in descending order alphabetically.