報表引數

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填充報表的三個主要輸入是：報表模板、引數和資料來源。本章將描述引數，下一章我們將討論資料來源。

引數是物件引用，在報表填充操作期間傳遞給報表引擎。無法透過資料來源傳遞的資料可以透過引數傳遞。諸如作者姓名、報表標題等資料可以透過引數傳遞。JasperReports 模板或 JRXML 模板可以具有零個或多個引數元素。

引數宣告

引數宣告如下：

<parameter name = "exampleParameter" class = "java.lang.String" />

名稱屬性

<parameter> 元素的name 屬性是必需的。它透過名稱在報表表示式中引用引數。引數名稱應為單個單詞。它不應包含任何特殊字元，例如點或逗號。

類屬性

class 屬性也是必需的，它指定引數值的類名。其預設值為java.lang.String。這可以更改為執行時可用的任何類。無論報表引數的型別如何，引擎都會處理報表表示式中使用 $P{} 令牌的型別轉換，因此無需手動進行型別轉換。

報表引數值始終打包在一個 java.util.Map 物件中，該物件以引數名稱作為鍵。報表引數可用於報表的查詢字串，以便進一步自定義從資料庫檢索的資料集。這些充當查詢中的動態過濾器，為報表提供資料。

內建引數

以下是預定義的報表引數，可在表示式中使用：

序號 引數名稱和描述
1

REPORT_PARAMETERS_MAP

包含一個包含所有使用者定義和內建引數的對映。
2

REPORT_CONNECTION

指向使用者提供的類 java.sql.Connection，用於 JDBC 資料來源。
3

REPORT_DATA_SOURCE

這是使用者提供的 JRDataSource 例項，表示內建資料來源型別之一或使用者定義的資料來源。
4

REPORT_MAX_COUNT

這是一個java.lang.Integer 值，允許使用者限制來自資料來源的記錄數。
5

REPORT_SCRIPTLET

指向net.sf.jasperreports.engine.JRAbstractScriptlet，幷包含使用者提供的報表指令碼的例項。
6

REPORT_LOCALE

這是一個java.util.Locale 例項，包含所需資源包的區域設定。
7

REPORT_RESOURCE_BUNDLE

指向java.util.ResourceBundle 物件，幷包含本地化訊息。
8

REPORT_TIME_ZONE

這是一個java.util.TimeZone 例項，用於日期格式化。
9

REPORT_VIRTUALIZER

這是net.sf.jasperreports.engine.JRVirtualizer 物件的例項，用於頁面虛擬化（最佳化記憶體消耗）。
10

REPORT_CLASS_LOADER

這是一個java.lang.ClassLoader 例項，在報表填充過程中用於載入資源，例如影像、字型和子報表模板。
11

IS_IGNORE_PAGINATION

如果設定為java.lang.Boolean.TRUE，則報表將在一頁長頁上生成，並且不會發生分頁。

示例

讓我們將ReportTitle 和Author 傳遞給報表（由 JasperReportFill.java 生成）。修改後的檔案C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\JasperReportFill.java 如下所示：

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();
      }
   }
}

POJO 檔案C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBean.java 的內容如下：

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;
   }
}

檔案C:\tools\jasperreports-5.0.1\test\src\com\tutorialspoint\DataBeanList.java 的內容如下所示：

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;
   }
}

讓我們向現有的報表模板新增引數<ReportTitle> 和 <Author>（章節報表設計）。報表標題和作者將顯示在報表的開頭。修改後的報表模板 (jasper_report_template.jrxml) 如下所示。將其儲存到 C:\tools\jasperreports-5.0.1\test 目錄：

<?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>

   <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>

報表生成

我們將使用常規的 ANT 構建過程編譯並執行上述檔案。檔案 build.xml（儲存在目錄 C:\tools\jasperreports-5.0.1\test 下）的內容如下所示。

匯入檔案 - baseBuild.xml 來自章節環境設定，應與 build.xml 放在同一目錄下。

<?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>

接下來，讓我們開啟命令列視窗並轉到放置 build.xml 的目錄。最後，執行命令ant -Dmain-class=com.tutorialspoint.JasperReportFill（viewFullReport 是預設目標）如下所示：

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

編譯的結果是開啟一個 JasperViewer 視窗，如下面的螢幕截圖所示：

Jasper Report Parameter Example

在這裡，我們可以看到，報表標題“聯絡人列表”和作者“由 Manisha 準備”顯示在報表的開頭。

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