JasperReport和iReport是不錯(cuò)的Java報(bào)表工具.?在實(shí)際項(xiàng)目中,?本人用它們開發(fā)了20個(gè)Report,?涉及SubReport,?Image,?Graph,?積累了一些經(jīng)驗(yàn).?尤其是關(guān)于Export到Excel方面,?文檔上也很少提及,?純粹是摸索出來的,?有的問題還是通過讀源代碼才解決的.?此貼并非入門教程,?差不多算是筆記吧,?以問答形式記錄.?

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1. iReport

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2. 安裝

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   1. 下載，解壓iReport 0.4.0 (推薦src版本）

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   2. 確認(rèn)JDK是1.4以上

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   3. 把JDK /lib下的tools.jar拷貝到{ireport_home}/lib目錄中

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3. 運(yùn)行

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   1. 對于下載的Binary版本，只能運(yùn)行/bin/startup.bat

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   2. 對于下載的Src版本，可以通過ant iReport運(yùn)行（先安裝ant)

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   3. 如果運(yùn)行startup.bat，出現(xiàn)java.lang.NoSuchMethodError錯(cuò)誤，一般是JDK版本太低。如果確認(rèn)已安裝了1.4或以上，檢查path系統(tǒng)變量，看看有1.3的JRE是不是排在前面（比如安裝了Oracle的客戶端，往往有1.3的JRE），如果出現(xiàn)Class Not Found，檢查classpath。對于通過ant的方式運(yùn)行，一般都沒什么問題，所以推薦下載src版本

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4. JasperReport 常見問題

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   1. .jrxml vs .jasper

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      • 如果在運(yùn)行時(shí)載入.jrxml, 那么每次調(diào)用還得編譯, 不如預(yù)先編譯成.jasper.不過預(yù)先編譯的jasper,必須用同樣版本的JasperReport載入,而且靈活性差些. 不過對于大部分報(bào)表,還是預(yù)先編譯成jasper方便

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   2. 如果批量編譯jrxml

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      • 用Ant很容易解決
        
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   3. 如何使用圖片？

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      • 很容易,用Image控件就可以了. 在Image Express里面可以用String來表示圖片的路徑, 或者用InputStream, File對象.不過不管用File還是String對象, 都不得不用絕對路徑, 這顯然很不靈活. 解決辦法是,穿入一個(gè)$P的參數(shù),表示圖片所在的目錄,然后用$P和文件名拼接出完整的絕對路徑. 更好的方法是用InputStream, 例如this.getClass().getResourceAsStream("logo.jpg")?,這時(shí)只要把圖片放在當(dāng)前.jasper所在的目錄就可以了,不必考慮什么參數(shù),什么路徑了

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   4. 顯示非數(shù)據(jù)庫字段變量

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      • 顯示如運(yùn)行日期等,可以直接在Text Field里面輸入new java.util.Date(), 然后把Pattern設(shè)成如mm/dd/yyyy.

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   5. 動(dòng)態(tài)控制某些Field是否顯示

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      • 每個(gè)Static Text, Text Field甚至整個(gè)Band的屬性里面都有Print When Expression, 比如設(shè)成new Boolean(!$P{isDisplay}.equalsIgnoreCase("yes")), 那么只有當(dāng)參數(shù)display的值為yes的時(shí)候才顯示

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   6. 使用Sub Report, 如何使用相對路徑

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      • 見1.3, 和使用圖片類似, 用InputStream或者傳入?yún)?shù)

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   7. Query里面如何使用參數(shù)

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      • $P!{xxx} 或者 $P{xxx} 后者只能用于類似PreparedStatement參數(shù)綁定, 而前者可替換Sql的任意部分. 在需要?jiǎng)討B(tài)排序的時(shí)候, 前者特別有用. 比如 select a,b,c from t order by $P!{orderClause}???不管用$P還是$P!, SQL最終是以PreparedStatement方式執(zhí)行的, 不必太擔(dān)心性能問題?? 注意:參數(shù)是不能嵌套的, 比如$P{a} =''$P''?? , $P=''value'', 不要指望$P{a}能被替換成''value''

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   8. 如何使用圖表(Graph)

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      • JasperReport本身沒有圖表功能, 只有顯示Image的功能(見4.3). iReport里有個(gè)Graph向?qū)? 其實(shí)質(zhì)是通過jFreeChart生成Image. 更另外, 更直接的做法是放一個(gè)Image控件, Image Express Class設(shè)置成java.awt.Image, 在Image Expression里通過自定義的類返回java.awt.Image對象. 例如''GraphProvider.getImage($P{REPORT_DATASOURCE},title, subtitle.....)''.? GraphProvider是自己的類, public static Image getImage(JRDataSource, ....)

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   9. 如果顯示多個(gè)圖表

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      • 在一張報(bào)表上顯示一個(gè)圖表和顯示多個(gè)圖表是不同的. 假設(shè)Query是select name,price,qty from xxx, 第一張圖顯示name-price, 第二張圖顯示name-qty, 如果還是按3.8的方法, 第二張圖根本顯示不出來! 為什么? 因?yàn)閭魅氲氖荍RDataSource, 而JRDataSource僅僅是對ResultSet的簡單封裝, 在第一張圖處理完后, 游標(biāo)已經(jīng)到了eof位置了, 在開始處理第二張圖的時(shí)候,就必然拋出游標(biāo)耗盡的異常! 怎么辦?? 自己寫個(gè)JRDataSourceAdapter, 把JRDataSource對象里面的值預(yù)先保存到一個(gè)Collection (相當(dāng)于一個(gè)Offline的數(shù)據(jù)集), 然后把這個(gè)Collection傳個(gè)getImage方法. 具體是, 建一個(gè)Variable? mydate, 類型是java.util.Map, Calculation Type- System, Initial Value Expression是JRDataSourceAdapter.JRDataSource2Map($P{REPORT_DATA_SOURCE},new String[]{"NAME","PRICE","QTY"},new Class[]{java.lang.String.class,java.lang.Double.class,java.lang.Double.class}), JRDataSource2Map是自己寫的一個(gè)Adapter. 然后在Image的Expression里面換成如''GraphProvider.getImage(mydata,title, other params...), 當(dāng)然得修改getImage方法

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5. Export到Excel的問題

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   1. 如何去掉報(bào)表頭等

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      • 直接把不需要的Band刪除(把其高度設(shè)為0). 如果僅僅是export到Excel的時(shí)候不需要報(bào)表頭, 而輸出到PDF等仍然需要保留, 那么使用print when expression, 見4.4

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   2. 如果讓Excel看起來整齊

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      • 不要有空白地方! 首先把所有的Field設(shè)成一樣高, 對齊! 把所在Band的高度也設(shè)成和Field一樣高, 讓Field正好放入Band. 然后調(diào)整Field的寬度, 讓每個(gè)Field都相鄰,沒有空隙. 最后,記得設(shè)置參數(shù): exporter.setParameter(JRXlsExporterParameter.IS_REMOVE_EMPTY_SPACE_BETWEEN_ROWS,
        ??????????????????? Boolean.TRUE);
        

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   3. 如何保留GridLine

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      • 首先, 設(shè)置參數(shù)exporter.setParameter(JRXlsExporterParameter.IS_WHITE_PAGE_BACKGROUND, Boolean.FALSE); 然后,把每個(gè)Field或者Static Text框的''Transparent''屬性都勾上

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   4. 如何使字段名只顯示一次

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      • 如果把字段名放在ColumnHead區(qū)域, 那么輸出到Excel, 會(huì)每個(gè)Page都顯示一遍. 在設(shè)計(jì)Report時(shí)候, 一般會(huì)設(shè)定Page大小. 然而對于Excel, 這個(gè)Page設(shè)定仍然存在,而且往往很討厭, 因?yàn)樵贓xcel里, 通常希望得到連續(xù)的數(shù)據(jù), 然而Jasper仍然會(huì)''自作多情''進(jìn)行分頁. 比如說, 設(shè)計(jì)JasperReport的時(shí)候, 設(shè)定page size為Letter, Portrait, 那么輸出到Excel的時(shí)候每隔大約30行(具體取決于Field的高度), page header, column header, column foot, page foot 會(huì)被重復(fù)一次, 而且還附帶一個(gè)高度為0的Excel Row, 表示Page Break的地方. 把字段名放在title band里, 可以解決字段名重復(fù)的問題, 當(dāng)然page header也不要顯示了. 如果需要, 可以把title band的print when expression設(shè)成只有輸出Excel的時(shí)候才顯示

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   5. 為什么Excel里面的數(shù)據(jù)是從第二行,第B列開始顯示的?

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      • 因?yàn)榈谝恍泻偷贏列分別是用來表示page top margin 和 page left margin的. 對于Excel來說, 純粹多余. 解決方法是把page margin 設(shè)成0. 不過如果這個(gè)report還需要以PDF等顯示, 那么設(shè)成0就不好看了. 最好能動(dòng)態(tài)的改變page margin. 當(dāng)然,這個(gè)改變只能在外部(調(diào)用Report的地方) 進(jìn)行, 在設(shè)計(jì)Report的時(shí)候是無能為力的. 不幸的是, JasperReport類居然沒有setMargin的方法,只有g(shù)etter. 折中的方法只能是reflect了. 代碼示意如下: //use reflect to set the private field of JRBaseReport
        ???????????????? java.lang.reflect.Field margin = JRBaseReport.class.getDeclaredField(
        ??????????????????????? "leftMargin");
        ??????????????? margin.setAccessible(true);
        ??????????????? margin.setInt(myRpt, 0); ??????????????? margin = JRBaseReport.class.getDeclaredField("topMargin");
        ??????????????? margin.setAccessible(true);
        ??????????????? margin.setInt(myRpt, 0); ??????????????? margin = JRBaseReport.class.getDeclaredField("bottomMargin");
        ??????????????? margin.setAccessible(true);
        ??????????????? margin.setInt(myRpt, 0);

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   6. 如何去掉Excel中隱藏的行?

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      • 如前說述, 由于page break的關(guān)系, Excel中每隔幾十行,就有一個(gè)高度為0的row, 即使把page botom margin設(shè)為0, 把page footer去掉都沒有辦法. 唯一的解決辦法是把page height設(shè)為很大. 同5.5一樣, 不得不使用reflect:

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        • java.lang.reflect.Field pageHeight = JRBaseReport.class.getDeclaredField(
          ??????????????????????? "pageHeight");
          ??????????????? pageHeight.setAccessible(true);
          ??????????????? pageHeight.setInt(myRpt, Integer.MAX_VALUE);
          

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6. 文檔

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   1. 哪里有文檔?

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      • JasperReport有份Ultimate Guide, 不過不是免費(fèi)的, 和jFreeChart一個(gè)德行. 不過網(wǎng)上有流傳, 寫的還可以, 60多頁, 不過也沒詳細(xì)到哪里去. 如果下載源代碼版, 那么看看自帶的Demo也不錯(cuò). SF的論壇也是問問題的最好地方

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7. 源代碼 僅供參考(reportProvider--一個(gè)Servlet, GraphProider, JRDataAdapter都是普通類)

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/**
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Title: ReportProviderServlet

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Description: Servlet to generate Jasper reports

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Copyright: Copyright (c) 2004

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Company:?*****

?* @author zephyr
?* @version 1.0
?*/
package xyz;

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import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.base.*;
import net.sf.jasperreports.engine.export.*;
import net.sf.jasperreports.engine.util.*;

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import org.apache.log4j.*;

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import java.io.*;

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import java.sql.*;

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import java.util.*;

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import javax.servlet.*;
import javax.servlet.http.*;

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public class ReportProviderServlet extends HttpServlet
{
??? private static Logger log = LogManager.getLogger(ReportProviderServlet.class);

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??? //Initialize: Setup DataSourceManager
??? public void init() throws javax.servlet.ServletException
??? {
??????? String prefix = getServletContext().getRealPath("/");
??????? String file = getInitParameter("data-source-file");

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??????? DataSourceManager.configure(prefix + file);

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??????? log.info("initialized successfully!");
??? }

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??? //Process the HTTP request
??? public void service(HttpServletRequest request, HttpServletResponse response)
??????? throws ServletException, IOException
??? {
??????? String reportClass = request.getParameter("reportClass");

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??????? log.debug("Running Report:" + reportClass);

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??????? boolean isExcelFormat = false;

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??????? if (reportClass == null)
??????? {
??????????? throw new IllegalArgumentException("Jasper Class Unspecified");
??????? }

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??????? String reportFormat = request.getParameter("reportFormat");

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??????? if (reportFormat == null)
??????? {
??????????? reportFormat = "jasperPrint";
??????? }

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??????? try
??????? {
??????????? JasperReport myRpt = JasperManager.loadReport(this.getClass()
????????????????????????????????????????????????????????????? .getResourceAsStream("/jasperReports/" +
??????????????????????? reportClass + ".jasper"));

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??????????? //set ReprintHeaderOnEachPage=false for Excel Format
??????????? isExcelFormat = reportFormat.equalsIgnoreCase("excel");

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??????????? if (isExcelFormat)
??????????? {
??????????????? //use reflect to set the private field of JRBaseReport
??????????????? //No margin for excel format, max pageHeight
??????????????? java.lang.reflect.Field margin = JRBaseReport.class.getDeclaredField(
??????????????????????? "leftMargin");
??????????????? margin.setAccessible(true);
??????????????? margin.setInt(myRpt, 0);

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??????????????? margin = JRBaseReport.class.getDeclaredField("topMargin");
??????????????? margin.setAccessible(true);
??????????????? margin.setInt(myRpt, 0);

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??????????????? margin = JRBaseReport.class.getDeclaredField("bottomMargin");
??????????????? margin.setAccessible(true);
??????????????? margin.setInt(myRpt, 0);

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??????????????? java.lang.reflect.Field pageHeight = JRBaseReport.class.getDeclaredField(
??????????????????????? "pageHeight");
??????????????? pageHeight.setAccessible(true);
??????????????? pageHeight.setInt(myRpt, Integer.MAX_VALUE);

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??????????????? //Don't print group header on each page
??????????????? if (null != myRpt.getGroups())
??????????????? {
??????????????????? for (int i = 0; i < myRpt.getGroups().length; i++)
??????????????????? {
??????????????????????? myRpt.getGroups()[i].setReprintHeaderOnEachPage(false);
??????????????????? }
??????????????? }
??????????? }

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??????????? Map params = new HashMap(10);
??????????? Enumeration enu = request.getParameterNames();

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??????????? while (enu.hasMoreElements())
??????????? {
??????????????? String key = (String) enu.nextElement();
??????????????? params.put(key,
??????????????????? request.getParameter(key).toUpperCase().replaceAll("'", "''"));
??????????????? log.debug(key + "=" + request.getParameter(key));
??????????? }

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??????????? log.debug("Before Filling");

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??????????? OutputStream httpOut = response.getOutputStream();

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??????????? Connection conn = DataSourceManager.getConnection(request.getSession());

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??????????? JasperPrint rptPnt = JasperManager.fillReport(myRpt, params, conn);

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??????????? conn.close();

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??????????? if (reportFormat.equalsIgnoreCase("jasperPrint"))
??????????? {
??????????????? response.setContentType("application/octet-stream");
??????????????? JRSaver.saveObject(rptPnt, httpOut);
??????????? }
??????????? else if (reportFormat.equalsIgnoreCase("pdf"))
??????????? {
??????????????? response.setContentType("application/pdf");
??????????????? response.setHeader("Content-Disposition",
??????????????????? "attachment;filename=\"" + reportClass + ".PDF\"");
??????????????? JasperManager.printReportToPdfStream(rptPnt, httpOut);
??????????? }
??????????? else if (reportFormat.equalsIgnoreCase("excel"))
??????????? {
??????????????? response.setContentType("application/vnd.ms-excel");
??????????????? response.setHeader("Content-Disposition",
??????????????????? "attachment;filename=\"" + reportClass + ".XLS\"");

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??????????????? JRXlsExporter exporter = new JRXlsExporter();

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??????????????? exporter.setParameter(JRExporterParameter.JASPER_PRINT, rptPnt);
??????????????? exporter.setParameter(JRExporterParameter.OUTPUT_STREAM, httpOut);
??????????????? exporter.setParameter(JRXlsExporterParameter.IS_REMOVE_EMPTY_SPACE_BETWEEN_ROWS,
??????????????????? Boolean.TRUE);
??????????????? exporter.setParameter(JRXlsExporterParameter.IS_ONE_PAGE_PER_SHEET,
??????????????????? Boolean.FALSE);
??????????????? exporter.setParameter(JRXlsExporterParameter.IS_WHITE_PAGE_BACKGROUND,
??????????????????? Boolean.FALSE);
??????????????? exporter.exportReport();
??????????? }
??????????? else if (reportFormat.equalsIgnoreCase("html"))
??????????? {
??????????????? JRHtmlExporter exporter = new JRHtmlExporter();
??????????????? response.setContentType("text/html");

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??????????????? Map imagesMap = new HashMap();

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??????????????? request.getSession().setAttribute("IMAGES_MAP", imagesMap);

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??????????????? exporter.setParameter(JRHtmlExporterParameter.IMAGES_MAP,
??????????????????? imagesMap);
??????????????? exporter.setParameter(JRHtmlExporterParameter.IMAGES_URI,
??????????????????? "image.jsp?image=");
??????????????? exporter.setParameter(JRExporterParameter.JASPER_PRINT, rptPnt);
??????????????? exporter.setParameter(JRExporterParameter.OUTPUT_STREAM, httpOut);

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??????????????? exporter.exportReport();
??????????? }

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??????????? log.debug("Report Exported");
??????? }
??????? catch (Exception ex)
??????? {
??????????? log.error("Error Occured", ex);
??????? }
??? }
}

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/**
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Title: JRDataSourceAdapter

?*

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Description: Converting JRDataSource to Mapped ArrayList

?*

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Copyright: Copyright (c) 2004

?*

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Company: *****

?* @author zephyr
?* @version 1.0
?*/
package xyz;

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import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.design.*;

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import java.util.*;

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public class JRDataSourceAdapter
{
??? public static Map JRDataSource2Map(JRDataSource dataSource, String[] fieldNames,
??????? Class[] fieldClasses) throws JRException
??? {
??????? HashMap result;

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??????? if (fieldNames.length != fieldClasses.length)
??????? {
??????????? throw new JRException("Number of Field Name & Class unmatch");
??????? }

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??????? JRDesignField[] fields = new JRDesignField[fieldNames.length];

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??????? result = new HashMap(4);

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??????? for (int i = 0; i < fieldNames.length; i++)
??????? {
??????????? fields[i] = new JRDesignField();
??????????? fields[i].setName(fieldNames[i]);
??????????? fields[i].setValueClass(fieldClasses[i]);
??????????? result.put(fieldNames[i], new ArrayList());
??????? }

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??????? do
??????? {
??????????? for (int i = 0; i < fields.length; i++)
??????????? {
??????????????? Object value = dataSource.getFieldValue(fields[i]);
??????????????? ((ArrayList) result.get(fields[i].getName())).add(value);
??????????? }
??????? }
??????? while (dataSource.next());

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??????? return result;
??? }
}

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/**
?*

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Title: GraphProvider

?*

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Description: Generate JFreeChart Image

?*

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Copyright: Copyright (c) 2004

?*

?

Company: ****

?* @author zephyr?
?* @version 1.0
?*/
package xyz;

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import net.sf.jasperreports.engine.*;
import net.sf.jasperreports.engine.design.*;
import net.sf.jasperreports.engine.export.*;

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import org.jfree.chart.*;
import org.jfree.chart.axis.*;
import org.jfree.chart.plot.*;

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import org.jfree.data.*;

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import java.awt.*;
import java.awt.image.*;

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import java.io.*;

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import java.util.*;

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public class GraphProvider
{
??? public static Image getImage(Map dataSource, String fieldNameX, String fieldNameY,
??????? String chartName, String titleX, String titleY, boolean isBarChart, int imageWidth,
??????? int imageHeight) throws JRException
??? {
??????? JRDesignField fieldX = new JRDesignField();
??????? fieldX.setName(fieldNameX);
??????? fieldX.setValueClass(java.lang.String.class);

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??????? JRDesignField fieldY = new JRDesignField();
??????? fieldY.setName(fieldNameY);
??????? fieldY.setValueClass(java.lang.Double.class);

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??????? ArrayList periods = (ArrayList) dataSource.get(fieldNameX);
??????? ArrayList values = (ArrayList) dataSource.get(fieldNameY);

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??????? DefaultCategoryDataset categoryDs = new DefaultCategoryDataset();

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??????? for (int i = 0; i < values.size(); i++)
??????? {
??????????? Object obj = values.get(i);
??????????? double dataValue = 0;

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??????????? if (obj != null)
??????????? {
??????????????? dataValue = ((Double) obj).doubleValue();
??????????? }

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??????????? categoryDs.addValue(dataValue, null, (String) periods.get(i));
??????? }

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??????? JFreeChart c = null;

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??????? if (isBarChart)
??????? {
??????????? c = ChartFactory.createBarChart(chartName, titleX, titleY, categoryDs,
??????????????????? PlotOrientation.VERTICAL, false, false, false);
??????? }
??????? else
??????? {
??????????? c = ChartFactory.createLineChart(chartName, titleX, titleY, categoryDs,
??????????????????? PlotOrientation.VERTICAL, false, false, false);
??????? }

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??????? c.getTitle().setFont(new Font("Arial", Font.BOLD, 16));

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??????? NumberAxis axis = (NumberAxis) c.getCategoryPlot().getRangeAxis();
??????? axis.setAutoRange(true);

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??????? TickUnitSource tickUnits = NumberAxis.createIntegerTickUnits();
??????? axis.setStandardTickUnits(tickUnits);

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????????return (c.createBufferedImage(imageWidth, imageHeight));

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???????}
}