在實際項目開發中，尤其是報表開發經常要用來熱點圖片
JAVA的開源項目JfreeChart提供了熱點生成圖片的方法
這裏介紹幾種方法
第一在JSP頁面中：
<%@ page language="java" pageEncoding="UTF-8"%>
<%@ include file="/WEB-INF/jsp/include.jsp"%><%@ page import="org.jfree.data.general.DefaultPieDataset"%> <%@ page import="org.jfree.chart.*"%> <%@ page import="org.jfree.chart.plot.*"%> <%@ page import="org.jfree.chart.servlet.ServletUtilities"%> <%@ page import="org.jfree.chart.urls.StandardPieURLGenerator"%> <%@ page import="org.jfree.chart.entity.StandardEntityCollection"%> <%@ page import="java.io.*"%> 
<HTML> <HEAD> <META http-equiv=Content-Type content="text/html; charset=utf-8"> <TITLE>JfreeChart</TITLE> </HEAD> <BODY> <% 
DefaultPieDataset data = new DefaultPieDataset(); data.setValue("高中以下",370); data.setValue("高中",1530); data.setValue("大專",5700); data.setValue("本科",8280); data.setValue("碩士",4420); data.setValue("博士",80); PiePlot3D plot = new PiePlot3D(data);//3D餅圖 plot.setURLGenerator(new StandardPieURLGenerator("barview.jsp","lion"));//設定鏈接 JFreeChart chart = new JFreeChart("",JFreeChart.DEFAULT_TITLE_FONT, plot, true); chart.setBackgroundPaint(java.awt.Color.white);//可選，設置圖片背景色 chart.setTitle("程序員學歷情況調查表");//可選，設置圖片標題 StandardEntityCollection sec = new StandardEntityCollection(); ChartRenderingInfo info = new ChartRenderingInfo(sec); PrintWriter w = new PrintWriter(out);//輸出MAP信息 //500是圖片長度，300是圖片高度 String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info, session); ChartUtilities.writeImageMap(w, "map0", info, false); 
String graphURL = request.getContextPath() + "/servletDisplayChart?filename=" + filename; %> <P ALIGN="CENTER"> <img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#map0"> </P> </BODY> </HTML> 相應的web.xml加入如下配置
<servlet> <servlet-name>DisplayChart</servlet-name> <servlet-class>org.jfree.chart.servlet.DisplayChart</servlet-class> </servlet> <servlet-mapping> <servlet-name>DisplayChart</servlet-name> <url-pattern>/servletDisplayChart</url-pattern> </servlet-mapping> 生成的圖片如下
該方法引用網站：http://dev.yesky.com/307/2036307.shtml
第二種方法
把java代碼寫在jsp頁面中在大的工程維護起來極不方便，我所用的項目採用Struts框架做表現層
這裏我就介紹我所用的方法
java文件：
public class ImageAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response) {
HttpServletRequest request, HttpServletResponse response) ImageForm image = (ImageForm)form; int width=0, height=0; JFreeChart chart = null; width = 248; height = 240; chart = createEventShareImage(); try { StandardEntityCollection sec = new StandardEntityCollection(); ChartRenderingInfo info = new ChartRenderingInfo(sec); String filename = ServletUtilities.saveChartAsJPEG(chart, width, 240, info, request.getSession()); String mapMessage = ChartUtilities.getImageMap("map0", info); String src = request.getContextPath()+"/servletDisplayChart?filename=" + filename ; String useMap = "#" + filename ; } catch (IOException e) { e.printStackTrace();
} image.setMap(mapMessage); image.setSrc(src) ; image.setUseMap(useMap) ; return mapping.getInputForward(); } private JFreeChart createEventShareImage() { Object[] share = eventCommonService.getEventShare(); DefaultPieDataset pieDataset = new DefaultPieDataset(); pieDataset.setValue("嚴重", new Long("100")); pieDataset.setValue("高級", new Long("200")); pieDataset.setValue("中級", new Long("150")); pieDataset.setValue("低級", new Long("300")); pieDataset.setValue("輕微", new Long("288")); PiePlot plot = new PiePlot(pieDataset); plot.setNoDataMessage("No data available"); plot.setSectionPaint("嚴重", Constant.TERRIBLE_COLOR); plot.setSectionPaint("高級", Constant.HIGH_COLOR); plot.setSectionPaint("中級", Constant.MIDDLE_COLOR); plot.setSectionPaint("低級", Constant.LOW_COLOR); plot.setSectionPaint("輕微", Constant.INFO_COLOR); plot.setLabelGenerator(new StandardPieSectionLabelGenerator("{0} ({2})")); plot.setURLGenerator(new StandardPieURLGenerator("eventImage.do","type","id")); JFreeChart chart = new JFreeChart("",JFreeChart.DEFAULT_TITLE_FONT, plot, true); return chart; }jsp頁面：
<bean:write name="imageForm" property="mapMessage" filter="false"/><img src="<bean:write name="imageForm" property="src" />" usemap="<bean:write name="imageForm" property="useMap" />"/>xml的配置和上面一樣
生成圖片：
