网上好多人都转载过这段代码,有谁知道这个PrintWriter w = new PrintWriter(out);里面的out是怎么来的吗?这里的ChartRenderingInfo又有什么用啊?谁能给讲讲吗?<%@ page contentType="text/html;charset=GBK"%>
<%@ 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.labels.StandardPieToolTipGenerator "%>
<%@ 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=GBK">
<TITLE>[email protected]</TITLE>
</HEAD>
<BODY>
<% DefaultPieDataset data = new DefaultPieDataset();
data.setValue("高中以下",370);
data.setValue("高中",1530);
data.setValue("大专",5700);
data.setValue("本科",8280);
data.setValue("硕士",4420);
data.setValue("博士",80);
PiePlot3D plot = new PiePlot3D(data);//3D饼图
plot.setURLGenerator(new StandardPieURLGenerator("barview.jsp"));//设定链接
JFreeChart chart = new JFreeChart("",JFreeChart.DEFAULT_TITLE_FONT, plot, true);
chart.setBackgroundPaint(java.awt.Color.white);//可选,设置图片背景色
chart.setTitle("程序员学历情况调查表");//可选,设置图片标题
plot.setToolTipGenerator(new StandardPieToolTipGenerator());
StandardEntityCollection sec = new StandardEntityCollection();
ChartRenderingInfo info = new ChartRenderingInfo(sec);
PrintWriter w = new PrintWriter(out);//输出MAP信息
//500是图片长度,300是图片高度
String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info, session);
ChartUtilities.writeImageMap(w, "map0", info, false); String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename; %> <P ALIGN="CENTER">
<img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#map0">
</P>
</BODY>
</HTML>
<%@ 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.labels.StandardPieToolTipGenerator "%>
<%@ 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=GBK">
<TITLE>[email protected]</TITLE>
</HEAD>
<BODY>
<% DefaultPieDataset data = new DefaultPieDataset();
data.setValue("高中以下",370);
data.setValue("高中",1530);
data.setValue("大专",5700);
data.setValue("本科",8280);
data.setValue("硕士",4420);
data.setValue("博士",80);
PiePlot3D plot = new PiePlot3D(data);//3D饼图
plot.setURLGenerator(new StandardPieURLGenerator("barview.jsp"));//设定链接
JFreeChart chart = new JFreeChart("",JFreeChart.DEFAULT_TITLE_FONT, plot, true);
chart.setBackgroundPaint(java.awt.Color.white);//可选,设置图片背景色
chart.setTitle("程序员学历情况调查表");//可选,设置图片标题
plot.setToolTipGenerator(new StandardPieToolTipGenerator());
StandardEntityCollection sec = new StandardEntityCollection();
ChartRenderingInfo info = new ChartRenderingInfo(sec);
PrintWriter w = new PrintWriter(out);//输出MAP信息
//500是图片长度,300是图片高度
String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300, info, session);
ChartUtilities.writeImageMap(w, "map0", info, false); String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename; %> <P ALIGN="CENTER">
<img src="<%= graphURL %>" width=500 height=300 border=0 usemap="#map0">
</P>
</BODY>
</HTML>
解决方案 »
- 菜鸟问几个小问题……
- 急求一个tomcat+SSL做登录的问题,请高手指教
- java web项目中有大量的图形界面,采用什么技术会比较合适
- JSP+XML分页技术
- 关于weblogic 9.2启动时的问题,请大侠帮忙
- Hibernate 发出这个异常HibernateQueryException: could not resolve property: 请教各位高手怎末办
- 简单问题,送分啦。
- Eclipse+Lomboz用Weblogic7做为Server启动后访问不了JSP?
- jtable中列的拖动问题
- 求助:CMP2.0中有关findXXX方法的问题
- DIV的用法
- Collections.synchronizedList入门级请教
、
ServletOutputStream out = response.getOutputStream();方法就可以获取到呀
这段程序能够正常显示饼图的,但是我没有定义out对象啊?你能在细点解释吗?还有这个ChartRenderingInfo一般有什么用?
哈哈,菜鸭说话当然算话。
out对象是JspWriter类的实例,是向客户端输出内容常用的对象
嗯,如果是jsp 的话,是有9个内置对象的。out对象是JspWriter类的实例,是向客户端输出内容常用的对象
序号 方 法 说 明1 void clear() 清除缓冲区的内容2 void clearBuffer() 清除缓冲区的当前内容3 void flush() 清空流4 int getBufferSize() 返回缓冲区以字节数的大小,如不设缓冲区则为05 int getRemaining() 返回缓冲区还剩余多少可用6 boolean isAutoFlush() 返回缓冲区满时,是自动清空还是抛出异常7 void close() 关闭输出流
PiePlot3D vPiePlot3D = (PiePlot3D) vFreeChart.getPlot();
if (vPiePlot3D != null) {
for (int i = 0; i < rowcount; i++)
vPiePlot3D.setSectionOutlinePaint(0,Color.BLACK); vPiePlot3D.setToolTipGenerator(new StandardPieToolTipGenerator());
StandardEntityCollection sec = new StandardEntityCollection();
ChartRenderingInfo info = new ChartRenderingInfo(sec);
PrintWriter p = new PrintWriter(out);//输出MAP信息
String filename = ServletUtilities.saveChartAsPNG(vFreeChart, 500, 300, info, session);
ChartUtilities.writeImageMap(w, "map0", info, false); String graphURL = request.getContextPath() + "/servlet/DisplayChart?filename=" + filename;