struts中调用servlet动态生成柱状图到jsp页面

首先要用到 JFreeChart.jar、jcommon-1.0.15.jar、log4j.jar

servlet代码:

package com.framework.test;

import javax.servlet.*;

import javax.servlet.http.*;

import java.awt.Color;

import java.awt.Font;

import java.io.*;

import java.text.DecimalFormat;

import java.util.*;

import org.jfree.data.category.*;

import org.jfree.chart.*;

import org.jfree.data.*;

import org.jfree.chart.axis.NumberAxis;

import org.jfree.chart.labels.StandardCategoryItemLabelGenerator;

import org.jfree.chart.plot.*;

import com.framework.AppSession;

public class Test extends HttpServlet{

private static final String CONTENT_TYPE = "text/html;charset=utf-8";

public void init() throws ServletException {

}

//Process the HTTP Get request

public void doGet(HttpServletRequest request,HttpServletResponse response) throws

ServletException, IOException {

response.setContentType( "image/jpeg ");

response.setCharacterEncoding("utf-8");

response.reset();

CategoryDataset data=(CategoryDataset) request.getSession().getAttribute("catedataset");//从session中取到CategoryDataset 对象

//CategoryDataset data=getDataSet2();

JFreeChart chart=ChartFactory.createBarChart( "", "", "点击率",data,PlotOrientation.VERTICAL,true,true,true);

//设置图表的纵轴和横轴org.jfree.chart.axis.CategoryAxis

org.jfree.chart.axis.CategoryAxis domainAxis = chart.getCategoryPlot().getDomainAxis();

domainAxis.setLowerMargin(0.1);//设置距离图片左端距离此时为10%

domainAxis.setUpperMargin(0.1);//设置距离图片右端距离此时为百分之10

domainAxis.setCategoryLabelPositionOffset(10);//图表横轴与标签的距离(10像素)

domainAxis.setCategoryMargin(0.2);//横轴标签之间的距离20%

//取得纵轴

NumberAxis numberAxis = (NumberAxis)chart.getCategoryPlot().getRangeAxis();

//设置纵轴显示标签的字体

numberAxis.setLabelFont(new Font("宋体" , Font.BOLD , 18));

//设置最高的一个柱与图片顶端的距离

numberAxis.setUpperMargin(0.1);

//numberAxis.setFixedAutoRange(100);

//设置整数显示

//numberAxis.setStandardTickUnits(NumberAxis.createIntegerTickUnits());

//numberAxis.setNegativeArrowVisible(true);

//取最大数Math.max(supportCount, blackballCount)

int totalcount= (Integer) request.getSession().getAttribute("totalcount");

numberAxis.setUpperBound(totalcount);//动态设置纵坐标高度

numberAxis.setLowerBound(0.01);

//设置百分比显示

// numberAxis.setNumberFormatOverride(new DecimalFormat("0%"));

//numberAxis.setNumberFormatOverride(new DecimalFormat("0.00%"));

//设置最小显示数,小于的话会显示在中间（正负）

//numberAxis.setAutoRangeMinimumSize(1);

Font font=new Font("宋体" , Font.BOLD , 12);

String tit=(String) request.getSession().getAttribute("title");

TextTitle title = new TextTitle(tit, font);//动态设置主标题

chart.setTitle(title);

//设定柱子的属性

org.jfree.chart.axis.ValueAxis rangeAxis = chart.getCategoryPlot().getRangeAxis();

rangeAxis.setUpperMargin(0.1);//设置最高的一个柱与图片顶端的距离(最高柱的10%)

org.jfree.chart.renderer.category.BarRenderer3D renderer;

renderer = new org.jfree.chart.renderer.category.BarRenderer3D();

renderer.setItemMargin(0.4);//组内柱子间隔为组宽的10%

//显示每个柱的数值，并修改该数值的字体属性

renderer.setItemLabelGenerator(new StandardCategoryItemLabelGenerator());

renderer.setItemLabelFont(new Font("黑体",Font.BOLD,10));//12号黑体加粗

renderer.setItemLabelPaint(Color.black);//字体为黑色

renderer.setItemLabelsVisible(true);

chart.getCategoryPlot().setRenderer(renderer);

chart.getLegend().setItemFont(new Font("宋体",Font.BOLD,12));//设置图下面框内中文字体不为乱码

ChartUtilities.writeChartAsJPEG(response.getOutputStream(),1,chart,400,300,null);

}

public void doPost(HttpServletRequest request, HttpServletResponse response) throws

ServletException, IOException {

doGet(request, response);

}

private static CategoryDataset getDataSet2() {

DefaultCategoryDataset dataset = new DefaultCategoryDataset();

dataset.addValue(0.25, "beijing", "test");

dataset.addValue(0.5, "shanghai", "test");

dataset.addValue(0.8, "guangzhou", "test");

dataset.addValue(0.1, "shanxi", "test");

return dataset;

}

public void destroy() {

}

}

Action代码：

DefaultCategoryDataset catedataset = new DefaultCategoryDataset();

catedataset.addValue();//动态添加，参考Test中getDataSet2()

AppContext.getServletRequest().getSession(). setProperty("catedataset",catedataset);

AppContext.getServletRequest().getSession(). setProperty("totalcount", totalcount);

AppContext.getServletRequest().getSession(). setProperty("title", investigate.getTitle());

jsp页面代码：

<img src="${pageContext.request.contextPath}/s/draw.htm" alt="" />

web.xml中配置：

<servlet>

<servlet-name>draw</servlet-name>

<servlet-class>com.framework.test.Test</servlet-class>

</servlet>

<servlet-mapping>

<servlet-name>draw</servlet-name>

<url-pattern>/s/draw.htm</url-pattern>

</servlet-mapping>

——————————————————————————————————————————————

其实可以不用这个，完全可以根据生成的数据在jsp页面动态控制一张图片的高度或宽度来显示比例