JSP+Struts2+JFreeChart显示图表+鼠标事件
Struts2+JFreeChart使用的是Struts2的返回类型来显示图片，但是在页面貌似没有鼠标事件，此方式可参考这篇：
1、http://liyanboss.iteye.com/blog/181282
2、http://www.cnblogs.com/over140/articles/971663.html
以下JSP+Struts2+JFreeChart是能显示鼠标事件的，但是不是Struts2的返回类型，以下是实现。
action:

package action;

import java.awt.Rectangle;
import java.awt.Shape;
import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartRenderingInfo;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.entity.ChartEntity;
import org.jfree.chart.entity.StandardEntityCollection;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.chart.servlet.ServletUtilities;
import org.jfree.data.category.DefaultCategoryDataset;

import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport{
	//页面鼠标事件时需要的参数
	private String hy_filename;
	/**
	 * 显示图片
	 * @return
	 */
	public String show(){
		HttpServletRequest req = ServletActionContext.getRequest();
		HttpServletResponse res = ServletActionContext.getResponse();
		hy_filename = createChartImage(req, res);
		return SUCCESS;
	}
	
	private String createChartImage(HttpServletRequest req, HttpServletResponse res){
		JFreeChart chart = createChart(createData());
		String filename = createUseMap(chart, 510, 300, req, res);
		return filename;
	}
	
	private JFreeChart createChart(DefaultCategoryDataset defaultcategorydataset){
		JFreeChart chart = ChartFactory.createLineChart(null, //图形标题名称
		null,  					    //domain轴 Lable,横坐标Lable
		null, 					    //range 轴 Lable,纵坐标Lable
		defaultcategorydataset,		// dataset
		PlotOrientation.VERTICAL,	//垂直显示
		true,						// legend?
		true,						// tooltips?
		false);	 					//URLs?
		return chart;
	}
	
	private String createUseMap(JFreeChart chart, int width, int height, HttpServletRequest req, HttpServletResponse res){
		//在矩形框中显示信息
	    Shape shape = new Rectangle(20, 10);
	    ChartEntity entity = new ChartEntity(shape);
	    StandardEntityCollection coll = new StandardEntityCollection();
	    coll.add(entity);
	    //该工具类上面没有介绍，在鼠标移动到图片时显示提示信息是用Map实现的，这些Map是用该类生成的。
	    ChartRenderingInfo info = new ChartRenderingInfo(coll);
	    PrintWriter pw;
	    String filename = null;
		try {
			res.setContentType("text/html;charset=utf-8");
			res.setCharacterEncoding("utf-8");
			pw = res.getWriter();//输出MAP信息 
		    //写入到输出流生成图像文件，同时把图片的具体信息放入ChartRenderingInfo的一个实例为以后生成Map提供信息 
		    //ChartUtilities.writeChartAsPNG(out, chart, width, height, info);
		    filename = ServletUtilities.saveChartAsPNG(chart, width , height, info, req.getSession());//保存图表为文件
		    //读取info对象，生成Map信息。这些信息写在pw的输出流中，这里的输出流就是Response.out，也就是直接输出到页面了
		    ChartUtilities.writeImageMap(pw, filename, info, false);
		    pw.flush();

		} catch (IOException e) {
			e.printStackTrace();
		}
		return filename;
	}
	
	private DefaultCategoryDataset createData(){
		String series1 = "血糖";
		String series2 = "舒张压";
		String series3 = "收缩压";
		String type1 = "2009-01-01";
		String type2 = "2009-02-01";
		String type3 = "2009-03-01";
		String type4 = "2009-04-01";
		String type5 = "2009-05-01";
		String type6 = "2009-06-01";
		String type7 = "2009-07-01";
		String type8 = "2009-08-01";
		DefaultCategoryDataset defaultcategorydataset = new DefaultCategoryDataset();
		defaultcategorydataset.addValue(1.0D, series1, type1);
		defaultcategorydataset.addValue(2D, series1, type2);
		defaultcategorydataset.addValue(3D, series1, type3);
		defaultcategorydataset.addValue(5D, series1, type4);
		defaultcategorydataset.addValue(5D, series1, type5);
		defaultcategorydataset.addValue(7D, series1, type6);
		defaultcategorydataset.addValue(7D, series1, type7);
		defaultcategorydataset.addValue(8D, series1, type8);

		defaultcatego