jinteractiveservlet.java

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// Fig. 8.3_03:  JInteractiveServlet.java
// JFreeChart实例26: 利用JFreeChart编写的具有交互功能的Servlet

package com.fatcat.webchart;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.awt.image.*;
import java.awt.*;
import javax.imageio.*;

import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.chart.servlet.ServletUtilities;
import org.jfree.chart.entity.StandardEntityCollection;
import org.jfree.data.*;
import org.jfree.data.category.*;
import org.jfree.data.general.*;

public class JInteractiveServlet extends HttpServlet
{
  String chartTitle = "利用JFreeChart编写的具有交互功能的Servlet";
  int width = 500, height = 375;
  String bookTitle[] =
  {
    "Python", "JAVA", "C#", "Perl", "PHP"
  };
  String category[] =
  {
    "第1周", "第2周", "第3周", "第4周"
  };

  int bookSales = 0;
  DefaultCategoryDataset barDataset = null;
  DefaultPieDataset pieDataset = null;

  // 处理 HTTP get 请求
  public void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
  {
    // 清空缓冲区
    response.reset();

    // 注意这里的MIME类型
    response.setContentType("image/png");

    String chartType = request.getParameter("chartType");
    if (chartType == null)
    {
      chartType = "bar";
    }
    
	JFreeChart chart = null;

    if (chartType.equals("pie"))
    {
      chart = createPieChart();
    }
    else if (chartType.equals("pie3D"))
    {
      chart = createPieChart3D();
    }
    else if (chartType.equals("bar"))
    {
      chart = createBarChart();
    }
    else if (chartType.equals("bar3D"))
    {
      chart = createBarChart3D();
    }

    ServletOutputStream out = response.getOutputStream();

    // 利用ChartUtilities类的writeChartAsPNG方法对图像进行编码
    ChartUtilities.writeChartAsPNG(out, chart, width, height);
  }

  // 处理 HTTP post 请求, 和doGet一样
  public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException
  {
    doGet(request, response);
  }

  // 创建直方图数据集
  public void createBarDataset()
  {
    barDataset = new DefaultCategoryDataset();

    for (int i = 0; i < bookTitle.length; i++)
    {
      for (int j = 0; j < category.length; j++)
      {
        bookSales = 1+(int)(Math.random() * 100);
        barDataset.addValue(bookSales, bookTitle[i], category[j]);
      }
    }
  }  
  
  // 创建直方图
  public JFreeChart createBarChart()
  {
    createBarDataset();

    JFreeChart chart = ChartFactory.createBarChart
    (
		chartTitle,  // 图表标题
		"销售时间:2005年2月",  // 坐标标题
		"销售量",  // 坐标标题
		barDataset,  // 定义绘制数据
		PlotOrientation.VERTICAL,  // 直方图的方向
		true,  // 定义图表是否包含图例
		true,  // 定义图表是否包含提示
		false  // 定义图表是否包含URL
    );
    return chart;
  }

// 创建3D直方图 
  public JFreeChart createBarChart3D()
  {
    createBarDataset();

    JFreeChart chart = ChartFactory.createBarChart3D
    (
		chartTitle,  // 图表标题
		"销售时间:2005年2月",  // 坐标标题
		"销售量",  // 坐标标题
		barDataset,  // 定义绘制数据
		PlotOrientation.VERTICAL,  // 直方图的方向
		true,  // 定义图表是否包含图例
		true,  // 定义图表是否包含提示
		false  // 定义图表是否包含URL
    );
    return chart;
  }

  // 创建饼图数据集
  public void createPieDataset()
  {
    pieDataset = new DefaultPieDataset();
    for (int i = 0; i < bookTitle.length; i++)
    {
      pieDataset.setValue(bookTitle[i], (int)(10+Math.random() * 40));
    }
  }

  // 创建饼图  
  public JFreeChart createPieChart()
  {
    createPieDataset();

    JFreeChart chart = ChartFactory.createPieChart
    (
		chartTitle,  // 图表标题
		pieDataset,  // 数据集
		true,  // 定义图例
		true, false);
		return chart;
  }

  // 创建3D饼图
  public JFreeChart createPieChart3D()
  {
    createPieDataset();

    JFreeChart chart = ChartFactory.createPieChart3D
    (
		chartTitle,  // 图表标题
		pieDataset,  // 数据集
		true,  // 定义图例
		true, false);
		PiePlot plot = (PiePlot3D)chart.getPlot();
		plot.setForegroundAlpha(0.4f);

		return chart;
  }
}


/**************************************************************************
 * (C) Copyright 2004-2005 by Jingkui Zhong(钟京馗) and Huan Tang(唐桓).  *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors of this code have used their                   *
 * best efforts in preparing the code. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these codes. The authors *
 * shall not be liable in any event for incidental or consequential       *
 * damages in connection with, or arising out of, the furnishing,         *
 * performance, or use of these programs.                                 *
 **************************************************************************/