jdbc_pie_demo.java

JFreeChart开发全攻略,JFreeChart开发全攻略

package com.jfreechart;

import java.awt.Color;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.sql.*;

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

import org.jfree.chart.*;
import org.jfree.chart.entity.StandardEntityCollection;
import org.jfree.chart.plot.PiePlot;
import org.jfree.chart.servlet.ServletUtilities;
import org.jfree.data.general.PieDataset;
import org.jfree.data.jdbc.JDBCPieDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;

public class JDBC_Pie_Demo extends ApplicationFrame {

	public JDBC_Pie_Demo(String s) {
		super(s);
	}

	private PieDataset readData() {
		JDBCPieDataset jdbcpiedataset = null;
		// 设置数据库地址
		String s = "jdbc:mysql://localhost/jfreechartdb";
		try {
			// 设置JDBC驱动
			Class.forName("com.mysql.jdbc.Driver");
		} catch (ClassNotFoundException classnotfoundexception) {
			System.err.print("找不到相应的class文件: ");
			System.err.println(classnotfoundexception.getMessage());
		}
		try {
			// 建立连接
			Connection connection = DriverManager.getConnection(s, 
					"root", // 用户
					"root" // 密码
			);
			//使用已经建立好的连接创建新的JDBCPieDataset 
			jdbcpiedataset = new JDBCPieDataset(connection);
			String s1 = "SELECT * FROM PIEDATA1;";
			jdbcpiedataset.executeQuery(s1);
			connection.close();
		} catch (SQLException sqlexception) {
			System.err.print("SQL错误: ");
			System.err.println(sqlexception.getMessage());
		} catch (Exception exception) {
			System.err.print("错误: ");
			System.err.println(exception.getMessage());
		}
		return jdbcpiedataset;
	}

	public  void JfreeChart(HttpServletRequest request,HttpServletResponse response) throws IOException {
		Writer out = response.getWriter();
		HttpSession session = request.getSession();
		
		//获得图形对象
		JFreeChart chart = createChart();

		// 把生成的图片放到临时目录
		StandardEntityCollection sec = new StandardEntityCollection();
		ChartRenderingInfo info = new ChartRenderingInfo(sec);

		// 500是图片长度，300是图片高度，session 为HttpSession对象
		String filename = ServletUtilities.saveChartAsPNG(chart, 500, 300,info, session);
		
		//输出图片
		PrintWriter pw = new PrintWriter(out);
		ChartUtilities.writeImageMap(pw, "map0", info, false);
		
		String graphURL = request.getContextPath()
				+ "/DisplayChart?filename=" + filename;
		request.setAttribute("graphURL", graphURL);
	}
	
	private  JFreeChart createChart()
	{
		//PieDataset通过学习JDBC从数据库中读取数据，返回的数据格式要求有两列，
		//第一列包含 VARCHAR的数据，第二列包含数字型数据
		PieDataset piedataset = readData();
		JFreeChart jfreechart = ChartFactory.createPieChart("Java IDE使用率分布图",piedataset, true, true, false);
		jfreechart.setBackgroundPaint(Color.yellow);
		PiePlot pieplot = (PiePlot) jfreechart.getPlot();
		pieplot.setNoDataMessage("无可显示的数据");
		return jfreechart;
	}
}