使用Jfree实现吧条形图，java代码

package test1;

import org.jfree.chart.*;
import org.jfree.chart.plot.*;
import org.jfree.chart.labels.*;
import org.jfree.data.category.*;

import java.awt.*;
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import org.jfree.ui.*;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.renderer.category.BarRenderer3D;
import org.jfree.chart.servlet.*;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.general.DatasetUtilities;

import com.dao.DBConnection;

public class JfreeChart {

	public static void main(String[] args) throws IOException, SQLException {
		// TODO Auto-generated method stub
		double[][] data = new double[][] {
				{ 1230, 1110, 1120, 1210, 720, 750, 860, 800, 1230, 1110, 1120,
						1210, 720, 750, 860, 800, 1230, 1110, 1120, 1210, 720,
						750, 860, 800 },
				{ 720, 750, 860, 800, 1230, 1110, 1120, 1210, 720, 750, 860,
						800, 720, 750, 860, 800, 1230, 1110, 1120, 1210, 720,
						750, 860, 800 } };
		String[] rowKeys = { "a", "b" };
		String[] columnKeys = { "0", "1", "2", "3", "4", "5", "6", "7", "8",
				"9", "10", "11", "12", "13", "14", "15", "16", "17", "18",
				"19", "20", "21", "22", "23" };
		CategoryDataset dataset = DatasetUtilities.createCategoryDataset(
				rowKeys, columnKeys, data);
		JFreeChart chart = ChartFactory.createBarChart(getNextDay() + "日交易量",
				"时间（/h）", "交易量", dataset, PlotOrientation.VERTICAL, true, true,
				false);
		CategoryPlot plot = chart.getCategoryPlot();
		// 设置网格背景颜色
		plot.setBackgroundPaint(Color.white);
		// 设置网格竖线颜色
		plot.setDomainGridlinePaint(Color.pink);
		// 设置网格横线颜色
		plot.setRangeGridlinePaint(Color.pink);

		// 显示每一个柱的数值，并改动该数值的字体属性
		BarRenderer renderer = new BarRenderer();
		// renderer.setBaseItemLabelGenerator(new
		// StandardCategoryItemLabelGenerator());
		// renderer.setBaseItemLabelsVisible(true);

		// 默认的数字显示在柱子中，通过例如以下两句可调整数字的显示
		// 注意：此句非常关键，若无此句，那数字的显示会被覆盖，给人数字没有显示出来的问题
		// renderer.setBasePositiveItemLabelPosition(new ItemLabelPosition(
		// ItemLabelAnchor.OUTSIDE12, TextAnchor.BASELINE_LEFT));
		// renderer.setItemLabelAnchorOffset(10D);

		// 设置每一个地区所包括的平行柱的之间距离
		renderer.setItemMargin(0.05);
		plot.setRenderer(renderer);

		// 设置地区、销量的显示位置
		// 将下方的“标注”放到上方
		// plot.setDomainAxisLocation(AxisLocation.TOP_OR_RIGHT);
		// 将默认放在左边的“销量”放到右方
		// plot.setRangeAxisLocation(AxisLocation.BOTTOM_OR_RIGHT);
		drawToOutputStream("src//a.jpg", chart);
	}

	/**
	 * step3: 输出图表到指定的磁盘
	 * 
	 * @param destPath
	 * @param chart
	 */
	public static void drawToOutputStream(String destPath, JFreeChart chart) {
		FileOutputStream fos = null;
		try {
			fos = new FileOutputStream(destPath);
			// ChartUtilities.writeChartAsJPEG(
			ChartUtilities.writeChartAsPNG(fos, // 指定目标输出流
					chart, // 图表对象
					1000, // 宽
					500, // 高
					null); // ChartRenderingInfo信息
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				fos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}

	public static String getNextDay() {
		Calendar calendar = Calendar.getInstance();
		calendar.add(Calendar.DATE, -1); // 得到前一天
		Date date = calendar.getTime();
		DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
		// System.out.println(df.format(date));
		return df.format(date);
	}
}

显示生成结果：