根据数据生产echats图片（柱图、折线图）

package com.ruoyi.common.file.docEChar;

import com.ruoyi.common.utils.DateUtils;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartUtils;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.CategoryAxis;
import org.jfree.chart.axis.CategoryLabelPositions;
import org.jfree.chart.plot.CategoryPlot;
import org.jfree.chart.renderer.category.BarRenderer;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.category.CategoryDataset;
import org.jfree.data.category.DefaultCategoryDataset;

import java.awt.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Random;

public class SeriesBarChart {
    public static String seriesChart() {
        CategoryDataset categoryDataset = createDataset2();
        JFreeChart jfreechart = ChartFactory.createBarChart("Legal & General单位信托基金价格", "日期", "价格", categoryDataset);
        CategoryPlot ca