无法使用 JFree 在 Struts 2 Action Class 中实现 ModelDriven 或 ServletRequestAware

Question

我正在尝试根据用户输入生成图表。我在 Struts 2 框架中使用 JFree Charts。在图表生成动作类中，我无法实现ModelDriven 概念；我也无法从HttpServletRequest 对象中检索参数值。 .

如果我通过实现ModelDriven 或ServletRequestAware 调用图表生成操作类，它可以正常工作，但它会在下一页显示图表。我需要根据用户输入生成图表。

我没有成功搜索有关 JFree an Struts 2 的信息；任何有用的教程链接也将不胜感激。

这是我的 struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd ">
<struts>
<package name="jfree" extends="jfreechart-default">
            <action name="chartAction" class="com.kogent.action.ChartAction">
                <result name="success" type="chart">
                    <param name="width">500</param>
                    <param name="height">300</param> 
                </result>
            </action>
    </package>          
</struts>

这是我的动作类

package com.kogent.action;

import java.util.Random;

import org.jfree.chart.JFreeChart;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.chart.axis.ValueAxis;
import org.jfree.chart.plot.XYPlot;
import org.jfree.chart.renderer.xy.StandardXYItemRenderer;

import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;

import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.opensymphony.xwork2.Preparable;

public class ChartAction extends ActionSupport implements ModelDriven<FormBean>,Preparable{

    private JFreeChart chart;
    private FormBean bean;

    @Override
    public FormBean getModel() {
        // TODO Auto-generated method stub
        return bean;
    }
    @Override
    public void prepare() throws Exception {
        // TODO Auto-generated method stub
        bean=new FormBean();
    }



    public String execute() throws Exception {
        // chart creation logic...
        System.out.print(bean.getCategory()+"    "+bean.getChartType());
        //if remove this above line my action runs fine but i require this vales from the user
        XYSeries dataSeries = new XYSeries(new Integer(1)); 
        for (int i = 0; i <= 100; i++) {

            dataSeries.add(i, new Random().nextInt(50));
        }

        XYSeriesCollection xyDataSet = new XYSeriesCollection(dataSeries);

        ValueAxis xAxis = new NumberAxis("Marks");
        ValueAxis yAxis = new NumberAxis("Age");
        chart =
            new JFreeChart("Chart Title", JFreeChart.DEFAULT_TITLE_FONT,
                new XYPlot(xyDataSet,xAxis, yAxis,
                        new StandardXYItemRenderer(StandardXYItemRenderer.LINES)),
                false);
        chart.setBackgroundPaint(java.awt.Color.white);

        return super.SUCCESS;
    }

    public JFreeChart getChart() {
        return chart;
    }
}

Answer 1

基于这个 jfree 图表，有很多例子， 我只是给这些链接检查一下。

First: 实现任何 jfree 图表除了servlet request aware 和servlet response aware 之外什么都不需要，request 用于接收用户的请求，response 用于将输出提供给用户。您希望使用'ModelDriven' interface ( it gains the extra ability to transfer the form data into the object automatically)。

只需使用此链接。

Create chart and Display them dynamically in JSP.

Create area chart in JSP page using JFreeChart.

Creating Pie Charts with JFreeChart

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