Question

我正在使用servlet代码来显示雷达图，但是错误505被抛出，所以我能为此做些什么我的鳕鱼是

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.jfree.chart.ChartRenderingInfo;
import org.jfree.chart.ChartUtilities;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.labels.StandardCategoryToolTipGenerator;
import org.jfree.chart.plot.SpiderWebPlot;
import org.jfree.chart.title.TextTitle;
import org.jfree.data.category.DefaultCategoryDataset;

/**
 * Servlet implementation class chartexample
 */
public class chartexample extends HttpServlet {
    private static final long serialVersionUID = 1L;

     public DefaultCategoryDataset dataset;
     public SpiderWebPlot plot;


    /**
     * Default constructor. 
     */
    public void service(HttpServletRequest request,HttpServletResponse response){

        response.setContentType ("image / jpeg"); 
        ServletOutputStream sos = null;
        try {
            sos = response.getOutputStream ();
        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }


        String series1 = "First";
        String series2 = "Second";
        String series3 = "Third";

        String category1 = "Task Completion";
        String category2 = "Accuracy";
        String category3 = "Sophistication";
        String category4 = "Listening";
        String category5 = "Pronunciation";

        DefaultCategoryDataset dataset = new DefaultCategoryDataset();
        dataset.addValue(5.0, series1, category1);
        dataset.addValue(5.0, series1, category2);
        dataset.addValue(5.0, series1, category3);
        dataset.addValue(5.0, series1, category4);
        dataset.addValue(5.0, series1, category5);

        dataset.addValue(2.0, series2, category1);
        dataset.addValue(4.0, series2, category2);
        dataset.addValue(5.0, series2, category3);
        dataset.addValue(3.0, series2, category4);
        dataset.addValue(5.0, series2, category5);


        SpiderWebPlot plot = new SpiderWebPlot(dataset);

        plot.setStartAngle(90);

        plot.setInteriorGap(0.30);

        plot.setToolTipGenerator(new StandardCategoryToolTipGenerator());

        JFreeChart chart = new JFreeChart("", TextTitle.DEFAULT_FONT, plot, false);

        ChartUtilities.applyCurrentTheme(chart);

        ChartRenderingInfo render = new ChartRenderingInfo();

        response.setContentType ("image / jpeg"); 


        try {
            ChartUtilities.writeChartAsJPEG(sos, chart, 800, 800);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }

}

，错误是

javax.servlet.ServletException: Error instantiating servlet class chartexample
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    java.lang.Thread.run(Unknown Source)


root cause 

java.lang.NoClassDefFoundError: org/jfree/data/category/CategoryDataset
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.newInstance0(Unknown Source)
    java.lang.Class.newInstance(Unknown Source)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    java.lang.Thread.run(Unknown Source)


root cause 

java.lang.ClassNotFoundException: org.jfree.data.category.CategoryDataset
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1645)
    org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1491)
    java.lang.Class.getDeclaredConstructors0(Native Method)
    java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
    java.lang.Class.getConstructor0(Unknown Source)
    java.lang.Class.newInstance0(Unknown Source)
    java.lang.Class.newInstance(Unknown Source)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    java.lang.Thread.run(Unknown Source)

Answer 1

java.lang.ClassNotFoundException: org.jfree.data.category.CategoryDataset

运行时类路径中缺少JFreeChart JAR文件。将它们放在/WEB-INF/lib文件夹中。

servlet显示雷达图

1 个答案: