JSP "java.lang.NullPointerException"
Bonjour j'essaye depuis quelques jours de dessiner une courbe a partir de donnees deja enregistreés dans une BD oracle SUR JSP
j'ai utilisé jfreechart
Bon je crois que mon problème est plus SQL que JAVA
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<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%@ page import="org.jfree.chart.ChartFactory" %>
<%@ page import="org.jfree.chart.ChartUtilities" %>
<%@ page import="org.jfree.chart.JFreeChart" %>
<%@ page import="org.jfree.chart.plot.PlotOrientation"%>
<%@ page import="org.jfree.data.*" %>
<%@ page import="org.jfree.data.jdbc.JDBCCategoryDataset"%>
<%@ page import="org.jfree.chart.ChartPanel"%>
<%@ page import="org.jfree.ui.ApplicationFrame" %>
<%@ page import="java.sql.SQLException"%>
<%@ page import = "java.util.Date,java.util.Locale,java.text.SimpleDateFormat,java.text.DateFormat,java.text.Parse %>
<%
String query="select * from pop_stat_date_emm_bscs";
JDBCCategoryDataset dataset=new JDBCCategoryDataset("url","oracle.jdbc.driver.OracleDriver","user","pswd");
dataset.executeQuery(query);
JFreeChart chart = ChartFactory.createBarChart3D
( "fig","dat","prd",dataset, PlotOrientation.VERTICAL,true, true, false);
ChartPanel chartPanel = new ChartPanel(chart);
chartPanel.setPreferredSize(new java.awt.Dimension(500, 270));
ApplicationFrame f = new ApplicationFrame("Chart");
f.setContentPane(chartPanel);
f.pack();
f.setVisible(true);
try
{
ChartUtilities.saveChartAsJPEG(new File("C:/chart.jpg"), chart, 400, 300);
}
catch (IOException e)
{
System.out.println("Problem in creating chart.");
}
%> |
resultat
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org.apache.jasper.JasperException: An exception occurred processing JSP page /jsp/chart4.jsp at line 34
31: JDBCCategoryDataset dataset=new JDBCCategoryDataset("","oracle.jdbc.driver.OracleDriver","","");
32:
33:
34: dataset.executeQuery(query);
35: JFreeChart chart = ChartFactory.createBarChart3D
36: ( "fig","dat","prd",dataset, PlotOrientation.VERTICAL,true, true, false);
37:
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
cause mère
java.lang.NullPointerException
org.jfree.data.jdbc.JDBCCategoryDataset.executeQuery(JDBCCategoryDataset.java:258)
org.jfree.data.jdbc.JDBCCategoryDataset.executeQuery(JDBCCategoryDataset.java:188)
org.apache.jsp.jsp.chart4_jsp._jspService(chart4_jsp.java:111)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
note La trace complète de la cause mère de cette erreur est disponible dans les fichiers journaux de Apache Tomcat/7.0.26. |
