无法在浏览器上显示 Jasper 报告，为 servlet JaspersJob_servlet java.lang.ClassNotFoundException 分配异常

Question

帮帮我，我有一个关于 servlet 的 jasper 报告的问题，下面提到了错误

严重：为 servlet JaspersJob_servlet 分配异常 java.lang.ClassNotFoundException： net.sf.jasperreports.engine.JRRuntimeException 在 org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680) 在 org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526) 在 java.lang.Class.getDeclaredConstructors0(Native Method) 在 java.lang.Class.privateGetDeclaredConstructors（未知来源）在 java.lang.Class.getConstructor0（未知来源）在 java.lang.Class.newInstance（未知来源）在 org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1149) 在 org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:827) 在 org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:129) 在 org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) 在 org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) 在 org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) 在 org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) 在 org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:293） 在 org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861) 在 org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:606) 在 org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) 在 java.lang.Thread.run(Unknown Source)

Servlet 代码：

 package jasper_job_Print;

 import java.io.File;
 import java.io.IOException;
 import java.io.PrintWriter;
 import java.sql.*;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import net.sf.jasperreports.engine.*;
 import net.sf.jasperreports.engine.design.JRDesignQuery;
 import net.sf.jasperreports.engine.export.JRPdfExporter;
 import net.sf.jasperreports.engine.util.JRLoader;

 public class JaspersJob_servlet extends HttpServlet {

 private static final long serialVersionUID = -3478873702336546526L;

 protected void service(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
Connection con=null;
File reportFile = null;
JasperPrint jasperPrint = null;
ResultSet rs=null;
Statement statement = null;
    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://localhost:3306/cloudinterdataset",                                                      "root","cosmos123");
        reportFile = new File("C:\\abd\\JasperJava\\report10.jasper");
        String sql1 = "SELECT * FROM userdetails "
                + "ORDER BY Lastname ";
        statement = con.createStatement();
        rs = statement.executeQuery(sql1);
        if (!reportFile.exists())
            throw new JRRuntimeException(
                    "File WebappReport.jasper not found. The report design must be compiled first.");
    } catch(Exception e) {
        System.out.println("Exception : "+e);
    }

    try {
        JRResultSetDataSource resultSetDataSource = new
                JRResultSetDataSource(rs);
        System.out.println("Filling Jasper PDF report...");
        JasperReport jasperReport = (JasperReport) JRLoader
                .loadObject(reportFile.getPath());
        jasperPrint = JasperFillManager.fillReport(jasperReport,null,resultSetDataSource);
        System.out.println("Done!");
        if (jasperPrint != null)
        {
            JRExporter exporter = null;
            exporter = new JRPdfExporter();

            exporter.setParameter(JRExporterParameter.JASPER_PRINT,
                    jasperPrint);
            exporter.setParameter(JRExporterParameter.OUTPUT_STREAM,
                    response.getOutputStream());

            exporter.exportReport();
        } else {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<head>");
        out.println("<title>JasperReports </title>");
        out.println("<link rel=\"stylesheet\" type=\"text/css\" href=\"../stylesheet.css\"    title=\"Style\">");
        out.println("</head>");
        out.println("<body bgcolor=\"white\">");
        out.println("<span class=\"bold\">Empty response.</span>");
        out.println("</body>");
        out.println("</html>");
        }
    } catch(Exception e) {
        System.out.println("Exception :"+e);
    }
}

}

Answer 1

这是一个非常简单的解决方案，我没有将 Jar 文件放在我的项目库中。它现在正在工作，正好有时间发布我的答案