JasperReports 打印空 PDF
我正在尝试使用 JasperReports 和 java servlet 从数据库中的数据生成 pdf 文件。我第一次使用数据库中的数据成功生成了 pdf 文件。然后，我对数据库表进行了一些更改，重新创建了 jrxml 文件，并使用该 jrxml 文件创建了 jasper 文件。但现在当我尝试生成 pdf 时，pdf 文件始终为空。
我的 Servlet 中的代码
response.setContentType("application/pdf");
try {
HttpSession hs = request.getSession();
String id = (String) hs.getAttribute("id");
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/exam", "root", "pass");
Statement statement = con.createStatement();
ResultSet resultSet = statement.executeQuery
("SELECT marks, date_time FROM result where sub_id = 1 and user_id = 3");
ServletOutputStream set = response.getOutputStream();
InputStream re = getServletConfig().getServletContext().getResourceAsStream("./results.jasper");
JRResultSetDataSource resultSetDataSource = new JRResultSetDataSource(resultSet);
JasperRunManager.runReportToPdfStream(re,set, new HashMap(), resultSetDataSource);
} catch (Exception e) {
}
我该如何解决这个问题？
I'm trying to generate a pdf file from data in a database using JasperReports with a java servlet. The first time I generated a pdf file successfully with data in database. Then I made some changes in my database table and recreated jrxml file and created a jasper file using that jrxml file. But now when I am trying to generate a pdf, the pdf file is always empty.
Code in my Servlet
response.setContentType("application/pdf");
try {
HttpSession hs = request.getSession();
String id = (String) hs.getAttribute("id");
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/exam", "root", "pass");
Statement statement = con.createStatement();
ResultSet resultSet = statement.executeQuery
("SELECT marks, date_time FROM result where sub_id = 1 and user_id = 3");
ServletOutputStream set = response.getOutputStream();
InputStream re = getServletConfig().getServletContext().getResourceAsStream("./results.jasper");
JRResultSetDataSource resultSetDataSource = new JRResultSetDataSource(resultSet);
JasperRunManager.runReportToPdfStream(re,set, new HashMap(), resultSetDataSource);
} catch (Exception e) {
}
How could I solve this?
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将每个
catch更改为That 将提供问题所在和位置的详细信息。
Change every
catchtoThat will provide details of what is going wrong, and where.