这是我的代码。与数据库的连接正在工作。当语句posts=s.executeQuery（query）；执行时，它甚至没有进入循环并从最后开始执行。不幸的是，没有抛出异常。
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String docType = "<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 "
+ "Transitional//EN">n";
String title = "Trend Blog";
out.println(docType + "<HTML>n" + "<HEAD><TITLE>" + title
+ "</TITLE></HEAD>n" + "<BODY BGCOLOR="#FDF5E6">n"
+ "<H1 ALIGN=CENTER>" + title + "</H1>n");
Connection connection = null;
ResultSet posts = null;
ConnectMySql connectMySql = new ConnectMySql();
String query = "select title,post from posts order by desc number";
try {
connection = connectMySql.getConnection("jdbc");
Statement s = connection.createStatement();
posts = s.executeQuery(query);
int i = 1;
while (posts.next()) {
String postTitle = posts.getString(1);
String post = posts.getString(2);
HttpSession session = request.getSession();
out.println("<h4>Welcome " + session.getAttribute("username")
+ "</h4>");
out.println("<p>");
out.print("<h3><strong>" + i + "." + postTitle
+ "</strong></h3>");
out.println("<p>" + post + "</p>");
out.print("</p><hr>");
out.print("</body></html>");
}
} catch (SQLException e) {
} finally {
try {
connection.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
您正在捕获第一个异常块，但您并没有打印以查看它抛出了什么异常。
所以在你的第一个异常块中做
} catch (SQLException e) {
e.printStackTrace();
} finally {
......
在第二个catch中，如果异常可能发生在第一个try-catch块中，它就不会引发任何异常。