学步园

做毕设出现一个java.lang.StackOverflowError异常。弄了半天，又是问高手，又是查资料的。最后发现，解决问题啦！特记录下来！

StackOverflowError是由于当前线程的栈满了  ，也就是函数调用层级过多导致。

比如死递归。

以上是网上查阅的资料。

看懂后，我发现我的项目用的servlet技术，讲doGet()方法添加方法this.doPost()得到解决。

思考：应该是我在实现分页的时候，在点击上一页，下一页时，调用servlet函数后再调回本页面是，出现循环。

result.jsp

			<%
				int pageNow = Integer.parseInt((String) request
						.getAttribute("pageNow"));
				if (pageNow != 1) {
					out.println("<a href=Db_sel_Servlet?dbversion=Mysql&pageNow="
							+ (pageNow - 1) + ">上一页</a>");
				}
				String s_pageCount = (String) request.getAttribute("pageCount");
				int pageCount = Integer.parseInt(s_pageCount);

				for (int i = 1; i <= pageCount; i++) {
					out.println("<a href=Db_sel_Servlet?dbversion=Mysql&pageNow=" + i
							+ ">[" + i + "]</a>");
				}
				if (pageNow != pageCount) {
					out.println("<a href=Db_sel_Servlet?dbversion=Mysql&pageNow="
							+ (pageNow + 1) + ">下一页</a>");
				}
			%>

Db_sel_Servlet.java

public class Db_sel_Servlet extends HttpServlet {
	public String flag;

	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		this.doPost(req, resp);
	}

	public void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {

		try {
			String s_pageNow=req.getParameter("pageNow");
			int pageNow=Integer.parseInt(s_pageNow);
			System.out.println("DB_sel_Servlet.java---->>>pageNow:"+pageNow);
			flag = req.getParameter("dbversion");
			System.out.println("DB_sel_Servlet---->>" + flag);
			File file = new File("D:\\workspace\\version");
			FileUtil.WriteFile(file, flag);
			UserDaoImpl userDaoImpl = new UserDaoImpl();
			List<User> user_list = userDaoImpl.getUsersByPage(pageNow);
			int pageCount=userDaoImpl.getPageCount();
			System.out.println("DB_sel_Servlet.java---->>>pageCount:"+pageCount);
			req.setAttribute("result", user_list);
			req.setAttribute("pageCount", pageCount+"");
			req.setAttribute("pageNow",pageNow+"");
			System.out.println(user_list);
			// 清空文件内的内容
			FileUtil.EmptyFile(file);
			// 跳转到用户管理页面
			req.getRequestDispatcher("result.jsp").forward(req, resp);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}