晚上好,我想知道如何清除写入 PrintWriter 的数据,即是否可以在打印后从 PrintWriter 中删除数据?
在此 servlet 中,我将一些文本打印到响应中,并在 # 表示的行中删除所有先前打印的数据并打印新内容:
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
PrintWriter out = response.getWriter();
String uName = request.getParameter("uName");
String uPassword = request.getParameter("uPassword");
if (uName .equals("Islam")) {
out.println("Valid-Name");
if (uPassword !=null) {
if (uPassword .equals("Islam")) {
// # clear the writer from any printed data here
out.println("Valid-password");
} else {
out.println("");
out.println("InValid-password");
}
}
} else {
out.println("InValid-Name");
}
}
注意:我尝试了 .flush() 但旧的打印文本仍然存在
最佳答案
使用 StringWriter
创建内存中的 PrintWriter
。您可以从 StringWriter
获取底层缓冲区,并在需要时清除它。
StringWriter sr = new StringWriter();
PrintWriter w = new PrintWriter(sr);
w.print("Some stuff");
// Flush writer to ensure that it's not buffering anything
w.flush();
// clear stringwriter
sr.getBuffer().setLength(0);
w.print("New stuff");
// write to Servlet out
w.flush();
response.getWriter().print(sr.toString());
关于java - 如何在写入后清除 PrintWriter 的内容,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15593086/