我有jsf网页,这需要从之前的页面查询一些字符串。
我的问题是这个主页似乎有缓存的值,没有变化即使我将这些值更改为null,它应该得到空页但它会变得更旧。
所以我的问题是:每次调用时我如何让我的主jsf页面重新加载或缓存被删除,或者我按下F按钮?
我的JSF示例代码我试过:
<h:head style="width: 200px; ">
<f:facet name="first">
<meta http-equiv="X-UA-Compatible" content="edge, chrome=1" />
<meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate" />
<meta http-equiv="Pragma" content="no-cache" />
<meta http-equiv="Expires" content="-1" />
</f:facet>
java class:
String SID = FacesContext.getCurrentInstance().getExternalContext()
.getRequestParameterMap().get("SID");
String from = FacesContext.getCurrentInstance().getExternalContext()
.getRequestParameterMap().get("from");
String to = FacesContext.getCurrentInstance().getExternalContext()
.getRequestParameterMap().get("to");
String class_id = FacesContext.getCurrentInstance()
.getExternalContext().getRequestParameterMap().get("class_id");
if (SID==null) {
try {
Dbconnection NewConnect = new Dbconnection();
Connection con = NewConnect.MakeConnect();
Statement stmt = con.createStatement();
ResultSet rs = stmt
.executeQuery("SELECT a.course_id, a.teacher_id, a.class_id, a.day_id, a.state, a.apssent_date, a.interval_id,s.student_id,s.first_name FROM student AS s INNER JOIN apsent AS a ON s.student_id = a.student_id where apssent_date between '"
+ from
+ "' and '"
+ to
+ "' and a.class_id = "
+ Integer.parseInt(class_id));
while (rs.next()) {
ids.add(rs.getInt(8));
names.add(rs.getString(9));
intervals.add(rs.getInt(7));
teachers.add(rs.getInt(2));
dates.add(rs.getString(6));
state.add(rs.getString(5));
}
} catch (Exception ex) {
System.out.println(ex);
}
}
System.out.println(SID + from + class_id + to);
if (class_id==null) {
try {
Dbconnection NewConnect = new Dbconnection();
Connection con = NewConnect.MakeConnect();
Statement stmt = con.createStatement();
ResultSet rs = stmt
.executeQuery("SELECT a.course_id, a.teacher_id, a.class_id, a.day_id, a.state, a.apssent_date, a.interval_id,s.student_id,s.first_name FROM student AS s INNER JOIN apsent AS a ON s.student_id = a.student_id where apssent_date between '"
+ from
+ "' and '"
+ to
+ "' and s.student_id = " + SID);
while (rs.next()) {
// System.out.println(rs.getInt(1));
ids.add(rs.getInt(8));
names.add(rs.getString(9));
intervals.add(rs.getInt(7));
teachers.add(rs.getInt(2));
dates.add(rs.getString(6));
state.add(rs.getString(5));
}
} catch (Exception ex) {
System.out.println(ex);
}
}
carsSmall = new ArrayList<Car>();
populateRandomCars(carsSmall, ids.size(), ids, names,
intervals, teachers, dates, state);
}
答案 0 :(得分:7)
<meta http-equiv>
标记仅在从非HTTP资源(例如本地磁盘文件系统(通过file://
URI))打开有问题的HTML文件时使用,而不是在HTML文件打开时使用问题是从真实的HTTP资源(通过http://
URI)打开的。相反,已使用通过HttpServletResponse#setHeader()
设置的真实HTTP响应标头。
因此,在您的JSF页面的情况下,这些标记仅在Web浏览器中打开JSF页面时解释,并且其HTML输出由最终用户通过webbrowser的文件&gt;保存到HTML文件。另存为,然后双击文件资源管理器中保存的文件重新打开。
因此,您的具体问题很可能是因为<meta http-equiv>
标记被忽略。您需要在HTTP响应中直接设置这些标头,而不是在HTML头中。您可以使用servlet过滤器。在下面的“另请参见”链接中,您可以找到具体的代码示例。
无关,您的JDBC代码正在泄漏资源。这是一个严重的问题。一段时间后,您的JDBC将停止运行。 Don't forget to fix that as well