JSP 應用代碼記錄

判斷Cookie 值

• JSTL 直接判斷

<c:choose>
    <c:when test="${cookie['loginName'].value ne null }">
        value="${cookie['loginName'].value}"
    </c:when>
    <c:otherwise>
        value="${username}" autofocus="autofocus"
    </c:otherwise>
</c:choose>

• java 讀取並判斷

<%
    String loginName;
    //讀取cookie
    Cookie cookie[] = request.getCookies();
    if (cookie != null) {
        for (int i = 0; i < cookie.length; i++) {
            Cookie c = cookie[i];
            if (c.getName().equals("loginName")) {//查找cookie裏面的是否存在cookie鍵位c_name的cookie
                loginName = c.getValue();
            }
        }
    }
%>

• 服務器向客戶端寫Cookie

Cookie cookie = new Cookie("loginName", user.getLoginName());
cookie.setMaxAge(3600 * 24 * 31);
cookie.setPath("/"); //設置路徑，該工程下都可以訪問該cookie 如果不設置路徑，那麼只有設置該URL路徑及其子路徑可以訪問
response.addCookie(cookie);

• 刪除客戶端Cookie

  cookies[0].setMaxAge(0); //刪除第1個cookie

• Session 操作類似

    <%
    HttpSession s = request.getSession(); 
    s.setAttribute("name","test");
    %>
    得到Session的值是<%=s.getAttribute("name") %>