Implemented a simple UserIdSource, that stores the user in a cookie

[examples/facebook-app] / src / main / java / de / juplo / yourshouter / UserCookieGenerator.java

diff --git a/src/main/java/de/juplo/yourshouter/UserCookieGenerator.java b/src/main/java/de/juplo/yourshouter/UserCookieGenerator.java
new file mode 100644 (file)
index 0000000..48d7078
--- /dev/null
+++ b/src/main/java/de/juplo/yourshouter/UserCookieGenerator.java
@@ -0,0 +1,100 @@
+package de.juplo.yourshouter;
+
+
+import javax.servlet.http.Cookie;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.springframework.web.util.CookieGenerator;
+import org.thymeleaf.util.StringUtils;
+
+
+/**
+ * Utility class for managing the cookie that remembers the user.
+ *
+ * @author Kai Moritz
+ */
+final class UserCookieGenerator
+{
+  private final static Logger LOG =
+      LoggerFactory.getLogger(UserCookieGenerator.class);
+
+  public final static UserCookieGenerator INSTANCE = new UserCookieGenerator();
+
+
+  private final CookieGenerator generator = new CookieGenerator();
+
+
+  /**
+   * Constructs an instance of this class, using <code>user</code> as the
+   * cookie-name.
+   */
+  private UserCookieGenerator()
+  {
+    generator.setCookieName("user");
+  }
+
+
+  /**
+   * Creates a cookie with the name <code>user</code>, that stores the ID of
+   * the user for subsequent calls.
+   *
+   * @param user
+   *     The ID of the current user
+   * @param response
+   *     The {@link HttpServletResponse} to store the cookie in.
+   */
+  public void addCookie(String user, HttpServletResponse response)
+  {
+    LOG.debug("adding cookie {}={}", generator.getCookieName(), user);
+    generator.addCookie(response, user);
+  }
+
+  /**
+   * Removes the cookie with the name <code>user</code> by storing an empty
+   * string as its value.
+   *
+   * @param response
+   *     The {@link HttpServletResponse} to remove the cookie from.
+   */
+  public void removeCookie(HttpServletResponse response)
+  {
+    LOG.debug("removing cookie {}", generator.getCookieName());
+    generator.addCookie(response, "");
+  }
+
+  /**
+   * Reads the current value of the cookie with the name <code>user</code>.
+   *
+   * @param request
+   *   The {@link HttpServletRequest} to read the cookie-value from.
+   * @return
+   *   The value of the cookie with the name <code>user</code>, or
+   *   <code>null</code>, if no cookie by that name can be found or the value
+   *   of the cookie is an empty string.
+   */
+  public String readCookieValue(HttpServletRequest request)
+  {
+    String name = generator.getCookieName();
+    Cookie[] cookies = request.getCookies();
+    if (cookies != null)
+    {
+      for (Cookie cookie : cookies)
+      {
+        if (cookie.getName().equals(name))
+        {
+          String value = cookie.getValue();
+          if (!StringUtils.isEmptyOrWhitespace(value))
+          {
+            LOG.debug("found cookie {}={}", name, value);
+            return value;
+          }
+        }
+      }
+    }
+    LOG.debug("cookie \"{}\" not found!", name);
+    return null;
+  }
+}