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<time datetime="2013-07-09T02:35:04.000Z"><a href="/2013/07/09/guava_optional_1/">7月 9 2013</a></time>
<h1 class="title"><a href="/2013/07/09/guava_optional_1/">Guava Optaional</a></h1>
</header>
<div class="entry">
<p>Using and avoiding null</p>
<pre><code><figure class="highlight"><pre> Many <span class="keyword">of</span> <span class="keyword">the</span> cases <span class="keyword">where</span> programmers use null <span class="keyword">is</span> <span class="keyword">to</span> indicate
<span class="keyword">some</span> sort <span class="keyword">of</span> absence: perhaps <span class="keyword">where</span> there might have been a value,
there <span class="keyword">is</span> none, <span class="keyword">or</span> one could <span class="keyword">not</span> be found.
For example, Map.<span class="keyword">get</span> returns null when no value <span class="keyword">is</span> found <span class="keyword">for</span> a key.
Optional<T> <span class="keyword">is</span> a way <span class="keyword">of</span> replacing a nullable T <span class="keyword">reference</span> <span class="keyword">with</span> a non-null value.
An Optional may either <span class="keyword">contain</span> a non-null T <span class="keyword">reference</span>
(<span class="keyword">in</span> which case we <span class="command">say</span> <span class="keyword">the</span> <span class="keyword">reference</span> <span class="keyword">is</span> <span class="string">"present"</span>),
<span class="keyword">or</span> <span class="keyword">it</span> may <span class="keyword">contain</span> nothing (<span class="keyword">in</span> which case we <span class="command">say</span> <span class="keyword">the</span> <span class="keyword">reference</span> <span class="keyword">is</span> <span class="string">"absent"</span>).
It <span class="keyword">is</span> never said <span class="keyword">to</span> <span class="string">"contain null."</span>
Making an Optional
Static method
Optional.<span class="keyword">of</span>(T) Make an Optional containing <span class="keyword">the</span> <span class="keyword">given</span> non
-null value, <span class="keyword">or</span> fail fast <span class="function_start"><span class="keyword">on</span> <span class="title">null</span></span>.
(java.lang.NullPointerException)
Optional.absent() Return an absent Optional <span class="keyword">of</span> <span class="keyword">some</span> type.
<span class="command">
return</span> rs.next() ? rs.getString(<span class="string">"nickname"</span>) : null;
==>
<span class="command"> return</span> rs.next() ? Optional.<span class="keyword">of</span>(rs.getString(<span class="string">"nickname"</span>)) : Optional.absent();
Optional.fromNullable(T) Turn <span class="keyword">the</span> <span class="keyword">given</span> possibly-null <span class="keyword">reference</span> <span class="keyword">into</span> an Optional,
treating non-null <span class="keyword">as</span> present <span class="keyword">and</span> null <span class="keyword">as</span> absent.
許多程式庫中使用了不少 null，Guava 提供fromNullabe(T)用來銜接程式庫中 null 的方法
String nickName = Optional.fromNullable(getNickName(<span class="string">"Duke"</span>)).<span class="keyword">or</span>(<span class="string">"CoDeData User"</span>);
Query methods
non-static methods
<span class="type">boolean</span> isPresent() Returns <span class="constant">true</span> <span class="keyword">if</span> this Optional <span class="keyword">contains</span> a non-null instance.
T <span class="keyword">get</span>() Returns <span class="keyword">the</span> contained T instance, which must be present;
otherwise, throws an IllegalStateException.
T <span class="keyword">or</span>(T) Returns <span class="keyword">the</span> present value <span class="keyword">in</span> this Optional,
<span class="keyword">or</span> <span class="keyword">if</span> there <span class="keyword">is</span> none, returns <span class="keyword">the</span> specified default.
String nickName = Optional.fromNullable(getNickName(<span class="string">"Duke"</span>)).<span class="keyword">or</span>(<span class="string">"CoDeData User"</span>);
T orNull() Returns <span class="keyword">the</span> present value <span class="keyword">in</span> this Optional, <span class="keyword">or</span> <span class="keyword">if</span> there <span class="keyword">is</span> none, returns null.
The inverse operation <span class="keyword">of</span> fromNullable.
String nickName = Optional.fromNullable(getNickName(<span class="string">"Duke"</span>)).orNull();
Set<T> asSet() Returns an immutable singleton Set containing <span class="keyword">the</span> instance <span class="keyword">in</span> this Optional,
<span class="keyword">if</span> there <span class="keyword">is</span> one, <span class="keyword">or</span> otherwise an empty immutable <span class="keyword">set</span>.
</pre></figure></code></pre>
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<time datetime="2013-07-08T14:03:20.000Z"><a href="/2013/07/08/vertx_common_util/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/vertx_common_util/">vertx_common_util</a></h1>
</header>
<div class="entry">
<p>Logger
...
import org.vertx.java.core.logging.Logger;
....</p>
<pre><code><figure class="highlight"><pre> <span class="comment">private</span> <span class="comment">Logger</span> <span class="comment">logger;</span>
<span class="comment">public</span> <span class="comment">void</span> <span class="comment">start()</span> <span class="comment">{</span>
<span class="comment">logger</span> <span class="comment">=</span> <span class="comment">getContainer()</span>.<span class="comment">getLogger();</span>
<span class="string">.</span><span class="string">.</span><span class="string">.</span><span class="string">.</span>
<span class="comment">}
</pre></figure></code></pre>
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<time datetime="2013-07-08T08:55:17.000Z"><a href="/2013/07/08/vertx_concept_eventbox/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/vertx_concept_eventbox/">Event Box</a></h1>
</header>
<div class="entry">
<p>Event Box </p>
<pre><code><figure class="highlight"><pre>Addressing:
-String
-Dot-style namespacing recommended
- e.g. <span class="string">"messages.inbound.A"</span>
Handlers
-A handler <span class="keyword">is</span> a thing <span class="keyword">that</span> receives messages <span class="keyword">from</span> <span class="keyword">the</span> bus.
-You register a handler <span class="keyword">at</span> an address.
-Many different handlers <span class="keyword">from</span> <span class="keyword">the</span> same <span class="keyword">or</span> different verticles
can be registered <span class="keyword">at</span> <span class="keyword">the</span> same address.
-A single handler can be registered <span class="keyword">by</span> <span class="keyword">the</span> verticle <span class="keyword">at</span> many different addresses.
Handler Registration
EventBus eb = vertx.eventbus();
Handler<Message> myHandler = new Handle<Message>() {
public boid handle(Message message)
System.out.println(<span class="string">"received a message "</span> + message);
};
eb.registerHandle(<span class="string">"test.address"</span>,myHandler);
Pub/Sub (Publish / subscribe messaging)
The event bus supports publishing messages.
Messages are published <span class="keyword">to</span> an address.
Publishing means delivering <span class="keyword">the</span> message <span class="keyword">to</span> all handlers <span class="keyword">that</span> are registered <span class="keyword">at</span> <span class="keyword">that</span> address.
This <span class="keyword">is</span> <span class="keyword">the</span> familiar publish/subscribe messaging pattern.
P2P (Point <span class="keyword">to</span> point messaging)
The event bus supports point <span class="keyword">to</span> point messaging.
Messages are sent <span class="keyword">to</span> an address.
This means a message <span class="keyword">is</span> delivered <span class="keyword">to</span> <span class="keyword">at</span> most one <span class="keyword">of</span> <span class="keyword">the</span> handlers registered <span class="keyword">at</span> <span class="keyword">that</span> address.
If there <span class="keyword">is</span> more than one handler regsitered <span class="keyword">at</span> <span class="keyword">the</span> address,
one will be chosen using a non-strict <span class="command">round</span>-robin algorithm.
With point <span class="keyword">to</span> point messaging, an optional reply handler can be specified when sending <span class="keyword">the</span> message. When a message <span class="keyword">is</span> received <span class="keyword">by</span> a recipient, <span class="keyword">and</span> has been processed, <span class="keyword">the</span> recipient can optionally decide <span class="keyword">to</span> reply <span class="keyword">to</span> <span class="keyword">the</span> message.
If they do so <span class="keyword">that</span> reply handler will be called.
When <span class="keyword">the</span> reply <span class="keyword">is</span> received <span class="keyword">back</span> <span class="keyword">at</span> <span class="keyword">the</span> sender, <span class="keyword">it</span> too can be replied <span class="keyword">to</span>.
This can be repeated ad-infinitum, <span class="keyword">and</span> allows a dialog <span class="keyword">to</span> be <span class="keyword">set</span>-up <span class="keyword">between</span> two different verticles. This <span class="keyword">is</span> a common messaging pattern called <span class="keyword">the</span> Request-Response pattern.
Sender :
//eb.send
eb.send(<span class="string">"test.address"</span>,<span class="string">"This is a message"</span> ,new Handler<Message<String>>(){
public void handle(Message<String> message) {
System.our.println(<span class="string">"receuved a reply"</span> + message.body);
}
});
Receiver:
Handler<Message<String>> myHandler = new Handler<Message<String>>(){
public void handle(Message<String> message) {
System.out.println(<span class="string">"I received a message "</span> +message.body);
message.reply(<span class="string">"This is a reply"</span>);
}
}
eb.registerHandler(<span class="string">"test.address"</span>,myHandler);
Message Types
-String
-Primitives
-Boxed Primitives
-<span class="type">boolean</span>/Boolean
-org.vertx.java.core.json.JsonObject
-org.vertx.java.core.buffer.Buffer
Transient
All messages <span class="keyword">in</span> <span class="keyword">the</span> event bus are transient, <span class="keyword">and</span> <span class="keyword">in</span> case <span class="keyword">of</span> failure <span class="keyword">of</span> all <span class="keyword">or</span>
parts <span class="keyword">of</span> <span class="keyword">the</span> event bus, there <span class="keyword">is</span> a possibility messages will be lost.
If your <span class="type">application</span> cares <span class="keyword">about</span> lost messages, you should code your handlers <span class="keyword">to</span> be idempotent, <span class="keyword">and</span> your senders <span class="keyword">to</span> retry <span class="keyword">after</span> recovery.
If you want <span class="keyword">to</span> persist your messages you can use a persistent work queue module <span class="keyword">for</span> <span class="keyword">that</span>.
</pre></figure></code></pre>
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<time datetime="2013-07-08T08:27:16.000Z"><a href="/2013/07/08/vertx_concept_verticle/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/vertx_concept_verticle/">Verticle</a></h1>
</header>
<div class="entry">
<p>Verticle
-unit of deployment
-Script/Java Class</p>
<p>Verticle run inside a vert.x instance </p>
<p>A single vert.x instance runs inside its own JVM instance.</p>
<p>Concuurency
-Verticle instance assigned thread/event loop
-Verticle instance ALWAYS executes on assigned thread
-Verticles have isolated classloaders and cnnot shared global satae (static members,global variables etc)
-can write all code assuming single threading</p>
<p>Verticles are executed using the same thread</p>
<p>Every Java verticle must extend the class org.vertx.java.deploy.Verticle.
You must override the start method - this is called by Vert.x when the verticle is started.</p>
<p>Verticle clean-up</p>
<p>Servers, clients and event bus handlers will be automatically closed when the verticle is stopped.
However, if you have any other clean-up logic that you want to execute when the verticle is stopped,
you can implement a stop method which will be called when the verticle is undeployed.</p>
<p>Specifying number of instances</p>
<p>By default, when you deploy a verticle only one instance of the verticle is deployed.
If you want more than one instance to be deployed, e.g. so you can scale over your cores better,
you can specify the number of instances as follows:
container.deployVerticle("foo.ChildVerticle", 10);
The above example would deploy 10 instances.</p>
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<time datetime="2013-07-08T06:32:08.000Z"><a href="/2013/07/08/spring_security_filter_2/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/spring_security_filter_2/">logoutFilter</a></h1>
</header>
<div class="entry">
<p>1.notices that the URL that is being requested is for logout</p>
<p>2.The filter calls the configured LogoutHandle(implement the LogoutHandler interface)
SecurityContextLogoutHandler
invalidates the Servlet session, in the standard Servlet way, calling the invalidate method
on the HttpSession object and also clearing the SecurityContext from Spring Security
(JSESSIONID cookie not clear)
TokenBasedRememberMeServices
removes the remember-me cookie by setting its age to 0.</p>
<pre><code><figure class="highlight"><pre>JSESSIONID cookie
<span class="tag"><<span class="title">security:http</span>></span>
....
<span class="tag"><<span class="title">security:logout</span> <span class="attribute">delete-cookies</span>=<span class="value">"JSESSIONID"</span>/></span>.
...
<span class="tag"></<span class="title">security:http</span>></span>
To enable the CookieClearingLogoutHandler handler (removes cookies)
</pre></figure></code></pre>
<p>3.calls the LogoutSuccessHandler’s onLogoutSuccess method
in the default configuration, redirects to a target URL
The target URL ( default the root of the application) can be configured using </p>
<pre><code><figure class="highlight"><pre> request parameter
<span class="tag"><<span class="title">security:logout</span> <span class="attribute">logout-success-url</span>=<span class="value">"/index"</span> /></span>
the referrer header from the request
<span class="tag"><<span class="title">security:logout</span> <span class="attribute">delete-cookies</span>=<span class="value">"JSESSIONID"</span> <span class="attribute">success-handler-ref</span>=<span class="value">"logoutRedirectToAny"</span>/></span>
...
<span class="tag"><<span class="title">bean</span> <span class="attribute">id</span>=<span class="value">"logoutRedirectToAny"</span>
<span class="attribute">class</span>=<span class="value">"org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler"</span>></span>
<span class="tag"><<span class="title">property</span> <span class="attribute">name</span>=<span class="value">"targetUrlParameter"</span> <span class="attribute">value</span>=<span class="value">"redirectTo"</span>/></span>
<span class="tag"></<span class="title">bean</span>></span>
request the following URL
/j_spring_security_logout?redirectTo=http://www.google.com
You will be logged out and redirected to Google
The current implementation LogoutSuccessHandler (SimpleUrlLogoutSuccessHandler)
extends from AbstractAuthenticationTargetUrlRequestHandler, which is also used by
the authentication process to redirect to a determined URL after authenticating successfully
</pre></figure></code></pre>
<p>LogoutFilter extends GenericFilterBean</p>
<pre><code><figure class="highlight"><pre> ....
<span class="keyword">private</span> String filterProcessesUrl = <span class="string">"/j_spring_security_logout"</span>;
<span class="keyword">private</span> final List<LogoutHandler> handlers;
<span class="keyword">private</span> final LogoutSuccessHandler logoutSuccessHandler;
...
<span class="keyword">public</span> <span class="keyword">void</span> doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
<span class="comment">//if the request's URL is /j_spring_security_logout</span>
<span class="keyword">if</span> (requiresLogout(request, response)) {
Authentication auth = SecurityContextHolder<span class="variable">.getContext</span>()<span class="variable">.getAuthentication</span>();
<span class="keyword">if</span> (logger<span class="variable">.isDebugEnabled</span>()) {
logger<span class="variable">.debug</span>(<span class="string">"Logging out user '"</span> + auth + <span class="string">"' and transferring to logout destination"</span>);
}
<span class="keyword">for</span> (LogoutHandler handler : handlers) {
handler<span class="variable">.logout</span>(request, response, auth);
}
logoutSuccessHandler<span class="variable">.onLogoutSuccess</span>(request, response, auth);
<span class="keyword">return</span>;
}
chain<span class="variable">.doFilter</span>(request, response);
}
....
<span class="keyword">protected</span> boolean requiresLogout(HttpServletRequest request, HttpServletResponse response) {
String uri = request<span class="variable">.getRequestURI</span>();
<span class="keyword">int</span> pathParamIndex = uri<span class="variable">.indexOf</span>(<span class="string">';'</span>);
<span class="keyword">if</span> (pathParamIndex > <span class="number">0</span>) {
<span class="comment">// strip everything from the first semi-colon</span>
uri = uri<span class="variable">.substring</span>(<span class="number">0</span>, pathParamIndex);
}
<span class="keyword">int</span> queryParamIndex = uri<span class="variable">.indexOf</span>(<span class="string">'?'</span>);
<span class="keyword">if</span> (queryParamIndex > <span class="number">0</span>) {
<span class="comment">// strip everything from the first question mark</span>
uri = uri<span class="variable">.substring</span>(<span class="number">0</span>, queryParamIndex);
}
<span class="keyword">if</span> (<span class="string">""</span><span class="variable">.equals</span>(request<span class="variable">.getContextPath</span>())) {
<span class="keyword">return</span> uri<span class="variable">.endsWith</span>(filterProcessesUrl);
}
<span class="keyword">return</span> uri<span class="variable">.endsWith</span>(request<span class="variable">.getContextPath</span>() + filterProcessesUrl);
}
</pre></figure></code></pre>
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<time datetime="2013-07-08T05:49:34.000Z"><a href="/2013/07/08/spring_security_filter_1/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/spring_security_filter_1/">SecurityContextPersistenceFilter</a></h1>
</header>
<div class="entry">
<ul>
<li>The first security filter that gets hit by the request is SecurityContextPersistenceFilter.</li>
<li>When the request hits this filter, the framework tries to retrieve a SecurityContext from the standard Servlet session
(javax.servlet.http.HttpSession).</li>
<li><p>If there is not a context in the session, or the session itself is null (that is, it still doesn’t exist because it hasn’t been
created yet), the framework creates a new empty SecurityContext(or, more accurately, an instance of its implementation class SecurityContextImpl).</p>
</li>
<li><p>A new SecurityContext is created and associated to the current thread of execution.</p>
</li>
</ul>
<p>SecurityContextPersistenceFilter</p>
<pre><code><figure class="highlight"><pre> ....
static final String FILTER_APPLIED = <span class="string">"__spring_security_scpf_applied"</span><span class="comment">;</span>
private SecurityContextRepository repo<span class="comment">;</span>
private boolean forceEagerSessionCreation = false<span class="comment">;</span>
.....
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req<span class="comment">;</span>
HttpServletResponse response = (HttpServletResponse) res<span class="comment">;</span>
if (request<span class="preprocessor">.getAttribute</span>(FILTER_APPLIED) != null) {
// ensure that filter is only applied once per request
chain<span class="preprocessor">.doFilter</span>(request, response)<span class="comment">;</span>
return<span class="comment">;</span>
}
final boolean debug = logger<span class="preprocessor">.isDebugEnabled</span>()<span class="comment">;</span>
request<span class="preprocessor">.setAttribute</span>(FILTER_APPLIED, Boolean<span class="preprocessor">.TRUE</span>)<span class="comment">;</span>
if (forceEagerSessionCreation) {
HttpSession session = request<span class="preprocessor">.getSession</span>()<span class="comment">;</span>
if (debug && session<span class="preprocessor">.isNew</span>()) {
logger<span class="preprocessor">.debug</span>(<span class="string">"Eagerly created session: "</span> + session<span class="preprocessor">.getId</span>())<span class="comment">;</span>
}
}
HttpRequestResponseHolder holder = new HttpRequestResponseHolder(request, response)<span class="comment">;</span>
//repo<span class="preprocessor">.loadContext</span>(holder)
<span class="comment">/*retrieve a SecurityContext from the standard Servlet session (javax.servlet.http.HttpSession).
If there is not a context in the session, or the session itself is null (that is, it still doesn’t exist because it
hasn’t been created yet), the framework creates a new empty SecurityContext(or, more accurately, an instance of its
implementation class SecurityContextImpl).
*/</span>
SecurityContext contextBeforeChainExecution = repo<span class="preprocessor">.loadContext</span>(holder)<span class="comment">;</span>
try {
SecurityContextHolder<span class="preprocessor">.setContext</span>(contextBeforeChainExecution)<span class="comment">;</span>
chain<span class="preprocessor">.doFilter</span>(holder<span class="preprocessor">.getRequest</span>(), holder<span class="preprocessor">.getResponse</span>())<span class="comment">;</span>
} finally {
SecurityContext contextAfterChainExecution = SecurityContextHolder<span class="preprocessor">.getContext</span>()<span class="comment">;</span>
// Crucial removal of SecurityContextHolder contents - do this before anything else.
SecurityContextHolder<span class="preprocessor">.clearContext</span>()<span class="comment">;</span>
repo<span class="preprocessor">.saveContext</span>(contextAfterChainExecution, holder<span class="preprocessor">.getRequest</span>(), holder<span class="preprocessor">.getResponse</span>())<span class="comment">;</span>
request<span class="preprocessor">.removeAttribute</span>(FILTER_APPLIED)<span class="comment">;</span>
if (debug) {
logger<span class="preprocessor">.debug</span>(<span class="string">"SecurityContextHolder now cleared, as request processing completed"</span>)<span class="comment">;</span>
}
}
}
</pre></figure></code></pre>
<p>HttpSessionSecurityContextRepository implements SecurityContextRepository</p>
<pre><code><figure class="highlight"><pre> ....
<span class="keyword">private</span> String springSecurityContextKey = SPRING_SECURITY_CONTEXT_KEY;
....
<span class="keyword">public</span> SecurityContext loadContext(HttpRequestResponseHolder requestResponseHolder) {
HttpServletRequest request = requestResponseHolder.getRequest();
HttpServletResponse response = requestResponseHolder.getResponse();
HttpSession httpSession = request.getSession(<span class="literal">false</span>);
SecurityContext context = readSecurityContextFromSession(httpSession);
<span class="keyword">if</span> (context == <span class="literal">null</span>) {
<span class="keyword">if</span> (logger.isDebugEnabled()) {
logger.<span class="keyword">debug</span>(<span class="string">"No SecurityContext was available from the HttpSession: "</span> + httpSession +<span class="string">". "</span> +
<span class="string">"A new one will be created."</span>);
}
context = generateNewContext();
}
requestResponseHolder.setResponse(<span class="keyword">new</span> SaveToSessionResponseWrapper(response, request, httpSession != <span class="literal">null</span>, context));
<span class="keyword">return</span> context;
}
<span class="keyword">private</span> SecurityContext readSecurityContextFromSession(HttpSession httpSession) {
<span class="keyword">final</span> boolean <span class="keyword">debug</span> = logger.isDebugEnabled();
<span class="keyword">if</span> (httpSession == <span class="literal">null</span>) {
<span class="keyword">if</span> (<span class="keyword">debug</span>) {
logger.<span class="keyword">debug</span>(<span class="string">"No HttpSession currently exists"</span>);
}
<span class="keyword">return</span> <span class="literal">null</span>;
}
<span class="comment">// Session exists, so try to obtain a context from it.</span>
Object contextFromSession = httpSession.getAttribute(springSecurityContextKey);
<span class="keyword">if</span> (contextFromSession == <span class="literal">null</span>) {
<span class="keyword">if</span> (<span class="keyword">debug</span>) {
logger.<span class="keyword">debug</span>(<span class="string">"HttpSession returned null object for SPRING_SECURITY_CONTEXT"</span>);
}
<span class="keyword">return</span> <span class="literal">null</span>;
}
<span class="comment">// We now have the security context object from the session.</span>
<span class="keyword">if</span> (!(contextFromSession instanceof SecurityContext)) {
<span class="keyword">if</span> (logger.isWarnEnabled()) {
logger.warn(springSecurityContextKey + <span class="string">" did not contain a SecurityContext but contained: '"</span>
+ contextFromSession + <span class="string">"'; are you improperly modifying the HttpSession directly "</span>
+ <span class="string">"(you should always use SecurityContextHolder) or using the HttpSession attribute "</span>
+ <span class="string">"reserved for this class?"</span>);
}
<span class="keyword">return</span> <span class="literal">null</span>;
}
<span class="keyword">if</span> (<span class="keyword">debug</span>) {
logger.<span class="keyword">debug</span>(<span class="string">"Obtained a valid SecurityContext from "</span> + springSecurityContextKey + <span class="string">": '"</span> + contextFromSession + <span class="string">"'"</span>);
}
<span class="comment">// Everything OK. The only non-null return from this method.</span>
<span class="keyword">return</span> (SecurityContext) contextFromSession;
}
</pre></figure></code></pre>
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<header>
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<time datetime="2013-07-08T03:03:47.000Z"><a href="/2013/07/08/spring_security_service_layer/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/spring_security_service_layer/">spring_security_service_layer</a></h1>
</header>
<div class="entry">
<p>security.xml
1.<security:global-method-security secured-annotations="enabled" /></p>
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<time datetime="2013-07-08T01:49:11.000Z"><a href="/2013/07/08/spring_security_note/">7月 8 2013</a></time>
<h1 class="title"><a href="/2013/07/08/spring_security_note/">spring_security_note</a></h1>
</header>
<div class="entry">
<p>Spring security
(1) uses Spring Security to access our current user.
The Authentication object represents all the information we gathered at the time of authentication (username,password, roles, and so on).</p>
<pre><code><figure class="highlight"><pre> String username = SecurityContextHolder<span class="preprocessor">.getContext</span>() //o<span class="preprocessor">.s</span><span class="preprocessor">.s</span><span class="preprocessor">.core</span><span class="preprocessor">.context</span><span class="preprocessor">.SecurityContext</span>
<span class="preprocessor">.getAuthentication</span>() //o<span class="preprocessor">.s</span><span class="preprocessor">.s</span><span class="preprocessor">.core</span><span class="preprocessor">.Authentication</span>
<span class="preprocessor">.getName</span>()<span class="comment">; //login user name</span>
===============================================================
SecurityContext context = SecurityContextHolder<span class="preprocessor">.getContext</span>()<span class="comment">;</span>
Authentication authentication = context<span class="preprocessor">.getAuthentication</span>()<span class="comment">;</span>
if (authentication == null) {
return null<span class="comment">;</span>
}
String email = authentication<span class="preprocessor">.getName</span>()<span class="comment">;</span>
return calendarService<span class="preprocessor">.findUserByEmail</span>(email)<span class="comment">;</span>
note:It should be noted that null checks should always be done on the Authentication object,
as it could be null if the user is not logged <span class="keyword">in</span>.
===============================================================
User user = (User)SecurityContextHolder<span class="preprocessor">.getContext</span>()<span class="preprocessor">.getAuthentication</span>()<span class="preprocessor">.getPrincipal</span>()<span class="comment">;</span>
</pre></figure></code></pre>
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<time datetime="2013-07-06T23:56:55.000Z"><a href="/2013/07/07/spring_security_simple_example/">7月 7 2013</a></time>
<h1 class="title"><a href="/2013/07/07/spring_security_simple_example/">spring_security_simple_example</a></h1>
</header>
<div class="entry">
<p>簡單的security 設定檔
securiy.xml
<!--excluse /resources/** -->
<http pattern="/resources/**" security="none"/></p>
<pre><code><figure class="highlight"><pre> <span class="comment"><!-- auto-config="true" 使用spring secuirty 一些基本的設定--></span>
<span class="comment"><!-- use-expressions="true" 使用SpEL --></span>
<span class="tag"><<span class="title">http</span> <span class="attribute">auto-config</span>=<span class="value">"true"</span> <span class="attribute">use-expressions</span>=<span class="value">"true"</span>></span>
<span class="comment"><!-- ConfigAttribute : ROLE_ADMIN , ROLE_USER --></span>
<span class="comment"><!-- Security Metadata <intercept-url pattern=... access=... --></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/"</span> <span class="attribute">access</span>=<span class="value">"permitAll"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/login/*"</span> <span class="attribute">access</span>=<span class="value">"permitAll"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/logout"</span> <span class="attribute">access</span>=<span class="value">"permitAll"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/errors/**"</span> <span class="attribute">access</span>=<span class="value">"permitAll"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/events/"</span> <span class="attribute">access</span>=<span class="value">"hasRole('ROLE_ADMIN')"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/admin/**"</span> <span class="attribute">access</span>=<span class="value">"hasRole('ROLE_ADMIN')"</span>/></span>
<span class="tag"><<span class="title">intercept-url</span> <span class="attribute">pattern</span>=<span class="value">"/**"</span> <span class="attribute">access</span>=<span class="value">"hasRole('ROLE_USER')"</span>/></span>
<span class="tag"><<span class="title">access-denied-handler</span> <span class="attribute">error-page</span>=<span class="value">"/errors/403"</span>/></span>
<span class="comment"><!-- spring security filter --></span>
<span class="tag"><<span class="title">form-login
</span> <!<span class="attribute">--</span> <span class="attribute">customer</span> <span class="attribute">login</span> <span class="attribute">use</span> /<span class="attribute">login</span>/<span class="attribute">form</span>
<span class="attribute">If</span> <span class="attribute">a</span> <span class="attribute">login</span> <span class="attribute">page</span> <span class="attribute">is</span> <span class="attribute">not</span> <span class="attribute">specified</span>,
<span class="attribute">Spring</span> <span class="attribute">Security</span> <span class="attribute">will</span> <span class="attribute">redirect</span> <span class="attribute">the</span> <span class="attribute">user</span> <span class="attribute">to</span> /<span class="attribute">spring_security_login.</span>
<span class="attribute">--</span>></span>
login-page="/login/form"
login-processing-url="/login"
username-parameter="username"
password-parameter="password"
authentication-failure-url="/login/form?error"
<span class="comment"><!-- default-target-url will be the context root of the application
depending on the user's role
send the user to a different default-target-url attribute
ref controller that processes /default
--></span>
default-target-url="/default"/>
<span class="comment"><!-- spring security filter --></span>
<span class="tag"><<span class="title">logout</span> <span class="attribute">logout-success-url</span>=<span class="value">"/login/form?logout"</span>/></span>
<span class="tag"></<span class="title">http</span>></span>
<span class="tag"><<span class="title">authentication-manager</span>></span>
<span class="tag"><<span class="title">authentication-provider</span>></span>
<span class="tag"><<span class="title">user-service</span>></span>
<span class="tag"><<span class="title">user</span> <span class="attribute">name</span>=<span class="value">"user"</span> <span class="attribute">password</span>=<span class="value">"user"</span> <span class="attribute">authorities</span>=<span class="value">"ROLE_USER"</span>/></span>
<span class="tag"><<span class="title">user</span> <span class="attribute">name</span>=<span class="value">"admin"</span> <span class="attribute">password</span>=<span class="value">"admin"</span><span class="attribute">authorities</span>=<span class="value">"ROLE_USER,ROLE_ADMIN"</span>/></span>
<span class="tag"></<span class="title">user-service</span>></span>
<span class="tag"></<span class="title">authentication-provider</span>></span>
<span class="tag"></<span class="title">authentication-manager</span>></span>
</pre></figure></code></pre>
<p>DefaultController.java</p>
<pre><code><figure class="highlight"><pre> <span class="comment">// imports omitted</span>
<span class="annotation">@Controller</span>
<span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">DefaultController</span> {</span>
<span class="annotation">@RequestMapping</span>(<span class="string">"/default"</span>)
<span class="keyword">public</span> String defaultAfterLogin(HttpServletRequest request) {
<span class="keyword">if</span> (request.isUserInRole(<span class="string">"ROLE_ADMIN"</span>)) {
<span class="keyword">return</span> <span class="string">"redirect:/events/"</span>;
}
<span class="keyword">return</span> <span class="string">"redirect:/"</span>;
}
}
</pre></figure></code></pre>
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<time datetime="2013-07-06T13:05:41.000Z"><a href="/2013/07/06/number-format/">7月 6 2013</a></time>
<h1 class="title"><a href="/2013/07/06/number-format/">number format</a></h1>
</header>
<div class="entry">
<p>number format</p>
<pre><code><figure class="highlight"><pre> ....
<fmt:formatNumber value=<span class="string">"<span class="subst">${item.PRICE}</span>"</span> pattern=<span class="string">"#,##0.00"</span>/>
....
</pre></figure></code></pre>
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