session儲存到redis簡單實作

在負載均衡情況下，如果使用者通路不同的機器，如果沒有做session同步，使用者就會被提出，這樣使用者體驗非常不好，是以我們很遠必要做session同步，把session放到reids緩存伺服器就能很好的解決問題。下面是代碼簡單的實作。

一、配置web.xml過濾器：

<filter>
		<filter-name>sessionFilter</filter-name>
		<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
	</filter>
	
	<filter-mapping>
		<filter-name>sessionFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
           

二、配置對應的過濾器名字：

<bean id="sessionFilter" class="com.plateno.interceptor.SessionFilter">
		<property name="redisTemplate" ref="redisTemplate"/>
	</bean>
           

三、 SessionFilter的實作：

public class SessionFilter extends GenericFilterBean {

	private RedisTemplate redisTemplate;
	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("filter");
		HttpServletRequest re = (HttpServletRequest)request;
		HttpServletResponse res = (HttpServletResponse)response;
		TerryHttpServletRequestWrapper wrapper = new TerryHttpServletRequestWrapper(re,res,redisTemplate);
		chain.doFilter(wrapper, response);
	}
	public RedisTemplate getRedisTemplate() {
		return redisTemplate;
	}
	public void setRedisTemplate(RedisTemplate redisTemplate) {
		this.redisTemplate = redisTemplate;
	}
}
           

四、 TerryHttpServletRequestWrapper的實作：

public class TerryHttpServletRequestWrapper extends HttpServletRequestWrapper {

	private CacheHttpSession session;
	private HttpServletResponse response;
	private RedisTemplate redisTemplate;
	public TerryHttpServletRequestWrapper(HttpServletRequest request, HttpServletResponse response,RedisTemplate redisTemplate) {
		super(request);
		this.response = response;
		this.redisTemplate = redisTemplate;
	}

	@Override
	public HttpSession getSession(boolean create) {
		if(session != null) {
			return session;
		}
		String sid = "terry" + System.currentTimeMillis();
		writeSidToCookie(sid);
		session = new CacheHttpSession(null,sid,redisTemplate);
		return session;
	}

	@Override
	public HttpSession getSession() {
		return getSession(false);
	}
	protected void writeSidToCookie(String sid) {
		Cookie mycookies = new Cookie("terry", sid);
		mycookies.setMaxAge(-1);
		mycookies.setDomain("locahost");
		mycookies.setPath("/");
		response.addCookie(mycookies);
	}
}
           

五、CacheHttpSession的實作：

public class CacheHttpSession extends HttpSessionWrapper {

	private String sid;
	private RedisTemplate redisTemplate;
	private StringRedisSerializer stringSerializer = new StringRedisSerializer();
	public CacheHttpSession(HttpSession session,String sid,RedisTemplate redisTemplate) {
		super(session);
		this.sid = sid;
		this.redisTemplate = redisTemplate;
	}

	@SuppressWarnings("unchecked")
	@Override
	public Enumeration<String> getAttributeNames() {
		final byte[] key = stringSerializer.serialize(sid);
		Object result = redisTemplate.execute(new RedisCallback<Object>() {
			@Override
			public Object doInRedis(RedisConnection connection)
					throws DataAccessException {
				Set<byte[]> set = connection.keys(key);
				return set;
			}
		});
		if(result != null) {
			Set<byte[]> s = (Set<byte[]>)result;
			Set<String> ss = new HashSet<String>();
			for(byte[] b : s) {
				ss.add(stringSerializer.deserialize(b));
			}
			Enumeration<String> en = new Vector(ss).elements();
			return en;
		}
		return null;
	}

	@SuppressWarnings("unchecked")
	@Override
	public void setAttribute(String name, Object value) {
		final byte[] key = stringSerializer.serialize(name);
		final byte[] v = stringSerializer.serialize((String)value);
		redisTemplate.execute(new RedisCallback<Object>() {
			@Override
			public Object doInRedis(RedisConnection connection)
					throws DataAccessException {
				connection.set(key, v);
				return null;
			}
		});
	}

	@Override
	public Object getAttribute(String name) {
		final byte[] key = stringSerializer.serialize(name);
		@SuppressWarnings("unchecked")
		Object value = redisTemplate.execute(new RedisCallback<Object>() {
			@Override
			public Object doInRedis(RedisConnection connection)
					throws DataAccessException {
				return connection.get(key);
			}
		});
		return value;
	}

	@Override
	public String getId() {
		return sid;
	}
}
           

六、HttpSessionWrapper的實作：

public class HttpSessionWrapper implements HttpSession {

	private HttpSession session;
	public HttpSessionWrapper(HttpSession session) {
		this.session = session;
	}
	@Override
	public long getCreationTime() {
		return this.session.getCreationTime();
	}

	@Override
	public String getId() {
		return this.session.getId();
	}

	@Override
	public long getLastAccessedTime() {
		return this.session.getLastAccessedTime();
	}

	@Override
	public ServletContext getServletContext() {
		return this.session.getServletContext();
	}

	@Override
	public void setMaxInactiveInterval(int interval) {
		this.session.setMaxInactiveInterval(interval);
	}

	@Override
	public int getMaxInactiveInterval() {
		return this.session.getMaxInactiveInterval();
	}

	@Override
	public HttpSessionContext getSessionContext() {
		return this.session.getSessionContext();
	}

	@Override
	public Object getAttribute(String name) {
		return this.session.getAttribute(name);
	}

	@Override
	public Object getValue(String name) {
		return this.session.getValue(name);
	}

	@Override
	public Enumeration<String> getAttributeNames() {
		return this.session.getAttributeNames();
	}

	@Override
	public String[] getValueNames() {
		return this.session.getValueNames();
	}

	@Override
	public void setAttribute(String name, Object value) {
		this.session.setAttribute(name,value);
	}

	@Override
	public void putValue(String name, Object value) {
		this.session.putValue(name,value);
	}

	@Override
	public void removeAttribute(String name) {
		this.session.removeAttribute(name);
	}

	@Override
	public void removeValue(String name) {
		this.session.removeValue(name);
	}

	@Override
	public void invalidate() {
		this.session.invalidate();
	}

	@Override
	public boolean isNew() {
		return this.session.isNew();
	}
}
           

以上代碼就能把session儲存到redis，當然這其中還有很多問題，比如sessionId的生成，session過去，對象序列化（測試為了友善統一用了string），等等很多問題。以後有時間再完善。