session保存到redis简单实现

在负载均衡情况下，如果用户访问不同的机器，如果没有做session同步，用户就会被提出，这样用户体验非常不好，所以我们很远必要做session同步，把session放到reids缓存服务器就能很好的解决问题。下面是代码简单的实现。

一、配置web.xml过滤器：

		sessionFilter
		org.springframework.web.filter.DelegatingFilterProxy
	
	
	
		sessionFilter
		/*
	

二、配置对应的过滤器名字：

三、 SessionFilter的实现：

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的实现：

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的实现：

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 getAttributeNames() {
		final byte[] key = stringSerializer.serialize(sid);
		Object result = redisTemplate.execute(new RedisCallback