本文实例讲述了Java简单实现session保存到redis的方法。分享给大家供大家参考，具体如下：
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，所以我们很有必要做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：
<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、配置对应的过滤器名字：
<bean id="sessionFilter"> <property name="redisTemplate" ref="redisTemplate"/></bean>
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<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的实现：
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(); }}以上代码就能把session保存到redis，当然这其中还有很多问题，比如sessionId的生成，session过去，对象序列化（测试为了方便统一用了string），等等很多问题。以后有时间再完善。
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