java redis 问题

Posted 2023-03-23

代码如下：
public String getInfo(String infoName)
try
Jedis jedis = jedisPool.getResource();
try
String key = infoName+":" + infoName;
byte[] bytes = jedis.get(key.getBytes());
if (bytes != null)
String info = schema.newMessage();
ProtostuffIOUtil.mergeFrom(bytes, info, schema);
return info;

finally
jedis.close();

catch (java.lang.Exception e)
logger.error(e.getMessage(), e);

return null;


public String putInfo(String infoName,String info)
try
Jedis jedis = jedisPool.getResource();
try
String key = infoName+":" + info;
byte[] bytes = ProtostuffIOUtil.toByteArray(info, schema, LinkedBuffer.allocate(LinkedBuffer.DEFAULT_BUFFER_SIZE));
int timeout = 60 * 60;
String result=jedis.setex(key.getBytes(), timeout, bytes);
return result;
finally
jedis.close();

catch (Exception e)
logger.error(e.getMessage(), e);

return null;


public long getTotalPage()
if (redisDao.getInfo("totalPage") == null)
long allBlogCount = blogDao.getCount();
System.out.println("allBlogCount..............:"+allBlogCount);
redisDao.putInfo("totalPage", (allBlogCount / 8 + 1) + "");
return allBlogCount / 8 + 1;
else
System.out.println("totalPage..............: "+redisDao.getInfo("totalPage"));
return Long.getLong(redisDao.getInfo("totalPage"));



@RequestMapping("/")
public String home(Model model)
List<Blog> blogs = blogServiceImpl.queryAll(0, 0);
model.addAttribute("blogs", blogs);
model.addAttribute("categorys",categoryServiceImpl.queryAll());
model.addAttribute("pageIndex", 1);
System.out.println(redisDao.getInfo("totalPage")+" controller totalPage ");
model.addAttribute("totalPage",blogServiceImpl.getTotalPage()); // redisDao.getInfo("totalPage") 这行出错
return "/home";

提示：
org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [seckill-dispatcher] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause
java.lang.NullPointerException

参考技术A 错误很明显是空指针异常，点个debug运行，跟踪一下，一遍就能找出是哪个为空。redisDao.getInfo("totalPage")这句为空的话，很大可能是redisDao 是null,可以跟踪代码看一下，是不是没有实例化这个对象。 参考技术B redisDao是空的，看看有没有实例化