Three ways to implement caching and summary of problems in Java

public class LocalCache {
    public static HashMap<String,String> cache = new HashMap<>();
    static {
        String name = ().toString();
        ((1),name);
        ("Data with id 1 is added to cache");
    }
}
// There are static code blocks modified by `static` in the class, which will be executed when the class is loaded. If you don't understand, you can follow the blog// /weixin_62636014/article/details/136851287

@Component
public class LocalCache {
    public static HashMap<String,String> cache = new HashMap<>();
    static {
        String name = ().toString();
        ((1),name);
        ("Data with id 1 is added to cache");
    }
    @PostConstruct
    public void init() {
        String name = ().toString();
        ((2),name);
        ("Data with id 2 is added to cache");
    }
}

@RequestMapping("test")
public String test(Long id) {
    String name = ((id));
    if (name != null) {
        ("Exist in cache, query cache");
        (name);
        return name;
    }
    ("Do not exist in the cache, query the database");
    // After querying the database operation, the queryDataName method is not written;    // You can match Mybatis and JDBC to query the database yourself. The result is to find out the name from the library;    name = queryDataName(id);
    (name);
    ((id),name);
    return name;
}
public String queryDataName(Long id) {
    String name = ().toString();
    return name;
}

<dependency>
            <groupId></groupId>
            <artifactId>guava</artifactId>
            <version>32.1.3-jre</version>
        </dependency>

import ;
import ;
import ;
import ;
@Component
public class GuavaLocalCache{
    private Cache<String,String> fiveSecondCache = ()
        //Set the initial cache size, it should be set reasonably, and the capacity will be expanded in the future        .initalCapacity(10)
        //Maximum value        .maximumSize(100)
        //Concurrent number setting        .concurrencyLevel(5)
        //Cached expiration time, expires 5 seconds after writing        .expireAfterWrite(5,)
        //Statistics of cache hit rate        .recordStats()
        .build()
    public Cache<String,String> getFiveSecondCache() {
        return fiveSecondCache;
    } // Here is to get the cache object.    public void setFiveSecondCache(Cache<String,String> fiveSecondCache) {
         = fiveSecondCache;
    }
}

public class test {
    @Autowired
    private GuavaLocalCache guavaLocalCache;
    @RequestMapping("guavaTest")
    public String guavaTest(Long id) {
        // Get cache        Cache<String,String> fiveSecondCache = ();
        // Get object from cache        String nameCache = ((id));
        // Exist in the cache        if (nameCache != null) {
            ("Cached Hit:"+ nameCache + "," + getCacheStats(fiveSecondCache));
            return nameCache;
        }
        // Save data into cache        ("Cached Miss," + getCacheStats(fiveSecondCache));
        nameCache = id + "-" + ().toString();
        ((id),nameCache);
        return nameCache;
    }
    public String getCacheStats(Cache<String,String> cahce) {
        CacheStats stats = ();
        return "Buffer hit rate:"+() +"Cleared buffer count:" + ();
    }
}

        <dependency>
            <groupId></groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

  redis:
    # IP address    host: 
    # password    password: XXXXXXXX
    # port, default is 6379    port: 6379
    # Database Index    database: 0
    # Connection timeout    timeout: 10s
    lettuce:
      pool:
        # Minimum idle connection in the connection pool        min-idle: 1
        # Maximum free connection in the connection pool        max-idle: 8
        # Maximum number of database connections to the connection pool        max-active: 8
        # #Maximum blocking waiting time for connection pools (using negative values ​​means there is no limit)        max-wait: -1ms

public class TestRedis{
    // The following StringRedisTemplate is a class inherited from RedisTemplate    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @RequestMapping("/redisTest")
    public String redisCacheTest(Long id){
        String name = ().get((id));
        if (name != null){
            ("Exist in cache, query cache");
            (name);
            return name;
        }
        ("Do not exist in the cache, query the database");
        name = id + "-" + ().toString();
        (name);
        ().set((id),name);
        return name;
    }
}