本文来源于我的另一篇博客，由于另一篇博客不再更新，遂 全部转入CSDN

注：redis服务器要先开启! 或者连接远程服务器上的 Redis,但是依然要开启服务，不然会一直 TimeOut! 欢迎关注公众哦，每日推文

Pom文件添加依赖

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

配置 application.properties

# redis
# Redis数据库索引（默认为0）
spring.redis.database=0
# Redis服务器地址
spring.redis.host=localhost
# Redis服务器连接端口
spring.redis.port=6379
# Redis服务器连接密码（默认为空）
spring.redis.password=
# 连接池最大连接数（使用负值表示没有限制）
spring.redis.jedis.pool.max-active=20
# 连接池最大阻塞等待时间（使用负值表示没有限制）
spring.redis.jedis.pool.max-wait=-1
# 连接池中的最大空闲连接
spring.redis.jedis.pool.max-idle=10
# 连接池中的最小空闲连接
spring.redis.jedis.pool.min-idle=0
# 连接超时时间（毫秒）
spring.redis.timeout=1000

缓存测试

配置文件写完之后基础环境也算是已经搭建好了，开始测试使用 Test
接下来 我们测试上代码：

    //注入redisTemplate
    @Autowired
    private StringRedisTemplate redisTemplate;

    /** 
     * 存入缓存键 key：value
     * 			first ：siwei
     * 			second：siweiWu （30秒过期时间）
     */
    @Test
    public void setRedis() {　　　　 
        //缓存中最常用的方法
        redisTemplate.opsForValue().set("first","siwei");　　　
        　
         //设置缓存过期时间为30   单位：秒　　　　 
         //关于TimeUnit下面有部分源码截图
        redisTemplate.opsForValue().set("second","siweiWu",30, TimeUnit.SECONDS);
        System.out.println("存入缓存成功");
    }


    /** 
     * 根据key 获取 value
     */
    @Test
    public void getRedis(){
        String first = redisTemplate.opsForValue().get("first");
        String second = redisTemplate.opsForValue().get("second");

        System.out.println("取出缓存中first的数据是:"+first);
        System.out.println("取出缓存中second的数据是:"+second);

    }


    /** 
     * 根据key 删除缓存
     */
    @Test
    public void delRedis() {
        //根据key删除缓存
        Boolean first = redisTemplate.delete("first");

        System.out.println("是否删除成功:"+first);
    }

项目开发使用

贴上公司日常项目开发中使用的缓存服务层代码（可直接拷贝使用，我把包也贴出来，自行导包奥～
请原谅我不会折叠代码,MarkDown语法的小菜鸡一枚～）

• RedisService 服务层接口代码

import org.springframework.data.redis.core.ListOperations;

import java.util.List;
import java.util.Set;


/**
* @author wusw
* @date 2020/4/16 13:11
*/
public interface RedisService {


    /**
     * 添加 key:string 缓存
     *
     * @param key    key
     * @param value    value
     * @param time time
     * @return
     */
    boolean cacheValue(String key, String value, long time);


    /**
     * 添加 key:string 缓存
     *
     * @param key   key
     * @param value value
     * @return
     */
    boolean cacheValue(String key, String value);


    /**
     * 根据 key:string 判断缓存是否存在
     *
     * @param key key
     * @return boolean
     */
    boolean containsValueKey(String key);


    /**
     * 判断缓存 key:set集合 是否存在
     *
     * @param key key
     * @return
     */
    boolean containsSetKey(String key);


    /**
     * 判断缓存 key:list集合 是否存在
     *
     * @param key key
     * @return boolean
     */
    boolean containsListKey(String key);


    /**
     * 查询缓存 key 是否存在
     * @param key key
     * @return true/false
     */
    boolean containsKey(String key);


    /**
     * 根据 key 获取缓存value
     *
     * @param key key
     * @return value
     */
    String getValue(String key);


    /**
     * 根据 key 移除 value 缓存
     *
     * @param key key
     * @return true/false
     */
    boolean removeValue(String key);


    /**
     * 根据 key 移除 set 缓存
     *
     * @param key key
     * @return true/false
     */
    boolean removeSet(String key);


    /**
     * 根据 key 移除 list 缓存
     *
     * @param key key
     * @return true/false
     */
    boolean removeList(String key);


    /**
     * 缓存set操作
     *
     * @param key    key
     * @param value    value
     * @param time time
     * @return boolean
     */
    boolean cacheSet(String key, String value, long time);


    /**
     * 添加 set 缓存
     *
     * @param key   key
     * @param value value
     * @return true/false
     */
    boolean cacheSet(String key, String value);


    /**
     * 添加 缓存 set
     *
     * @param k    key
     * @param v    value
     * @param time 时间
     * @return
     */
    boolean cacheSet(String k, Set<String> v, long time);


    /**
     * 缓存 set
     * @param k key
     * @param v value
     * @return
     */
    boolean cacheSet(String k, Set<String> v);


    /**
     * 获取缓存set数据
     * @param k key
     * @return set集合
     */
    Set<String> getSet(String k);


    /**
     * list 缓存
     * @param k key
     * @param v value
     * @param time 时间
     * @return true/false
     */
    boolean cacheList(String k, String v, long time);


    /**
     * 缓存 list
     * @param k key
     * @param v value
     * @return true/false
     */
    boolean cacheList(String k, String v);


    /**
     * 缓存 list 集合
     * @param k key
     * @param v value
     * @param time 时间
     * @return
     */
    boolean cacheList(String k, List<String> v, long time);


    /**
     *  缓存 list
     * @param k key
     * @param v value
     * @return true/false
     */
    boolean cacheList(String k, List<String> v);


    /**
     * 根据 key 获取 list 缓存
     * @param k key
     * @param start 开始
     * @param end 结束
     * @return 获取缓存区间内 所有value
     */
    List<String> getList(String k, long start, long end);


    /**
     * 根据 key 获取总条数 用于分页
     * @param key key
     * @return 条数
     */
    long getListSize(String key);


    /**
     * 获取总条数 用于分页
     * @param listOps =redisTemplate.opsForList();
     * @param k key
     * @return size
     */
    long getListSize(ListOperations<String, String> listOps, String k);


    /**
     * 根据 key 移除 list 缓存
     * @param k key
     * @return
     */
    boolean removeOneOfList(String k);
}

• RedisServiceImpl 服务层实现类代码

import com.technologies.bear.service.RedisService;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.ListOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.SetOperations;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;
import java.util.List;
import java.util.Set;
import java.util.concurrent.TimeUnit;


/**
* @author wusw
* @date 2020/4/16 13:11
*/
@Service
public class RedisServiceImpl implements RedisService {
    /**
     * slf4j 日志
     */
    private final Logger log = LoggerFactory.getLogger(this.getClass());


    /**
     * 自定义 key 三种
     *  String key:String value         普通key:value
     *  String key:Set<String> set      key:set集合
     *  String key:List<String> list    key:list集合
     */
    private static final String KEY_PREFIX_KEY = "info:bear:key";
    private static final String KEY_PREFIX_SET = "info:bear:set";
    private static final String KEY_PREFIX_LIST = "info:bear:list";


    private final RedisTemplate<String, String> redisTemplate;


    /**
     * 注入
     * @param redisTemplate 模板
     */
    @Autowired
    public RedisServiceImpl(RedisTemplate<String, String> redisTemplate) {
        this.redisTemplate = redisTemplate;
    }


    /**
     * 添加 key:string 缓存
     *
     * @param k    key
     * @param v    value
     * @param time time
     * @return
     */
    @Override
    public boolean cacheValue(String k, String v, long time) {
        try {
            String key = KEY_PREFIX_KEY + k;
            ValueOperations<String, String> ops = redisTemplate.opsForValue();
            ops.set(key, v);
            if (time > 0) {
                redisTemplate.expire(key, time, TimeUnit.SECONDS);
            }
            return true;
        } catch (Throwable e) {
            log.error("缓存存入失败key:[{}] value:[{}]", k, v);
        }
        return false;
    }


    /**
     * 添加 key:string 缓存
     *
     * @param key   key
     * @param value value
     * @return
     */
    @Override
    public boolean cacheValue(String key, String value) {
        return cacheValue(key, value, -1);
    }


    /**
     * 根据 key:string 判断缓存是否存在
     *
     * @param key key
     * @return boolean
     */
    @Override
    public boolean containsValueKey(String key) {
        return containsKey(KEY_PREFIX_KEY + key);
    }


    /**
     * 判断缓存 key:set集合 是否存在
     *
     * @param key key
     * @return
     */
    @Override
    public boolean containsSetKey(String key) {
        return containsKey(KEY_PREFIX_SET + key);
    }


    /**
     * 判断缓存 key:list集合 是否存在
     *
     * @param key key
     * @return boolean
     */
    @Override
    public boolean containsListKey(String key) {
        return containsKey(KEY_PREFIX_LIST + key);
    }


    /**
     * 查询缓存 key 是否存在
     * @param key key
     * @return true/false
     */
    @Override
    public boolean containsKey(String key) {
        try {
            return redisTemplate.hasKey(key);
        } catch (Throwable e) {
            log.error("判断缓存存在失败key:[" + key + "],错误信息 Codeor[{}]", e);
        }
        return false;
    }


    /**
     * 根据 key 获取缓存value
     *
     * @param key key
     * @return value
     */
    @Override
    public String getValue(String key) {
        try {
            ValueOperations<String, String> ops = redisTemplate.opsForValue();
            return ops.get(KEY_PREFIX_KEY + key);
        } catch (Throwable e) {
            log.error("根据 key 获取缓存失败，当前key:[{}],失败原因 Codeor:[{}]", key, e);
        }
        return null;
    }


    /**
     * 缓存set操作
     *
     * @param k    key
     * @param v    value
     * @param time time
     * @return boolean
     */
    @Override
    public boolean cacheSet(String k, String v, long time) {
        try {
            String key = KEY_PREFIX_SET + k;
            SetOperations<String, String> opsForSet = redisTemplate.opsForSet();
            opsForSet.add(key, v);
            if (time > 0) {
                redisTemplate.expire(key, time, TimeUnit.SECONDS);
            }
            return true;
        } catch (Throwable e) {
            log.error("缓存 set 失败 当前 key:[{}] 失败原因 [{}]", k, e);
        }
        return false;
    }


    /**
     * 添加 set 缓存
     *
     * @param key   key
     * @param value value
     * @return true/false
     */
    @Override
    public boolean cacheSet(String key, String value) {
        return cacheSet(key, value, -1);
    }


    /**
     * 添加 缓存 set
     *
     * @param k    key
     * @param v    value
     * @param time 时间
     * @return
     */
    @Override
    public boolean cacheSet(String k, Set<String> v, long time) {
        try {
            String key = KEY_PREFIX_SET + k;
            SetOperations<String, String> opsForSet = redisTemplate.opsForSet();
            opsForSet.add(key, v.toArray(new String[v.size()]));
            if (time > 0){
                redisTemplate.expire(key,time,TimeUnit.SECONDS);
            }
            return true;
        } catch (Throwable e) {
            log.error("缓存 set 失败 当前 key:[{}],失败原因 [{}]", k, e);
        }
        return false;
    }


    /**
     * 缓存 set
     * @param k key
     * @param v value
     * @return
     */
    @Override
    public boolean cacheSet(String k, Set<String> v) {
        return cacheSet(k,v,-1);
    }


    /**
     * 获取缓存set数据
     * @param k key
     * @return set集合
     */
    @Override
    public Set<String> getSet(String k) {
        try {
            String key = KEY_PREFIX_SET + k;
            SetOperations<String, String> opsForSet = redisTemplate.opsForSet();
            return opsForSet.members(key);
        }catch (Throwable e){
            log.error("获取缓存set失败 当前 key:[{}],失败原因 [{}]", k, e);
        }
        return null;
    }


    /**
     * list 缓存
     * @param k key
     * @param v value
     * @param time 时间
     * @return true/false
     */
    @Override
    public boolean cacheList(String k, String v, long time) {
        try {
            String key = KEY_PREFIX_LIST + k;
            ListOperations<String, String> opsForList = redisTemplate.opsForList();
            //此处为right push 方法/ 也可以 left push ..
            opsForList.rightPush(key,v);
            if (time > 0){
                redisTemplate.expire(key,time,TimeUnit.SECONDS);
            }
            return true;
        }catch (Throwable e){
            log.error("缓存list失败 当前 key:[{}],失败原因 [{}]", k, e);
        }
        return false;
    }


    /**
     * 缓存 list
     * @param k key
     * @param v value
     * @return true/false
     */
    @Override
    public boolean cacheList(String k, String v) {
        return cacheList(k,v,-1);
    }


    /**
     * 缓存 list 集合
     * @param k key
     * @param v value
     * @param time 时间
     * @return
     */
    @Override
    public boolean cacheList(String k, List<String> v, long time) {
        try {
            String key = KEY_PREFIX_LIST + k;
            ListOperations<String, String> opsForList = redisTemplate.opsForList();
            opsForList.rightPushAll(key,v);
            if (time > 0){
                redisTemplate.expire(key,time,TimeUnit.SECONDS);
            }
            return true;
        }catch (Throwable e){
            log.error("缓存list失败 当前 key:[{}],失败原因 [{}]", k, e);
        }
        return false;
    }


    /**
     *  缓存 list
     * @param k key
     * @param v value
     * @return true/false
     */
    @Override
    public boolean cacheList(String k, List<String> v) {
        return cacheList(k,v,-1);
    }


    /**
     * 根据 key 获取 list 缓存
     * @param k key
     * @param start 开始
     * @param end 结束
     * @return 获取缓存区间内 所有value
     */
    @Override
    public List<String> getList(String k, long start, long end) {
        try {
            String key = KEY_PREFIX_LIST + k;
            ListOperations<String, String> opsForList = redisTemplate.opsForList();
            return opsForList.range(key,start,end);
        }catch (Throwable e){
            log.error("获取list缓存失败 当前 key:[{}],失败原因 [{}]", k, e);
        }
        return null;
    }


    /**
     * 根据 key 获取总条数 用于分页
     * @param key key
     * @return 条数
     */
    @Override
    public long getListSize(String key) {
        try {
            ListOperations<String, String> opsForList = redisTemplate.opsForList();
            return opsForList.size(KEY_PREFIX_LIST + key);
        }catch (Throwable e){
            log.error("获取list长度失败key[" + KEY_PREFIX_LIST + key + "], Codeor[" + e + "]");
        }
        return 0;
    }


    /**
     * 获取总条数 用于分页
     * @param listOps =redisTemplate.opsForList();
     * @param k key
     * @return size
     */
    @Override
    public long getListSize(ListOperations<String, String> listOps, String k) {
        try {
            return listOps.size(k);
        }catch (Throwable e){
            log.error("获取list长度失败key[" + KEY_PREFIX_LIST + k + "], Codeor[" + e + "]");
        }
        return 0;
    }


    /**
     * 根据 key 移除 list 缓存
     * @param k key
     * @return
     */
    @Override
    public boolean removeOneOfList(String k) {
        try {
            String key = KEY_PREFIX_LIST + k;
            ListOperations<String, String> opsForList = redisTemplate.opsForList();
            opsForList.rightPop(key);
            return true;
        }catch (Throwable e){
            log.error("移除list缓存失败 key[" + KEY_PREFIX_LIST + k + "], Codeor[" + e + "]");
        }
        return false;
    }


    /**
     * 根据 key 移除 value 缓存
     *
     * @param key key
     * @return true/false
     */
    @Override
    public boolean removeValue(String key) {
        return remove(KEY_PREFIX_KEY + key);
    }


    /**
     * 根据 key 移除 set 缓存
     *
     * @param key key
     * @return true/false
     */
    @Override
    public boolean removeSet(String key) {
        return remove(KEY_PREFIX_SET + key);
    }


    /**
     * 根据 key 移除 list 缓存
     *
     * @param key key
     * @return true/false
     */
    @Override
    public boolean removeList(String key) {
        return remove(KEY_PREFIX_LIST + key);
    }


    /**
     * 移除缓存
     *
     * @param key key
     * @return boolean
     */
    private boolean remove(String key) {
        try {
            redisTemplate.delete(key);
            return true;
        } catch (Throwable e) {
            log.error("移除缓存失败 key:[{}] 失败原因 [{}]", key, e);
        }
        return false;
    }
}

注：其他 Service 层使用时，只需要将 RedisService 注入即可像普通Service层一样调用

常用方法总结

StringRedisTemplate相关方法我也总结了一下，可能不是很全 不过还是够用了

TimeUnit源码

上面设置缓存过期时间的TimeUnit源码 部分截图说明(后面会附上全部的源码——总390行，)：

全部源码：

/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

/*
 *
 *
 *
 *
 *
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

package java.util.concurrent;

/**
 * A {@code TimeUnit} represents time durations at a given unit of
 * granularity and provides utility methods to convert across units,
 * and to perform timing and delay operations in these units.  A
 * {@code TimeUnit} does not maintain time information, but only
 * helps organize and use time representations that may be maintained
 * separately across various contexts.  A nanosecond is defined as one
 * thousandth of a microsecond, a microsecond as one thousandth of a
 * millisecond, a millisecond as one thousandth of a second, a minute
 * as sixty seconds, an hour as sixty minutes, and a day as twenty four
 * hours.
 *
 * <p>A {@code TimeUnit} is mainly used to inform time-based methods
 * how a given timing parameter should be interpreted. For example,
 * the following code will timeout in 50 milliseconds if the {@link
 * java.util.concurrent.locks.Lock lock} is not available:
 *
 *  <pre> {@code
 * Lock lock = ...;
 * if (lock.tryLock(50L, TimeUnit.MILLISECONDS)) ...}</pre>
 *
 * while this code will timeout in 50 seconds:
 *  <pre> {@code
 * Lock lock = ...;
 * if (lock.tryLock(50L, TimeUnit.SECONDS)) ...}</pre>
 *
 * Note however, that there is no guarantee that a particular timeout
 * implementation will be able to notice the passage of time at the
 * same granularity as the given {@code TimeUnit}.
 *
 * @since 1.5
 * @author Doug Lea
 */
public enum TimeUnit {
    /**
     * Time unit representing one thousandth of a microsecond
     */
    NANOSECONDS {
        public long toNanos(long d)   { return d; }
        public long toMicros(long d)  { return d/(C1/C0); }
        public long toMillis(long d)  { return d/(C2/C0); }
        public long toSeconds(long d) { return d/(C3/C0); }
        public long toMinutes(long d) { return d/(C4/C0); }
        public long toHours(long d)   { return d/(C5/C0); }
        public long toDays(long d)    { return d/(C6/C0); }
        public long convert(long d, TimeUnit u) { return u.toNanos(d); }
        int excessNanos(long d, long m) { return (int)(d - (m*C2)); }
    },

    /**
     * Time unit representing one thousandth of a millisecond
     */
    MICROSECONDS {
        public long toNanos(long d)   { return x(d, C1/C0, MAX/(C1/C0)); }
        public long toMicros(long d)  { return d; }
        public long toMillis(long d)  { return d/(C2/C1); }
        public long toSeconds(long d) { return d/(C3/C1); }
        public long toMinutes(long d) { return d/(C4/C1); }
        public long toHours(long d)   { return d/(C5/C1); }
        public long toDays(long d)    { return d/(C6/C1); }
        public long convert(long d, TimeUnit u) { return u.toMicros(d); }
        int excessNanos(long d, long m) { return (int)((d*C1) - (m*C2)); }
    },

    /**
     * Time unit representing one thousandth of a second
     */
    MILLISECONDS {
        public long toNanos(long d)   { return x(d, C2/C0, MAX/(C2/C0)); }
        public long toMicros(long d)  { return x(d, C2/C1, MAX/(C2/C1)); }
        public long toMillis(long d)  { return d; }
        public long toSeconds(long d) { return d/(C3/C2); }
        public long toMinutes(long d) { return d/(C4/C2); }
        public long toHours(long d)   { return d/(C5/C2); }
        public long toDays(long d)    { return d/(C6/C2); }
        public long convert(long d, TimeUnit u) { return u.toMillis(d); }
        int excessNanos(long d, long m) { return 0; }
    },

    /**
     * Time unit representing one second
     */
    SECONDS {
        public long toNanos(long d)   { return x(d, C3/C0, MAX/(C3/C0)); }
        public long toMicros(long d)  { return x(d, C3/C1, MAX/(C3/C1)); }
        public long toMillis(long d)  { return x(d, C3/C2, MAX/(C3/C2)); }
        public long toSeconds(long d) { return d; }
        public long toMinutes(long d) { return d/(C4/C3); }
        public long toHours(long d)   { return d/(C5/C3); }
        public long toDays(long d)    { return d/(C6/C3); }
        public long convert(long d, TimeUnit u) { return u.toSeconds(d); }
        int excessNanos(long d, long m) { return 0; }
    },

    /**
     * Time unit representing sixty seconds
     */
    MINUTES {
        public long toNanos(long d)   { return x(d, C4/C0, MAX/(C4/C0)); }
        public long toMicros(long d)  { return x(d, C4/C1, MAX/(C4/C1)); }
        public long toMillis(long d)  { return x(d, C4/C2, MAX/(C4/C2)); }
        public long toSeconds(long d) { return x(d, C4/C3, MAX/(C4/C3)); }
        public long toMinutes(long d) { return d; }
        public long toHours(long d)   { return d/(C5/C4); }
        public long toDays(long d)    { return d/(C6/C4); }
        public long convert(long d, TimeUnit u) { return u.toMinutes(d); }
        int excessNanos(long d, long m) { return 0; }
    },

    /**
     * Time unit representing sixty minutes
     */
    HOURS {
        public long toNanos(long d)   { return x(d, C5/C0, MAX/(C5/C0)); }
        public long toMicros(long d)  { return x(d, C5/C1, MAX/(C5/C1)); }
        public long toMillis(long d)  { return x(d, C5/C2, MAX/(C5/C2)); }
        public long toSeconds(long d) { return x(d, C5/C3, MAX/(C5/C3)); }
        public long toMinutes(long d) { return x(d, C5/C4, MAX/(C5/C4)); }
        public long toHours(long d)   { return d; }
        public long toDays(long d)    { return d/(C6/C5); }
        public long convert(long d, TimeUnit u) { return u.toHours(d); }
        int excessNanos(long d, long m) { return 0; }
    },

    /**
     * Time unit representing twenty four hours
     */
    DAYS {
        public long toNanos(long d)   { return x(d, C6/C0, MAX/(C6/C0)); }
        public long toMicros(long d)  { return x(d, C6/C1, MAX/(C6/C1)); }
        public long toMillis(long d)  { return x(d, C6/C2, MAX/(C6/C2)); }
        public long toSeconds(long d) { return x(d, C6/C3, MAX/(C6/C3)); }
        public long toMinutes(long d) { return x(d, C6/C4, MAX/(C6/C4)); }
        public long toHours(long d)   { return x(d, C6/C5, MAX/(C6/C5)); }
        public long toDays(long d)    { return d; }
        public long convert(long d, TimeUnit u) { return u.toDays(d); }
        int excessNanos(long d, long m) { return 0; }
    };

    // Handy constants for conversion methods
    static final long C0 = 1L;
    static final long C1 = C0 * 1000L;
    static final long C2 = C1 * 1000L;
    static final long C3 = C2 * 1000L;
    static final long C4 = C3 * 60L;
    static final long C5 = C4 * 60L;
    static final long C6 = C5 * 24L;

    static final long MAX = Long.MAX_VALUE;

    /**
     * Scale d by m, checking for overflow.
     * This has a short name to make above code more readable.
     */
    static long x(long d, long m, long over) {
        if (d >  over) return Long.MAX_VALUE;
        if (d < -over) return Long.MIN_VALUE;
        return d * m;
    }

    // To maintain full signature compatibility with 1.5, and to improve the
    // clarity of the generated javadoc (see 6287639: Abstract methods in
    // enum classes should not be listed as abstract), method convert
    // etc. are not declared abstract but otherwise act as abstract methods.

    /**
     * Converts the given time duration in the given unit to this unit.
     * Conversions from finer to coarser granularities truncate, so
     * lose precision. For example, converting {@code 999} milliseconds
     * to seconds results in {@code 0}. Conversions from coarser to
     * finer granularities with arguments that would numerically
     * overflow saturate to {@code Long.MIN_VALUE} if negative or
     * {@code Long.MAX_VALUE} if positive.
     *
     * <p>For example, to convert 10 minutes to milliseconds, use:
     * {@code TimeUnit.MILLISECONDS.convert(10L, TimeUnit.MINUTES)}
     *
     * @param sourceDuration the time duration in the given {@code sourceUnit}
     * @param sourceUnit the unit of the {@code sourceDuration} argument
     * @return the converted duration in this unit,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long convert(long sourceDuration, TimeUnit sourceUnit) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) NANOSECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toNanos(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MICROSECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toMicros(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MILLISECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toMillis(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) SECONDS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     */
    public long toSeconds(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) MINUTES.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     * @since 1.6
     */
    public long toMinutes(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) HOURS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration,
     * or {@code Long.MIN_VALUE} if conversion would negatively
     * overflow, or {@code Long.MAX_VALUE} if it would positively overflow.
     * @since 1.6
     */
    public long toHours(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Equivalent to
     * {@link #convert(long, TimeUnit) DAYS.convert(duration, this)}.
     * @param duration the duration
     * @return the converted duration
     * @since 1.6
     */
    public long toDays(long duration) {
        throw new AbstractMethodError();
    }

    /**
     * Utility to compute the excess-nanosecond argument to wait,
     * sleep, join.
     * @param d the duration
     * @param m the number of milliseconds
     * @return the number of nanoseconds
     */
    abstract int excessNanos(long d, long m);

    /**
     * Performs a timed {@link Object#wait(long, int) Object.wait}
     * using this time unit.
     * This is a convenience method that converts timeout arguments
     * into the form required by the {@code Object.wait} method.
     *
     * <p>For example, you could implement a blocking {@code poll}
     * method (see {@link BlockingQueue#poll BlockingQueue.poll})
     * using:
     *
     *  <pre> {@code
     * public synchronized Object poll(long timeout, TimeUnit unit)
     *     throws InterruptedException {
     *   while (empty) {
     *     unit.timedWait(this, timeout);
     *     ...
     *   }
     * }}</pre>
     *
     * @param obj the object to wait on
     * @param timeout the maximum time to wait. If less than
     * or equal to zero, do not wait at all.
     * @throws InterruptedException if interrupted while waiting
     */
    public void timedWait(Object obj, long timeout)
            throws InterruptedException {
        if (timeout > 0) {
            long ms = toMillis(timeout);
            int ns = excessNanos(timeout, ms);
            obj.wait(ms, ns);
        }
    }

    /**
     * Performs a timed {@link Thread#join(long, int) Thread.join}
     * using this time unit.
     * This is a convenience method that converts time arguments into the
     * form required by the {@code Thread.join} method.
     *
     * @param thread the thread to wait for
     * @param timeout the maximum time to wait. If less than
     * or equal to zero, do not wait at all.
     * @throws InterruptedException if interrupted while waiting
     */
    public void timedJoin(Thread thread, long timeout)
            throws InterruptedException {
        if (timeout > 0) {
            long ms = toMillis(timeout);
            int ns = excessNanos(timeout, ms);
            thread.join(ms, ns);
        }
    }

    /**
     * Performs a {@link Thread#sleep(long, int) Thread.sleep} using
     * this time unit.
     * This is a convenience method that converts time arguments into the
     * form required by the {@code Thread.sleep} method.
     *
     * @param timeout the minimum time to sleep. If less than
     * or equal to zero, do not sleep at all.
     * @throws InterruptedException if interrupted while sleeping
     */
    public void sleep(long timeout) throws InterruptedException {
        if (timeout > 0) {
            long ms = toMillis(timeout);
            int ns = excessNanos(timeout, ms);
            Thread.sleep(ms, ns);
        }
    }

}

---

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