RedisTemplate源码使用详解-opsForValue(一)

RedisTemplate 是spring集成的redis上层操作模版，底层集成了很多redis 的API,今天开始我们从源码的角度依次分析每个API接口的功能。

首先分析 RedisTemplate类：如下图

1、六种类型的API接口

    private @Nullable ValueOperations valueOps;
	private @Nullable ListOperations listOps;
	private @Nullable SetOperations setOps;
	private @Nullable ZSetOperations zSetOps;
	private @Nullable GeoOperations geoOps;
	private @Nullable HyperLogLogOperations hllOps;

1、取到数据源-opsForValue

    @Override
	public ValueOperations opsForValue() {

		if (valueOps == null) {
			valueOps = new DefaultValueOperations<>(this);
		}
		return valueOps;
	}

2、点击 DefaultValueOperations 类名，进入后显示其下所有API：

3、分析每个接口详情：

class DefaultValueOperations extends AbstractOperations implements ValueOperations {

	DefaultValueOperations(RedisTemplate template) {
		super(template);
	}

	/*
	 *  获取key键对应的值。
	 */
	@Override
	public V get(Object key) {

		return execute(new ValueDeserializingRedisCallback(key) {

			@Override
			protected byte[] inRedis(byte[] rawKey, RedisConnection connection) {
				return connection.get(rawKey);
			}
		}, true);
	}

	/*
	 *  获取原来key键对应的值并重新赋新值
	 */
	@Override
	public V getAndSet(K key, V newValue) {

		byte[] rawValue = rawValue(newValue);
		return execute(new ValueDeserializingRedisCallback(key) {

			@Override
			protected byte[] inRedis(byte[] rawKey, RedisConnection connection) {
				return connection.getSet(rawKey, rawValue);
			}
		}, true);
	}

	/*
	 *  以增量的方式将值存储在变量中。
	 */
	@Override
	public Long increment(K key) {

		byte[] rawKey = rawKey(key);
		return execute(connection -> connection.incr(rawKey), true);
	}

	/*
	 *  以增量的方式将long值存储在变量中。
	 */
	@Override
	public Long increment(K key, long delta) {

		byte[] rawKey = rawKey(key);
		return execute(connection -> connection.incrBy(rawKey, delta), true);
	}

	/*
	 * 以增量的方式将double值存储在变量中
	 */
	@Override
	public Double increment(K key, double delta) {

		byte[] rawKey = rawKey(key);
		return execute(connection -> connection.incrBy(rawKey, delta), true);
	}

	/*
	 *  以减量的方式将值存储在变量中。
	 */
	@Override
	public Long decrement(K key) {

		byte[] rawKey = rawKey(key);
		return execute(connection -> connection.decr(rawKey), true);
	}

	/*
	 *  以减量的方式将long值存储在变量中
	 */
	@Override
	public Long decrement(K key, long delta) {

		byte[] rawKey = rawKey(key);
		return execute(connection -> connection.decrBy(rawKey, delta), true);
	}

	/*
	 *  在原有的值基础上新增字符串到末尾
	 */
	@Override
	public Integer append(K key, String value) {

		byte[] rawKey = rawKey(key);
		byte[] rawString = rawString(value);

		return execute(connection -> {
			Long result = connection.append(rawKey, rawString);
			return (result != null) ? result.intValue() : null;
		}, true);
	}

	/*
	 *  截取key键对应值得字符串，从开始下标位置开始到结束下标的位置(包含结束下标)的字符串
	 */
	@Override
	public String get(K key, long start, long end) {
		byte[] rawKey = rawKey(key);
		byte[] rawReturn = execute(connection -> connection.getRange(rawKey, start, end), true);

		return deserializeString(rawReturn);
	}

	/*
	 *  根据集合取出对应的value值
	 */
	@Override
	public List multiGet(Collection keys) {

		if (keys.isEmpty()) {
			return Collections.emptyList();
		}

		byte[][] rawKeys = new byte[keys.size()][];

		int counter = 0;
		for (K hashKey : keys) {
			rawKeys[counter++] = rawKey(hashKey);
		}

		List rawValues = execute(connection -> connection.mGet(rawKeys), true);

		return deserializeValues(rawValues);
	}

	/*
	 *   设置map集合到redis
	 */
	@Override
	public void multiSet(Map m) {

		if (m.isEmpty()) {
			return;
		}

		Map rawKeys = new LinkedHashMap<>(m.size());

		for (Map.Entry entry : m.entrySet()) {
			rawKeys.put(rawKey(entry.getKey()), rawValue(entry.getValue()));
		}

		execute(connection -> {
			connection.mSet(rawKeys);
			return null;
		}, true);
	}

	/*
	 *  如果对应的map集合名称不存在，则添加，如果存在则不做修改
	 */
	@Override
	public Boolean multiSetIfAbsent(Map m) {

		if (m.isEmpty()) {
			return true;
		}

		Map rawKeys = new LinkedHashMap<>(m.size());

		for (Map.Entry entry : m.entrySet()) {
			rawKeys.put(rawKey(entry.getKey()), rawValue(entry.getValue()));
		}

		return execute(connection -> connection.mSetNX(rawKeys), true);
	}

	/*
	 *  新增一个字符串类型的值,key是键，value是值
	 */
	@Override
	public void set(K key, V value) {

		byte[] rawValue = rawValue(value);
		execute(new ValueDeserializingRedisCallback(key) {

			@Override
			protected byte[] inRedis(byte[] rawKey, RedisConnection connection) {
				connection.set(rawKey, rawValue);
				return null;
			}
		}, true);
	}

	/*
	 *  设置变量值的过期时间
	 */
	@Override
	public void set(K key, V value, long timeout, TimeUnit unit) {

		byte[] rawKey = rawKey(key);
		byte[] rawValue = rawValue(value);

		execute(new RedisCallback