SpringCache
学习博客:
maven依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-cache</artifactId>
</dependency>
开启缓存
需要在启动类上开启缓存功能
常用注解:
@Cacheable # 一般用在查询方法上，将方法的返回值缓存起来
@CachePut # 一般用在新增方法上，将方法的返回值放到缓存使用
@CacheEvict # 一般用在更新或者删除的方法上，清楚缓存
@Caching
@CacheConfig
cacheName指定组件的名称,key指定缓存的key,key应当不重复
@EnableCaching
@SpringBootApplication
public class application{
public static void main(String[] args){
SpringApplication.run(application.class,args);
}
}
key的生成,默认使用
SimpleKeyGenerateor生成,源码如下,如果params为空,即无参,会返回SimpleKey.Empty生成一个空的SimpleKey类,当作key返回,如果参数单一且params不为空且param不为数组,直接将单数作为key返回,其他情况的话，像多参数或者是数组,转入SimpleKey构造SimpleKey。以上都是在未指定
key的情况下,
key属性和keyGenerator属性只能⼆选⼀
public class SimpleKeyGenerator implements KeyGenerator {
@Override
public Object generate(Object target, Method method, Object... params) {
return generateKey(params);
}
/**
* Generate a key based on the specified parameters.
*/
public static Object generateKey(Object... params) {
if (params.length == 0) {
return SimpleKey.EMPTY;
}
if (params.length == 1) {
Object param = params[0];
if (param != null && !param.getClass().isArray()) {
return param;
}
}
return new SimpleKey(params);
}
}
/*
* Copyright 2002-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.cache.interceptor;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.Arrays;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A simple key as returned from the {@link SimpleKeyGenerator}.
*
* @author Phillip Webb
* @author Juergen Hoeller
* @since 4.0
* @see SimpleKeyGenerator
*/
@SuppressWarnings("serial")
public class SimpleKey implements Serializable {
/**
* An empty key.
*/
public static final SimpleKey EMPTY = new SimpleKey();
private final Object[] params;
// Effectively final, just re-calculated on deserialization
private transient int hashCode;
/**
* Create a new {@link SimpleKey} instance.
* @param elements the elements of the key
*/
public SimpleKey(Object... elements) {
Assert.notNull(elements, "Elements must not be null");
this.params = elements.clone();
// Pre-calculate hashCode field
this.hashCode = Arrays.deepHashCode(this.params);
}
@Override
public boolean equals(@Nullable Object other) {
return (this == other ||
(other instanceof SimpleKey && Arrays.deepEquals(this.params, ((SimpleKey) other).params)));
}
@Override
public final int hashCode() {
// Expose pre-calculated hashCode field
return this.hashCode;
}
@Override
public String toString() {
return getClass().getSimpleName() + " [" + StringUtils.arrayToCommaDelimitedString(this.params) + "]";
}
private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
ois.defaultReadObject();
// Re-calculate hashCode field on deserialization
this.hashCode = Arrays.deepHashCode(this.params);
}
}
