springboot增加注解缓存@Cacheable的实现

springboot增加注解缓存@cacheable

业务层使用

@cacheable(value = "dictionary#1800", key = "#root.targetclass.simplename +':'+ #root.methodname +':'+ #code")
    public object findbycode(string code) {
        //业务
    }

配置

import org.springframework.cache.cache;
import org.springframework.data.redis.cache.rediscache;
import org.springframework.data.redis.cache.rediscachemanager;
import org.springframework.data.redis.core.redisoperations; 
import java.util.concurrent.concurrenthashmap;
import java.util.concurrent.concurrentmap;
 
public class myrediscachemanager extends rediscachemanager {  
    /**
     * 过期时间分隔符
     */
    private static final string ttlseparator = "#";
    private final concurrentmap<string, cache> cachemap = new concurrenthashmap(16);
    /**
     * 过期时间, 单位为 秒
     */
    private long defaultexpiration = 0;  
    public myrediscachemanager(redisoperations redisoperations) {
        super(redisoperations);
    } 
 
    @override
    public cache getcache(string name) { 
        long expiredtime = defaultexpiration;
        if (name.contains(ttlseparator)) {
            string[] split = name.split(ttlseparator);
            string cachename = split[0];
            try {
                expiredtime = double.valueof(split[1]).longvalue();
            } catch (exception e) {
                e.printstacktrace();
            }
            cache cache = this.cachemap.get(name);
            if (cache != null) {
                return cache;
            } else {
                synchronized (this.cachemap) {
                    cache = this.cachemap.get(name);
                    if (cache == null) {
                        cache = new rediscache(cachename, null, super.getredisoperations(), expiredtime);
                        if (cache != null) {
                            cache = this.decoratecache(cache);
                            this.cachemap.put(name, cache);
                        }
                    }
 
                    return cache;
                }
            }
        } 
        return super.getcache(name);
    }  
}

import com.fasterxml.jackson.annotation.jsontypeinfo;
import com.fasterxml.jackson.databind.objectmapper;
import org.springframework.cache.cachemanager;
import org.springframework.cache.annotation.cacheconfig;
import org.springframework.cache.annotation.cachingconfigurersupport;
import org.springframework.cache.annotation.enablecaching;
import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;
import org.springframework.data.redis.core.redistemplate;
import org.springframework.data.redis.serializer.genericjackson2jsonredisserializer;
import org.springframework.data.redis.serializer.stringredisserializer;
 
@cacheconfig
@configuration
@enablecaching
public class redisconfig extends cachingconfigurersupport {
 
    @bean
    public cachemanager cachemanager(redistemplate redistemplate) {
        //设置序列化key的实例化对象
        redistemplate.setkeyserializer(new stringredisserializer());
        //设置序列化value的实例化对象 
        objectmapper mapper = new objectmapper();
        mapper.findandregistermodules();
        mapper.enabledefaulttyping(objectmapper.defaulttyping.non_final, jsontypeinfo.as.property);
        genericjackson2jsonredisserializer serializer = new genericjackson2jsonredisserializer(mapper);
        redistemplate.setvalueserializer(serializer);
        myrediscachemanager mrc = new myrediscachemanager(redistemplate);
        return mrc;
    } 
}

@cacheable注解的属性使用

cachenames和value

指定缓存组件的名字，通过下面代码可以看出可以将返回结果放在哪个缓存中，可以通过数组的方式指定多个缓存

 /**
  * alias for {@link #cachenames}.
  */
 @aliasfor("cachenames")
 string[] value() default {};
 /**
  * names of the caches in which method invocation results are stored.
  * <p>names may be used to determine the target cache (or caches), matching
  * the qualifier value or bean name of a specific bean definition.
  * @since 4.2
  * @see #value
  * @see cacheconfig#cachenames
  */
 @aliasfor("value")
 string[] cachenames() default {};

key

缓存数据的时候使用的key，它是用来指定对应的缓存，模拟使用方法参数值作为key的值。也可以使用spel表达式的值来指定

 /**
  * spring expression language (spel) expression for computing the key dynamically.
  * <p>default is {@code ""}, meaning all method parameters are considered as a key,
  * unless a custom {@link #keygenerator} has been configured.
  * <p>the spel expression evaluates against a dedicated context that provides the
  * following meta-data:
  * <ul>
  * <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
  * references to the {@link java.lang.reflect.method method}, target object, and
  * affected cache(s) respectively.</li>
  * <li>shortcuts for the method name ({@code #root.methodname}) and target class
  * ({@code #root.targetclass}) are also available.
  * <li>method arguments can be accessed by index. for instance the second argument
  * can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. arguments
  * can also be accessed by name if that information is available.</li>
  * </ul>
  */
 string key() default "";

名称	位置	描述	示例
methodname	root object	被调用的方法名称	#root.methodname
method	root object	被调用的方法	#root.method.name
target	root object	当前被调用的目标对象	#root.target
targetclass	root object	当前被调用的目标对象类	#root.targetclass
args	root object	被调用方法的参数列表#root.args[0]
caches	root object	调用的缓存列表	#root.caches[0].name
argument name	evaluation context	方法的参数名称可以直接使用#参数名	#p0,#a0等等
result	evaluation context	执行方法后的返回值	#result

可以通过这个参数提示列表看看到这个key所支持的root object对象有哪些，通过这样的方式可以指定对应的key值。

keygenerator

这个是表示指定的key的生成器，当然在之前分享中我们说过一个简单的key的生成策略。这里我们还可以通过自定的方式来实现这个key的生成策略。

keygenerator

这个是表示指定的key的生成器，当然在之前分享中我们说过一个简单的key的生成策略。这里我们还可以通过自定的方式来实现这个key的生成策略。

import org.springframework.cache.interceptor.keygenerator;
import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;
import java.lang.reflect.method;
import java.util.arrays;
@configuration
public class mycacheconfig {
    @bean("mykeygenerator")
    public keygenerator keygenerator(){
        return new keygenerator() {
            @override
            public object generate(object target, method method, object... params) {
                return method.getname()+"["+ arrays.aslist(params).tostring()+"]";
            }
        };
    }
}

在使用的时候可以通过一下的方式进行配置

@cacheable(cachenames = {"emp"},keygenerator = "mykeygenerator")

cachemanager指定缓存管理器
/**
  * the bean name of the custom {@link org.springframework.cache.cachemanager} to use to
  * create a default {@link org.springframework.cache.interceptor.cacheresolver} if none
  * is set already.
  * <p>mutually exclusive with the {@link #cacheresolver}  attribute.
  * @see org.springframework.cache.interceptor.simplecacheresolver
  * @see cacheconfig#cachemanager
  */
 string cachemanager() default "";
 /**
  * the bean name of the custom {@link org.springframework.cache.interceptor.cacheresolver}
  * to use.
  * @see cacheconfig#cacheresolver
  */
 string cacheresolver() default "";

condition

指定复合条件的情况下才缓存。也可以通过spel表达式进行设置。这个配置规则和上面表格中的配置规则是相同的。

 /**
  * spring expression language (spel) expression used for making the method
  * caching conditional.
  * <p>default is {@code ""}, meaning the method result is always cached.
  * <p>the spel expression evaluates against a dedicated context that provides the
  * following meta-data:
  * <ul>
  * <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
  * references to the {@link java.lang.reflect.method method}, target object, and
  * affected cache(s) respectively.</li>
  * <li>shortcuts for the method name ({@code #root.methodname}) and target class
  * ({@code #root.targetclass}) are also available.
  * <li>method arguments can be accessed by index. for instance the second argument
  * can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. arguments
  * can also be accessed by name if that information is available.</li>
  * </ul>
  */
 string condition() default "";

unless(除非)

当这个条件为true的时候，方法的返回值就不会被缓存。

/**
  * spring expression language (spel) expression used to veto method caching.
  * <p>unlike {@link #condition}, this expression is evaluated after the method
  * has been called and can therefore refer to the {@code result}.
  * <p>default is {@code ""}, meaning that caching is never vetoed.
  * <p>the spel expression evaluates against a dedicated context that provides the
  * following meta-data:
  * <ul>
  * <li>{@code #result} for a reference to the result of the method invocation. for
  * supported wrappers such as {@code optional}, {@code #result} refers to the actual
  * object, not the wrapper</li>
  * <li>{@code #root.method}, {@code #root.target}, and {@code #root.caches} for
  * references to the {@link java.lang.reflect.method method}, target object, and
  * affected cache(s) respectively.</li>
  * <li>shortcuts for the method name ({@code #root.methodname}) and target class
  * ({@code #root.targetclass}) are also available.
  * <li>method arguments can be accessed by index. for instance the second argument
  * can be accessed via {@code #root.args[1]}, {@code #p1} or {@code #a1}. arguments
  * can also be accessed by name if that information is available.</li>
  * </ul>
  * @since 3.2
  */
 string unless() default "";

sync

是否异步

/**
  * synchronize the invocation of the underlying method if several threads are
  * attempting to load a value for the same key. the synchronization leads to
  * a couple of limitations:
  * <ol>
  * <li>{@link #unless()} is not supported</li>
  * <li>only one cache may be specified</li>
  * <li>no other cache-related operation can be combined</li>
  * </ol>
  * this is effectively a hint and the actual cache provider that you are
  * using may not support it in a synchronized fashion. check your provider
  * documentation for more details on the actual semantics.
  * @since 4.3
  * @see org.springframework.cache.cache#get(object, callable)
  */
 boolean sync() default false;

注意

在使用这个属性的时候，当这个属性为true的时候，unless属性是不能使用的。

{@link #unless()} is not supported

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。