配置Spring Cache

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>com.github.ulisesbocchio</groupId>
    <artifactId>jasypt-spring-boot-starter</artifactId>
    <version>1.16</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.10.3</version>
</dependency>

spring:
  cache:
    type: redis
    ### 配置Redis
    # Redis数据库索引（默认为0）
    redis:
      database: 0
      # Redis服务器地址
      host: mmren.edu.redis.server
      # Redis服务器连接端口
      port: 6379
      # Redis服务器连接密码（默认为空）
      password: ENC(bIx3PYzFf0CcZ+6CdAGHruIaTgY1/CyB)
      # 配置连接池
      jedis:
        pool:
          # 连接池最大连接数（使用负值表示没有限制）
          max-active: 8
          # 连接池最大阻塞等待时间（使用负值表示没有限制）
          max-wait: -1
          # 连接池中的最大空闲连接
          max-idle: 500
          # 连接池中的最小空闲连接
          min-idle: 0
      # 连接超时时间（毫秒）
      timeout: 2000
      lettuce:
        shutdown-timeout: 0
jasypt:
  encryptor:
    password: gerrymmrenedu # 设置根密码

缓存配置类

@EnableCaching
@Configuration
public class RedisCacheConfig extends CachingConfigurerSupport {

    @Bean
    public CacheManager cacheManager(RedisConnectionFactory factory) {
        // 创建Redis序列化对象
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        // 使用Jackson的序列化对象
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);

        //解决查询缓存转换异常的问题
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.activateDefaultTyping(om.getPolymorphicTypeValidator(), ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);

        // 配置序列化（解决乱码的问题）
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig()
                // 7 天缓存过期
                .entryTtl(Duration.ofDays(7))
                .serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer))
                .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer))
                .disableCachingNullValues();

        RedisCacheManager cacheManager = RedisCacheManager.builder(factory)
                .cacheDefaults(config)
                .build();

        return cacheManager;
    }
}

创建实体

public class Book implements Serializable {
    private static final long serialVersionUID = 2629983876059197650L;
    
    private String id;
    private String name; // 书名
    private Integer price; // 价格
    private Date update; // 

    public Book(String id, String name, Integer price, Date update) {
        super();
        this.id = id;
        this.name = name;
        this.price = price;
        this.update = update;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Integer getPrice() {
        return price;
    }
    public void setPrice(Integer price) {
        this.price = price;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public Date getUpdate() {
        return update;
    }
    public void setUpdate(Date update) {
        this.update = update;
    }
}
--------------------------------
public class BookQry {
    private String id;
    private String name; // 书名
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
    @Override
    public String toString(){
        return JSON.toJSONString(this);
    }
}

数据初始化类

public abstract class AbstractService {

    protected static Map<String, Book> repositoryBook = new HashMap<>();
    public AbstractService() {
        super();
    }
    
    @PostConstruct
    public void init() {
        // 1
        Book book1 = new Book("1001", "牧码人", 11, new Date());
        repositoryBook.put(book1.getId(), book1);
        // 2
        Book book2 = new Book("1002", "张三", 43, new Date());
        repositoryBook.put(book2.getId(), book2);
        // 3
        Book book3 = new Book("1003", "Gerry", 5433, new Date());
        repositoryBook.put(book3.getId(), book3);
        // 4
        Book book4 = new Book("1004", "教育", 54, new Date());
        repositoryBook.put(book4.getId(), book4);
    }
}

自定义缓存key生成类

@Component
public class MyKeyGenerator implements KeyGenerator {

    @Override
    public Object generate(Object target, Method method, Object... params) {
        System.out.println("自定义缓存，使用第一参数作为缓存key. params = " + Arrays.toString(params));
        // 仅仅用于测试，实际不可能这么写
        return params[0] + "0";
    }

}

Spring缓存的基本用法

@Component
public class BookService extends AbstractService {
    private static final Logger logger = LoggerFactory.getLogger(BookService.class);
    
    // ==================== @Cacheable ========================
    /**
     * cacheNames 设置缓存的值 
     *     key：指定缓存的key，这是指参数id值。 key可以使用spEl表达式
     * @param id
     * @return
     */
    @Cacheable(cacheNames="book1", key="#id")
    public Book queryBookCacheable(String id){
        logger.info("queryBookCacheable,id={}",id);
        return repositoryBook.get(id);
    }
    
    /**
     * 这里使用另一个缓存存储缓存
     * 
     * @param id
     * @return
     */
    @Cacheable(cacheNames="book2", key="#id")
    public Book queryBookCacheable_2(String id){
        logger.info("queryBookCacheable_2,id={}",id);
        return repositoryBook.get(id);
    }
    
    /**
     * 缓存的key也可以指定对象的成员变量
     * @param qry
     * @return
     */
    @Cacheable(cacheNames="book1", key="#qry.id")
    public Book queryBookCacheableByBookQry(BookQry qry){
        logger.info("queryBookCacheableByBookQry,qry={}",qry);
        String id = qry.getId();
        Assert.notNull(id, "id can't be null!");
        String name = qry.getName();
        Book book = null;
        if(id != null){
            book = repositoryBook.get(id);
            if(book != null && !(name != null && book.getName().equals(name))){
                book = null;
            }
        }
        return book;
    }
    
    /**
     * 以上我们使用默认的keyGenerator，对应spring的SimpleKeyGenerator 
     *     如果你的使用很复杂，我们也可以自定义myKeyGenerator的生成key
     * 
     *  key和keyGenerator是互斥，如果同时制定会出异常
     *     The key and keyGenerator parameters are mutually exclusive and an operation specifying both will result in an exception.
     * 
     * @param id
     * @return
     */
    @Cacheable(cacheNames="book3",  keyGenerator="myKeyGenerator")
    public Book queryBookCacheableUseMyKeyGenerator(String id){
        logger.info("queryBookCacheableUseMyKeyGenerator,id={}",id);
        return repositoryBook.get(id);
    }
    
    /***
     * 如果设置sync=true，
     *     如果缓存中没有数据，多个线程同时访问这个方法，则只有一个方法会执行到方法，其它方法需要等待
     *     如果缓存中已经有数据，则多个线程可以同时从缓存中获取数据
     * @param id
     * @return
     */
    @Cacheable(cacheNames="book3", sync=true)
    public Book queryBookCacheableWithSync(String id) {
        logger.info("begin ... queryBookCacheableByBookQry,id={}",id);
        try {
            Thread.sleep(1000 * 2);
        } catch (InterruptedException e) {
        }
        logger.info("end ... queryBookCacheableByBookQry,id={}",id);
        return repositoryBook.get(id);
    }
    
    /**
     * 条件缓存：
     * 只有满足condition的请求才可以进行缓存，如果不满足条件，则跟方法没有@Cacheable注解的方法一样
     *     如下面只有id < 3才进行缓存
     * 
     */
    @Cacheable(cacheNames="book11", condition="T(java.lang.Integer).parseInt(#id) < 3 ")
    public Book queryBookCacheableWithCondition(String id) {
        logger.info("queryBookCacheableByBookQry,id={}",id);
        return repositoryBook.get(id);
    }
    
    /**
     * 条件缓存：
     * 对不满足unless的记录，才进行缓存
     *     "unless expressions" are evaluated after the method has been called
     *     如下面：只对不满足返回 'T(java.lang.Integer).parseInt(#result.id) <3 ' 的记录进行缓存
     * @param id
     * @return
     */
    @Cacheable(cacheNames="book22", unless = "T(java.lang.Integer).parseInt(#result.id) <3 ")
    public Book queryBookCacheableWithUnless(String id) {
        logger.info("queryBookCacheableByBookQry,id={}",id);
        return repositoryBook.get(id);
    }
    
    
    // ==================== @CacheEvict ========================
    /**
     * allEntries = true: 清空book1里的所有缓存
     */
    @CacheEvict(cacheNames="book1", allEntries=true)
    public void clearBook1All(){
        logger.info("clearAll");
    }
    /**
     * 对符合key条件的记录从缓存中book1移除
     */
    @CacheEvict(cacheNames="book1", key="#id")
    public void updateBook(String id, String name){
        logger.info("updateBook");
        Book book = repositoryBook.get(id);
        if(book != null){
            book.setName(name);
            book.setUpdate(new Date());
        }
    }
    
    // ==================== @CachePut ========================
    /**
     * 每次执行都会执行方法，无论缓存里是否有值，同时使用新的返回值的替换缓存中的值
     *     这里不同于@Cacheable：@Cacheable如果缓存没有值，从则执行方法并缓存数据，如果缓存有值，则从缓存中获取值
     * @param id
     * @return
     */
    @CachePut(cacheNames="book1", key="#id")
    public Book queryBookCachePut(String id){
        logger.info("queryBookCachePut,id={}",id);
        return repositoryBook.get(id);
    }
    
}

@CacheConfig配置定义

/**
 * @CacheConfig: 类级别的注解
 *     如果我们在此注解中定义cacheNames，则此类中的所有方法上@Cacheable的cacheNames默认都是此值。当然    * @Cacheable也可以重定义cacheNames的值
 *
 */
@Component
@CacheConfig(cacheNames="booksAll") 
public class BookService2 extends AbstractService {
    private static final Logger logger = LoggerFactory.getLogger(BookService2.class);
    
    /**
     * 此方法的@Cacheable没有定义cacheNames，则使用类上的注解@CacheConfig里的值 cacheNames
     * @param id
     * @return
     */
    @Cacheable(key="#id")
    public Book queryBookCacheable(String id){
        logger.info("queryBookCacheable,id={}",id);
        return repositoryBook.get(id);
    }

    /**
     * 此方法的@Cacheable有定义cacheNames，则使用此值覆盖类注解@CacheConfig里的值cacheNames
     * 
     * @param id
     * @return
     */
    @Cacheable(cacheNames="books_custom", key="#id")
    public Book queryBookCacheable2(String id){
        logger.info("queryBookCacheable2,id={}",id);
        return repositoryBook.get(id);
    }
}

编写测试用例

public class RedisCacheTests  extends  ApplicationTests{
    @Autowired
    private BookService bookService;

    @Test
    public void testCache1() throws Exception {
        Book book = bookService.queryBookCacheable("1001");
        convertToString(book);
    }

    @Test
    public void testCache2() throws Exception {
        Book book = bookService.queryBookCacheable_2("1001");
        convertToString(book);
    }

    @Test
    public void testCache3() throws Exception {
        BookQry qry = new BookQry();
        qry.setId("1004");
        qry.setName("教育");
        Book book = bookService.queryBookCacheableByBookQry(qry);
        convertToString(book);
    }

    @Test
    public void testCache4() throws Exception {
        Book book = bookService.queryBookCacheableUseMyKeyGenerator("1003");
        convertToString(book);
    }

    @Test
    public void testCache5() throws Exception {
        Book book = bookService.queryBookCachePut("1003");
        convertToString(book);
    }

    public void convertToString(Object object) {
        String jsonString = JSON.toJSONString(object, true);
        System.out.println(jsonString);
    }
}