Use spring's interceptor to customize the cache implementation example code

This paper mainly studies the implementation of custom cache using spring interceptor. The specific implementation code is shown below.

Memcached is a high-performance distributed memory object caching system for dynamic Web applications to reduce database load. It improves the speed of dynamic, database-driven Web sites by caching data and objects in memory to reduce the number of database reads. This article uses Memcached instances and spring interceptors to implement a custom implementation of caching. Using interceptors to read the generation strategy for key values taken from the defined cache tags.

Custom Cacheable

package com.jeex.sci;
@Target(ElementType.METHOD)  
@Retention(RetentionPolicy.RUNTIME) 
@Inherited 
@Documented 
public @interface Cacheable {
	String namespace();
	String key() default "";
	int[] keyArgs() default {
	}
	;
	String[] keyProperties() default {
	}
	;
	String keyGenerator() default "";
	int expires() default 1800;
}

Custom CacheEvict

package com.jeex.sci;
@Target(ElementType.METHOD)  
@Retention(RetentionPolicy.RUNTIME) 
@Inherited 
@Documented 
public @interface CacheEvict {
	String namespace();
	String key() default "";
	int[] keyArgs() default {
	}
	;
	String[] keyProperties() default {
	}
	;
	String keyGenerator() default "";
}

spring: MethodInterceptor public Object invoke(MethodInvocation invocation) throws Throwable (MethodInvocation invocation) spring: MethodInterceptor public Object invoke(MethodInvocation invocation) Throwable

public Object invoke(MethodInvocation invoction) throws Throwable {
	Method method = invoction.getMethod();
	Cacheable c = method.getAnnotation(Cacheable.class);
	if (c != null) {
		return handleCacheable(invoction, method, c);
	}
	CacheEvict ce = method.getAnnotation(CacheEvict.class);
	if (ce != null) {
		return handleCacheEvict(invoction, ce);
	}
	return invoction.proceed();
}

Process cacheable tags

private Object handleCacheable(MethodInvocation invoction, Method method, 
    Cacheable c) throws Throwable {
	String key = getKey(invoction, KeyInfo.fromCacheable(c));
	if (key.equals("")) {
		if (log.isDebugEnabled()){
			log.warn("Empty cache key, the method is " + method);
		}
		return invoction.proceed();
	}
	long nsTag = (long) memcachedGet(c.namespace());
	if (nsTag == null) {
		nsTag = long.valueOf(System.currentTimeMillis());
		memcachedSet(c.namespace(), 24*3600, long.valueOf(nsTag));
	}
	key = makeMemcachedKey(c.namespace(), nsTag, key);
	Object o = null;
	o = memcachedGet(key);
	if (o != null) {
		if (log.isDebugEnabled()) {
			log.debug("CACHE HIT: Cache Key = " + key);
		}
	} else {
		if (log.isDebugEnabled()) {
			log.debug("CACHE MISS: Cache Key = " + key);
		}
		o = invoction.proceed();
		memcachedSet(key, c.expires(), o);
	}
	return o;
}

Process cacheEvit labels

private Object handleCacheEvict(MethodInvocation invoction,  
    CacheEvict ce) throws Throwable { 
  String key = getKey(invoction, KeyInfo.fromCacheEvict(ce));    
   
  if (key.equals("")) {  
    if (log.isDebugEnabled()) { 
      log.debug("Evicting " + ce.namespace()); 
    } 
    memcachedDelete(ce.namespace()); 
  } else { 
    Long nsTag = (Long) memcachedGet(ce.namespace()); 
    if (nsTag != null) { 
      key = makeMemcachedKey(ce.namespace(), nsTag, key); 
      if (log.isDebugEnabled()) { 
        log.debug("Evicting " + key); 
      } 
      memcachedDelete(key);         
    } 
  } 
  return invoction.proceed(); 
} 

key is generated according to the parameters

// Generate parameters using the parameters of the intercepted method  
private String getKeyWithArgs(Object[] args, int[] argIndex) { 
  StringBuilder key = new StringBuilder(); 
  boolean first = true; 
  for (int index: argIndex) { 
    if (index < 0 || index >= args.length) { 
      throw new IllegalArgumentException("Index out of bound"); 
    } 
    if (!first) { 
      key.append(':'); 
    } else { 
      first = false; 
    } 
    key = key.append(args[index]); 
  } 
  return key.toString(); 
} 

key is generated based on the properties

private String getKeyWithProperties(Object o, String props[])  
    throws Exception { 
  StringBuilder key = new StringBuilder(); 
  boolean first = true; 
  for (String prop: props) { 
    // the bean To get the name of the method  
    String methodName = "get"  
        + prop.substring(0, 1).toUpperCase()  
        + prop.substring(1); 
    Method m = o.getClass().getMethod(methodName); 
    Object r = m.invoke(o, (Object[]) null); 
    if (!first) { 
      key.append(':'); 
    } else { 
      first = false; 
    } 
    key = key.append(r); 
  } 
  return key.toString(); 
} 

key is generated using a custom generator

// Generate using a generator key 
private String getKeyWithGenerator(MethodInvocation invoction, String keyGenerator)  
    throws Exception { 
  Class<?> ckg = Class.forName(keyGenerator); 
  CacheKeyGenerator ikg = (CacheKeyGenerator)ckg.newInstance(); 
  return ikg.generate(invoction.getArguments()); 
} 

Helper class that holds key information

private static class KeyInfo {
	String key;
	int[] keyArgs;
	String keyProperties[];
	String keyGenerator;
	static KeyInfo fromCacheable(Cacheable c) {
		KeyInfo ki = new KeyInfo();
		ki.key = c.key();
		ki.keyArgs = c.keyArgs();
		ki.keyGenerator = c.keyGenerator();
		ki.keyProperties = c.keyProperties();
		return ki;
	}
	static KeyInfo fromCacheEvict(CacheEvict ce) {
		KeyInfo ki = new KeyInfo();
		ki.key = ce.key();
		ki.keyArgs = ce.keyArgs();
		ki.keyGenerator = ce.keyGenerator();
		ki.keyProperties = ce.keyProperties();
		return ki;
	}
	String key() {
		return key;
	}
	int[] keyArgs() {
		return keyArgs;
	}
	String[] keyProperties() {
		return keyProperties;
	}
	String keyGenerator() {
		return keyGenerator;
	}
}

Parameter setting

// Use parameter Settings key 
@Cacheable(namespace="BlackList", keyArgs={0, 1}) 
public int anotherMethond(int a, int b) { 
  return 100; 
} 

The test class:

package com.jeex.sci;
@Target(ElementType.METHOD)  
@Retention(RetentionPolicy.RUNTIME) 
@Inherited 
@Documented 
public @interface CacheEvict {
	String namespace();
	String key() default "";
	int[] keyArgs() default {
	}
	;
	String[] keyProperties() default {
	}
	;
	String keyGenerator() default "";
}

0

conclusion

This article is about the use of spring interceptor custom cache implementation example code is all content, I hope to help you. Interested friends can continue to refer to the site of other related topics, if there are shortcomings, welcome to leave a message to point out. Thank you for your support!