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注解 #50

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e48503a
注解
HuiquanYang Mar 24, 2020
4755229
还原了xml
HuiquanYang Mar 24, 2020
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50 changes: 25 additions & 25 deletions pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -55,31 +55,31 @@
<argLine>-Dfile.encoding=UTF-8</argLine>
</configuration>
</plugin>
<plugin>
<artifactId>maven-checkstyle-plugin</artifactId>
<version>3.1.0</version>
<configuration>
<configLocation>${basedir}/.circleci/checkstyle.xml</configLocation>
<includeTestSourceDirectory>true</includeTestSourceDirectory>
<enableRulesSummary>false</enableRulesSummary>
</configuration>
<executions>
<execution>
<id>compile</id>
<phase>compile</phase>
<goals>
<goal>check</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>com.puppycrawl.tools</groupId>
<artifactId>checkstyle</artifactId>
<version>8.29</version>
</dependency>
</dependencies>
</plugin>
<plugin>
<artifactId>maven-checkstyle-plugin</artifactId>
<version>3.1.0</version>
<configuration>
<configLocation>${basedir}/.circleci/checkstyle.xml</configLocation>
<includeTestSourceDirectory>true</includeTestSourceDirectory>
<enableRulesSummary>false</enableRulesSummary>
</configuration>
<executions>
<execution>
<id>compile</id>
<phase>compile</phase>
<goals>
<goal>check</goal>
</goals>
</execution>
</executions>
<dependencies>
<dependency>
<groupId>com.puppycrawl.tools</groupId>
<artifactId>checkstyle</artifactId>
<version>8.29</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
5 changes: 5 additions & 0 deletions src/main/java/com/github/hcsp/annotation/Cache.java
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@@ -1,5 +1,10 @@
package com.github.hcsp.annotation;


import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface Cache {
// 标记缓存的时长（秒），默认60s
int cacheSeconds() default 60;
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109 changes: 107 additions & 2 deletions src/main/java/com/github/hcsp/annotation/CacheClassDecorator.java
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@@ -1,14 +1,119 @@
package com.github.hcsp.annotation;

import net.bytebuddy.ByteBuddy;
import net.bytebuddy.implementation.MethodDelegation;
import net.bytebuddy.implementation.bind.annotation.*;
import net.bytebuddy.matcher.ElementMatchers;

import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;

public class CacheClassDecorator {
// 将传入的服务类Class进行增强
// 使得返回一个具有如下功能的Class：
// 如果某个方法标注了@Cache注解，则返回值能够被自动缓存注解所指定的时长
// 这意味着，在短时间内调用同一个服务的同一个@Cache方法两次
// 它实际上只被调用一次，第二次的结果直接从缓存中获取
// 注意，缓存的实现需要是线程安全的
public static <T> Class<T> decorate(Class<T> klass) {
return klass;

@SuppressWarnings("unchecked")
public static <T> Class<T> decorate(Class<T> klass) throws IllegalAccessException, InstantiationException {
return (Class) new ByteBuddy()
.subclass(klass)
.method(ElementMatchers.isAnnotatedWith(Cache.class))
.intercept(MethodDelegation.to(CacheAdvisor.class))
.make()
.load(klass.getClassLoader())
.getLoaded();
}

private static class CacheKey {
private String method;
private Object object;
private Object[] argument;

CacheKey(String method, Object object, Object[] argument) {
this.method = method;
this.object = object;
this.argument = argument;
}

@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
CacheKey cacheKey = (CacheKey) o;
return Objects.equals(method, cacheKey.method) &&
Objects.equals(object, cacheKey.object) &&
Arrays.equals(argument, cacheKey.argument);
}

@Override
public int hashCode() {
int result = Objects.hash(method, object);
result = 31 * result + Arrays.hashCode(argument);
return result;
}
}

private static class CacheValue {
private Object value;
private long time;

CacheValue(Object value, long time) {
this.value = value;
this.time = time;
}
}

public static class CacheAdvisor {
private static ConcurrentHashMap<CacheKey, CacheValue> cache = new ConcurrentHashMap<>();

@RuntimeType
public static Object cache(
//调用父类的方法
@SuperCall Callable<Object> superCall,
//当前正在被调用的方法
@Origin Method method,
//实体方法的对象
@This Object object,
//所有的参数
@AllArguments Object[] arguments) throws Exception {
//获取缓存的结果
CacheKey cacheKey = new CacheKey(method.getName(), object, arguments);
int cacheSeconds = method.getAnnotation(Cache.class).cacheSeconds();
final CacheValue obj = cache.get(cacheKey);

if (obj != null) {
long time = cache.get(cacheKey).time;
if (cacheIsExpired(time, cacheSeconds)) {
//缓存过期
return putNewValueIntoCache(superCall, cacheKey);
} else {
return obj.value;
}
} else {
return putNewValueIntoCache(superCall, cacheKey);
}
}

private static boolean cacheIsExpired(long time, long cacheSeconds) {
return ((System.currentTimeMillis() - time) > cacheSeconds * 1000);
}

private static Object putNewValueIntoCache(@SuperCall Callable<Object> superCall, CacheKey cacheKey) throws Exception {
Object realResult = superCall.call();
CacheValue cacheValue = new CacheValue(realResult, System.currentTimeMillis());
cache.put(cacheKey, cacheValue);
return realResult;
}
}

public static void main(String[] args) throws Exception {
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