掌握聚合最新动态了解行业最新趋势
API接口,开发服务,免费咨询服务

利用redis做业务缓存和配置项

背景

​ 从以前的C/S应用到现在的B/S,系统配置项都是必不可少的。一般都有一个SettingUtils类,提供read和write方法,然后就一大堆作为Key的常量。通过这样来实现:

String ip = SettingUtils.read(SettingConsts.IP);//获取ip
SettingUtils.write(SettingConsts.IP, "127.0.0.1");//设置ip

​ 然而,现在并发要求越来越高,缓存是个标配。无论是业务数据还是配置项,都可以往缓存里扔。缓存,也离不开Key,一大堆作为Key的常量。治理这些Key是个大问题。

遇到动态代理

​ 动态代理,早些年就了解过,可一直没真正用到项目里,直到一次研究了一下mybatis源代码,发现其核心代码就是动态代理。那什么是动态代理呢?我就不详细解释了,对它不了解的还是乖乖的 百度一下动态代理 。这里从网上投了一张图,如下:

它大概就是我们可以动态的自定义的控制实现。给你Object proxy、Method method、Object[] args三个参数,然后你自己决定怎么实现。给个简单的例子:

/**
* 接口
*/
public interface Something {
    String get(String key);
    String set(String key, String value);
}

/**
 * 调用处理器
 */
public class MyInvocationHandler implements InvocationHandler {

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        System.out.println(method.getName() + " doing ...");
        System.out.println("proxy is " + proxy.getClass().getName());
        System.out.println("method is " + method.getName());
        System.out.println("args is " + Arrays.toString(args));
        System.out.println(method.getName() + " done!");

        return method.getName() + " invoked";
    }
}

public class Test {
    public static void main(String[] args) {
        Something somethingProxy = (Something) java.lang.reflect.Proxy.newProxyInstance(Something.class.getClassLoader(),
                new Class<?>[]{Something.class},
                new MyInvocationHandler());

        System.out.println("somethingProxy.get(\"name\"): " + somethingProxy.get("name"));
        System.out.println();

        System.out.println("somethingProxy.set(\"name\", \"018\"): " + somethingProxy.set("name", "018"));
        System.out.println();
    }
}

以上代码的输出结果:

get doing ...
proxy is com.sun.proxy.$Proxy0
method is get
args is [name]
get done!
somethingProxy.get("name"): get invoked

set doing ...
proxy is com.sun.proxy.$Proxy0
method is set
args is [name, 018]
set done!
somethingProxy.set("name", "018"): set invoked
  • 通过Proxy.newProxyInstance创建一个Something的代理对象somethingProxy。
  • 通过somethingProxy实例调用其方法get/set时,会执行MyInvocationHandler.invoke方法。

思考

​ 缓存,通过Key,返回值。

​ 动态代理,通过Method(方法),执行返回值。

​ 怎么把它们关联起来呢?方法有方法名,那能不能把Method method的方法名对应到Key?能!!!

方案

​ 在最开始的例子获取ip就应该这样写:

public interface DataSourceSettings {
    String getIp();
    void setIp(String ip);
  
    int getPort();
    void setPort(int port);
  
  	// 其他项 ...
}

public class SettingsInvocationHandler implements InvocationHandler {

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        String methodName = method.getName();

        // TODO: 
      	// 1、去掉get/set,截图后面的字符串作为Key
      	// 2、redis客户端通过Key获取值返回
    }
}

配置项完美解决了。

​ 但业务缓存呢?相对来说,配置项的Key是固定的,而业务缓存的Key则是不固定的。比如缓存商品信息,商品id为001和002等等,得缓存不同的Key。就得有一个动态Key的解决方案,即productCaches.put(商品id, 商品实体)这样的实现方式。

​ 参考spring-data-redis的BoundHashOperations,可以对其进行扩展实现这一功能。这样我们就可以这样定义一个商品缓存接口:

public interface HashSessionOperations<HK, HV> extends BoundHashOperations<String, HK, HV> {
}

public interface ProductCaches extends HashSessionOperations {
}

缓存数据和获取数据则如下:

productCaches.put(product1.prod_id, product1);//缓存数据
Product product = (Product)productCaches.get(prod_id);//获取缓存数据

至此,业务缓存也完美解决。

​ 当然,我们对BoundListOperations、BoundSetOperations、BoundValueOperations、BoundZSetOperations进行对应的扩展。这样,这些不仅仅做业务缓存,也可以用它来作为redis的一个客户端使用。

​ 看到这里,只看到了接口,也即是结果,知道了怎么使用它应用到项目中。但,怎么实现的呢?但是是动态代理。来,废话不多说,两个InvocationHandler码上来:

/**
 * 简单的InvocationHandler
 * 主要用于执行配置项
 */
public class SimpleSessionOperationInvocationHandler implements InvocationHandler {
    private static final String METHOD_SET = "set";
    private static final String METHOD_GET = "get";
    private static final String METHOD_TOSTRING = "toString";
    private DefaultSimpleSessionOperations defaultSimpleSessionOperations;

    public SimpleSessionOperationInvocationHandler(DefaultSimpleSessionOperations defaultSimpleSessionOperations) {
        this.defaultSimpleSessionOperations = defaultSimpleSessionOperations;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Class<?> cls = method.getDeclaringClass();
        String group = cls.getSimpleName().replace("Settings", "").replace("Setting", "");
        String methodName = method.getName();
        String methodString = null;
        String item = null;
        Object value = null;

        if (METHOD_TOSTRING.equals(methodName)) {
            return cls.getName();
        } else if (METHOD_SET.equals(methodName)) {
            // void set(String item, ? value)
            if (method.getParameterCount() != 2 || !method.getParameterTypes()[0].getSimpleName().equals(String.class.getSimpleName()) ||
                    !method.getParameterTypes()[1].getSimpleName().equals(Object.class.getSimpleName()) ||
                    args == null || args.length != 2) {
                throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                        "方法声明错误,正确为 void set(String key, ? value)。");
            }

            methodString = METHOD_SET;
            item = args[0].toString();
            value = args[1];
        } else if (METHOD_GET.equals(methodName)) {
            // ? get(String item)
            if (method.getParameterCount() != 1 || !method.getParameterTypes()[0].getSimpleName().equals(String.class.getSimpleName()) ||
                    args == null || args.length != 1) {
                throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                        "方法声明错误,正确为 ? get(String item)。");
            }

            methodString = METHOD_GET;
            item = args[0].toString();
        } else if (methodName.startsWith(METHOD_SET)) {
            // void setXXX(? value)
            if (method.getParameterCount() != 1 ||
                    args == null || args.length != 1) {
                throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                        "方法声明错误,正确为 void setXXX(? value)。");
            }

            methodString = METHOD_SET;
            item = methodName.substring(METHOD_SET.length());
            value = args[0];
        } else if (methodName.startsWith(METHOD_GET)) {
            // Object getXXX()
            if (method.getParameterCount() != 0 ||
                    (args != null && args.length != 0)) {
                throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                        "方法声明错误,正确为 Object getXXX()。");
            }

            methodString = METHOD_GET;
            item = methodName.substring(METHOD_GET.length());
        } else {
            throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                    "不支持的方法,只能是void set(String item, ? value)、? get(String item)、void setXXX(? value)、? getXXX()。");
        }

        switch (methodString) {
            case (METHOD_GET):
                Object val = this.defaultSimpleSessionOperations.get(group, item);
                return val;
            case (METHOD_SET):
                this.defaultSimpleSessionOperations.put(group, item, value);
        }
        return null;
    }
}
/**
 * redis操作动态代理执行类
 * 主要用于执行业务缓存
 */
public class RedisSessionOperationInvocationHandler implements InvocationHandler {
    private static final String METHOD_TOSTRING = "toString";

    BoundKeyOperations<?> sessionOperations; // 具体执行的redis对象

    public RedisSessionOperationInvocationHandler(BoundKeyOperations<?> sessionOperations) {
        this.sessionOperations = sessionOperations;
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Class<?> cls = method.getDeclaringClass();
        String methodName = method.getName();

        Class<?> targetCls = sessionOperations.getClass();
        Method methodTarget = targetCls.getDeclaredMethod(methodName, method.getParameterTypes());
        if (methodTarget == null) {
            throw new NonsupportMethodException(cls.getPackage().getName(), cls.getSimpleName(), methodName,
                    "不支持" + methodName + "方法。");
        }

        if (METHOD_TOSTRING.equals(methodName)) {
            return cls.getName();
        }

        Object result = methodTarget.invoke(sessionOperations, args);
        return result;
    }
}

至于接口创建代理,就交给ClassScannerConfigurer吧。

/**
 * 类扫描配置类
 */
public class ClassScannerConfigurer implements InitializingBean, ApplicationContextAware, BeanFactoryAware, BeanNameAware {

    /**
     * 待扫描的包
     */
    private String basePackage;
    private String beanName;
    private DefaultListableBeanFactory beanFactory;
    private ApplicationContext applicationContext;
    private SessionOperationsFactory sessionOperationsFactory;
    private List<ClassInfo> classInfos;

    public String getBasePackage() {
        return basePackage;
    }

    public void setBasePackage(String basePackage) {
        this.basePackage = basePackage;
    }

    public SessionOperationsFactory getSessionOperationsFactory() {
        return sessionOperationsFactory;
    }

    public void setSessionOperationsFactory(SessionOperationsFactory sessionOperationsFactory) {
        this.sessionOperationsFactory = sessionOperationsFactory;
    }

    @Override
    public void setBeanName(String name) {
        this.beanName = name;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        Assert.notNull(this.basePackage, "Property 'basePackage' is required");

        // 扫描并创建接口的动态代理
        ClassPathScanner scanner = new ClassPathScanner();
        scanner.setResourceLoader(this.applicationContext);
        Set<Class> classes = scanner.doScans(StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));

        if (Objects.isNull(classInfos)) {
            classInfos = new ArrayList<>(classes.size());
        }

        for (Class<?> cls : classes) {
            Object proxyObject = ProxyManager.newProxyInstance(this.sessionOperationsFactory, cls);
            String beanName = cls.getSimpleName().substring(0, 1).toLowerCase() + cls.getSimpleName().substring(1);
            this.beanFactory.registerSingleton(beanName, proxyObject);

            ClassInfo classInfo = new ClassInfo(beanName, cls, proxyObject);
            classInfos.add(classInfo);
        }
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
        this.beanFactory = (DefaultListableBeanFactory) beanFactory;
    }
}

怎么加载这些呢,交给spring吧。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

	<!--Redis 线程池配置 -->
	<bean id="jpoolConfig" class="redis.clients.jedis.JedisPoolConfig">
		<property name="maxIdle" value="200"></property>
		<property name="testOnBorrow" value="true"></property>
	</bean>

	<!--连接工厂 -->
	<bean id="connectionFactory"
		  class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
		<property name="hostName" value="127.0.0.1"></property>
		<property name="port" value="6339"></property>
		<property name="usePool" value="true"></property>
		<property name="timeout" value="100000"></property>
		<property name="poolConfig" ref="jpoolConfig"></property>
	</bean>

	<!--数据模板 -->
	<bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate">
		<property name="connectionFactory" ref="connectionFactory"></property>
	</bean>

	<!--redis template 缓存管理 -->
	<bean id="cacheManager" class="org.springframework.data.redis.cache.RedisCacheManager">
		<constructor-arg ref="redisTemplate"></constructor-arg>
		<property name="usePrefix" value="true"></property>
		<property name="loadRemoteCachesOnStartup" value="true"></property>
	</bean>

    <!-- 上面是配置redis的,从这里开始才是 -->
	<!-- 配置settingSessionFactory -->
	<bean id="settingSessionFactory" class="com.o18.redis.cache.SessionOperationsFactory">
		<constructor-arg ref="redisTemplate"/>
		<constructor-arg value="ORDER"/>
	</bean>

	<!-- 扫描Setting -->
	<bean class="com.o18.redis.cache.ClassScannerConfigurer">
		<property name="sessionOperationsFactory" ref="settingSessionFactory" />
		<property name="basePackage" value="原文来自:018/RedisCache

声明:所有来源为“聚合数据”的内容信息,未经本网许可,不得转载!如对内容有异议或投诉,请与我们联系。邮箱:marketing@think-land.com

0512-88869195
数 据 驱 动 未 来
Data Drives The Future