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ehcache整合spring注解方式
一、简介
在hibernate中就是用到了ehcache 充当缓存。spring对ehcache也提供了支持，使用也比较简单，只需在spring的配置文件中将ehcache的ehcache.xml文件配置进去即可。在spring中使用ehcache有两种方式，一种是使用spring提供的封装，使用注解的方式配置在某个方法上面，第一次调用该方法的时候，将该方法执行返回的数据缓存，当再次执行的时候如果时间没有变，就直接冲缓存获取，该方法不执行；另一种方式是获取到ehcache本地接口，直接使用ehcache本地接口进行数据缓存。第一种的方式使用简单，代码简洁，但灵活度不高，而第二种方式灵活度高，但是代码就比较到，需要自己去判断数据是否缓存，如何没有缓存就去获取上海并本放入缓；如果缓存了，就直接去缓存中获取。本例子是用的是第一种方式。
工程使用maven构建，需要的依赖如下：
<dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>3.2.6.RELEASE</version> </dependency> <dependency> <groupId>net.sf.ehcache</groupId> <artifactId>ehcache-core</artifactId> <version>2.4.2</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>3.2.6.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>3.2.6.RELEASE</version> </dependency>
二、示例代码
ehcache.xml代码如下：
<?xml version="1.0" encoding="UTF-8"?><ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd" updateCheck="false"> <!-- 默认缓存配置 ，缓存名称为 default --> <defaultCache maxElementsInMemory="50" eternal="false" overflowToDisk="false" memoryStoreEvictionPolicy="LFU" /> <!-- 自定义缓存，名称为lt.ehcache --> <cache name="lt.ecache" maxElementsInMemory="50" eternal="false" overflowToDisk="false" memoryStoreEvictionPolicy="LFU" /></ehcache>
Spring-config-ehcache.xml代码如下：
<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:cache="http://www.springframework.org/schema/cache" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsdhttp://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <cache:annotation-driven /> <context:component-scan base-package="com.ehcache.test" /> <!-- 注解扫描路径 --> <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager"> <property name="cacheManager" ref="ehcache" /> </bean> <bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> <property name="configLocation" value="classpath:ehcache.xml" /> </bean> </beans>
ehcache.xml与Spring-config-ehcache.xml存放在系统目录下。
相关代码如下：
实体Employee.java
1 package com.ehcache.test; 2 3 import java.io.Serializable; 4 5 public class Employee implements Serializable { 6 private static final long serialVersionUID = -6534180255882276966L; 7 private int id; 8 private String name; 9 private String designation;10 11 public Employee(int id, String name, String designation) {12 super();13 this.id = id;14 this.name = name;15 this.designation = designation;16 }17 18 public int getId() {19 return id;20 }21 22 public void setId(int id) {23 this.id = id;24 }25 26 @Override27 public String toString() {28 return "Employee [id=" + id + ", name=" + name + ", designation=" + designation + "]";29 }30 31 public String getName() {32 return name;33 }34 35 public void setName(String name) {36 this.name = name;37 }38 39 public String getDesignation() {40 return designation;41 }42 43 public void setDesignation(String designation) {44 this.designation = designation;45 }46 }
EmployeeDAO.java
1 package com.ehcache.test; 2 3 import java.util.ArrayList; 4 import java.util.List; 5 6 import org.springframework.cache.annotation.CacheEvict; 7 import org.springframework.cache.annotation.CachePut; 8 import org.springframework.cache.annotation.Cacheable; 9 import org.springframework.stereotype.Component;10 11 @Component("employeeDAO")12 public class EmployeeDAO {13 14 // key 当前类，缓存对象为返回值list15 @Cacheable(value = http://www.mamicode.com/{"lt.ecache"}, key = "#root.targetClass")16 public List<Employee> getEmployees() {17 System.out.println("*** getEmployees() 已经调用 ***");18 List<Employee> list = new ArrayList<Employee>(5);19 list.add(new Employee(1, "Ben", "Architect"));20 list.add(new Employee(2, "Harley", "Programmer"));21 list.add(new Employee(3, "Peter", "BusinessAnalyst"));22 list.add(new Employee(4, "Sasi", "Manager"));23 list.add(new Employee(5, "Abhi", "Designer"));24 return list;25 }26 27 // key id，缓存数据为返回值Employee对象28 @Cacheable(value = "http://www.mamicode.com/lt.ecache", key = "#id")29 public Employee getEmployee(int id, List<Employee> employees) {30 System.out.println("*** getEmployee(): " + id + " ***");31 Employee emp = null;32 for (Employee employee : employees) {33 if (employee.getId() == id) {34 emp = employee;35 }36 }37 return emp;38 }39 40 // @CachePut会去替换缓存中的Employee对象为当前id对应的对象41 @CachePut(value = "http://www.mamicode.com/lt.ecache", key = "#id")42 public Employee updateEmployee(int id, String designation, List<Employee> employees) {43 System.out.println("*** updateEmployee() " + id + " ***");44 Employee emp = null;45 int i = 0;46 for (Employee employee : employees) {47 if (employee.getId() == id) {48 employee.setDesignation(designation);49 emp = employee;50 }51 }52 System.out.println(emp);53 return emp;54 }55 56 //key为参数中Employee对象的id，缓存指定id对应的Employee对象57 @Cacheable(value = "http://www.mamicode.com/lt.ecache", key = "#employee.id")58 public Employee addEmployee(Employee employee, List<Employee> employees) {59 System.out.println("*** addEmployee() : " + employee.getId() + " ***");60 employees.add(employee);61 System.out.println(employee);62 return employee;63 }64 65 //key为参数中的id，移除缓存，移除指定id对应的Employee对象66 @CacheEvict(value = "http://www.mamicode.com/lt.ecache", key = "#id")67 public Employee removeEmployee(int id, List<Employee> employees) {68 System.out.println("*** removeEmployee() : " + id + " ***");69 Employee emp = null;70 int i = 0;71 for (Employee employee : employees) {72 if (employee.getId() == id) {73 emp = employee;74 } else {75 i++;76 }77 }78 employees.remove(i);79 return emp;80 }81 82 //key为当前类，移除缓存，移除employees列表对象83 @CacheEvict(value = "http://www.mamicode.com/lt.ecache", key = "#root.targetClass")84 public List<Employee> removeAllEmployee(List<Employee> employees) {85 System.out.println("*** removeAllEmployee() : ***");86 employees.clear();87 System.out.println(employees.size());88 return employees;89 }90 91 }
lt.ecache为ehcache.xml中配置的缓存名称。对于要使用到缓存的方法必须使用@注解，同时还要将缓存对象在方法的最后return，否则会报错。
类中使用到了Spring Expression Language（SpEL）,其中相关说明如下
#root.methodName 被执行方法的名称
#root.method.name 被执行的方法
#root.target 被执行的目标对象
#root.targetClass 被执行的目标对象的class
#root.args[0] 调用目标方法的时候目标方法里面的参数（可将参数列表类比成对象数组）的第一个
#root.caches[0].name 获取当前执行方法的缓存
Main.java
1 package com.ehcache.test; 2 3 import java.util.List; 4 5 import org.springframework.context.ApplicationContext; 6 import org.springframework.context.support.ClassPathXmlApplicationContext; 7 8 9 public class Main {10 11 public static void main(String[] args) {12 13 ApplicationContext context = new ClassPathXmlApplicationContext("spring-config-ehcache.xml");14 15 EmployeeDAO dao = (EmployeeDAO) context.getBean("employeeDAO"); 16 17 System.out.println("-----------------------第1次调用----------------------------");18 List<Employee> employees = dao.getEmployees(); 19 System.out.println(employees.toString()); 20 System.out.println("------------------------第2次调用---------------------------");21 employees = dao.getEmployees();22 System.out.println(employees.toString()); 23 System.out.println("------------------------第3次调用---------------------------");24 employees = dao.getEmployees();25 System.out.println(employees.toString()); 26 27 28 System.out.println("-------------------------第1次调用--------------------------");29 Employee employee = dao.getEmployee(1, employees);30 System.out.println(employee.toString());31 System.out.println("-------------------------第2次调用--------------------------");32 employee = dao.getEmployee(1, employees);33 System.out.println(employee.toString());34 35 36 System.out.println("------------------------- 对象更新--------------------------"); 37 dao.updateEmployee(1, "已经更新的对象", employees); 38 System.out.println("-------------------------第1次调用--------------------------");39 employee = dao.getEmployee(1, employees);40 System.out.println(employee.toString());41 System.out.println("-------------------------第2次调用--------------------------");42 employee = dao.getEmployee(1, employees);43 System.out.println(employee.toString());44 45 46 System.out.println("------------------------- 添加对象--------------------------");47 dao.addEmployee(new Employee(6, "555", "Designer5555"),employees);48 System.out.println("-------------------------第1次调用--------------------------");49 employee = dao.getEmployee(6, employees);50 System.out.println(employee);51 System.out.println("-------------------------第2次调用--------------------------");52 employee = dao.getEmployee(6, employees);53 System.out.println(employee.toString());54 55 56 System.out.println("------------------------- 清除一个对象--------------------------");57 System.out.println(employees.size());58 employee = dao.removeEmployee(6, employees);59 System.out.println("-------------------------第1次调用--------------------------");60 employees = dao.getEmployees();61 System.out.println(employees);62 System.out.println(employees.size());63 System.out.println("-------------------------第2次调用--------------------------");64 employees = dao.getEmployees();65 System.out.println(employees); 66 67 68 System.out.println("------------------------- 清除所有--------------------------");69 System.out.println(employees.size());70 employees = dao.removeAllEmployee(employees);71 System.out.println("-------------------------第1次调用--------------------------");72 employees = dao.getEmployees();73 System.out.println(employees); 74 System.out.println("-------------------------第2次调用--------------------------");75 employees = dao.getEmployees();76 System.out.println(employees); 77 }78 }
当对象缓存之后方法就不会执行，而是直接从缓存中获取。
ehcache整合spring注解方式
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