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.xsd

http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsd

http://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     @Override

27     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list

15     @Cacheable(value = {"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 = "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 = "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 = "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 = "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 = "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。 

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