ehcache整合spring注解方式

╰+哭是因爲堅強的太久メ 2022-09-22 11:37 1阅读 0赞

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：

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<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>

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二、示例代码

ehcache.xml代码如下：

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<?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">
    
        
        <defaultCache maxElementsInMemory="50" eternal="false"
            overflowToDisk="false" memoryStoreEvictionPolicy="LFU" />
        
        <cache name="lt.ecache" maxElementsInMemory="50" eternal="false"
            overflowToDisk="false" memoryStoreEvictionPolicy="LFU" />
    </ehcache>

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Spring-config-ehcache.xml代码如下：

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<?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" /> 
            
        <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>

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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

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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 }

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EmployeeDAO.java

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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 }

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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

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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 }

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当对象缓存之后方法就不会执行，而是直接从缓存中获取。

转载自http://www.cnblogs.com/always-online/p/4116771.html

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