引子
我門知道一個程序的瓶頸在于數據庫，我門也知道內存的速度是大大快于硬盤的速度的。當我門需要重復的獲取相同的數據的時候，我門一次又一次的請求數據庫或者遠程服務，導致大量的時間耗費在數據庫查詢或者遠程方法的調用上，導致程序性能的惡化，這更是數據緩存要解決的問題。
spring 緩存支持
spring定義了 org.springframework.cache.cachemanager和org.springframework.cache.cache接口來統一不同的緩存技術。其中，cachemanager是spring提供的各種緩存技術抽象接口，cache接口包含了緩存的各種操作（增加、刪除獲得緩存，我門一般不會直接和此接口打交道）
spring 支持的cachemanager
針對不同的緩存技術，需要實現不同的cachemanager ,spring 定義了如下表的cachemanager實現。
實現任意一種cachemanager 的時候，需要注冊實現cachemanager的bean，當然每種緩存技術都有很多額外的配置，但配置cachemanager 是必不可少的。
聲明式緩存注解
spring提供了4個注解來聲明緩存規則（又是使用注解式的aop的一個生動例子），如表。
開啟聲明式緩存
開啟聲明式緩存支持非常簡單，只需要在配置類上使用@enabelcaching 注解即可。
springboot 的支持
在spring中國年使用緩存技術的關鍵是配置cachemanager 而springbok 為我門自動配置了多個cachemanager的實現。在spring boot 環境下，使用緩存技術只需要在項目中導入相關緩存技術的依賴包，并配置類使用@enabelcaching開啟緩存支持即可。
小例子
小例子是使用 springboot+jpa ＋cache 實現的。
實例步驟目錄
- 創建maven項目
- 數據庫配置
- jpa配置和cache配置
- 編寫bean 和dao層
- 編寫service層
- 編寫controller
- 啟動cache
- 測試校驗
1.創建maven項目
新建maven 項目pom.xml文件如下內容如下：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
|
<?xml version="1.0" encoding="utf-8"?><project xmlns="http://maven.apache.org/pom/4.0.0" xmlns:xsi="http://www.w3.org/2001/xmlschema-instance" xsi:schemalocation="http://maven.apache.org/pom/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelversion>4.0.0</modelversion> <groupid>com.us</groupid> <artifactid>springboot-cache</artifactid> <version>1.0-snapshot</version> <parent> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-parent</artifactid> <version>1.3.0.release</version> </parent> <properties> <start-class>com.us.application</start-class> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> <!-- add typical dependencies for a web application --> <dependencies> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-cache</artifactid> </dependency> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-data-jpa</artifactid> </dependency> <dependency> <groupid>org.springframework.boot</groupid> <artifactid>spring-boot-starter-web</artifactid> </dependency> <dependency> <groupid>net.sf.ehcache</groupid> <artifactid>ehcache</artifactid> </dependency> <!--db--> <dependency> <groupid>mysql</groupid> <artifactid>mysql-connector-java</artifactid> <version>6.0.5</version> </dependency> <dependency> <groupid>com.mchange</groupid> <artifactid>c3p0</artifactid> <version>0.9.5.2</version> <exclusions> <exclusion> <groupid>commons-logging</groupid> <artifactid>commons-logging</artifactid> </exclusion> </exclusions> </dependency> </dependencies></project> |
2.數據庫配置
在src/main/esouces目錄下新建application.properties 文件，內容為數據庫連接信息，如下：
application.properties
|
1
2
3
4
5
|
ms.db.driverclassname=com.mysql.jdbc.driverms.db.url=jdbc:mysql://localhost:3306/cache?prepstmtcachesize=517&cacheprepstmts=true&autoreconnect=true&useunicode=true&characterencoding=utf-8&usessl=false&allowmultiqueries=truems.db.username=rootms.db.password=xxxxxxms.db.maxactive=500 |
新建dbconfig.java 配置文件，配置數據源
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
|
package com.us.example.config;/** * created by yangyibo on 17/1/13. */import java.beans.propertyvetoexception;import org.springframework.beans.factory.annotation.autowired;import org.springframework.context.annotation.bean;import org.springframework.context.annotation.configuration;import org.springframework.core.env.environment;import com.mchange.v2.c3p0.combopooleddatasource;@configurationpublic class dbconfig { @autowired private environment env; @bean(name="datasource") public combopooleddatasource datasource() throws propertyvetoexception { combopooleddatasource datasource = new combopooleddatasource(); datasource.setdriverclass(env.getproperty("ms.db.driverclassname")); datasource.setjdbcurl(env.getproperty("ms.db.url")); datasource.setuser(env.getproperty("ms.db.username")); datasource.setpassword(env.getproperty("ms.db.password")); datasource.setmaxpoolsize(20); datasource.setminpoolsize(5); datasource.setinitialpoolsize(10); datasource.setmaxidletime(300); datasource.setacquireincrement(5); datasource.setidleconnectiontestperiod(60); return datasource; }} |
數據庫設計，數據庫只有一張person表，設計如下：
3.jpa配置
spring－data－ jpa 配置文件如下：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
package com.us.example.config;import java.util.hashmap;import java.util.map;import javax.persistence.entitymanagerfactory;import javax.sql.datasource;import org.springframework.beans.factory.annotation.autowired;import org.springframework.context.annotation.bean;import org.springframework.context.annotation.componentscan;import org.springframework.context.annotation.configuration;import org.springframework.data.jpa.repository.config.enablejparepositories;import org.springframework.orm.jpa.jpatransactionmanager;import org.springframework.orm.jpa.localcontainerentitymanagerfactorybean;import org.springframework.orm.jpa.vendor.hibernatejpavendoradapter;import org.springframework.transaction.platformtransactionmanager;import org.springframework.transaction.annotation.enabletransactionmanagement;/** * created by yangyibo on 17/1/13. */@configuration@enablejparepositories("com.us.example.dao")@enabletransactionmanagement@componentscanpublic class jpaconfig { @autowired private datasource datasource; @bean public entitymanagerfactory entitymanagerfactory() { hibernatejpavendoradapter vendoradapter = new hibernatejpavendoradapter(); localcontainerentitymanagerfactorybean factory = new localcontainerentitymanagerfactorybean(); factory.setjpavendoradapter(vendoradapter); factory.setpackagestoscan("com.us.example.bean"); factory.setdatasource(datasource); map<string, object> jpaproperties = new hashmap<>(); jpaproperties.put("hibernate.ejb.naming_strategy","org.hibernate.cfg.improvednamingstrategy"); jpaproperties.put("hibernate.jdbc.batch_size",50); factory.setjpapropertymap(jpaproperties); factory.afterpropertiesset(); return factory.getobject(); } @bean public platformtransactionmanager transactionmanager() { jpatransactionmanager txmanager = new jpatransactionmanager(); txmanager.setentitymanagerfactory(entitymanagerfactory()); return txmanager; }} |
4.編寫bean 和dao層
實體類 person.java
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
package com.us.example.bean;import javax.persistence.entity;import javax.persistence.generatedvalue;import javax.persistence.id;import javax.persistence.table;/** * created by yangyibo on 17/1/13. */@entity@table(name = "person")public class person { @id @generatedvalue private long id; private string name; private integer age; private string address; public person() { super(); } public person(long id, string name, integer age, string address) { super(); this.id = id; this.name = name; this.age = age; this.address = address; } public long getid() { return id; } public void setid(long id) { this.id = id; } public string getname() { return name; } public void setname(string name) { this.name = name; } public integer getage() { return age; } public void setage(integer age) { this.age = age; } public string getaddress() { return address; } public void setaddress(string address) { this.address = address; }} |
dao層，personrepository.java
|
1
2
3
4
5
6
7
8
9
10
|
package com.us.example.dao;import com.us.example.bean.person;import org.springframework.data.jpa.repository.jparepository;/** * created by yangyibo on 17/1/13. */public interface personrepository extends jparepository<person, long> {} |
5.編寫service層
service 接口
|
1
2
3
4
5
6
7
8
9
10
11
12
|
package com.us.example.service;import com.us.example.bean.person;/** * created by yangyibo on 17/1/13. */public interface demoservice { public person save(person person); public void remove(long id); public person findone(person person);} |
實現：(重點，此處加緩存)
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
package com.us.example.service.impl;import com.us.example.bean.person;import com.us.example.dao.personrepository;import com.us.example.service.demoservice;import org.springframework.beans.factory.annotation.autowired;import org.springframework.cache.annotation.cacheevict;import org.springframework.cache.annotation.cacheput;import org.springframework.cache.annotation.cacheable;import org.springframework.stereotype.service;/** * created by yangyibo on 17/1/13. */@servicepublic class demoserviceimpl implements demoservice { @autowired private personrepository personrepository; @override //@cacheput緩存新增的或更新的數據到緩存,其中緩存名字是 people 。數據的key是person的id @cacheput(value = "people", key = "#person.id") public person save(person person) { person p = personrepository.save(person); system.out.println("為id、key為:"+p.getid()+"數據做了緩存"); return p; } @override //@cacheevict 從緩存people中刪除key為id 的數據 @cacheevict(value = "people") public void remove(long id) { system.out.println("刪除了id、key為"+id+"的數據緩存"); //這里不做實際刪除操作 } @override //@cacheable緩存key為person 的id 數據到緩存people 中,如果沒有指定key則方法參數作為key保存到緩存中。 @cacheable(value = "people", key = "#person.id") public person findone(person person) { person p = personrepository.findone(person.getid()); system.out.println("為id、key為:"+p.getid()+"數據做了緩存"); return p; }} |
6.編寫controller
為了測試方便請求方式都用了get
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
package com.us.example.controller;import com.us.example.bean.person;import com.us.example.service.demoservice;import org.springframework.beans.factory.annotation.autowired;import org.springframework.stereotype.controller;import org.springframework.web.bind.annotation.requestmapping;import org.springframework.web.bind.annotation.responsebody;import org.springframework.web.bind.annotation.restcontroller;/** * created by yangyibo on 17/1/13. */@restcontrollerpublic class cachecontroller { @autowired private demoservice demoservice; //http://localhost:8080/put?name=abel&age=23&address=shanghai @requestmapping("/put") public person put(person person){ return demoservice.save(person); } //http://localhost:8080/able?id=1 @requestmapping("/able") @responsebody public person cacheable(person person){ return demoservice.findone(person); } //http://localhost:8080/evit?id=1 @requestmapping("/evit") public string evit(long id){ demoservice.remove(id); return "ok"; }} |
7.啟動cache
啟動類中要記得開啟緩存配置。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
|
package com.us.example;import org.springframework.boot.autoconfigure.springbootapplication;import org.springframework.cache.annotation.enablecaching;import org.springframework.context.configurableapplicationcontext;import org.springframework.context.annotation.componentscan;import static org.springframework.boot.springapplication.*;/** * created by yangyibo on 17/1/13. */@componentscan(basepackages ="com.us.example")@springbootapplication@enablecachingpublic class application { public static void main(string[] args) { configurableapplicationcontext run = run(application.class, args); }} |
8.測試校驗檢驗able：
啟動application 類，啟動后在瀏覽器輸入：http://localhost:8080/able?id=1（首先要在數據庫中初始化幾條數據。）
控制臺輸出：
“為id、key為:1數據做了緩存“ 此時已經為此次查詢做了緩存，再次查詢該條數據將不會出現此條語句，也就是不查詢數據庫了。
檢驗put
在瀏覽器輸入：http://localhost:8080/put?name=abel&age=23&address=shanghai（向數據庫插入一條數據，并將數據放入緩存。）
此時控制臺輸出為該條記錄做了緩存：
然后再次調用able 方法，查詢該條數據，將不再查詢數據庫，直接從緩存中讀取數據。
測試evit
在瀏覽器輸入：http://localhost:8080/evit?id=1（將該條記錄從緩存中清楚，清除后，在次訪問該條記錄，將會重新將該記錄放入緩存。）
控制臺輸出：
切換緩存
1.切換為ehcache作為緩存
pom.xml 文件中添加依賴
|
1
2
3
4
|
<dependency> <groupid>net.sf.ehcache</groupid> <artifactid>ehcache</artifactid> </dependency> |
在resource 文件夾下新建ehcache的配置文件ehcache.xml 內容如下，此文件spring boot 會自動掃描
|
1
2
3
4
5
|
<?xml version="1.0" encoding="utf-8"?><ehcache> <!--切換為ehcache 緩存時使用--><cache name="people" maxelementsinmemory="1000" /></ehcache> |
2.切換為guava作為緩存
只需要在pom中添加依賴
|
1
2
3
4
5
|
<dependency> <groupid>com.google.guava</groupid> <artifactid>guava</artifactid> <version>18.0</version> </dependency> |
3.切換為redis作為緩存
請看下篇博客
本文參考：《javaee開發的顛覆者：spring boot實戰 》
本文源代碼：https://github.com/527515025/springboot.git
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持服務器之家。
原文鏈接：https://blog.csdn.net/u012373815/article/details/54564076/
