引子
我門知道一個(gè)程序的瓶頸在于數(shù)據(jù)庫，我門也知道內(nèi)存的速度是大大快于硬盤的速度的。當(dāng)我門需要重復(fù)的獲取相同的數(shù)據(jù)的時(shí)候，我門一次又一次的請(qǐng)求數(shù)據(jù)庫或者遠(yuǎn)程服務(wù)，導(dǎo)致大量的時(shí)間耗費(fèi)在數(shù)據(jù)庫查詢或者遠(yuǎn)程方法的調(diào)用上，導(dǎo)致程序性能的惡化，這更是數(shù)據(jù)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(tǒng)一不同的緩存技術(shù)。其中，cachemanager是spring提供的各種緩存技術(shù)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(huì)直接和此接口打交道）
spring 支持的cachemanager
針對(duì)不同的緩存技術(shù)，需要實(shí)現(xiàn)不同的cachemanager ,spring 定義了如下表的cachemanager實(shí)現(xiàn)。
實(shí)現(xiàn)任意一種cachemanager 的時(shí)候，需要注冊(cè)實(shí)現(xiàn)cachemanager的bean，當(dāng)然每種緩存技術(shù)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(gè)注解來聲明緩存規(guī)則（又是使用注解式的aop的一個(gè)生動(dòng)例子），如表。
開啟聲明式緩存
開啟聲明式緩存支持非常簡(jiǎn)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(shù)的關(guān)鍵是配置cachemanager 而springbok 為我門自動(dòng)配置了多個(gè)cachemanager的實(shí)現(xiàn)。在spring boot 環(huán)境下，使用緩存技術(shù)只需要在項(xiàng)目中導(dǎo)入相關(guān)緩存技術(shù)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(shí)現(xiàn)的。
實(shí)例步驟目錄
- 創(chuàng)建maven項(xiàng)目
- 數(shù)據(jù)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(dòng)cache
- 測(cè)試校驗(yàn)
1.創(chuàng)建maven項(xiàng)目
新建maven 項(xiàng)目pom.xml文件如下內(nèi)容如下：
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<?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(shù)據(jù)庫配置
在src/main/esouces目錄下新建application.properties 文件，內(nèi)容為數(shù)據(jù)庫連接信息，如下：
application.properties
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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(shù)據(jù)源
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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(shù)據(jù)庫設(shè)計(jì)，數(shù)據(jù)庫只有一張person表，設(shè)計(jì)如下：
3.jpa配置
spring－data－ jpa 配置文件如下：
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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(shí)體類 person.java
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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
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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
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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(shí)現(xiàn)：(重點(diǎn)，此處加緩存)
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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(shù)據(jù)到緩存,其中緩存名字是 people 。數(shù)據(jù)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(shù)據(jù)做了緩存"); return p; } @override //@cacheevict 從緩存people中刪除key為id 的數(shù)據(jù) @cacheevict(value = "people") public void remove(long id) { system.out.println("刪除了id、key為"+id+"的數(shù)據(jù)緩存"); //這里不做實(shí)際刪除操作 } @override //@cacheable緩存key為person 的id 數(shù)據(jù)到緩存people 中,如果沒有指定key則方法參數(shù)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(shù)據(jù)做了緩存"); return p; }} |
6.編寫controller
為了測(cè)試方便請(qǐng)求方式都用了get
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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(dòng)cache
啟動(dòng)類中要記得開啟緩存配置。
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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(cè)試校驗(yàn)檢驗(yàn)able：
啟動(dòng)application 類，啟動(dòng)后在瀏覽器輸入：http://localhost:8080/able?id=1（首先要在數(shù)據(jù)庫中初始化幾條數(shù)據(jù)。）
控制臺(tái)輸出：
“為id、key為:1數(shù)據(jù)做了緩存“ 此時(shí)已經(jīng)為此次查詢做了緩存，再次查詢?cè)摋l數(shù)據(jù)將不會(huì)出現(xiàn)此條語句，也就是不查詢數(shù)據(jù)庫了。
檢驗(yàn)put
在瀏覽器輸入：http://localhost:8080/put?name=abel&age=23&address=shanghai（向數(shù)據(jù)庫插入一條數(shù)據(jù)，并將數(shù)據(jù)放入緩存。）
此時(shí)控制臺(tái)輸出為該條記錄做了緩存：
然后再次調(diào)用able 方法，查詢?cè)摋l數(shù)據(jù)，將不再查詢數(shù)據(jù)庫，直接從緩存中讀取數(shù)據(jù)。
測(cè)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(huì)重新將該記錄放入緩存。）
控制臺(tái)輸出：
切換緩存
1.切換為ehcache作為緩存
pom.xml 文件中添加依賴
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<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(nèi)容如下，此文件spring boot 會(huì)自動(dòng)掃描
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<?xml version="1.0" encoding="utf-8"?><ehcache> <!--切換為ehcache 緩存時(shí)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
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<dependency> <groupid>com.google.guava</groupid> <artifactid>guava</artifactid> <version>18.0</version> </dependency> |
3.切換為redis作為緩存
請(qǐng)看下篇博客
本文參考：《javaee開發(fā)的顛覆者：spring boot實(shí)戰(zhàn) 》
本文源代碼：https://github.com/527515025/springboot.git
以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持服務(wù)器之家。
原文鏈接：https://blog.csdn.net/u012373815/article/details/54564076/
