SpringBoot+Mybatis-Plus实现mysql读写分离方案的示例代码
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2022-07-01 16:34:31
1. 引入mybatis-plus相关包,pom.xml文件2. 配置文件application.property增加多库配置mysql 数据源配置spring.datasource.primary....
1. 引入mybatis-plus相关包,pom.xml文件
2. 配置文件application.property增加多库配置
mysql 数据源配置
spring.datasource.primary.jdbc-url=jdbc:mysql://xx.xx.xx.xx:3306/portal?useunicode=true&usejdbccomplianttimezoneshift=true&uselegacydatetimecode=false&servertimezone=utc&characterencoding=utf8&servertimezone=gmt%2b8 spring.datasource.primary.username=root spring.datasource.primary.password=root spring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.driver #mysql slave 数据源配置 spring.datasource.slave.jdbc-url=jdbc:mysql://xx.xx.xx.xx:3306/portal?useunicode=true&usejdbccomplianttimezoneshift=true&uselegacydatetimecode=false&servertimezone=utc&characterencoding=utf8&servertimezone=gmt%2b8 spring.datasource.slave.username=root spring.datasource.slave.password=root spring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.driver
3. 配置数据源及注解
数据源配置 multidatasourceconfig.java
/** * 配置多数据源 */ @profile("dev")//开发模式配置文件 @configuration @mapperscan(basepackages = "com.csc.portal.mapper")//扫描包 public class multidatasourceconfig { /** * 主数据源 * @return */ @bean @configurationproperties(prefix = "spring.datasource.primary") public datasource masterdatasource() { return datasourcebuilder.create().build(); } /** * 从数据源 * @return */ @bean @configurationproperties(prefix = "spring.datasource.slave") public datasource slavedatasource() { return datasourcebuilder.create().build(); } /** * 路由数据源,前面两个数据源是为了创建此数据源 * @param masterdatasource 主数据源 * @param slavedatasource 从数据源 * @return */ @bean public datasource myroutingdatasource(@qualifier("masterdatasource") datasource masterdatasource, @qualifier("slavedatasource") datasource slavedatasource) { map<object, object> targetdatasources = new hashmap<>(); targetdatasources.put(dbtypeenum.master, masterdatasource); targetdatasources.put(dbtypeenum.slave, slavedatasource); myroutingdatasource myroutingdatasource = new myroutingdatasource(); myroutingdatasource.setdefaulttargetdatasource(slavedatasource);//设置默认数据源 myroutingdatasource.settargetdatasources(targetdatasources);//设置路由表,使用map的key,value方式得到对应数据源 return myroutingdatasource; }
数据库枚举类
public enum dbtypeenum { master, slave; }
注解
@target({elementtype.method}) @retention(retentionpolicy.runtime) public @interface master { }
@target({elementtype.method}) @retention(retentionpolicy.runtime) public @interface slave { }
4. mybatis-plus配置
@enabletransactionmanagement @configuration @mapperscan(basepackages = "com.csc.portal.mapper") public class mybatisplusconfig { /** * 分页插件 */ @bean public paginationinterceptor paginationinterceptor() { return new paginationinterceptor(); } @resource(name = "myroutingdatasource") private datasource myroutingdatasource; /** * 使用mybatis plus的sqlsessionfactory代替, * 此处注意mybatis与mybatisplus的配置不同,不然扫描不到对数据操作的方法。会报未绑定错误 * @return sqlsessionfactory * @throws exception */ @bean public sqlsessionfactory sqlsessionfactory() throws exception { mybatissqlsessionfactorybean sqlsessionfactorybean = new mybatissqlsessionfactorybean(); sqlsessionfactorybean.setdatasource(myroutingdatasource); sqlsessionfactorybean.setmapperlocations(new pathmatchingresourcepatternresolver().getresources("classpath:mapper/*.xml")); mybatisconfiguration mybatisconfiguration = new mybatisconfiguration(); sqlsessionfactorybean.setconfiguration(mybatisconfiguration); return sqlsessionfactorybean.getobject(); } /** * 此处为使用mybatis时的sqlsessionfactory配置 * @return * @throws exception */ /* @bean public sqlsessionfactory sqlsessionfactory() throws exception { sqlsessionfactorybean sqlsessionfactorybean = new sqlsessionfactorybean(); sqlsessionfactorybean.setdatasource(myroutingdatasource); sqlsessionfactorybean.setmapperlocations(new pathmatchingresourcepatternresolver().getresources("classpath:mapper/*.xml")); return sqlsessionfactorybean.getobject(); } */ /** * 事务配置 * @return 事务管理器 */ @bean public datasourcetransactionmanager transactionmanager() { datasourcetransactionmanager tx = new datasourcetransactionmanager(); tx.setdatasource(myroutingdatasource); return tx; }
5. 增加数据源管理类
dbcontextholder.java
public class dbcontextholder { /** * 外部一个请求将会产生一个线程与之对应,每个线程的变量可用threadlocal进行存储 */ private static final threadlocal<dbtypeenum> contextholder = new threadlocal<>(); public static void set(dbtypeenum dbtype) { contextholder.set(dbtype); } public static dbtypeenum get() { return contextholder.get(); } public static void master() { set(dbtypeenum.master); system.out.println("切换到master"); } public static void slave() { set(dbtypeenum.slave); system.out.println("切换到slave"); } }
指定选择数据源
myroutingdatasource.java 方法determinecurrentlookupkey决定最终使用哪个数据源进行操作,若为空则使用默认数据源。
public class myroutingdatasource extends abstractroutingdatasource { @nullable @override protected object determinecurrentlookupkey() { system.out.println("线程名:"+thread.currentthread().getname()+":"+dbcontextholder.get()); return dbcontextholder.get(); /* if (dbcontextholder.get() != null) { system.out.println("线程名:"+thread.currentthread().getname()+":"+dbcontextholder.get()); return dbcontextholder.get(); } else { system.out.println("未匹配到指定数据库,默认切换到master"); return dbtypeenum.master; }*/ //return dbcontextholder.get(); } }
6. 增加aop切面
@aspect @component @order(0)//配置注解优先级,优于事物注解@transactional先进行数据源切换, //不然在事物中进行数据源切换无效 public class datasourceaop { @pointcut(/*"!@annotation(com.csc.portal.annotation.master) " + "&& (execution(* com.csc.portal.service..*.select*(..)) " + "|| execution(* com.csc.portal.service..*.get*(..))"+*/ " @annotation(com.csc.portal.annotation.slave)") public void readpointcut() { } @pointcut("@annotation(com.csc.portal.annotation.master) " //+ /* "|| execution(* com.csc.portal.service..*.insert*(..)) " + "|| execution(* com.csc.portal.service..*.add*(..)) " + "|| execution(* com.csc.portal.service..*.update*(..)) " + "|| execution(* com.csc.portal.service..*.edit*(..)) " + "|| execution(* com.csc.portal.service..*.delete*(..)) " + "|| execution(* com.csc.portal.service..*.remove*(..))"*/) public void writepointcut() { } @before("readpointcut()") public void read() { //获取拦截类 dbcontextholder.slave(); system.out.println(thread.currentthread().getname()+dbcontextholder.get()); } @before("writepointcut()") public void write() { //获取拦截类 /* string classname = pjp.gettarget().getclass().getname(); system.out.println("当前线程"+thread.currentthread().getname()+" 拦截类为:" + classname); //获取拦截的方法名 methodsignature msig = (methodsignature) pjp.getsignature(); method currentmethod = null; try { currentmethod = pjp.gettarget().getclass().getmethod(msig.getname(), msig.getparametertypes()); } catch (nosuchmethodexception e) { e.printstacktrace(); } string methodname = currentmethod.getname(); system.out.println("拦截方法名为:" + methodname);*/ dbcontextholder.master(); system.out.println(thread.currentthread().getname()+dbcontextholder.get()); } }
6. 实际应用
- 在service层方法前增加注解@master表示使用主库,进行增删改的操作使用主库。
- 在service层方法前增加注解@slave表示使用从库,进行查的操作使用从库,默认使用从库,可不配置。
- @ transactional注解加到service层,增加了@transactional注解后,启用事务后,一个事务内部的connection是复用的,所以就算aop切了数据源字符串,但是数据源并不会被真正修改。所以@transactional注解不要写在controller层,不然在service层也切换不了数据源。
- @transactional与@master可同时使用,已经配置@master注解的优先级较高,先切换数据源后执行事务。
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