MySQL 数据库主从同步与读写分离

电玩女神 2022-12-21 13:58 217阅读 0赞

## 1、MySQL 数据库主服务器配置 ##

root@master ~]# ifconfig
    eth1	Link encap:Ethernet HWaddr 00:16:3E:00:47:83
    		inet addr:120.24.64.163  Bcast:120.24.67.255  Mask:255.255.252.0

打开 master 的 binary log：

root@master ~]# vim /etc/my.cnf
    
    [mysqld]
    # datadir=/var/lib/mysql
    server-id=1
    log-bin=master-bin
    log-bin-index=master-bin.index
    datadir=/usr/local/yanyan/mysql_data
    socket=/var/lib/mysql/mysql.sock
    user=mysql
    # Disabling symbolic-links is recommended to prevent assorted security risks
    symbolic-links=0
    default-character-set=utf8
    [mysqld_safe]
    log-error=/var/log/mysqld.log
    pid-file=/var/run/mysqld/mysqld.pid
    [mysql]
    default-character-set=utf8

重启master上的mysql服务：

root@master ~]# service mysqld restart

显示master状态：

指定master访问slave的账号，并授权REPLICATION SLAVE权限。

mysql> create user repl;
    Query OK, 0 rows affected (0.00 sec)
    mysql> GRANT REPLICATION SLAVE ON *.* TO 'repl'@'115.28.159.6' IDENTIFIED BY 'mysql';
    Query OK, 0 rows affected (0.00 sec)
    mysql> flush privileges;
    Query OK, 0 rows affected (0.00 sec)

## 2、MySQL 数据库从服务器配置 ##

root@slave ~]# ifconfig
    eth1	Link encap:Ethernet HWaddr 00:16:3E:00:47:83
    		inet addr:115.28.159.6  Bcast:115.28.159.255  Mask:255.255.252.0

打开slave的 relay log：

root@master ~]# vim /etc/my.cnf
    
    # In this file, you can use all long options that a program supports.
    # If you want to know which options a program supports, run the program
    # with the "--help" option.
    
    # The following options will be passed to all MySQL clients
    [client]
    # password = your_password
    port		= 3306
    socket		= /var/lib/mysql/mysql.sock
    # Here follows entries for some specific programs.
    
    # The MySQL server
    [mysqld]
    server-id	= 2
    relay-log	= slave-relay-bin
    relay-log-index	= slave-relay-bin.index
    port		= 3306
    socket		= /var/lib/mysql/mysql.sock
    skip-external-locking
    key_buffer_size = 16M
    max_allowed_packet = 1M
    table_open_cache = 64
    sort_buffer_size = 512K
    net_buffer_length = 8K
    read_buffer_size = 256K
    read_rnd_buffer_size = 512K
    myisam_sort_buffer_size = 8M

重启slave上的mysql服务：

root@slave ~]# service mysqld restart

或者使用以下命令重启：

root@slave ~]# /etc/init.d/mysql stop
    root@slave ~]# /etc/init.d/mysql start

## 3、在 slave 上将 master 与 slave 联系起来 ##

mysql> change master to master_host='120.24.64.163', master_port=3306, master_user='repl', master_password='mysql', master_log_file='master-bin.000001', master_log_pos=0;
    Query OK, 0 rows affected (0.06 sec)

开启slave：

mysql> start slave;
    Query OK, 0 rows affected (0.00 sec)

查看slave状态：（\\G表示将输出竖向显示）

mysql> show slave status \G;

停止slave：

mysql> stop slave;
    Query OK, 0 rows affected (0.00 sec)

## 4、验证主库和从库同步 ##

主库添加数据：

从库显示数据：

主库删除数据：

从库也删除了数据：

## 5、将本地数据库导出到主库 ##

在本地执行如下命令：

~]# mysqldump -uroot -p o2o > o2o.sql
    Enter password:
    ~]# ls
    o2o.sql
    ~]# scp o2o.sql root@120.24.64.163:/root
    root@120.24.64.163's password:
    o2o.sql						100%	13KB 	12.8KB/s	00:00

在master中导入o2o.sql

root@master ~]# mysql -uroot -p
    Enter password:
    
    mysql> create database o2o;
    mysql> use o2o;
    mysql> source ~/o2o.sql;

这时，master和slave中的o2o数据库都已创建，并导入数据。

## 6、在项目中配置读写分离 ##

在master和slave中分别新建用户work，并授予权限（master和slave中都执行以下操作）。work账号就是项目代码访问数据库master和slave的账号。

mysql> create user work;
    Query OK, 0 rows affected (0.00 sec)
    mysql> GRANT SELECT, INSERT, UPDATE, DELETE ON *.* TO 'work'@'%' IDENTIFIED BY '123456' WITH GRANT OPTION;
    Query OK, 0 rows affected (0.00 sec)
    mysql> flush privileges;
    Query OK, 0 rows affected (0.00 sec)

在项目代码的jdbc.properties中做如下配置：  
（连接master数据库，可读可写；连接slave数据库，只可读）

## jdbc.properties
    
    jdbc.driver=com.mysql.cj.jdbc.Driver
    jdbc.master.url=jdbc:mysql://120.24.64.163:3306/o2o?useUnicode=true&characterEncoding=utf8
    jdbc.slave.url=jdbc:mysql://115.28.159.6:3306/o2o?useUnicode=true&characterEncoding=utf8
    jdbc.username=work
    jdbc.password=123456

## DynamicDataSource.java
    
    package com.imooc.o2o.dao.split;
    
    import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
    
    public class DynamicDataSource extends AbstractRoutingDataSource { 
    
        @Override
        protected Object determineCurrentLookupKey() { 
            return DynamicDataSourceHolder.getDbType();
        }
    }

## DynamicDataSourceHolder.java
    
    package com.imooc.o2o.dao.split;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    public class DynamicDataSourceHolder { 
        private static Logger logger = LoggerFactory.getLogger(DynamicDataSourceHolder.class);
        private static ThreadLocal<String> contextHolder = new ThreadLocal<>();
        public static final String DB_MASTER = "master";
        public static final String DB_SLAVE = "slave";
    
        // 获取线程的dbType
        public static String getDbType(){ 
            String db = contextHolder.get();
            if (db == null){ 
                db = DB_MASTER;
            }
            return db;
        }
    
        // 设置线程的dbType
        public static void setDbType(String str){ 
            logger.debug("所使用的数据源为：" + str);
            contextHolder.set(str);
        }
    
        // 清理连接类型
        public static void clearDBType(){ 
            contextHolder.remove();
        }
    }

## DynamicDataSourceInterceptor.java
    
    package com.imooc.o2o.dao.split;
    
    import org.apache.ibatis.executor.Executor;
    import org.apache.ibatis.executor.keygen.SelectKeyGenerator;
    import org.apache.ibatis.mapping.BoundSql;
    import org.apache.ibatis.mapping.MappedStatement;
    import org.apache.ibatis.mapping.SqlCommandType;
    import org.apache.ibatis.plugin.*;
    import org.apache.ibatis.session.ResultHandler;
    import org.apache.ibatis.session.RowBounds;
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    import org.springframework.transaction.support.TransactionSynchronizationManager;
    
    import java.util.Locale;
    import java.util.Properties;
    
    @Intercepts({ @Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class}),
    	@Signature(type = Executor.class, method = "query", args = { MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})})
    public class DynamicDataSourceInterceptor implements Interceptor { 
        private static Logger logger = LoggerFactory.getLogger(DynamicDataSourceInterceptor.class);
        private static final String REGEX = ".*insert\\u0020.*|.*delete\\u0020.*|.*update\\u0020.*";
        @Override
        public Object intercept(Invocation invocation) throws Throwable { 
            boolean synchronizationActive = TransactionSynchronizationManager.isActualTransactionActive();
            Object[] objects = invocation.getArgs();
            MappedStatement ms = (MappedStatement) objects[0];
            String lookupKey = DynamicDataSourceHolder.DB_MASTER;
            if (synchronizationActive != true){ 
                // 读方法
                if(ms.getSqlCommandType().equals(SqlCommandType.SELECT)){ 
                    // selectKey为自增id查询主键(SELECT LAST_INSERT_ID())方法，使用主库
                    if (ms.getId().contains(SelectKeyGenerator.SELECT_KEY_SUFFIX)){ 
                        lookupKey = DynamicDataSourceHolder.DB_MASTER;
                    } else { 
                        BoundSql boundSql = ms.getSqlSource().getBoundSql(objects[1]);
                        String sql = boundSql.getSql().toLowerCase(Locale.CHINA).replaceAll("[\\t\\n\\r]", " ");
                        if (sql.matches(REGEX)){ 
                            lookupKey = DynamicDataSourceHolder.DB_MASTER;
                        } else { 
                            lookupKey = DynamicDataSourceHolder.DB_SLAVE;
                        }
                    }
                }
            } else { 
                lookupKey = DynamicDataSourceHolder.DB_MASTER;
            }
            logger.debug("设置方法[{}] use [{}] Strategy, SqlCommandType [{}]",
                    ms.getId(), lookupKey, ms.getSqlCommandType().name());
            DynamicDataSourceHolder.setDbType(lookupKey);
            return invocation.proceed();
        }
    
        @Override
        public Object plugin(Object target) { 
            if (target instanceof Executor){ 
                return Plugin.wrap(target, this);
            } else { 
                return target;
            }
        }
    
        @Override
        public void setProperties(Properties properties) { 
    
        }
    }

## spring-dao.xml
    
    <?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:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
    
        <context:property-placeholder location="classpath:jdbc.properties" />
        <bean id="abstractDataSource" abstract="true" class="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">
            <property name="maxPoolSize" value="30" />
            <property name="minPoolSize" value="10" />
            <property name="autoCommitOnClose" value="false" />
            <property name="checkoutTimeout" value="10000" />
            <property name="acquireRetryAttempts" value="2" />
        </bean>
        <bean id="master" parent="abstractDataSource">
            <property name="driverClass" value="${jdbc.driver}" />
            <property name="jdbcUrl" value="${jdbc.master.url}" />
            <property name="user" value="${jdbc.username}" />
            <property name="password" value="${jdbc.password}" />
        </bean>
        <bean id="slave" parent="abstractDataSource">
            <property name="driverClass" value="${jdbc.driver}" />
            <property name="jdbcUrl" value="${jdbc.slave.url}" />
            <property name="user" value="${jdbc.username}" />
            <property name="password" value="${jdbc.password}" />
        </bean>
    	
        <bean id = "dynamicDataSource" class="com.imooc.o2o.dao.split.DynamicDataSource">
            <property name="targetDataSources">
                <map>
                    <entry value-ref="master" key="master"></entry>
                    <entry value-ref="slave" key="slave"></entry>
                </map>
            </property>
        </bean>
        <bean id="dataSource" class="org.springframework.jdbc.datasource.LazyConnectionDataSourceProxy">
            <property name="targetDataSource">
                <ref bean="dynamicDataSource" />
            </property>
        </bean>
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource" />
            <property name="configLocation" value="classpath:mybatis-config.xml" />
            <property name="typeAliasesPackage" value="com.imooc.o2o.entity" />
            <property name="mapperLocations" value="classpath:mapper/*.xml" />
        </bean>
        <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
            <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory" />
            <property name="basePackage" value="com.imooc.o2o.dao" />
        </bean>
    </beans>

## mybatis-config.xml
    
    <?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <settings>
            <setting name="useGeneratedKeys" value="true"/>
            <setting name="useColumnLabel" value="true"/>
            <setting name="mapUnderscoreToCamelCase" value="true"/>
        </settings>
        <plugins>
            <plugin interceptor="com.imooc.o2o.dao.split.DynamicDataSourceInterceptor"></plugin>
        </plugins>
    </configuration>