配置文件是通过springcloudconfig远程分布式配置。采用阿里Druid数据源。并支持一主多从的读写分离。分页组件通过拦截器拦截带有page后缀的方法名，动态的设置total总数。
1. 解析配置文件初始化数据源
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@Configurationpublic class DataSourceConfiguration { /** * 数据源类型 */ @Value("${spring.datasource.type}") private Class<? extends DataSource> dataSourceType; /** * 主数据源配置 * * @return */ @Bean(name = "masterDataSource", destroyMethod = "close") @Primary @ConfigurationProperties(prefix = "spring.datasource") public DataSource masterDataSource() { DataSource source = DataSourceBuilder.create().type(dataSourceType).build(); return source; } /** * 从数据源配置 * * @return */ @Bean(name = "slaveDataSource0") @ConfigurationProperties(prefix = "spring.slave0") public DataSource slaveDataSource0() { DataSource source = DataSourceBuilder.create().type(dataSourceType).build(); return source; } /** * 从数据源集合 * * @return */ @Bean(name = "slaveDataSources") public List<DataSource> slaveDataSources() { List<DataSource> slaveDataSources = new ArrayList(); slaveDataSources.add(slaveDataSource0()); return slaveDataSources; }} |
2. 定义数据源枚举类型
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public enum DataSourceType { master("master", "master"), slave("slave", "slave"); private String type; private String name; DataSourceType(String type, String name) { this.type = type; this.name = name; } public String getType() { return type; } public void setType(String type) { this.type = type; } public String getName() { return name; } public void setName(String name) { this.name = name; }} |
3. TheadLocal保存数据源类型
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public class DataSourceContextHolder { private static final ThreadLocal<String> local = new ThreadLocal<String>(); public static ThreadLocal<String> getLocal() { return local; } public static void slave() { local.set(DataSourceType.slave.getType()); } public static void master() { local.set(DataSourceType.master.getType()); } public static String getJdbcType() { return local.get(); } public static void clearDataSource(){ local.remove(); }} |
4. 自定义sqlSessionProxy
并将数据源填充到DataSourceRoute
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@Configuration@ConditionalOnClass({EnableTransactionManagement.class})@Import({DataSourceConfiguration.class})public class DataSourceSqlSessionFactory { private Logger logger = Logger.getLogger(DataSourceSqlSessionFactory.class); @Value("${spring.datasource.type}") private Class<? extends DataSource> dataSourceType; @Value("${mybatis.mapper-locations}") private String mapperLocations; @Value("${mybatis.type-aliases-package}") private String aliasesPackage; @Value("${slave.datasource.number}") private int dataSourceNumber; @Resource(name = "masterDataSource") private DataSource masterDataSource; @Resource(name = "slaveDataSources") private List<DataSource> slaveDataSources; @Bean @ConditionalOnMissingBean public SqlSessionFactory sqlSessionFactory() throws Exception { logger.info("======================= init sqlSessionFactory"); SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(roundRobinDataSourceProxy()); PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(); sqlSessionFactoryBean.setMapperLocations(resolver.getResources(mapperLocations)); sqlSessionFactoryBean.setTypeAliasesPackage(aliasesPackage); sqlSessionFactoryBean.getObject().getConfiguration().setMapUnderscoreToCamelCase(true); return sqlSessionFactoryBean.getObject(); } @Bean(name = "roundRobinDataSourceProxy") public AbstractRoutingDataSource roundRobinDataSourceProxy() { logger.info("======================= init robinDataSourceProxy"); DataSourceRoute proxy = new DataSourceRoute(dataSourceNumber); Map<Object, Object> targetDataSources = new HashMap(); targetDataSources.put(DataSourceType.master.getType(), masterDataSource); if(null != slaveDataSources) { for(int i=0; i<slaveDataSources.size(); i++){ targetDataSources.put(i, slaveDataSources.get(i)); } } proxy.setDefaultTargetDataSource(masterDataSource); proxy.setTargetDataSources(targetDataSources); return proxy; }} |
5. 自定义路由
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public class DataSourceRoute extends AbstractRoutingDataSource { private Logger logger = Logger.getLogger(DataSourceRoute.class); private final int dataSourceNumber; public DataSourceRoute(int dataSourceNumber) { this.dataSourceNumber = dataSourceNumber; } @Override protected Object determineCurrentLookupKey() { String typeKey = DataSourceContextHolder.getJdbcType(); logger.info("==================== swtich dataSource:" + typeKey); if (typeKey.equals(DataSourceType.master.getType())) { return DataSourceType.master.getType(); }else{ //从数据源随机分配 Random random = new Random(); int slaveDsIndex = random.nextInt(dataSourceNumber); return slaveDsIndex; } }} |
6. 定义切面，dao层定义切面
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@Aspect@Componentpublic class DataSourceAop { private Logger logger = Logger.getLogger(DataSourceAop.class); @Before("execution(* com.dbq.iot.mapper..*.get*(..)) || execution(* com.dbq.iot.mapper..*.isExist*(..)) " + "|| execution(* com.dbq.iot.mapper..*.select*(..)) || execution(* com.dbq.iot.mapper..*.count*(..)) " + "|| execution(* com.dbq.iot.mapper..*.list*(..)) || execution(* com.dbq.iot.mapper..*.query*(..))" + "|| execution(* com.dbq.iot.mapper..*.find*(..))|| execution(* com.dbq.iot.mapper..*.search*(..))") public void setSlaveDataSourceType(JoinPoint joinPoint) { DataSourceContextHolder.slave(); logger.info("=========slave, method:" + joinPoint.getSignature().getName()); } @Before("execution(* com.dbq.iot.mapper..*.add*(..)) || execution(* com.dbq.iot.mapper..*.del*(..))" + "||execution(* com.dbq.iot.mapper..*.upDate*(..)) || execution(* com.dbq.iot.mapper..*.insert*(..))" + "||execution(* com.dbq.iot.mapper..*.create*(..)) || execution(* com.dbq.iot.mapper..*.update*(..))" + "||execution(* com.dbq.iot.mapper..*.delete*(..)) || execution(* com.dbq.iot.mapper..*.remove*(..))" + "||execution(* com.dbq.iot.mapper..*.save*(..)) || execution(* com.dbq.iot.mapper..*.relieve*(..))" + "|| execution(* com.dbq.iot.mapper..*.edit*(..))") public void setMasterDataSourceType(JoinPoint joinPoint) { DataSourceContextHolder.master(); logger.info("=========master, method:" + joinPoint.getSignature().getName()); }} |
7. 最后在写库增加事务管理
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@Configuration@Import({DataSourceConfiguration.class})public class DataSouceTranscation extends DataSourceTransactionManagerAutoConfiguration { private Logger logger = Logger.getLogger(DataSouceTranscation.class); @Resource(name = "masterDataSource") private DataSource masterDataSource; /** * 配置事务管理器 * * @return */ @Bean(name = "transactionManager") public DataSourceTransactionManager transactionManagers() { logger.info("===================== init transactionManager"); return new DataSourceTransactionManager(masterDataSource); }} |
8. 在配置文件中增加数据源配置
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spring.datasource.name=writedbspring.datasource.url=jdbc:mysql://192.168.0.1/master?useUnicode=true&characterEncoding=utf8&autoReconnect=true&failOverReadOnly=falsespring.datasource.username=rootspring.datasource.password=1234spring.datasource.type=com.alibaba.druid.pool.DruidDataSourcespring.datasource.driver-class-name=com.mysql.jdbc.Driverspring.datasource.filters=statspring.datasource.initialSize=20spring.datasource.minIdle=20spring.datasource.maxActive=200spring.datasource.maxWait=60000#从库的数量slave.datasource.number=1spring.slave0.name=readdbspring.slave0.url=jdbc:mysql://192.168.0.2/slave?useUnicode=true&characterEncoding=utf8&autoReconnect=true&failOverReadOnly=falsespring.slave0.username=rootspring.slave0.password=1234spring.slave0.type=com.alibaba.druid.pool.DruidDataSourcespring.slave0.driver-class-name=com.mysql.jdbc.Driverspring.slave0.filters=statspring.slave0.initialSize=20spring.slave0.minIdle=20spring.slave0.maxActive=200spring.slave0.maxWait=60000 |
这样就实现了在springcloud框架下的读写分离，并且支持多个从库的负载均衡（简单的通过随机分配，也有网友通过算法实现平均分配，具体做法是通过一个线程安全的自增长Integer类型，取余实现。个人觉得没大必要。如果有大神有更好的方法可以一起探讨。）
Mabatis分页配置可通过dao层的拦截器对特定方法进行拦截，拦截后添加自己的逻辑代码，比如计算total等，具体代码如下（参考了网友的代码，主要是通过@Intercepts注解）：
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@Intercepts({@Signature(type = StatementHandler.class, method = "prepare", args = {Connection.class, Integer.class})})public class PageInterceptor implements Interceptor { private static final Log logger = LogFactory.getLog(PageInterceptor.class); private static final ObjectFactory DEFAULT_OBJECT_FACTORY = new DefaultObjectFactory(); private static final ObjectWrapperFactory DEFAULT_OBJECT_WRAPPER_FACTORY = new DefaultObjectWrapperFactory(); private static final ReflectorFactory DEFAULT_REFLECTOR_FACTORY = new DefaultReflectorFactory(); private static String defaultDialect = "mysql"; // 数据库类型(默认为mysql) private static String defaultPageSqlId = ".*Page$"; // 需要拦截的ID(正则匹配) private String dialect = ""; // 数据库类型(默认为mysql) private String pageSqlId = ""; // 需要拦截的ID(正则匹配) @Override public Object intercept(Invocation invocation) throws Throwable { StatementHandler statementHandler = (StatementHandler) invocation.getTarget(); MetaObject metaStatementHandler = MetaObject.forObject(statementHandler, DEFAULT_OBJECT_FACTORY, DEFAULT_OBJECT_WRAPPER_FACTORY,DEFAULT_REFLECTOR_FACTORY); // 分离代理对象链(由于目标类可能被多个拦截器拦截，从而形成多次代理，通过下面的两次循环可以分离出最原始的的目标类) while (metaStatementHandler.hasGetter("h")) { Object object = metaStatementHandler.getValue("h"); metaStatementHandler = MetaObject.forObject(object, DEFAULT_OBJECT_FACTORY, DEFAULT_OBJECT_WRAPPER_FACTORY,DEFAULT_REFLECTOR_FACTORY); } // 分离最后一个代理对象的目标类 while (metaStatementHandler.hasGetter("target")) { Object object = metaStatementHandler.getValue("target"); metaStatementHandler = MetaObject.forObject(object, DEFAULT_OBJECT_FACTORY, DEFAULT_OBJECT_WRAPPER_FACTORY,DEFAULT_REFLECTOR_FACTORY); } Configuration configuration = (Configuration) metaStatementHandler.getValue("delegate.configuration"); if (null == dialect || "".equals(dialect)) { logger.warn("Property dialect is not setted,use default 'mysql' "); dialect = defaultDialect; } if (null == pageSqlId || "".equals(pageSqlId)) { logger.warn("Property pageSqlId is not setted,use default '.*Page$' "); pageSqlId = defaultPageSqlId; } MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement"); // 只重写需要分页的sql语句。通过MappedStatement的ID匹配，默认重写以Page结尾的MappedStatement的sql if (mappedStatement.getId().matches(pageSqlId)) { BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql"); Object parameterObject = boundSql.getParameterObject(); if (parameterObject == null) { throw new NullPointerException("parameterObject is null!"); } else { PageParameter page = (PageParameter) metaStatementHandler .getValue("delegate.boundSql.parameterObject.page"); String sql = boundSql.getSql(); // 重写sql String pageSql = buildPageSql(sql, page); metaStatementHandler.setValue("delegate.boundSql.sql", pageSql); metaStatementHandler.setValue("delegate.rowBounds.offset", RowBounds.NO_ROW_OFFSET); metaStatementHandler.setValue("delegate.rowBounds.limit", RowBounds.NO_ROW_LIMIT); Connection connection = (Connection) invocation.getArgs()[0]; // 重设分页参数里的总页数等 setPageParameter(sql, connection, mappedStatement, boundSql, page); } } // 将执行权交给下一个拦截器 return invocation.proceed(); } /** * @param sql * @param connection * @param mappedStatement * @param boundSql * @param page */ private void setPageParameter(String sql, Connection connection, MappedStatement mappedStatement, BoundSql boundSql, PageParameter page) { // 记录总记录数 String countSql = "select count(0) from (" + sql + ") as total"; PreparedStatement countStmt = null; ResultSet rs = null; try { countStmt = connection.prepareStatement(countSql); BoundSql countBS = new BoundSql(mappedStatement.getConfiguration(), countSql, boundSql.getParameterMappings(), boundSql.getParameterObject()); Field metaParamsField = ReflectUtil.getFieldByFieldName(boundSql, "metaParameters"); if (metaParamsField != null) { try { MetaObject mo = (MetaObject) ReflectUtil.getValueByFieldName(boundSql, "metaParameters"); ReflectUtil.setValueByFieldName(countBS, "metaParameters", mo); } catch (SecurityException | NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) { // TODO Auto-generated catch block logger.error("Ignore this exception", e); } } Field additionalField = ReflectUtil.getFieldByFieldName(boundSql, "additionalParameters"); if (additionalField != null) { try { Map<String, Object> map = (Map<String, Object>) ReflectUtil.getValueByFieldName(boundSql, "additionalParameters"); ReflectUtil.setValueByFieldName(countBS, "additionalParameters", map); } catch (SecurityException | NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) { // TODO Auto-generated catch block logger.error("Ignore this exception", e); } } setParameters(countStmt, mappedStatement, countBS, boundSql.getParameterObject()); rs = countStmt.executeQuery(); int totalCount = 0; if (rs.next()) { totalCount = rs.getInt(1); } page.setTotalCount(totalCount); int totalPage = totalCount / page.getPageSize() + ((totalCount % page.getPageSize() == 0) ? 0 : 1); page.setTotalPage(totalPage); } catch (SQLException e) { logger.error("Ignore this exception", e); } finally { try { if (rs != null){ rs.close(); } } catch (SQLException e) { logger.error("Ignore this exception", e); } try { if (countStmt != null){ countStmt.close(); } } catch (SQLException e) { logger.error("Ignore this exception", e); } } } /** * 对SQL参数(?)设值 * * @param ps * @param mappedStatement * @param boundSql * @param parameterObject * @throws SQLException */ private void setParameters(PreparedStatement ps, MappedStatement mappedStatement, BoundSql boundSql, Object parameterObject) throws SQLException { ParameterHandler parameterHandler = new DefaultParameterHandler(mappedStatement, parameterObject, boundSql); parameterHandler.setParameters(ps); } /** * 根据数据库类型，生成特定的分页sql * * @param sql * @param page * @return */ private String buildPageSql(String sql, PageParameter page) { if (page != null) { StringBuilder pageSql = new StringBuilder(); pageSql = buildPageSqlForMysql(sql,page); return pageSql.toString(); } else { return sql; } } /** * mysql的分页语句 * * @param sql * @param page * @return String */ public StringBuilder buildPageSqlForMysql(String sql, PageParameter page) { StringBuilder pageSql = new StringBuilder(100); String beginrow = String.valueOf((page.getCurrentPage() - 1) * page.getPageSize()); pageSql.append(sql); pageSql.append(" limit " + beginrow + "," + page.getPageSize()); return pageSql; } @Override public Object plugin(Object target) { if (target instanceof StatementHandler) { return Plugin.wrap(target, this); } else { return target; } } @Override public void setProperties(Properties properties) { }} |
这里碰到一个比较有趣的问题，就是sql如果是foreach参数，在拦截后无法注入。需要加入以下代码才可以（有得资料上只提到重置metaParameters）。
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Field metaParamsField = ReflectUtil.getFieldByFieldName(boundSql, "metaParameters");if (metaParamsField != null) { try { MetaObject mo = (MetaObject) ReflectUtil.getValueByFieldName(boundSql, "metaParameters"); ReflectUtil.setValueByFieldName(countBS, "metaParameters", mo); } catch (SecurityException | NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) { // TODO Auto-generated catch block logger.error("Ignore this exception", e); }}Field additionalField = ReflectUtil.getFieldByFieldName(boundSql, "additionalParameters");if (additionalField != null) { try { Map<String, Object> map = (Map<String, Object>) ReflectUtil.getValueByFieldName(boundSql, "additionalParameters"); ReflectUtil.setValueByFieldName(countBS, "additionalParameters", map); } catch (SecurityException | NoSuchFieldException | IllegalArgumentException | IllegalAccessException e) { // TODO Auto-generated catch block logger.error("Ignore this exception", e); }} |
读写分离倒是写好了，但是发现增加了mysql一主多从的读写分离后，此分页拦截器直接失效。
最后分析原因是因为，我们在做主从分离时，自定义了SqlSessionFactory，导致此拦截器没有注入。
在上面第4步中，DataSourceSqlSessionFactory中注入拦截器即可，具体代码如下
通过注解引入拦截器类：
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@Import({DataSourceConfiguration.class,PageInterceptor.class}) |
注入拦截器
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@Autowired private PageInterceptor pageInterceptor; |
SqlSessionFactoryBean中设置拦截器
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sqlSessionFactoryBean.setPlugins(newInterceptor[]{pageInterceptor}); |
这里碰到一个坑，就是设置plugins时必须在sqlSessionFactoryBean.getObject()之前。
SqlSessionFactory在生成的时候就会获取plugins，并设置到Configuration中，如果在之后设置则不会注入。
可跟踪源码看到：
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sqlSessionFactoryBean.getObject() |
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public SqlSessionFactory getObject() throws Exception { if (this.sqlSessionFactory == null) { afterPropertiesSet(); } return this.sqlSessionFactory;} |
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public void afterPropertiesSet() throws Exception { notNull(dataSource, "Property 'dataSource' is required"); notNull(sqlSessionFactoryBuilder, "Property 'sqlSessionFactoryBuilder' is required"); state((configuration == null && configLocation == null) || !(configuration != null && configLocation != null), "Property 'configuration' and 'configLocation' can not specified with together"); this.sqlSessionFactory = buildSqlSessionFactory(); } |
buildSqlSessionFactory()
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if (!isEmpty(this.plugins)) { for (Interceptor plugin : this.plugins) { configuration.addInterceptor(plugin); if (LOGGER.isDebugEnabled()) { LOGGER.debug("Registered plugin: '" + plugin + "'"); } } } |
最后贴上正确的配置代码(DataSourceSqlSessionFactory代码片段)
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@Bean@ConditionalOnMissingBeanpublic SqlSessionFactory sqlSessionFactory() throws Exception { logger.info("======================= init sqlSessionFactory"); SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setPlugins(new Interceptor[]{pageInterceptor}); sqlSessionFactoryBean.setDataSource(roundRobinDataSourceProxy()); PathMatchingResourcePatternResolver resolver = new PathMatchingResourcePatternResolver(); sqlSessionFactoryBean.setMapperLocations(resolver.getResources(mapperLocations)); sqlSessionFactoryBean.setTypeAliasesPackage(aliasesPackage); SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBean.getObject(); sqlSessionFactory.getConfiguration().setMapUnderscoreToCamelCase(true); return sqlSessionFactory;} |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://www.jianshu.com/p/36fb90db79ce
