背景 

在做分表时，需要自定义算法。 这里实现的算法是：  分表字段的 hashCode 取余。

算法

public class UserShardingAlgorithm implements StandardShardingAlgorithm<String> {public static String type = "USER_SHARDING_STRATEGY";/*** 分表数量*/private int num;@Overridepublic void init(Properties props) {this.num = Integer.valueOf(props.get("number").toString());}@Overridepublic String getType() {return type;}@Overridepublic String doSharding(Collection<String> availableTargetNames, PreciseShardingValue<String> shardingValue) {String value = shardingValue.getValue();return shardingValue.getDataNodeInfo().getPrefix() + (value.hashCode() % num);}@Overridepublic Collection<String> doSharding(Collection<String> availableTargetNames, RangeShardingValue<String> shardingValue) {return availableTargetNames;}
}

测试代码

 修改下数据库配置，直接运行main 方法就可以。

public static void main(String[] args) throws Exception {ShardingRuleConfiguration result = new ShardingRuleConfiguration();// 分表配置ShardingTableRuleConfiguration shardingTableRuleConfiguration =new ShardingTableRuleConfiguration("user", "user_read.user_$->{0..1}");//  分表字段， 分表算法StandardShardingStrategyConfiguration standardShardingStrategyConfiguration= new StandardShardingStrategyConfiguration("open_id", UserShardingAlgorithm.type);shardingTableRuleConfiguration.setTableShardingStrategy(standardShardingStrategyConfiguration);// 住建 key  生成策略KeyGenerateStrategyConfiguration keyGenerateStrategyConfiguration =new KeyGenerateStrategyConfiguration("id", "SNOWFLAKE");shardingTableRuleConfiguration.setKeyGenerateStrategy(keyGenerateStrategyConfiguration);result.getTables().add(shardingTableRuleConfiguration);// key 生成算法的 work_idProperties properties = new Properties();properties.put("work_id", new Random().nextInt(1024));result.getKeyGenerators().put("SNOWFLAKE", new AlgorithmConfiguration("SNOWFLAKE", properties));Properties userSharding = new Properties();userSharding.put("strategy", "standard");userSharding.put("number", 2);userSharding.put("algorithmClassName", UserShardingAlgorithm.class.getName());result.getShardingAlgorithms().put(UserShardingAlgorithm.type,new AlgorithmConfiguration("CLASS_BASED", userSharding));Map<String, DataSource> map = createDatasource();// 创建 dbDataSource dataSource =ShardingSphereDataSourceFactory.createDataSource(map, Lists.newArrayList(result), new Properties());Connection connection = dataSource.getConnection();PreparedStatement preparedStatement = connection.prepareStatement("insert into user (open_id) values (?)");preparedStatement.setString(1, UUID.randomUUID().toString());// 执行int execute = preparedStatement.executeUpdate();System.out.printf("ShardingJdbcDemo.main: " + execute);connection.close();}private static Map<String, DataSource> createDatasource() {DruidDataSource druidDataSource = new DruidDataSource();Map<String, DataSource> objectObjectHashMap = new HashMap<>();druidDataSource.setUrl("jdbc:mysql://127.0.0.1:3306/user_read?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true");druidDataSource.setUsername("root");druidDataSource.setPassword("123456");druidDataSource.setDriverClassName("com.mysql.jdbc.Driver");objectObjectHashMap.put("user_read", druidDataSource);return objectObjectHashMap;}