sharding-jdbc如何配置分析Configuration

sharding-jdbc如何配置分析Configuration，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

Sharding核心配置主要如下（官网）：

• 分片规则

  分片规则配置的总入口。包含数据源配置、表配置、绑定表配置以及读写分离配置等

• 数据源配置

  真实数据源列表

• 表配置

  逻辑表名称、数据节点与分表规则的配置

• 数据节点配置

  用于配置逻辑表与真实表的映射关系。可分为均匀分布和自定义分布两种形式

• 分片策略配置

  对于分片策略存有数据源分片策略和表分片策略两种维度

• 数据源分片策略：

  对应于DatabaseShardingStrategy。用于配置数据被分配的目标数据源

• 表分片策略
  对应于TableShardingStrategy。用于配置数据被分配的目标表，该目标表存在与该数据的目标数据源内。故表分片策略是依赖与数据源分片策略的结果的

• 自增主键生成策略

  通过在客户端生成自增主键替换以数据库原生自增主键的方式，做到分布式主键无重复。

接下来对各个核心配置进行分析：

1. 以多主多从读写分离、表分片为例

   public final class ShardingMasterSlaveConfigurationPrecise implements ExampleConfiguration {        @Override    public DataSource getDataSource() throws SQLException {        ShardingRuleConfiguration shardingRuleConfig = new ShardingRuleConfiguration();        //分片表规则配置        shardingRuleConfig.getTableRuleConfigs().add(getOrderTableRuleConfiguration());        shardingRuleConfig.getTableRuleConfigs().add(getOrderItemTableRuleConfiguration());        //绑定分片表，主要用来路由        shardingRuleConfig.getBindingTableGroups().add("t_order, t_order_item");        //设置默认数据源分片策略        shardingRuleConfig.setDefaultDatabaseShardingStrategyConfig(new StandardShardingStrategyConfiguration("user_id", new PreciseModuloShardingDatabaseAlgorithm()));        //设置默认表分片策略        shardingRuleConfig.setDefaultTableShardingStrategyConfig(new StandardShardingStrategyConfiguration("order_id", new PreciseModuloShardingTableAlgorithm()));        //主从配置，支持多主多从        shardingRuleConfig.setMasterSlaveRuleConfigs(getMasterSlaveRuleConfigurations());        //创建ShardingDataSource数据源        return ShardingDataSourceFactory.createDataSource(createDataSourceMap(), shardingRuleConfig, new Properties());    }        private static TableRuleConfiguration getOrderTableRuleConfiguration() {        //分片表配置        TableRuleConfiguration result = new TableRuleConfiguration(/*逻辑表*/"t_order", /*数据源名.真实表*/"ds_${0..1}.t_order_${[0, 1]}");        //自定义主键生成配置        result.setKeyGeneratorConfig(new KeyGeneratorConfiguration("SNOWFLAKE", "order_id", getProperties()));        return result;    }        private static TableRuleConfiguration getOrderItemTableRuleConfiguration() {        TableRuleConfiguration result = new TableRuleConfiguration("t_order_item", "ds_${0..1}.t_order_item_${[0, 1]}");        result.setKeyGeneratorConfig(new KeyGeneratorConfiguration("SNOWFLAKE", "order_item_id", getProperties()));        return result;    }        private static List getMasterSlaveRuleConfigurations() {        MasterSlaveRuleConfiguration masterSlaveRuleConfig1 = new MasterSlaveRuleConfiguration("ds_0", "demo_ds_master_0", Arrays.asList("demo_ds_master_0_slave_0", "demo_ds_master_0_slave_1"));        MasterSlaveRuleConfiguration masterSlaveRuleConfig2 = new MasterSlaveRuleConfiguration("ds_1", "demo_ds_master_1", Arrays.asList("demo_ds_master_1_slave_0", "demo_ds_master_1_slave_1"));        return Lists.newArrayList(masterSlaveRuleConfig1, masterSlaveRuleConfig2);    }        private static Map createDataSourceMap() {        final Map result = new HashMap<>();        result.put("demo_ds_master_0", DataSourceUtil.createDataSource("demo_ds_master_0"));        result.put("demo_ds_master_0_slave_0", DataSourceUtil.createDataSource("demo_ds_master_0_slave_0"));        result.put("demo_ds_master_0_slave_1", DataSourceUtil.createDataSource("demo_ds_master_0_slave_1"));        result.put("demo_ds_master_1", DataSourceUtil.createDataSource("demo_ds_master_1"));        result.put("demo_ds_master_1_slave_0", DataSourceUtil.createDataSource("demo_ds_master_1_slave_0"));        result.put("demo_ds_master_1_slave_1", DataSourceUtil.createDataSource("demo_ds_master_1_slave_1"));        return result;    }        private static Properties getProperties() {        Properties result = new Properties();        result.setProperty("worker.id", "123");        return result;    }}

   
   

2. ShardingRuleConfiguration分片规则核心配置

   @Getter@Setterpublic final class ShardingRuleConfiguration implements RuleConfiguration {    //表规则配置    private Collection tableRuleConfigs = new LinkedList<>();    //绑定表配置    private Collection bindingTableGroups = new LinkedList<>();    //广播表配置    private Collection broadcastTables = new LinkedList<>();    //默认数据源名称    private String defaultDataSourceName;    //默认分库策略    private ShardingStrategyConfiguration defaultDatabaseShardingStrategyConfig;    //默认分片策略    private ShardingStrategyConfiguration defaultTableShardingStrategyConfig;    //默认主键生成工具类    private KeyGeneratorConfiguration defaultKeyGeneratorConfig;    //主从规则配置    private Collection masterSlaveRuleConfigs = new LinkedList<>();    //数据脱敏规则配置    private EncryptRuleConfiguration encryptRuleConfig;}

   
   

3. 分析ShardingDataSourceFactory#createDataSource中的ShardingRule配置

   /** * Sharding data source factory. *  * @author zhangliang  */@NoArgsConstructor(access = AccessLevel.PRIVATE)public final class ShardingDataSourceFactory {        /**     * Create sharding data source.     *     * @param dataSourceMap data source map     * @param shardingRuleConfig rule configuration for databases and tables sharding     * @param props properties for data source     * @return sharding data source     * @throws SQLException SQL exception     */    public static DataSource createDataSource(            final Map dataSourceMap, final ShardingRuleConfiguration shardingRuleConfig, final Properties props) throws SQLException {        //创建ShardingDataSource数据源，同时创建sharding rule配置        return new ShardingDataSource(dataSourceMap, new ShardingRule(shardingRuleConfig, dataSourceMap.keySet()), props);    }}

   
   

4. ShardingRule分片规则

   public ShardingRule(final ShardingRuleConfiguration shardingRuleConfig, final Collection dataSourceNames) {        Preconditions.checkArgument(null != shardingRuleConfig, "ShardingRuleConfig cannot be null.");        Preconditions.checkArgument(null != dataSourceNames && !dataSourceNames.isEmpty(), "Data sources cannot be empty.");        this.shardingRuleConfig = shardingRuleConfig;        //sharding数据源名称        shardingDataSourceNames = new ShardingDataSourceNames(shardingRuleConfig, dataSourceNames);        //创建表规则集合        tableRules = createTableRules(shardingRuleConfig);        //创建分组绑定表        //1.从tableRules查找        //2.是否广播表，如果是广播表，dataSourceNames.size() == 1 ? dataSourceNames.iterator().next() : shardingRuleConfig.getDefaultDataSourceName();        //3.已上两种情况都不满足，则使用默认数据源创建tableRule        bindingTableRules = createBindingTableRules(shardingRuleConfig.getBindingTableGroups());        //广播表        broadcastTables = shardingRuleConfig.getBroadcastTables();        //默认分库策略        defaultDatabaseShardingStrategy = createDefaultShardingStrategy(shardingRuleConfig.getDefaultDatabaseShardingStrategyConfig());        //默认表分片策略        defaultTableShardingStrategy = createDefaultShardingStrategy(shardingRuleConfig.getDefaultTableShardingStrategyConfig());        //默认主键生成工具类        defaultShardingKeyGenerator = createDefaultKeyGenerator(shardingRuleConfig.getDefaultKeyGeneratorConfig());        //创建主从规则        masterSlaveRules = createMasterSlaveRules(shardingRuleConfig.getMasterSlaveRuleConfigs());        //数据脱敏规则        encryptRule = createEncryptRule(shardingRuleConfig.getEncryptRuleConfig());    }

   
   

5. TableRule表规则

   public TableRule(final TableRuleConfiguration tableRuleConfig, final ShardingDataSourceNames shardingDataSourceNames, final String defaultGenerateKeyColumn) {        //获取逻辑表        logicTable = tableRuleConfig.getLogicTable().toLowerCase();        //inline表达式解析出真实表，比如：ds_${0..1}.t_order_${[0, 1]}        //解析出来为：        //ds_0.t_order_0        //ds_0.t_order_1        //ds_1.t_order_0        //ds_1.t_order_1        List dataNodes = new InlineExpressionParser(tableRuleConfig.getActualDataNodes()).splitAndEvaluate();        dataNodeIndexMap = new HashMap<>(dataNodes.size(), 1);        //真实表数据节点        //1.如果没有配置真实表，则根据逻辑表、数据源来生成对应真实表数据节点        //2.否则根据inline表达式解析出来的真实表来生成真实数据节点        actualDataNodes = isEmptyDataNodes(dataNodes)            ? generateDataNodes(tableRuleConfig.getLogicTable(), shardingDataSourceNames.getDataSourceNames()) : generateDataNodes(dataNodes, shardingDataSourceNames.getDataSourceNames());        //真实表        actualTables = getActualTables();        //数据源->分片策略        databaseShardingStrategy = null == tableRuleConfig.getDatabaseShardingStrategyConfig() ? null : ShardingStrategyFactory.newInstance(tableRuleConfig.getDatabaseShardingStrategyConfig());        //表->分片策略        tableShardingStrategy = null == tableRuleConfig.getTableShardingStrategyConfig() ? null : ShardingStrategyFactory.newInstance(tableRuleConfig.getTableShardingStrategyConfig());        //主键字段        generateKeyColumn = getGenerateKeyColumn(tableRuleConfig.getKeyGeneratorConfig(), defaultGenerateKeyColumn);        //生成主键工具类，比如SNOWFLAKE        shardingKeyGenerator = containsKeyGeneratorConfiguration(tableRuleConfig)                ? new ShardingKeyGeneratorServiceLoader().newService(tableRuleConfig.getKeyGeneratorConfig().getType(), tableRuleConfig.getKeyGeneratorConfig().getProperties()) : null;    }

   
   

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