sharding-jdbc如何配置分析Configuration

sharding-jdbc如何配置分析Configuration，很多新手對此不是很清楚，為了幫助大家解決這個難題，下面小編將為大家詳細講解，有這方面需求的人可以來學習下，希望你能有所收獲。

Sharding核心配置主要如下（官網）：

• 分片規則

  分片規則配置的總入口。包含數據源配置、表配置、綁定表配置以及讀寫分離配置等

• 數據源配置

  真實數據源列表

• 表配置

  邏輯表名稱、數據節點與分表規則的配置

• 數據節點配置

  用于配置邏輯表與真實表的映射關系。可分為均勻分布和自定義分布兩種形式

• 分片策略配置

  對于分片策略存有數據源分片策略和表分片策略兩種維度

• 數據源分片策略：

  對應于DatabaseShardingStrategy。用于配置數據被分配的目標數據源

• 表分片策略
  對應于TableShardingStrategy。用于配置數據被分配的目標表，該目標表存在與該數據的目標數據源內。故表分片策略是依賴與數據源分片策略的結果的

• 自增主鍵生成策略

  通過在客戶端生成自增主鍵替換以數據庫原生自增主鍵的方式，做到分布式主鍵無重復。

接下來對各個核心配置進行分析：

1. 以多主多從讀寫分離、表分片為例

   public final class ShardingMasterSlaveConfigurationPrecise implements ExampleConfiguration {
       
       @Override
       public DataSource getDataSource() throws SQLException {
           ShardingRuleConfiguration shardingRuleConfig = new ShardingRuleConfiguration();
           //分片表規則配置
           shardingRuleConfig.getTableRuleConfigs().add(getOrderTableRuleConfiguration());
           shardingRuleConfig.getTableRuleConfigs().add(getOrderItemTableRuleConfiguration());
           //綁定分片表，主要用來路由
           shardingRuleConfig.getBindingTableGroups().add("t_order, t_order_item");
           //設置默認數據源分片策略
           shardingRuleConfig.setDefaultDatabaseShardingStrategyConfig(new StandardShardingStrategyConfiguration("user_id", new PreciseModuloShardingDatabaseAlgorithm()));
           //設置默認表分片策略
           shardingRuleConfig.setDefaultTableShardingStrategyConfig(new StandardShardingStrategyConfiguration("order_id", new PreciseModuloShardingTableAlgorithm()));
           //主從配置，支持多主多從
           shardingRuleConfig.setMasterSlaveRuleConfigs(getMasterSlaveRuleConfigurations());
           //創建ShardingDataSource數據源
           return ShardingDataSourceFactory.createDataSource(createDataSourceMap(), shardingRuleConfig, new Properties());
       }
       
       private static TableRuleConfiguration getOrderTableRuleConfiguration() {
           //分片表配置
           TableRuleConfiguration result = new TableRuleConfiguration(/*邏輯表*/"t_order", /*數據源名.真實表*/"ds_${0..1}.t_order_${[0, 1]}");
           //自定義主鍵生成配置
           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<MasterSlaveRuleConfiguration> 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<String, DataSource> createDataSourceMap() {
           final Map<String, DataSource> 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分片規則核心配置

   @Getter
   @Setter
   public final class ShardingRuleConfiguration implements RuleConfiguration {
       //表規則配置
       private Collection<TableRuleConfiguration> tableRuleConfigs = new LinkedList<>();
   
       //綁定表配置
       private Collection<String> bindingTableGroups = new LinkedList<>();
   
       //廣播表配置
       private Collection<String> broadcastTables = new LinkedList<>();
   
       //默認數據源名稱
       private String defaultDataSourceName;
   
       //默認分庫策略
       private ShardingStrategyConfiguration defaultDatabaseShardingStrategyConfig;
   
       //默認分片策略
       private ShardingStrategyConfiguration defaultTableShardingStrategyConfig;
   
       //默認主鍵生成工具類
       private KeyGeneratorConfiguration defaultKeyGeneratorConfig;
   
       //主從規則配置
       private Collection<MasterSlaveRuleConfiguration> masterSlaveRuleConfigs = new LinkedList<>();
   
       //數據脫敏規則配置
       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<String, DataSource> dataSourceMap, final ShardingRuleConfiguration shardingRuleConfig, final Properties props) throws SQLException {
           //創建ShardingDataSource數據源，同時創建sharding rule配置
           return new ShardingDataSource(dataSourceMap, new ShardingRule(shardingRuleConfig, dataSourceMap.keySet()), props);
       }
   }

   
    

4. ShardingRule分片規則

   public ShardingRule(final ShardingRuleConfiguration shardingRuleConfig, final Collection<String> dataSourceNames) {
           Preconditions.checkArgument(null != shardingRuleConfig, "ShardingRuleConfig cannot be null.");
           Preconditions.checkArgument(null != dataSourceNames && !dataSourceNames.isEmpty(), "Data sources cannot be empty.");
           this.shardingRuleConfig = shardingRuleConfig;
           //sharding數據源名稱
           shardingDataSourceNames = new ShardingDataSourceNames(shardingRuleConfig, dataSourceNames);
           //創建表規則集合
           tableRules = createTableRules(shardingRuleConfig);
           //創建分組綁定表
           //1.從tableRules查找
           //2.是否廣播表，如果是廣播表，dataSourceNames.size() == 1 ? dataSourceNames.iterator().next() : shardingRuleConfig.getDefaultDataSourceName();
           //3.已上兩種情況都不滿足，則使用默認數據源創建tableRule
           bindingTableRules = createBindingTableRules(shardingRuleConfig.getBindingTableGroups());
           //廣播表
           broadcastTables = shardingRuleConfig.getBroadcastTables();
           //默認分庫策略
           defaultDatabaseShardingStrategy = createDefaultShardingStrategy(shardingRuleConfig.getDefaultDatabaseShardingStrategyConfig());
           //默認表分片策略
           defaultTableShardingStrategy = createDefaultShardingStrategy(shardingRuleConfig.getDefaultTableShardingStrategyConfig());
           //默認主鍵生成工具類
           defaultShardingKeyGenerator = createDefaultKeyGenerator(shardingRuleConfig.getDefaultKeyGeneratorConfig());
           //創建主從規則
           masterSlaveRules = createMasterSlaveRules(shardingRuleConfig.getMasterSlaveRuleConfigs());
           //數據脫敏規則
           encryptRule = createEncryptRule(shardingRuleConfig.getEncryptRuleConfig());
       }

   
   

    

5. TableRule表規則

   public TableRule(final TableRuleConfiguration tableRuleConfig, final ShardingDataSourceNames shardingDataSourceNames, final String defaultGenerateKeyColumn) {
           //獲取邏輯表
           logicTable = tableRuleConfig.getLogicTable().toLowerCase();
           //inline表達式解析出真實表，比如：ds_${0..1}.t_order_${[0, 1]}
           //解析出來為：
           //ds_0.t_order_0
           //ds_0.t_order_1
           //ds_1.t_order_0
           //ds_1.t_order_1
           List<String> dataNodes = new InlineExpressionParser(tableRuleConfig.getActualDataNodes()).splitAndEvaluate();
   
           dataNodeIndexMap = new HashMap<>(dataNodes.size(), 1);
   
           //真實表數據節點
           //1.如果沒有配置真實表，則根據邏輯表、數據源來生成對應真實表數據節點
           //2.否則根據inline表達式解析出來的真實表來生成真實數據節點
           actualDataNodes = isEmptyDataNodes(dataNodes)
               ? generateDataNodes(tableRuleConfig.getLogicTable(), shardingDataSourceNames.getDataSourceNames()) : generateDataNodes(dataNodes, shardingDataSourceNames.getDataSourceNames());
           //真實表
           actualTables = getActualTables();
           //數據源->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());
           //主鍵字段
           generateKeyColumn = getGenerateKeyColumn(tableRuleConfig.getKeyGeneratorConfig(), defaultGenerateKeyColumn);
           //生成主鍵工具類，比如SNOWFLAKE
           shardingKeyGenerator = containsKeyGeneratorConfiguration(tableRuleConfig)
                   ? new ShardingKeyGeneratorServiceLoader().newService(tableRuleConfig.getKeyGeneratorConfig().getType(), tableRuleConfig.getKeyGeneratorConfig().getProperties()) : null;
       }

   
   

    

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