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。
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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：
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;
}
} ShardingRuleConfiguration分片规则核心配置
@Getter
@Setter
public 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;
}
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);
}
}
ShardingRule分片规则
public ShardingRule(final ShardingRuleConfiguration shardingRuleConfig, final CollectiondataSourceNames) { 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()); }
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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