sharding-jdbc中AbstractDataSourceAdapter的用法

這篇文章主要介紹“sharding-jdbc中AbstractDataSourceAdapter的用法”，在日常操作中，相信很多人在sharding-jdbc中AbstractDataSourceAdapter的用法問題上存在疑惑，小編查閱了各式資料，整理出簡單好用的操作方法，希望對大家解答”sharding-jdbc中AbstractDataSourceAdapter的用法”的疑惑有所幫助！接下來，請跟著小編一起來學習吧！

序

本文主要研究一下sharding-jdbc的AbstractDataSourceAdapter

AbstractUnsupportedOperationDataSource

incubator-shardingsphere-4.0.0-RC1/sharding-jdbc/sharding-jdbc-core/src/main/java/org/apache/shardingsphere/shardingjdbc/jdbc/unsupported/AbstractUnsupportedOperationDataSource.java

public abstract class AbstractUnsupportedOperationDataSource extends WrapperAdapter implements DataSource {
    
    @Override
    public final int getLoginTimeout() throws SQLException {
        throw new SQLFeatureNotSupportedException("unsupported getLoginTimeout()");
    }
    
    @Override
    public final void setLoginTimeout(final int seconds) throws SQLException {
        throw new SQLFeatureNotSupportedException("unsupported setLoginTimeout(int seconds)");
    }
}

• AbstractUnsupportedOperationDataSource繼承了WrapperAdapter，聲明實現javax.sql.DataSource接口，其覆蓋了getLoginTimeout、setLoginTimeout方法，拋出SQLFeatureNotSupportedException異常

AbstractDataSourceAdapter

incubator-shardingsphere-4.0.0-RC1/sharding-jdbc/sharding-jdbc-core/src/main/java/org/apache/shardingsphere/shardingjdbc/jdbc/adapter/AbstractDataSourceAdapter.java

@Getter
@Setter
public abstract class AbstractDataSourceAdapter extends AbstractUnsupportedOperationDataSource implements AutoCloseable {
    
    private final DatabaseType databaseType;
    
    private final Map<String, DataSource> dataSourceMap;
    
    private ShardingTransactionManagerEngine shardingTransactionManagerEngine = new ShardingTransactionManagerEngine();
    
    private PrintWriter logWriter = new PrintWriter(System.out);
    
    public AbstractDataSourceAdapter(final Map<String, DataSource> dataSourceMap) throws SQLException {
        databaseType = getDatabaseType(dataSourceMap.values());
        shardingTransactionManagerEngine.init(databaseType, dataSourceMap);
        this.dataSourceMap = dataSourceMap;
    }
    
    protected final DatabaseType getDatabaseType(final Collection<DataSource> dataSources) throws SQLException {
        DatabaseType result = null;
        for (DataSource each : dataSources) {
            DatabaseType databaseType = getDatabaseType(each);
            Preconditions.checkState(null == result || result.equals(databaseType), String.format("Database type inconsistent with '%s' and '%s'", result, databaseType));
            result = databaseType;
        }
        return result;
    }
    
    private DatabaseType getDatabaseType(final DataSource dataSource) throws SQLException {
        if (dataSource instanceof AbstractDataSourceAdapter) {
            return ((AbstractDataSourceAdapter) dataSource).databaseType;
        }
        try (Connection connection = dataSource.getConnection()) {
            return DatabaseType.valueFrom(connection.getMetaData().getDatabaseProductName());
        }
    }
    
    @Override
    public final Logger getParentLogger() {
        return Logger.getLogger(Logger.GLOBAL_LOGGER_NAME);
    }
    
    @Override
    public final Connection getConnection(final String username, final String password) throws SQLException {
        return getConnection();
    }
    
    @Override
    public void close() throws Exception {
        for (DataSource each : dataSourceMap.values()) {
            try {
                Method method = each.getClass().getDeclaredMethod("close");
                method.setAccessible(true);
                method.invoke(each);
            } catch (final ReflectiveOperationException ignored) {
            }
        }
        shardingTransactionManagerEngine.close();
    }
}

• AbstractDataSourceAdapter繼承了AbstractUnsupportedOperationDataSource，實現了AutoCloseable接口；它的構造器接收一個DataSource的map，并執行shardingTransactionManagerEngine.init；close方法會遍歷dataSourceMap，挨個反射調用執行close方法

ShardingTransactionManagerEngine

incubator-shardingsphere-4.0.0-RC1/sharding-transaction/sharding-transaction-core/src/main/java/org/apache/shardingsphere/transaction/ShardingTransactionManagerEngine.java

@Slf4j
public final class ShardingTransactionManagerEngine {
    
    private final Map<TransactionType, ShardingTransactionManager> transactionManagerMap = new HashMap<>();
    
    public ShardingTransactionManagerEngine() {
        loadShardingTransactionManager();
    }
    
    private void loadShardingTransactionManager() {
        for (ShardingTransactionManager each : ServiceLoader.load(ShardingTransactionManager.class)) {
            if (transactionManagerMap.containsKey(each.getTransactionType())) {
                log.warn("Find more than one {} transaction manager implementation class, use `{}` now",
                    each.getTransactionType(), transactionManagerMap.get(each.getTransactionType()).getClass().getName());
                continue;
            }
            transactionManagerMap.put(each.getTransactionType(), each);
        }
    }
    
    /**
     * Initialize sharding transaction managers.
     *
     * @param databaseType database type
     * @param dataSourceMap data source map
     */
    public void init(final DatabaseType databaseType, final Map<String, DataSource> dataSourceMap) {
        for (Entry<TransactionType, ShardingTransactionManager> entry : transactionManagerMap.entrySet()) {
            entry.getValue().init(databaseType, getResourceDataSources(dataSourceMap));
        }
    }
    
    private Collection<ResourceDataSource> getResourceDataSources(final Map<String, DataSource> dataSourceMap) {
        List<ResourceDataSource> result = new LinkedList<>();
        for (Map.Entry<String, DataSource> entry : dataSourceMap.entrySet()) {
            result.add(new ResourceDataSource(entry.getKey(), entry.getValue()));
        }
        return result;
    }
    
    /**
     * Get sharding transaction manager.
     *
     * @param transactionType transaction type
     * @return sharding transaction manager
     */
    public ShardingTransactionManager getTransactionManager(final TransactionType transactionType) {
        ShardingTransactionManager result = transactionManagerMap.get(transactionType);
        if (TransactionType.LOCAL != transactionType) {
            Preconditions.checkNotNull(result, "Cannot find transaction manager of [%s]", transactionType);
        }
        return result;
    }
    
    /**
     * Close sharding transaction managers.
     * 
     * @throws Exception exception
     */
    public void close() throws Exception {
        for (Entry<TransactionType, ShardingTransactionManager> entry : transactionManagerMap.entrySet()) {
            entry.getValue().close();
        }
    }
}

• ShardingTransactionManagerEngine維護了ShardingTransactionManager的map，其構造器執行loadShardingTransactionManager方法，它會使用ServiceLoader.load(ShardingTransactionManager.class)加載，然后放入transactionManagerMap中；init方法會遍歷transactionManagerMap，然后挨個執行init方法；close方法則遍歷transactionManagerMap，挨個執行close方法

小結

AbstractDataSourceAdapter繼承了AbstractUnsupportedOperationDataSource，實現了AutoCloseable接口；它的構造器接收一個DataSource的map，并執行shardingTransactionManagerEngine.init；close方法會遍歷dataSourceMap，挨個反射調用執行close方法

到此，關于“sharding-jdbc中AbstractDataSourceAdapter的用法”的學習就結束了，希望能夠解決大家的疑惑。理論與實踐的搭配能更好的幫助大家學習，快去試試吧！若想繼續學習更多相關知識，請繼續關注億速云網站，小編會繼續努力為大家帶來更多實用的文章！