spring boot 2.x 动态多数据源
AbstractRoutingDataSource 源码如下:
/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.jdbc.datasource.lookup;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;
import javax.sql.DataSource;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jdbc.datasource.AbstractDataSource;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Abstract {@link javax.sql.DataSource} implementation that routes {@link #getConnection()}
* calls to one of various target DataSources based on a lookup key. The latter is usually
* (but not necessarily) determined through some thread-bound transaction context.
*
* @author Juergen Hoeller
* @since 2.0.1
* @see #setTargetDataSources
* @see #setDefaultTargetDataSource
* @see #determineCurrentLookupKey()
*/
public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
@Nullable
private Map<Object, Object> targetDataSources;
@Nullable
private Object defaultTargetDataSource;
private boolean lenientFallback = true;
private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
@Nullable
private Map<Object, DataSource> resolvedDataSources;
@Nullable
private DataSource resolvedDefaultDataSource;
/**
* Specify the map of target DataSources, with the lookup key as key.
* The mapped value can either be a corresponding {@link javax.sql.DataSource}
* instance or a data source name String (to be resolved via a
* {@link #setDataSourceLookup DataSourceLookup}).
* <p>The key can be of arbitrary type; this class implements the
* generic lookup process only. The concrete key representation will
* be handled by {@link #resolveSpecifiedLookupKey(Object)} and
* {@link #determineCurrentLookupKey()}.
*/
public void setTargetDataSources(Map<Object, Object> targetDataSources) {
this.targetDataSources = targetDataSources;
}
/**
* Specify the default target DataSource, if any.
* <p>The mapped value can either be a corresponding {@link javax.sql.DataSource}
* instance or a data source name String (to be resolved via a
* {@link #setDataSourceLookup DataSourceLookup}).
* <p>This DataSource will be used as target if none of the keyed
* {@link #setTargetDataSources targetDataSources} match the
* {@link #determineCurrentLookupKey()} current lookup key.
*/
public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
this.defaultTargetDataSource = defaultTargetDataSource;
}
/**
* Specify whether to apply a lenient fallback to the default DataSource
* if no specific DataSource could be found for the current lookup key.
* <p>Default is "true", accepting lookup keys without a corresponding entry
* in the target DataSource map - simply falling back to the default DataSource
* in that case.
* <p>Switch this flag to "false" if you would prefer the fallback to only apply
* if the lookup key was {@code null}. Lookup keys without a DataSource
* entry will then lead to an IllegalStateException.
* @see #setTargetDataSources
* @see #setDefaultTargetDataSource
* @see #determineCurrentLookupKey()
*/
public void setLenientFallback(boolean lenientFallback) {
this.lenientFallback = lenientFallback;
}
/**
* Set the DataSourceLookup implementation to use for resolving data source
* name Strings in the {@link #setTargetDataSources targetDataSources} map.
* <p>Default is a {@link JndiDataSourceLookup}, allowing the JNDI names
* of application server DataSources to be specified directly.
*/
public void setDataSourceLookup(@Nullable DataSourceLookup dataSourceLookup) {
this.dataSourceLookup = (dataSourceLookup != null ? dataSourceLookup : new JndiDataSourceLookup());
}
@Override
public void afterPropertiesSet() {
if (this.targetDataSources == null) {
throw new IllegalArgumentException("Property 'targetDataSources' is required");
}
this.resolvedDataSources = new HashMap<>(this.targetDataSources.size());
this.targetDataSources.forEach((key, value) -> {
Object lookupKey = resolveSpecifiedLookupKey(key);
DataSource dataSource = resolveSpecifiedDataSource(value);
this.resolvedDataSources.put(lookupKey, dataSource);
});
if (this.defaultTargetDataSource != null) {
this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
}
}
/**
* Resolve the given lookup key object, as specified in the
* {@link #setTargetDataSources targetDataSources} map, into
* the actual lookup key to be used for matching with the
* {@link #determineCurrentLookupKey() current lookup key}.
* <p>The default implementation simply returns the given key as-is.
* @param lookupKey the lookup key object as specified by the user
* @return the lookup key as needed for matching
*/
protected Object resolveSpecifiedLookupKey(Object lookupKey) {
return lookupKey;
}
/**
* Resolve the specified data source object into a DataSource instance.
* <p>The default implementation handles DataSource instances and data source
* names (to be resolved via a {@link #setDataSourceLookup DataSourceLookup}).
* @param dataSource the data source value object as specified in the
* {@link #setTargetDataSources targetDataSources} map
* @return the resolved DataSource (never {@code null})
* @throws IllegalArgumentException in case of an unsupported value type
*/
protected DataSource resolveSpecifiedDataSource(Object dataSource) throws IllegalArgumentException {
if (dataSource instanceof DataSource) {
return (DataSource) dataSource;
}
else if (dataSource instanceof String) {
return this.dataSourceLookup.getDataSource((String) dataSource);
}
else {
throw new IllegalArgumentException(
"Illegal data source value - only [javax.sql.DataSource] and String supported: " + dataSource);
}
}
@Override
public Connection getConnection() throws SQLException {
return determineTargetDataSource().getConnection();
}
@Override
public Connection getConnection(String username, String password) throws SQLException {
return determineTargetDataSource().getConnection(username, password);
}
@Override
@SuppressWarnings("unchecked")
public <T> T unwrap(Class<T> iface) throws SQLException {
if (iface.isInstance(this)) {
return (T) this;
}
return determineTargetDataSource().unwrap(iface);
}
@Override
public boolean isWrapperFor(Class<?> iface) throws SQLException {
return (iface.isInstance(this) || determineTargetDataSource().isWrapperFor(iface));
}
/**
* Retrieve the current target DataSource. Determines the
* {@link #determineCurrentLookupKey() current lookup key}, performs
* a lookup in the {@link #setTargetDataSources targetDataSources} map,
* falls back to the specified
* {@link #setDefaultTargetDataSource default target DataSource} if necessary.
* @see #determineCurrentLookupKey()
*/
protected DataSource determineTargetDataSource() {
Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
Object lookupKey = determineCurrentLookupKey();
DataSource dataSource = this.resolvedDataSources.get(lookupKey);
if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
dataSource = this.resolvedDefaultDataSource;
}
if (dataSource == null) {
throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
}
return dataSource;
}
/**
* Determine the current lookup key. This will typically be
* implemented to check a thread-bound transaction context.
* <p>Allows for arbitrary keys. The returned key needs
* to match the stored lookup key type, as resolved by the
* {@link #resolveSpecifiedLookupKey} method.
*/
@Nullable
protected abstract Object determineCurrentLookupKey();
}
DataSourceTransactionManager.java
/*
* Copyright 2002-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.jdbc.datasource;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.lang.Nullable;
import org.springframework.transaction.CannotCreateTransactionException;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionSystemException;
import org.springframework.transaction.support.AbstractPlatformTransactionManager;
import org.springframework.transaction.support.DefaultTransactionStatus;
import org.springframework.transaction.support.ResourceTransactionManager;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.transaction.support.TransactionSynchronizationUtils;
import org.springframework.util.Assert;
/**
* {@link org.springframework.transaction.PlatformTransactionManager}
* implementation for a single JDBC {@link javax.sql.DataSource}. This class is
* capable of working in any environment with any JDBC driver, as long as the setup
* uses a {@code javax.sql.DataSource} as its {@code Connection} factory mechanism.
* Binds a JDBC Connection from the specified DataSource to the current thread,
* potentially allowing for one thread-bound Connection per DataSource.
*
* <p><b>Note: The DataSource that this transaction manager operates on needs
* to return independent Connections.</b> The Connections may come from a pool
* (the typical case), but the DataSource must not return thread-scoped /
* request-scoped Connections or the like. This transaction manager will
* associate Connections with thread-bound transactions itself, according
* to the specified propagation behavior. It assumes that a separate,
* independent Connection can be obtained even during an ongoing transaction.
*
* <p>Application code is required to retrieve the JDBC Connection via
* {@link DataSourceUtils#getConnection(DataSource)} instead of a standard
* Java EE-style {@link DataSource#getConnection()} call. Spring classes such as
* {@link org.springframework.jdbc.core.JdbcTemplate} use this strategy implicitly.
* If not used in combination with this transaction manager, the
* {@link DataSourceUtils} lookup strategy behaves exactly like the native
* DataSource lookup; it can thus be used in a portable fashion.
*
* <p>Alternatively, you can allow application code to work with the standard
* Java EE-style lookup pattern {@link DataSource#getConnection()}, for example for
* legacy code that is not aware of Spring at all. In that case, define a
* {@link TransactionAwareDataSourceProxy} for your target DataSource, and pass
* that proxy DataSource to your DAOs, which will automatically participate in
* Spring-managed transactions when accessing it.
*
* <p>Supports custom isolation levels, and timeouts which get applied as
* appropriate JDBC statement timeouts. To support the latter, application code
* must either use {@link org.springframework.jdbc.core.JdbcTemplate}, call
* {@link DataSourceUtils#applyTransactionTimeout} for each created JDBC Statement,
* or go through a {@link TransactionAwareDataSourceProxy} which will create
* timeout-aware JDBC Connections and Statements automatically.
*
* <p>Consider defining a {@link LazyConnectionDataSourceProxy} for your target
* DataSource, pointing both this transaction manager and your DAOs to it.
* This will lead to optimized handling of "empty" transactions, i.e. of transactions
* without any JDBC statements executed. A LazyConnectionDataSourceProxy will not fetch
* an actual JDBC Connection from the target DataSource until a Statement gets executed,
* lazily applying the specified transaction settings to the target Connection.
*
* <p>This transaction manager supports nested transactions via the JDBC 3.0
* {@link java.sql.Savepoint} mechanism. The
* {@link #setNestedTransactionAllowed "nestedTransactionAllowed"} flag defaults
* to "true", since nested transactions will work without restrictions on JDBC
* drivers that support savepoints (such as the Oracle JDBC driver).
*
* <p>This transaction manager can be used as a replacement for the
* {@link org.springframework.transaction.jta.JtaTransactionManager} in the single
* resource case, as it does not require a container that supports JTA, typically
* in combination with a locally defined JDBC DataSource (e.g. an Apache Commons
* DBCP connection pool). Switching between this local strategy and a JTA
* environment is just a matter of configuration!
*
* <p>As of 4.3.4, this transaction manager triggers flush callbacks on registered
* transaction synchronizations (if synchronization is generally active), assuming
* resources operating on the underlying JDBC {@code Connection}. This allows for
* setup analogous to {@code JtaTransactionManager}, in particular with respect to
* lazily registered ORM resources (e.g. a Hibernate {@code Session}).
*
* @author Juergen Hoeller
* @since 02.05.2003
* @see #setNestedTransactionAllowed
* @see java.sql.Savepoint
* @see DataSourceUtils#getConnection(javax.sql.DataSource)
* @see DataSourceUtils#applyTransactionTimeout
* @see DataSourceUtils#releaseConnection
* @see TransactionAwareDataSourceProxy
* @see LazyConnectionDataSourceProxy
* @see org.springframework.jdbc.core.JdbcTemplate
*/
@SuppressWarnings("serial")
public class DataSourceTransactionManager extends AbstractPlatformTransactionManager
implements ResourceTransactionManager, InitializingBean {
@Nullable
private DataSource dataSource;
private boolean enforceReadOnly = false;
/**
* This implementation sets the isolation level but ignores the timeout.
*/
@Override
protected void doBegin(Object transaction, TransactionDefinition definition) {
DataSourceTransactionObject txObject = (DataSourceTransactionObject) transaction;
Connection con = null;
try {
if (!txObject.hasConnectionHolder() ||
txObject.getConnectionHolder().isSynchronizedWithTransaction()) {
Connection newCon = obtainDataSource().getConnection();
if (logger.isDebugEnabled()) {
logger.debug("Acquired Connection [" + newCon + "] for JDBC transaction");
}
txObject.setConnectionHolder(new ConnectionHolder(newCon), true);
}
txObject.getConnectionHolder().setSynchronizedWithTransaction(true);
con = txObject.getConnectionHolder().getConnection();
Integer previousIsolationLevel = DataSourceUtils.prepareConnectionForTransaction(con, definition);
txObject.setPreviousIsolationLevel(previousIsolationLevel);
txObject.setReadOnly(definition.isReadOnly());
// Switch to manual commit if necessary. This is very expensive in some JDBC drivers,
// so we don't want to do it unnecessarily (for example if we've explicitly
// configured the connection pool to set it already).
if (con.getAutoCommit()) {
txObject.setMustRestoreAutoCommit(true);
if (logger.isDebugEnabled()) {
logger.debug("Switching JDBC Connection [" + con + "] to manual commit");
}
con.setAutoCommit(false);
}
prepareTransactionalConnection(con, definition);
txObject.getConnectionHolder().setTransactionActive(true);
int timeout = determineTimeout(definition);
if (timeout != TransactionDefinition.TIMEOUT_DEFAULT) {
txObject.getConnectionHolder().setTimeoutInSeconds(timeout);
}
// Bind the connection holder to the thread.
if (txObject.isNewConnectionHolder()) {
TransactionSynchronizationManager.bindResource(obtainDataSource(), txObject.getConnectionHolder());
}
}
catch (Throwable ex) {
if (txObject.isNewConnectionHolder()) {
DataSourceUtils.releaseConnection(con, obtainDataSource());
txObject.setConnectionHolder(null, false);
}
throw new CannotCreateTransactionException("Could not open JDBC Connection for transaction", ex);
}
}
//此处略去其他方法
}
//1. 确保DynamicDataSourceAspect 切面方法在 finally代码块 调用clearDataSource()
try {
point.proceed();
} finally {
DynamicRoutingDataSource.clearDataSource();
log.info("cleared datasource");
}