Java tutorial
/* * Copyright 2002-2018 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 org.springframework.core.NamedThreadLocal; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.StringUtils; /** * An adapter for a target JDBC {@link javax.sql.DataSource}, applying the specified * user credentials to every standard {@code getConnection()} call, implicitly * invoking {@code getConnection(username, password)} on the target. * All other methods simply delegate to the corresponding methods of the * target DataSource. * * <p>Can be used to proxy a target JNDI DataSource that does not have user * credentials configured. Client code can work with this DataSource as usual, * using the standard {@code getConnection()} call. * * <p>In the following example, client code can simply transparently work with * the preconfigured "myDataSource", implicitly accessing "myTargetDataSource" * with the specified user credentials. * * <pre class="code"> * <bean id="myTargetDataSource" class="org.springframework.jndi.JndiObjectFactoryBean"> * <property name="jndiName" value="java:comp/env/jdbc/myds"/> * </bean> * * <bean id="myDataSource" class="org.springframework.jdbc.datasource.UserCredentialsDataSourceAdapter"> * <property name="targetDataSource" ref="myTargetDataSource"/> * <property name="username" value="myusername"/> * <property name="password" value="mypassword"/> * </bean></pre> * * <p>If the "username" is empty, this proxy will simply delegate to the * standard {@code getConnection()} method of the target DataSource. * This can be used to keep a UserCredentialsDataSourceAdapter bean definition * just for the <i>option</i> of implicitly passing in user credentials if * the particular target DataSource requires it. * * @author Juergen Hoeller * @since 1.0.2 * @see #getConnection */ public class UserCredentialsDataSourceAdapter extends DelegatingDataSource { @Nullable private String username; @Nullable private String password; @Nullable private String catalog; @Nullable private String schema; private final ThreadLocal<JdbcUserCredentials> threadBoundCredentials = new NamedThreadLocal<>( "Current JDBC user credentials"); /** * Set the default username that this adapter should use for retrieving Connections. * <p>Default is no specific user. Note that an explicitly specified username * will always override any username/password specified at the DataSource level. * @see #setPassword * @see #setCredentialsForCurrentThread(String, String) * @see #getConnection(String, String) */ public void setUsername(String username) { this.username = username; } /** * Set the default user's password that this adapter should use for retrieving Connections. * <p>Default is no specific password. Note that an explicitly specified username * will always override any username/password specified at the DataSource level. * @see #setUsername * @see #setCredentialsForCurrentThread(String, String) * @see #getConnection(String, String) */ public void setPassword(String password) { this.password = password; } /** * Specify a database catalog to be applied to each retrieved Connection. * @since 4.3.2 * @see Connection#setCatalog */ public void setCatalog(String catalog) { this.catalog = catalog; } /** * Specify a database schema to be applied to each retrieved Connection. * @since 4.3.2 * @see Connection#setSchema */ public void setSchema(String schema) { this.schema = schema; } /** * Set user credententials for this proxy and the current thread. * The given username and password will be applied to all subsequent * {@code getConnection()} calls on this DataSource proxy. * <p>This will override any statically specified user credentials, * that is, values of the "username" and "password" bean properties. * @param username the username to apply * @param password the password to apply * @see #removeCredentialsFromCurrentThread */ public void setCredentialsForCurrentThread(String username, String password) { this.threadBoundCredentials.set(new JdbcUserCredentials(username, password)); } /** * Remove any user credentials for this proxy from the current thread. * Statically specified user credentials apply again afterwards. * @see #setCredentialsForCurrentThread */ public void removeCredentialsFromCurrentThread() { this.threadBoundCredentials.remove(); } /** * Determine whether there are currently thread-bound credentials, * using them if available, falling back to the statically specified * username and password (i.e. values of the bean properties) otherwise. * <p>Delegates to {@link #doGetConnection(String, String)} with the * determined credentials as parameters. * @see #doGetConnection */ @Override public Connection getConnection() throws SQLException { JdbcUserCredentials threadCredentials = this.threadBoundCredentials.get(); Connection con = (threadCredentials != null ? doGetConnection(threadCredentials.username, threadCredentials.password) : doGetConnection(this.username, this.password)); if (this.catalog != null) { con.setCatalog(this.catalog); } if (this.schema != null) { con.setSchema(this.schema); } return con; } /** * Simply delegates to {@link #doGetConnection(String, String)}, * keeping the given user credentials as-is. */ @Override public Connection getConnection(String username, String password) throws SQLException { return doGetConnection(username, password); } /** * This implementation delegates to the {@code getConnection(username, password)} * method of the target DataSource, passing in the specified user credentials. * If the specified username is empty, it will simply delegate to the standard * {@code getConnection()} method of the target DataSource. * @param username the username to use * @param password the password to use * @return the Connection * @see javax.sql.DataSource#getConnection(String, String) * @see javax.sql.DataSource#getConnection() */ protected Connection doGetConnection(@Nullable String username, @Nullable String password) throws SQLException { Assert.state(getTargetDataSource() != null, "'targetDataSource' is required"); if (StringUtils.hasLength(username)) { return getTargetDataSource().getConnection(username, password); } else { return getTargetDataSource().getConnection(); } } /** * Inner class used as ThreadLocal value. */ private static final class JdbcUserCredentials { public final String username; public final String password; public JdbcUserCredentials(String username, String password) { this.username = username; this.password = password; } @Override public String toString() { return "JdbcUserCredentials[username='" + this.username + "',password='" + this.password + "']"; } } }