1 JdbcOperations接口提供了對數據庫的基本操作
public interface JdbcOperations {
<T> T execute(ConnectionCallback<T> action) throws DataAccessException;
.......
}
/*
* Copyright 2002-2012 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
*
* http://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.support;
import javax.sql.DataSource;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.InitializingBean;
/**
* Base class for {@link org.springframework.jdbc.core.JdbcTemplate} and
* other JDBC-accessing DAO helpers, defining common properties such as
* DataSource and exception translator.
*
* <p>Not intended to be used directly.
* See {@link org.springframework.jdbc.core.JdbcTemplate}.
*
* @author Juergen Hoeller
* @since 28.11.2003
* @see org.springframework.jdbc.core.JdbcTemplate
*/
public abstract class JdbcAccessor implements InitializingBean {
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
private DataSource dataSource;
private SQLExceptionTranslator exceptionTranslator;
private boolean lazyInit = true;
/**
* Set the JDBC DataSource to obtain connections from.
*/
public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}
/**
* Return the DataSource used by this template.
*/
public DataSource getDataSource() {
return this.dataSource;
}
/**
* Specify the database product name for the DataSource that this accessor uses.
* This allows to initialize a SQLErrorCodeSQLExceptionTranslator without
* obtaining a Connection from the DataSource to get the metadata.
* @param dbName the database product name that identifies the error codes entry
* @see SQLErrorCodeSQLExceptionTranslator#setDatabaseProductName
* @see java.sql.DatabaseMetaData#getDatabaseProductName()
*/
public void setDatabaseProductName(String dbName) {
this.exceptionTranslator = new SQLErrorCodeSQLExceptionTranslator(dbName);
}
/**
* Set the exception translator for this instance.
* <p>If no custom translator is provided, a default
* {@link SQLErrorCodeSQLExceptionTranslator} is used
* which examines the SQLException's vendor-specific error code.
* @see org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator
* @see org.springframework.jdbc.support.SQLStateSQLExceptionTranslator
*/
public void setExceptionTranslator(SQLExceptionTranslator exceptionTranslator) {
this.exceptionTranslator = exceptionTranslator;
}
/**
* Return the exception translator for this instance.
* <p>Creates a default {@link SQLErrorCodeSQLExceptionTranslator}
* for the specified DataSource if none set, or a
* {@link SQLStateSQLExceptionTranslator} in case of no DataSource.
* @see #getDataSource()
*/
public synchronized SQLExceptionTranslator getExceptionTranslator() {
if (this.exceptionTranslator == null) {
DataSource dataSource = getDataSource();
if (dataSource != null) {
this.exceptionTranslator = new SQLErrorCodeSQLExceptionTranslator(dataSource);
}
else {
this.exceptionTranslator = new SQLStateSQLExceptionTranslator();
}
}
return this.exceptionTranslator;
}
/**
* Set whether to lazily initialize the SQLExceptionTranslator for this accessor,
* on first encounter of a SQLException. Default is "true"; can be switched to
* "false" for initialization on startup.
* <p>Early initialization just applies if {@code afterPropertiesSet()} is called.
* @see #getExceptionTranslator()
* @see #afterPropertiesSet()
*/
public void setLazyInit(boolean lazyInit) {
this.lazyInit = lazyInit;
}
/**
* Return whether to lazily initialize the SQLExceptionTranslator for this accessor.
* @see #getExceptionTranslator()
*/
public boolean isLazyInit() {
return this.lazyInit;
}
/**
* Eagerly initialize the exception translator, if demanded,
* creating a default one for the specified DataSource if none set.
*/
public void afterPropertiesSet() {
if (getDataSource() == null) {
throw new IllegalArgumentException("Property 'dataSource' is required");
}
if (!isLazyInit()) {
getExceptionTranslator();
}
}
}
3 JdbcTemplate
public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
}
JdbcTempate的基本使用方式
JdbcTemplate temp = new JdbcTempalte(datasource);
public class ExecuteStatmentCallback implements StatementCallback<Object>,SqlProvider{
@Override
public String getSql() {
// TODO Auto-generated method stub
return null;
}
@Override
public Object doInStatement(Statement stmt) throws SQLException,
DataAccessException {
// TODO Auto-generated method stub
return null;
}
}
temp.setExecute(new ExecuteStatementCallback());JdbcTemplate的execute調用方式
代碼：
參數是sql語句
public void execute(final String sql) throws DataAccessException {
if (logger.isDebugEnabled()) {
logger.debug("Executing SQL statement [" + sql + "]");
}
class ExecuteStatementCallback implements StatementCallback<Object>, SqlProvider {
public Object doInStatement(Statement stmt) throws SQLException {
stmt.execute(sql);
return null;
}
public String getSql() {
return sql;
}
}
execute(new ExecuteStatementCallback());
}
參數是回調函數
//-------------------------------------------------------------------------
// Methods dealing with static SQL (java.sql.Statement)
//-------------------------------------------------------------------------
public <T> T execute(StatementCallback<T> action) throws DataAccessException {
Assert.notNull(action, "Callback object must not be null");
Connection con = DataSourceUtils.getConnection(getDataSource());
Statement stmt = null;
try {
Connection conToUse = con;
if (this.nativeJdbcExtractor != null &&
this.nativeJdbcExtractor.isNativeConnectionNecessaryForNativeStatements()) {
conToUse = this.nativeJdbcExtractor.getNativeConnection(con);
}
stmt = conToUse.createStatement();
applyStatementSettings(stmt);
Statement stmtToUse = stmt;
if (this.nativeJdbcExtractor != null) {
stmtToUse = this.nativeJdbcExtractor.getNativeStatement(stmt);
}
T result = action.doInStatement(stmtToUse);
handleWarnings(stmt);
return result;
}
catch (SQLException ex) {
// Release Connection early, to avoid potential connection pool deadlock
// in the case when the exception translator hasn't been initialized yet.
JdbcUtils.closeStatement(stmt);
stmt = null;
DataSourceUtils.releaseConnection(con, getDataSource());
con = null;
throw getExceptionTranslator().translate("StatementCallback", getSql(action), ex);
}
finally {
JdbcUtils.closeStatement(stmt);
DataSourceUtils.releaseConnection(con, getDataSource());
}
}
查詢源代碼：
/**
* Query using a prepared statement, allowing for a PreparedStatementCreator
* and a PreparedStatementSetter. Most other query methods use this method,
* but application code will always work with either a creator or a setter.
* @param psc Callback handler that can create a PreparedStatement given a
* Connection
* @param pss object that knows how to set values on the prepared statement.
* If this is null, the SQL will be assumed to contain no bind parameters.
* @param rse object that will extract results.
* @return an arbitrary result object, as returned by the ResultSetExtractor
* @throws DataAccessException if there is any problem
*/
public <T> T query(
PreparedStatementCreator psc, final PreparedStatementSetter pss, final ResultSetExtractor<T> rse)
throws DataAccessException {
Assert.notNull(rse, "ResultSetExtractor must not be null");
logger.debug("Executing prepared SQL query");
return execute(psc, new PreparedStatementCallback<T>() {
public T doInPreparedStatement(PreparedStatement ps) throws SQLException {
ResultSet rs = null;
try {
if (pss != null) {
pss.setValues(ps);
}
rs = ps.executeQuery();
ResultSet rsToUse = rs;
if (nativeJdbcExtractor != null) {
rsToUse = nativeJdbcExtractor.getNativeResultSet(rs);
}
return rse.extractData(rsToUse);
}
finally {
JdbcUtils.closeResultSet(rs);
if (pss instanceof ParameterDisposer) {
((ParameterDisposer) pss).cleanupParameters();
}
}
}
});
}
//-------------------------------------------------------------------------
// Methods dealing with prepared statements
//-------------------------------------------------------------------------
public <T> T execute(PreparedStatementCreator psc, PreparedStatementCallback<T> action)
throws DataAccessException {
Assert.notNull(psc, "PreparedStatementCreator must not be null");
Assert.notNull(action, "Callback object must not be null");
if (logger.isDebugEnabled()) {
String sql = getSql(psc);
logger.debug("Executing prepared SQL statement" + (sql != null ? " [" + sql + "]" : ""));
}
Connection con = DataSourceUtils.getConnection(getDataSource());
PreparedStatement ps = null;
try {
Connection conToUse = con;
if (this.nativeJdbcExtractor != null &&
this.nativeJdbcExtractor.isNativeConnectionNecessaryForNativePreparedStatements()) {
conToUse = this.nativeJdbcExtractor.getNativeConnection(con);
}
ps = psc.createPreparedStatement(conToUse);
applyStatementSettings(ps);
PreparedStatement psToUse = ps;
if (this.nativeJdbcExtractor != null) {
psToUse = this.nativeJdbcExtractor.getNativePreparedStatement(ps);
}
T result = action.doInPreparedStatement(psToUse);
handleWarnings(ps);
return result;
}
catch (SQLException ex) {
// Release Connection early, to avoid potential connection pool deadlock
// in the case when the exception translator hasn't been initialized yet.
if (psc instanceof ParameterDisposer) {
((ParameterDisposer) psc).cleanupParameters();
}
String sql = getSql(psc);
psc = null;
JdbcUtils.closeStatement(ps);
ps = null;
DataSourceUtils.releaseConnection(con, getDataSource());
con = null;
throw getExceptionTranslator().translate("PreparedStatementCallback", sql, ex);
}
finally {
if (psc instanceof ParameterDisposer) {
((ParameterDisposer) psc).cleanupParameters();
}
JdbcUtils.closeStatement(ps);
DataSourceUtils.releaseConnection(con, getDataSource());
}
}
DataSourceUtils
* Helper class that provides static methods for obtaining JDBC Connections from
* a {@link javax.sql.DataSource}. Includes special support for Spring-managed
* transactional Connections, e.g. managed by
{@link DataSourceTransactionManager}
* or {@link org.springframework.transaction.jta.JtaTransactionManager}.
*
* <p>Used internally by Spring's {@link org.springframework.jdbc.core.JdbcTemplate},
* Spring's JDBC operation objects and the JDBC
{@link DataSourceTransactionManager}.
* Can also be used directly in application code.
/**
* Obtain a Connection from the given DataSource. Translates SQLExceptions into
* the Spring hierarchy of unchecked generic data access exceptions, simplifying
* calling code and making any exception that is thrown more meaningful.
* <p>Is aware of a corresponding Connection bound to the current thread, for example
* when using {@link DataSourceTransactionManager}. Will bind a Connection to the
* thread if transaction synchronization is active, e.g. when running within a
* {@link org.springframework.transaction.jta.JtaTransactionManager JTA} transaction).
* @param dataSource the DataSource to obtain Connections from
* @return a JDBC Connection from the given DataSource
* @throws org.springframework.jdbc.CannotGetJdbcConnectionException
* if the attempt to get a Connection failed
* @see #releaseConnection
*/
public static Connection getConnection(DataSource dataSource) throws CannotGetJdbcConnectionException {
try {
return doGetConnection(dataSource);
}
catch (SQLException ex) {
throw new CannotGetJdbcConnectionException("Could not get JDBC Connection", ex);
}
}
/**
* Actually obtain a JDBC Connection from the given DataSource.
* Same as {@link #getConnection}, but throwing the original SQLException.
* <p>Is aware of a corresponding Connection bound to the current thread, for example
* when using {@link DataSourceTransactionManager}. Will bind a Connection to the thread
* if transaction synchronization is active (e.g. if in a JTA transaction).
* <p>Directly accessed by {@link TransactionAwareDataSourceProxy}.
* @param dataSource the DataSource to obtain Connections from
* @return a JDBC Connection from the given DataSource
* @throws SQLException if thrown by JDBC methods
* @see #doReleaseConnection
*/
public static Connection doGetConnection(DataSource dataSource) throws SQLException {
Assert.notNull(dataSource, "No DataSource specified");
ConnectionHolder conHolder = (ConnectionHolder) TransactionSynchronizationManager.getResource(dataSource);
if (conHolder != null && (conHolder.hasConnection() || conHolder.isSynchronizedWithTransaction())) {
conHolder.requested();
if (!conHolder.hasConnection()) {
logger.debug("Fetching resumed JDBC Connection from DataSource");
conHolder.setConnection(dataSource.getConnection());
}
return conHolder.getConnection();
}
// Else we either got no holder or an empty thread-bound holder here.
logger.debug("Fetching JDBC Connection from DataSource");
Connection con = dataSource.getConnection();
if (TransactionSynchronizationManager.isSynchronizationActive()) {
logger.debug("Registering transaction synchronization for JDBC Connection");
// Use same Connection for further JDBC actions within the transaction.
// Thread-bound object will get removed by synchronization at transaction completion.
ConnectionHolder holderToUse = conHolder;
if (holderToUse == null) {
holderToUse = new ConnectionHolder(con);
}
else {
holderToUse.setConnection(con);
}
holderToUse.requested();
TransactionSynchronizationManager.registerSynchronization(
new ConnectionSynchronization(holderToUse, dataSource));
holderToUse.setSynchronizedWithTransaction(true);
if (holderToUse != conHolder) {
TransactionSynchronizationManager.bindResource(dataSource, holderToUse);
}
}
return con;
}