jdbctemplate.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

/*
 * Copyright 2002-2004 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.core;

import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.sql.DataSource;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.CollectionFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.IncorrectResultSizeDataAccessException;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.dao.TypeMismatchDataAccessException;
import org.springframework.jdbc.SQLWarningException;
import org.springframework.jdbc.datasource.DataSourceUtils;
import org.springframework.jdbc.support.JdbcAccessor;
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.jdbc.support.KeyHolder;
import org.springframework.jdbc.support.nativejdbc.NativeJdbcExtractor;
import org.springframework.util.NumberUtils;

/**
 * <b>This is the central class in the JDBC core package.</b>
 * It simplifies the use of JDBC and helps to avoid common errors.
 * It executes core JDBC workflow, leaving application code to provide SQL
 * and extract results. This class executes SQL queries or updates, initiating
 * iteration over ResultSets and catching JDBC exceptions and translating
 * them to the generic, more informative exception hierarchy defined in the
 * <code>org.springframework.dao</code> package.
 *
 * <p>Code using this class need only implement callback interfaces, giving
 * them a clearly defined contract. The PreparedStatementCreator callback
 * interface creates a prepared statement given a Connection provided by this
 * class, providing SQL and any necessary parameters. The RowCallbackHandler
 * interface extracts values from each row of a ResultSet.
 *
 * <p>Can be used within a service implementation via direct instantiation
 * with a DataSource reference, or get prepared in an application context
 * and given to services as bean reference. Note: The DataSource should
 * always be configured as a bean in the application context, in the first case
 * given to the service directly, in the second case to the prepared template.
 *
 * <p>The motivation and design of this class is discussed
 * in detail in
 * <a href="http://www.amazon.com/exec/obidos/tg/detail/-/0764543857/">Expert One-On-One J2EE Design and Development</a>
 * by Rod Johnson (Wrox, 2002).
 *
 * <p>Because this class is parameterizable by the callback interfaces and
 * the SQLExceptionTranslator interface, it isn't necessary to subclass it.
 * All SQL issued by this class is logged.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Thomas Risberg
 * @since May 3, 2001
 * @see ResultSetExtractor
 * @see RowCallbackHandler
 * @see RowMapper
 * @see org.springframework.dao
 * @see org.springframework.jdbc.datasource
 * @see org.springframework.jdbc.object
 */
public class JdbcTemplate extends JdbcAccessor implements JdbcOperations, InitializingBean {

	/** Custom NativeJdbcExtractor */
	private NativeJdbcExtractor nativeJdbcExtractor;

	/** If this variable is false, we will throw exceptions on SQL warnings */
	private boolean ignoreWarnings = true;

	/**
	 * If this variable is set to a non-zero value, it will be used for setting the
	 * fetchSize property on statements used for query processing.
	 */
	private int fetchSize = 0;

	/**
	 * If this variable is set to a non-zero value, it will be used for setting the
	 * maxRows property on statements used for query processing.
	 */
	private int maxRows = 0;


	/**
	 * Construct a new JdbcTemplate for bean usage.
	 * Note: The DataSource has to be set before using the instance.
	 * This constructor can be used to prepare a JdbcTemplate via a BeanFactory,
	 * typically setting the DataSource via setDataSource.
	 * @see #setDataSource
	 */
	public JdbcTemplate() {
	}

	/**
	 * Construct a new JdbcTemplate, given a DataSource to obtain connections from.
	 * Note: This will trigger eager initialization of the exception translator.
	 * @param dataSource JDBC DataSource to obtain connections from
	 */
	public JdbcTemplate(DataSource dataSource) {
		setDataSource(dataSource);
		afterPropertiesSet();
	}

	/**
	 * Set a NativeJdbcExtractor to extract native JDBC objects from wrapped handles.
	 * Useful if native Statement and/or ResultSet handles are expected for casting
	 * to database-specific implementation classes, but a connection pool that wraps
	 * JDBC objects is used (note: <i>any</i> pool will return wrapped Connections).
	 */
	public void setNativeJdbcExtractor(NativeJdbcExtractor extractor) {
		this.nativeJdbcExtractor = extractor;
	}

	/**
	 * Return the current NativeJdbcExtractor implementation.
	 */
	public NativeJdbcExtractor getNativeJdbcExtractor() {
		return this.nativeJdbcExtractor;
	}

	/**
	 * Set whether or not we want to ignore SQLWarnings.
	 * Default is true.
	 */
	public void setIgnoreWarnings(boolean ignoreWarnings) {
		this.ignoreWarnings = ignoreWarnings;
	}

	/**
	 * Return whether or not we ignore SQLWarnings. Default is true.
	 */
	public boolean isIgnoreWarnings() {
		return ignoreWarnings;
	}

	/**
	 * Return whether or not we ignore SQLWarnings. Default is true.
	 * @deprecated in favor of <code>isIgnoreWarnings</code>
	 * @see #isIgnoreWarnings
	 */
	public boolean getIgnoreWarnings() {
		return ignoreWarnings;
	}

	/**
	 * Set the fetch size for this JdbcTemplate. This is important for processing
	 * large result sets: Setting this higher than the default value will increase
	 * processing speed at the cost of memory consumption; setting this lower can
	 * avoid transferring row data that will never be read by the application.
	 * <p>Default is 0, indicating to use the driver's default.
	 */
	public void setFetchSize(int fetchSize) {
		this.fetchSize = fetchSize;
	}

	/**
	 * Return the fetch size specified for this JdbcTemplate.
	 */
	public int getFetchSize() {
		return fetchSize;
	}

	/**
	 * Set the maximum number of rows for this JdbcTemplate. This is important
	 * for processing subsets of large result sets, avoiding to read and hold
	 * the entire result set in the database or in the JDBC driver.
	 * <p>Default is 0, indicating to use the driver's default.
	 */
	public void setMaxRows(int maxRows) {
		this.maxRows = maxRows;
	}

	/**
	 * Return the maximum number of rows specified for this JdbcTemplate.
	 */
	public int getMaxRows() {
		return maxRows;
	}

	public void afterPropertiesSet() {
		super.afterPropertiesSet();

		if (getFetchSize() > getMaxRows()) {
			throw new IllegalArgumentException("fetchSize must not be higher than maxRows");
		}
	}


	//-------------------------------------------------------------------------
	// Methods dealing with a plain java.sql.Connection
	//-------------------------------------------------------------------------

	public Object execute(final ConnectionCallback action) throws DataAccessException {
		Connection con = DataSourceUtils.getConnection(getDataSource());
		try {
			Connection conToUse = con;
			if (this.nativeJdbcExtractor != null) {
				conToUse = this.nativeJdbcExtractor.getNativeConnection(con);
			}
			return action.doInConnection(conToUse);
		}
		catch (SQLException ex) {
			throw getExceptionTranslator().translate("executing ConnectionCallback", getSql(action), ex);
		}
		finally {
			DataSourceUtils.closeConnectionIfNecessary(con, getDataSource());
		}
	}


	//-------------------------------------------------------------------------
	// Methods dealing with static SQL (java.sql.Statement)
	//-------------------------------------------------------------------------

	public Object execute(final StatementCallback action) throws DataAccessException {
		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();
			DataSourceUtils.applyTransactionTimeout(stmt, getDataSource());
			Statement stmtToUse = stmt;
			if (this.nativeJdbcExtractor != null) {
				stmtToUse = this.nativeJdbcExtractor.getNativeStatement(stmt);
			}
			Object result = action.doInStatement(stmtToUse);
			SQLWarning warning = stmt.getWarnings();
			throwExceptionOnWarningIfNotIgnoringWarnings(warning);
			return result;
		}
		catch (SQLException ex) {
			throw getExceptionTranslator().translate("executing StatementCallback", getSql(action), ex);
		}
		finally {
			JdbcUtils.closeStatement(stmt);
			DataSourceUtils.closeConnectionIfNecessary(con, getDataSource());
		}
	}

	public void execute(final String sql) throws DataAccessException {
		if (logger.isDebugEnabled()) {
			logger.debug("Executing SQL statement [" + sql + "]");
		}
		class ExecuteStatementCallback implements StatementCallback, SqlProvider {
			public Object doInStatement(Statement stmt) throws SQLException {
				stmt.execute(sql);
				return null;
			}
			public String getSql() {
				return sql;
			}
		}
		execute(new ExecuteStatementCallback());
	}

	public Object query(final String sql, final ResultSetExtractor rse) throws DataAccessException {
		if (sql == null) {
			throw new InvalidDataAccessApiUsageException("SQL must not be null");
		}
		if (JdbcUtils.countParameterPlaceholders(sql, '?', "'\"") > 0) {
			throw new InvalidDataAccessApiUsageException(
					"Cannot execute [" + sql + "] as a static query: it contains bind variables");
		}
		if (logger.isDebugEnabled()) {
			logger.debug("Executing SQL query [" + sql + "]");
		}
		class QueryStatementCallback implements StatementCallback, SqlProvider {
			public Object doInStatement(Statement stmt) throws SQLException {
				ResultSet rs = null;
				try {
					if (getFetchSize() > 0) {
						stmt.setFetchSize(getFetchSize());
					}
					if (getMaxRows() > 0) {
						stmt.setMaxRows(getMaxRows());
					}
					rs = stmt.executeQuery(sql);
					ResultSet rsToUse = rs;
					if (nativeJdbcExtractor != null) {
						rsToUse = nativeJdbcExtractor.getNativeResultSet(rs);
					}
					return rse.extractData(rsToUse);
				}
				finally {
					JdbcUtils.closeResultSet(rs);
				}
			}
			public String getSql() {
				return sql;
			}
		}
		return execute(new QueryStatementCallback());
	}

	public List query(String sql, RowCallbackHandler rch) throws DataAccessException {
		return (List) query(sql, new RowCallbackHandlerResultSetExtractor(rch));
	}

	public List query(String sql, RowMapper rowMapper) throws DataAccessException {
		return query(sql, new RowMapperResultReader(rowMapper));
	}

	public List queryForList(String sql) throws DataAccessException {
		return (List) query(sql, new ListResultSetExtractor());
	}

	public Object queryForObject(String sql, Class requiredType) throws DataAccessException {
		return query(sql, new ObjectResultSetExtractor(requiredType));
	}

	public long queryForLong(String sql) throws DataAccessException {
		Number number = (Number) queryForObject(sql, Number.class);
		return (number != null ? number.longValue() : 0);
	}

	public int queryForInt(String sql) throws DataAccessException {
		Number number = (Number) queryForObject(sql, Number.class);
		return (number != null ? number.intValue() : 0);
	}

	public int update(final String sql) throws DataAccessException {
		if (sql == null) {
			throw new InvalidDataAccessApiUsageException("SQL must not be null");
		}
		if (logger.isDebugEnabled()) {
			logger.debug("Executing SQL update [" + sql + "]");
		}
		class UpdateStatementCallback implements StatementCallback, SqlProvider {
			public Object doInStatement(Statement stmt) throws SQLException {
				int rows = stmt.executeUpdate(sql);
				if (logger.isDebugEnabled()) {
					logger.debug("SQL update affected " + rows + " rows");
				}
				return new Integer(rows);
			}
			public String getSql() {
				return sql;
			}
		}
		return ((Integer) execute(new UpdateStatementCallback())).intValue();
	}

	public int[] batchUpdate(final String[] sql) throws DataAccessException {
		if (sql == null) {
			throw new InvalidDataAccessApiUsageException("SQL must not be null");
		}
		if (logger.isDebugEnabled()) {
			logger.debug("Executing SQL batch update of " + sql.length + " statements");
		}
		class BatchUpdateStatementCallback implements StatementCallback, SqlProvider {
			private String currSql;
			public Object doInStatement(Statement stmt) throws SQLException, DataAccessException {
				int[] rowsAffected = new int[sql.length];
				if (JdbcUtils.supportsBatchUpdates(stmt.getConnection())) {
					for (int i = 0; i < sql.length; i++) {