Spring Framework example source code file (DefaultImageDatabase.java)

This example Spring Framework source code file (DefaultImageDatabase.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

dataaccessexception, dataaccessexception, from, imagedescriptor, inputstream, insert, io, ioexception, jdbc, select, sql, sqlexception, sqlexception, string, string, transactional, transactional, util

The Spring Framework DefaultImageDatabase.java source code

package org.springframework.samples.imagedb;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;

import org.springframework.dao.DataAccessException;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.jdbc.LobRetrievalFailureException;
import org.springframework.jdbc.core.simple.ParameterizedRowMapper;
import org.springframework.jdbc.core.simple.SimpleJdbcDaoSupport;
import org.springframework.jdbc.core.support.AbstractLobCreatingPreparedStatementCallback;
import org.springframework.jdbc.core.support.AbstractLobStreamingResultSetExtractor;
import org.springframework.jdbc.support.lob.LobCreator;
import org.springframework.jdbc.support.lob.LobHandler;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.util.FileCopyUtils;

/**
 * Default implementation of the central image database business interface.
 *
 * <p>Uses JDBC with a LobHandler to retrieve and store image data.
 * Illustrates direct use of the <code>jdbc.core package,
 * i.e. JdbcTemplate, rather than operation objects from the
 * <code>jdbc.object package.
 *
 * @author Juergen Hoeller
 * @since 07.01.2004
 * @see org.springframework.jdbc.core.JdbcTemplate
 * @see org.springframework.jdbc.support.lob.LobHandler
 */
public class DefaultImageDatabase extends SimpleJdbcDaoSupport implements ImageDatabase {

	private LobHandler lobHandler;

	/**
	 * Set the LobHandler to use for BLOB/CLOB access.
	 * Could use a DefaultLobHandler instance as default,
	 * but relies on a specified LobHandler here.
	 * @see org.springframework.jdbc.support.lob.DefaultLobHandler
	 */
	public void setLobHandler(LobHandler lobHandler) {
		this.lobHandler = lobHandler;
	}

	@Transactional(readOnly=true)
	public List<ImageDescriptor> getImages() throws DataAccessException {
		return getSimpleJdbcTemplate().query(
		    "SELECT image_name, description FROM imagedb",
		    new ParameterizedRowMapper<ImageDescriptor>() {
			    public ImageDescriptor mapRow(ResultSet rs, int rowNum) throws SQLException {
				    String name = rs.getString(1);
				    String description = lobHandler.getClobAsString(rs, 2);
				    return new ImageDescriptor(name, description);
			    }
		    });
	}

	@Transactional(readOnly=true)
	public void streamImage(final String name, final OutputStream contentStream) throws DataAccessException {
		getJdbcTemplate().query(
				"SELECT content FROM imagedb WHERE image_name=?", new Object[] {name},
				new AbstractLobStreamingResultSetExtractor() {
					protected void handleNoRowFound() throws LobRetrievalFailureException {
						throw new EmptyResultDataAccessException(
						    "Image with name '" + name + "' not found in database", 1);
					}
					public void streamData(ResultSet rs) throws SQLException, IOException {
						InputStream is = lobHandler.getBlobAsBinaryStream(rs, 1);
						if (is != null) {
							FileCopyUtils.copy(is, contentStream);
						}
					}
				}
		);
	}

	@Transactional
	public void storeImage(
	    final String name, final InputStream contentStream, final int contentLength, final String description)
	    throws DataAccessException {

		getJdbcTemplate().execute(
				"INSERT INTO imagedb (image_name, content, description) VALUES (?, ?, ?)",
				new AbstractLobCreatingPreparedStatementCallback(this.lobHandler) {
					protected void setValues(PreparedStatement ps, LobCreator lobCreator) throws SQLException {
						ps.setString(1, name);
						lobCreator.setBlobAsBinaryStream(ps, 2, contentStream, contentLength);
						lobCreator.setClobAsString(ps, 3, description);
					}
				}
		);
	}

	public void checkImages() {
		// Could implement consistency check here...
		logger.info("Checking images: not implemented but invoked by scheduling");
	}

	@Transactional
	public void clearDatabase() throws DataAccessException {
		getJdbcTemplate().update("DELETE FROM imagedb");
	}

}