Javaです。
データベースにイメージを格納します。
動機
シナリオ
画像を公開されているwebAPIから取得します。同じ画像を何度も、取得すると提供API側に負荷がかかります。
取得した画像をキャッシュするようにしてください。
というわけで、H2を使って、メモリ上にもたせてみる手習いです。
H2でなければいけないというわけではもちろんないです。
byteの配列を格納します。
その際に、ステートメントのsetBinaryStreamを使っています。
setBytesを使ってもいいようです。
参考
package h2test;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Test {
static class ImageUtils {
public static byte[] getImageBytes(BufferedImage image,
String imageFormat) throws IOException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
BufferedOutputStream os = new BufferedOutputStream(bos);
image.flush();
ImageIO.write(image, imageFormat, os);
os.flush();
os.close();
return bos.toByteArray();
}
}
public static void main(String[] args) throws SQLException,
ClassNotFoundException, IOException {
// 格納用の画像を作成
BufferedImage bufferedImage = new BufferedImage(200, 200,
BufferedImage.TYPE_INT_ARGB);
{
Graphics2D g2d = (Graphics2D) bufferedImage.createGraphics();
g2d.setColor(new Color(24, 65, 199, 30));
g2d.fillRect(0, 0, 200, 200);
g2d.dispose();
}
Test test = new Test();
test.init();
test.update("INSERT INTO imagetable ( id, image ) VALUES(?, ?)",
"1234", ImageUtils.getImageBytes(bufferedImage, "png"));
Connection connection = null;
Statement statement = null;
ResultSet resultSet = null;
try {
connection = test.getConnection();
statement = connection.createStatement();
resultSet = statement
.executeQuery("select id, image from imagetable");
if (resultSet.next()) {
String id = resultSet.getString("id");
Object o = resultSet.getBinaryStream("image");
try {
final BufferedImage image = ImageIO
.read((ByteArrayInputStream) o);
Thread thread = new Thread(new Runnable() {
public void run() {
JPanel p = new JPanel() {
protected void paintChildren(Graphics g) {
g.drawImage(image, 0, 0, null);
}
};
JFrame frame = new JFrame();
frame
.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(p);
frame.setVisible(true);
}
});
thread.start();
} catch (IOException e) {
e.printStackTrace();
}
}
System.out.println();
} catch (SQLException e) {
e.printStackTrace();
} finally {
Test.close(resultSet, statement, connection);
}
}
protected void init() throws SQLException, ClassNotFoundException {
update("CREATE TABLE imagetable ( id VARCHAR (64) NOT NULL,image BLOB)");
}
protected void update(String expression, Object... param)
throws SQLException, ClassNotFoundException {
Connection connection = getConnection();
PreparedStatement st = null;
st = connection.prepareStatement(expression);
int pos = 1;
for (Object o : param) {
if (o instanceof byte[]) {
byte[] bs = (byte[]) o;
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(
bs);
st.setBinaryStream(pos, byteArrayInputStream, bs.length);
continue;
}
st.setObject(pos, o);
pos++;
}
int i = st.executeUpdate(); // run the query
if (i == -1) {
System.err.println("update failed....");
}
st.close();
connection.close();
}
protected void update(String expression) throws SQLException,
ClassNotFoundException {
Connection connection = getConnection();
Statement st = null;
st = connection.createStatement(); // statements
int i = st.executeUpdate(expression); // run the query
if (i == -1) {
System.err.println("update failed....");
}
System.out.println("====>" + i);
st.close();
connection.close();
}
// BasicDataSource dataSource = new BasicDataSource();
// {
// dataSource.setUrl("jdbc:h2:mem:mydb");
// dataSource.setUsername("sa");
// dataSource.setPassword("");
// }
protected Connection getConnection() throws SQLException,
ClassNotFoundException {
Connection connection = null;
try {
Class.forName("org.h2.Driver");
connection = DriverManager.getConnection("jdbc:h2:mem:mydb;DB_CLOSE_DELAY=-1",
"sa",
"");
} catch (SQLException e) {
throw e;
} catch (ClassNotFoundException e) {
throw e;
}
return connection;
}
static void close(ResultSet resultSet, Statement statement,
Connection connection) {
if (resultSet != null) {
try {
resultSet.close();
} catch (SQLException e) {
}
}
if (statement != null) {
try {
statement.close();
} catch (SQLException e) {
}
}
if (connection != null) {
try {
connection.close();
} catch (SQLException e) {
}
}
}
}
h2database
java
