mysql blob字段存储图片操作示例
表结构：
create table view(id int unsigned NOT NULL AUTO_INCREMENT, catid int,title varchar(256),picture MEDIUMBLOB, content TEXT,PRIMARY KEY (id));
java类操作：
import java.awt.Image; import java.io.*; import java.nio.ByteBuffer; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.logging.Level; import java.util.logging.Logger; import javax.swing.ImageIcon; import org.bean.View; /** * * @author weijian.zhongwj */ public class ViewPointDao { public static View getView(Integer catId) { View view = new View(); try { String sql2 = “SELECT title, content, picture FROM view where catid=? limit 1”; PreparedStatement stmt2 = BaseDaoFactory.getInstance().prepareStatement(sql2); stmt2.setInt(1, catId); ResultSet resultSet = stmt2.executeQuery(); while (resultSet.next()) { String name = resultSet.getString(1); String description = resultSet.getString(2); ByteBuffer bb = ByteBuffer.allocate(1024 * 1024); byte[] buffer = new byte[1]; InputStream is = resultSet.getBinaryStream(3); while (is != null && is.read(buffer) > 0) { bb.put(buffer); } ImageIcon icon = new ImageIcon(bb.array()); view.setImage(icon.getImage()); view.setTitle(name); view.setContent(description); return view; } } catch (IOException ex) { Logger.getLogger(ViewPointDao.class.getName()).log(Level.SEVERE, null, ex); } catch (SQLException ex) { Logger.getLogger(ViewPointDao.class.getName()).log(Level.SEVERE, null, ex); } return null; } public static boolean addView(View view) { FileInputStream fis = null; try { if (exit(view.getCatId())) { return update(view); } String sql = “INSERT INTO view (title, content, catid, picture) VALUES (?, ?, ?, ?)”; PreparedStatement stmt = BaseDaoFactory.getInstance().prepareStatement(sql); stmt.setString(1, view.getTitle()); stmt.setString(2, view.getContent()); stmt.setInt(3, view.getCatId()); if (view.getImageFile() != null) { File image = new File(view.getImageFile()); fis = new FileInputStream(image); //image.length(),返回文件的大小 stmt.setBinaryStream(4, fis, (int) image.length()); } else { stmt.setBinaryStream(4, null, 0); } int count = stmt.executeUpdate(); if (count > 0) { return true; } else { return false; } } catch (IOException ex) { Logger.getLogger(ViewPointDao.class.getName()).log(Level.SEVERE, null, ex); } catch (SQLException ex) { Logger.getLogger(ViewPointDao.class.getName()).log(Level.SEVERE, null, ex); } finally { try { if (fis != null) { fis.close(); } } catch (IOException ex) { } } return false; } public static boolean update(View view) { FileInputStream fis = null; try { String sql = “update view set title= ? ,content= ? ” + (view.getImageFile() != null ? (“,picture= ? “) : ” “) + “where catid= ? “; PreparedStatement stmt = BaseDaoFactory.getInstance().prepareStatement(sql); stmt.setString(1, view.getTitle()); stmt.setString(2, view.getContent()); if (vi
