java向oracle中存取图片

ゝ一世哀愁。 2022-08-17 15:28 220阅读 0赞

//一般是先通过select   ... for update锁定blob列，然后写入blob值，然后提交。要用到特定的Oracle BLOB类。

《--------保存图片到数据库--------------》  
public void savePic(InputStream is)\{  
        String insertsql = "insert into pic(id,pic) values(1,empty\_blob())";//首先插入一个空的Blob类型  
        Connection conn = null;  
        Statement stmt = null;  
        PreparedStatement ps = null;  
        ResultSet rs = null;  
        try \{  
            conn = ds.getConnection();  
            conn.setAutoCommit(false);  
            stmt = conn.createStatement();  
            int rt = stmt.executeUpdate(insertsql);  
            if(rt > 0)\{  
                System.out.println("initialization succeed!!");  
                String preCursor = "select id,pic from pic where id='1' for update";  
                rs = stmt.executeQuery(preCursor);//锁定列  
                rs.next();  
                Blob b = (Blob)rs.getBlob("pic");  
                BufferedOutputStream bos = new BufferedOutputStream(b.setBinaryStream(0L));  
                BufferedInputStream bis = new BufferedInputStream(is);  
                int bytes;  
                try \{  
                    while((bytes = bis.read()) != -1)\{  
                        bos.write(bytes);  
                    \}

bis.close();  
                    bos.close();  
                    conn.commit();  
                \} catch (IOException e) \{  
                    e.printStackTrace();  
                \}  
            \}

\} catch (SQLException e) \{  
            e.printStackTrace();  
        \} finally\{  
            try \{  
                rs.close();  
                stmt.close();  
                conn.close();  
            \} catch (SQLException e) \{  
                e.printStackTrace();  
            \}  
        \}  
    \}

《--------获取图片到到页面--------------》  
public JPEGImageEncoder getPic(String id,HttpServletResponse res) throws IOException\{  
        Connection conn = null;  
        Statement stmt = null;  
        PreparedStatement ps = null;  
        ResultSet rs = null;  
        BufferedInputStream imageStream = null;  
        BufferedImage image = null;  
        JPEGImageEncoder encoder = null;  
        ServletOutputStream sos =  res.getOutputStream();  
        try \{  
            conn = ds.getConnection();  
            conn.setAutoCommit(false);  
            stmt = conn.createStatement();  
            System.out.println("initialization succeed!!");  
            String preCursor = "select id,pic from pic where id='1'";  
            rs = stmt.executeQuery(preCursor);  
            rs.next();  
            imageStream = new BufferedInputStream(((Blob)rs.getBlob(2)).getBinaryStream());  
            try \{  
                image = ImageIO.read(imageStream);  
                encoder =  JPEGCodec.createJPEGEncoder(sos);  
                encoder.encode(image);  
                imageStream.close();  
            \} catch (IOException e) \{  
                e.printStackTrace();  
            \}

\} catch (SQLException e) \{  
            e.printStackTrace();  
        \} finally\{  
            try \{  
                rs.close();  
                stmt.close();  
                conn.close();  
            \} catch (SQLException e) \{  
                e.printStackTrace();  
            \}  
        \}  
        return encoder;  
    \}

从数据库获取图片，导出到本地的完整代码：

package dbcon;

import java.awt.image.BufferedImage;  
import java.io.BufferedInputStream;  
import java.io.File;  
import java.io.FileOutputStream;  
import java.io.IOException;  
import java.io.OutputStream;  
import java.sql.Blob;  
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.servlet.ServletOutputStream;  
import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;  
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class DBManager \{  
    private String url = "jdbc:oracle:thin:@10.23.65.21:1521:orcl";  
    private String userName = "test";  
    private String password = "test";  
    private String driver   = "oracle.jdbc.driver.OracleDriver";  
    private Connection conn;  
      
      
    public DBManager()\{  
        try \{  
            Class.forName(driver);  
            conn = DriverManager.getConnection(url, userName, password);  
        \} catch (ClassNotFoundException e) \{  
            e.printStackTrace();  
        \} catch (SQLException e) \{  
            e.printStackTrace();  
        \}  
    \}  
      
    public void getPic(String picPath) throws IOException\{  
        Statement stmt = null;  
        PreparedStatement ps = null;  
        ResultSet rs = null;  
        BufferedInputStream imageStream = null;  
        BufferedImage image = null;  
        JPEGImageEncoder encoder = null;  
        try \{  
            conn.setAutoCommit(false);  
            stmt = conn.createStatement();  
            System.out.println("initialization succeed!!");  
            String preCursor = "select id,zp from zpb where id='2220087'";  
            rs = stmt.executeQuery(preCursor);  
            while(rs.next())\{  
                imageStream = new BufferedInputStream(((Blob)rs.getBlob(2)).getBinaryStream());  
                try \{  
                    String id = rs.getString(1);  
                    File picturePath = new File(picPath +"/"+ id +".jpg");  
                    boolean created  = false;  
                    if(!picturePath.exists())\{  
                        created = picturePath.createNewFile();  
                    \} else \{  
                        created  = true;  
                    \}  
                    if(created)\{  
//                        ServletOutputStream sos =  res.getOutputStream();  
                        OutputStream ostream = new FileOutputStream(picturePath);  
                        image = ImageIO.read(imageStream);  
                        encoder =  JPEGCodec.createJPEGEncoder(ostream);  
                        encoder.encode(image);  
                        imageStream.close();  
                        ostream.flush();  
                        ostream.close();  
                    \}  
                \} catch (IOException e) \{  
                    e.printStackTrace();  
                \}  
            \}

public static void main(String\[\] s)\{  
        DBManager manager = new DBManager();  
        String localPath = "E:\\testpics";  
        try \{  
            manager.getPic(localPath);  
        \} catch (IOException e) \{  
            e.printStackTrace();  
        \}  
    \}

//CLOB类专用处理：

public static String getClobString(ResultSet rs, int col) {
    		try {
    			Clob c = rs.getClob(2);
    			Reader reader = c.getCharacterStream();
    			if (reader == null) {
    				return null;
    			}
    			StringBuffer sb = new StringBuffer();
    			char[] charbuf = new char[4096];
    			for (int i = reader.read(charbuf); i > 0; i = reader.read(charbuf)) {
    				sb.append(charbuf, 0, i);
    			}
    			return sb.toString();
    		} catch (Exception e) {
    			return "";
    		}
    	}