Saving an image in MySQL from Java

问题:

I am trying to save images in MySQL database from a Java swing application. I am using JFileChsoser to get the path of the image. Then after that converting the file so that it can be saved in the MySQL column which is of BLOB type. But every image I try to save does not save properly or get converted properly. Could someone tell me what I'm doing wrong over here?

private void btn_choosepicActionPerformed(java.awt.event.ActionEvent evt) {
    JFileChooser picchooser = new JFileChooser();
    picchooser.setDialogTitle("Select Image");
    picchooser.showOpenDialog(null);
    File pic=picchooser.getSelectedFile();
    path= pic.getAbsolutePath();
    txt_path.setText(path.replace('\\','/'));
    try{
        File image = new File(path);
        FileInputStream fis = new FileInputStream(image);
        ByteArrayOutputStream baos= new ByteArrayOutputStream();
        byte[] buff = new byte[1024];
        for(int readNum; (readNum=fis.read(buff)) !=-1 ; ){
            baos.write(buff,0,readNum);
        }
        userimage=baos.toByteArray();
    }
    catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }     
}

And then after this Im saving it to the database like so.

private void btn_saveActionPerformed(java.awt.event.ActionEvent evt) {
    String user= txt_username.getText();
    try{
        String sql="insert into imgtst (username,image) values ('"+user+"','"+userimage+"')";
        pst=con.prepareStatement(sql);
        pst.executeUpdate();
        JOptionPane.showMessageDialog(null, "Saved");
    }
    catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }  
}

and I have declared the variable userimage and path as a global variables

String path=null;
byte[] userimage=null;

回答1:

You are converting the byte[] to a String in your sql statement, and you will end up with incorrect data.

The right way to use a BLOB would be to pass the InputStream itself. You can use the FileInputStream you are using to read the file.

File image = new File(path);
FileInputStream fis = new FileInputStream ( image );

String sql="insert into imgtst (username,image) values (?, ?)";
pst=con.prepareStatement(sql);

pst.setString(1, user);
pst.setBinaryStream (2, fis, (int) file.length() );

When you retrieve it back you can similarly get an InputStream from the ResultSet:

InputStream imgStream = resultSet.getBinaryStream(2);