CREATE TABLE images (imgname text, img bytea);

File file = new File("myimage.gif");
FileInputStream fis = new FileInputStream(file);
PreparedStatement ps = conn.prepareStatement("INSERT INTO images VALUES (?, ?)");
ps.setString(1, file.getName());
ps.setBinaryStream(2, fis, file.length());
ps.executeUpdate();
ps.close();
fis.close();

PreparedStatement ps = con.prepareStatement("SELECT img FROM images WHERE imgname = ?");
ps.setString(1, "myimage.gif");
ResultSet rs = ps.executeQuery();
if (rs != null) {
    while (rs.next()) {
        byte[] imgBytes = rs.getBytes(1);
        // use the data in some way here
    }
    rs.close();
}
ps.close();

CREATE TABLE imageslo (imgname text, imgoid oid);

// All LargeObject API calls must be within a transaction block
conn.setAutoCommit(false);
// Get the Large Object Manager to perform operations with
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
// Create a new large object
int oid = lobj.create(LargeObjectManager.READ | LargeObjectManager.WRITE);
// Open the large object for writing
LargeObject obj = lobj.open(oid, LargeObjectManager.WRITE);
// Now open the file
File file = new File("myimage.gif");
FileInputStream fis = new FileInputStream(file);
// Copy the data from the file to the large object
byte buf[] = new byte[2048];
int s, tl = 0;
while ((s = fis.read(buf, 0, 2048)) > 0) {
    obj.write(buf, 0, s);
    tl += s;
}
// Close the large object
obj.close();
// Now insert the row into imageslo
PreparedStatement ps = conn.prepareStatement("INSERT INTO imageslo VALUES (?, ?)");
ps.setString(1, file.getName());
ps.setInt(2, oid);
ps.executeUpdate();
ps.close();
fis.close();

// All LargeObject API calls must be within a transaction block
conn.setAutoCommit(false);
// Get the Large Object Manager to perform operations with
LargeObjectManager lobj = ((org.postgresql.PGConnection)conn).getLargeObjectAPI();
PreparedStatement ps = con.prepareStatement("SELECT imgoid FROM imageslo WHERE imgname = ?");
ps.setString(1, "myimage.gif");
ResultSet rs = ps.executeQuery();
if (rs != null) {
    while (rs.next()) {
        // Open the large object for reading
        int oid = rs.getInt(1);
        LargeObject obj = lobj.open(oid, LargeObjectManager.READ);
        // Read the data
        byte buf[] = new byte[obj.size()];
        obj.read(buf, 0, obj.size());
        // Do something with the data read here
        // Close the object
        obj.close();
    }
    rs.close();
}
ps.close();

// Fielder define field info
type Fielder interface {
    String() string
    FieldType() int
    SetRaw(interface{}) error
    RawValue() interface{}
}

type ByteArrayField []byte
// set value 
func (e *ByteArrayField) SetRaw(value interface{}) error {
    if value == nil {
        return nil
    }
    switch d := value.(type) {
    case []byte:
        *e = d
    case string:
        *e = []byte(d)
    default:
        return fmt.Errorf("[ByteArrayField] unsupported type")
    }
    return nil
}
func (e *ByteArrayField) RawValue() interface{} {
    return *e
}
// specified type
func (f *ByteArrayField) FieldType() int {
    return orm.TypeTextField
}
func (f *ByteArrayField) String() string {
    return string(*f)
}

type ImageModel struct{
    ImageName string `orm:"column(image_name)"`
    ImageData ByteArrayField `orm:"column(image_data);type(bytea)"`
}