Java文件流转为文件的代码

Java文件流转为文件的代码是什么？星辉小编来告诉大家。 

StringId=request.getParameter("userId");intuserId=Integer.parseInt(Id);Stringsql="select*fromUserwhereuserId=?";Useru=newUser();DbHelperdb=newDbHelper();Connectionconnect...

String Id = request.getParameter("userId");
int userId = Integer.parseInt(Id);
String sql = "select * from User where userId=?";
User u = new User();
DbHelper db = new DbHelper();
Connection connection = db.getConnection();
ResultSet rs = null;
PreparedStatement pstmt = null;
User u = new User();
try {
pstmt = connection.prepareStatement(sql);
pstmt.setInt(1, userId);
//list = (List)pstmt.executeQuery();
rs = pstmt.executeQuery();
while (rs.next()) {
u.setString(rs.getString("userName"));
u.setFile(rs.getFile("file"));//本意是这个地方是一个图片，在数据库中的格式是Blob类型，希望能转换成File类型，放在user对象中 }
} catch (Exception e) {
e.printStackTrace();
}
try {
pstmt.close();
connection.close();
} catch (Exception e) {
e.printStackTrace();
}
//如何将Blob类型的数据，放在user对象中