I have a program where I need to save a running application to be able to go back to it later
I know that I can write/read from a text file to achieve this but the program is pretty prodigious so it's not really a good way to do it because I have 10+ classes and thousands of JTextFields, JComboBoxs, etc. Does anyone know of a way I can achieve this without writing/reading from text files?
An example of what I need to be able to do is this:
In Microsoft Excel you can load files (.exl) into it and be able to edit them.
The Swing Application Framework provides a way to save session state when your application exits and restore the state when you restart. Session state is the graphical window configuration of your application. This state includes window size, internal frame locations, selected tabs, column widths, and other graphical properties.
How do you think Excel does this? It stores the type and value of each cell, along with metadata describing the worksheet in its own proprietary binary format in a file. If you have a custom application with complex internal state, you will have to design a storage format and serialize the state yourself. You may be able to use Java Serialization, but not without some effort.
A good way to do this is to save the data from your controls into a canonical form and then make that class serializable. You can then persist that data to a file. Here's a link about serialization in Java.
UPDATE
I just noticed that you said you have thousands of form controls. So you probably don't want to do all of this in one class, but you probably want to maintain a hierarchy of classes and split out the data into separate classes. This will also help you separate your concerns. Hopefully you have POJOs or domain classes that represents your data. If that is the case, your task will be much easier. This is also why separating concerns is good :).
To save the state of an application, i can think of two popular way:
1) save the state of the application in a Database
2) save the state of the application in a binary file or XML,json or any format you want.
Maybe giving more details about the app. would help.
is it a Web app, fat client app, client/server app... !^
Solution may vary with the type of application.
Hope it help.
Related
Unfortunately I couldn't find anything specific to this topic / to my problem. Here we go:
I'm building a JavaFX Business Application for a friend of mine. Unfortunately I do not have any possibility to connect to a Database. I want the Application to load a savestate from a file. The application contains a list with clients and the clients got some specific properties. I do not want to hardcode this to a .prop or .txt file, because I'm sure that there's a different way of doing this, isn't there?
Thanks in advance, appreciate it!
Lots of choices for persisting data to local storage. The exact choice depends on your needs. You do not describe enough details to make a specific recommendation.
Here is a list of possibilities, roughly in increasing order of complexity of your data.
Text file
If you have small amounts of simple data, save to a text file. You can store each piece in a separate file, or combine into a single file. Recent versions of Java have new classes to make this easier than ever. See Oracle Tutorial.
Comma-separate & Tab-delimited
For sets of structured data, write to text files in comma-separated values (CSV) or tab-delimited values. For example a list of people with rows for each person, and columns for name, phone number, and email address.
While reading/writing such files is easy enough to program yourself, I suggest using an established library to eliminate the drudgery, avoid bugs, and save yourself some time. There are a few such libraries written in Java.
My favorite is the Apache Commons CSV project. This library makes easy work of the chore of reading/writing such files. Despite the name, this library supports tab-delimited as well as comma-separated formats. I've written a few Answers here on Stack Overflow showing how to use this library, as you can see here, here, and here.
By the way, plain old ASCII defines a few character positions explicitly for delimiting in data files, with four levels of grouping (document, group, record/row, and field). Unicode, of course, inherits these from ASCII as code points. I am puzzled why these have remained so obscure and so infrequently used. Seems much more logical to me than using commas and tabs which may well exist inside the data payload.
Serialization
You can write out the data values stored within an object. This is called serialization. Java has a serialization facility built-in, but be sure to study up on the details.
To more simply write out an object’s values and later read them back in to reconstitute an object, I have enjoyed using the Simple XML Serialization project. This works well for relatively simple needs, and is aimed at the situation where you want the structure of a class to drive the process of determining what to write.
Java has other XML binding facilities both built-in and third-party. These are much more powerful in their flexibility. They are especially good for when you want to define and verify the XML structure in a rigid fashion such as defining a XML DTD or XML Schema against which to validate the data and perhaps even generate the Java class in which to represent the data.
Embedded database
For more complicated data, use an embedded relational database.
The SQLite database is bundled with many platforms. This is a C-based library, not pure Java. As the name indicates, SQLite is indeed quite “lite“, lacking rigid data types and many other common database features. SQLite is meant to be an alternative to writing text files than as a competitor to more serious databases. It is a great product if your needs fit the sweet-spot of its capabilities.
My first choice for an embedded database would be H2 Database Engine. Built in pure Java. Can be run inside your app, or separately as a server (you choice). Has sophisticated relational database features. Has been around for years, often updated, and is well-worn. The principal author has much experience in the field.
General question here. I have a Spring Web MVC Application that allows users to enter data one record at a time. Validation checks are run when adding/editing each individual record (database calls, client side validation, etc)
We want to provide users a way to bulk insert many records on a single load. Right now the obvious choice is importing an excel spreadsheet, however I feel like this will require a ton of redundant work as we will have to provide all the same validation checks, dynamic string building, and preloading drop downs in this excel sheet as we have done in our application. Thus my question is, is there a simple solution of recreating this process via a web interface that would imitate entering data into a spreadsheet (Any tool or framework of sorts)? If this could be done on the front end we would be able to utilize all the functionality we have already implemented
Hope this isn't a poor question, I would just really like to avoid spreadsheets all together
I use http://handsontable.com - it is a javascript component that I use.
You can get quite close to Excel-like behaviour, in a browser. You can also copy / paste to and from Excel with it.
I am inexperienced with Spring and I've been reading up on persistence options in Spring, as I am trying to find a suitable way to store data without the use of a database such as Oracle or MySQL etc...
When my app loads, it will read a file containing IDs. As the app runs, it may gain new IDs which will need to be written to the file in case of a crash. From what I can tell, I will need to replace the whole file each time, which is fine, as the data should be held in RAM and I can just overwrite the original file.
What I would prefer, however, is a way in Spring, or even Java, to sync the file and the data so that if I add 1 new ID to my list, it would automatically add a single line to the end of the file without me needing to write additional file management code. I know I can probably just concatenate the line, but something that basic probably won't be thread safe, and thread safety is a major concern here. I'd rather find a ready-made lib rather than re-invent the wheel.
So, can anyone point me in the direction of a tutorial, or technology, that allows for what I need? Or tell me if one exists, or how best I should go about this?
Thanks.
EDIT: It seems Springs resource bundle is the way forward. But I don't think it does exactly what I need to do. Using this, I will have to write code to both add to the map, and then add to the file.
Take a look of SQLite
Is a thread safe and server less sql database with Java driver.
EDIT
Other option is spring batch support for flat files.
see http://docs.spring.io/spring-batch/reference/html/readersAndWriters.html#flatfiles
Say, I have a pretty simple Java application that needs the way to store some user settings. XML is not a really good solution, since I want to store them in binary form. So, what would be the best solution in this case, embedded database (such as Apache Derby) or just plain old serialization?
I know that these are two completely different things, but both allow to persist some application state. So what would you chose, and why?
Edit
As far as storing simple user preferences go, .properties or xml files are fine, I agree with you. But what if I want to store passwords, or some application-specific data?
User settings are typically stored as
properties, using the properties file format
properties using the XML format
preferences, using the Preferences API. This has the advantage of storing and reading user and system preferences for you, without having to think about where to store them, etc. See http://download.oracle.com/javase/1.4.2/docs/guide/lang/preferences.html
As Apache Derby is an embeddable relational database, it makes sense to use it for storing and manipulating relational data. Using an embedded db for persisting a few user settings only is a bit overkill.
If it were me, I would use a simple key/value pair serialization for persisting user settings.
There is a Scenario to be developed for a 3-tier Application .We need to design a Framework or a utility sort of thing .
In tradional aspect of GUI Designing , either we tend to create a static gui page and code the elements on it along with other properties of the elements such as (disabled/enabled,image source,name ,id ,which function to be called under onclick event.) or we tend to drag and drop the elements from the control pallete provided by variety of gui frameworks.
Certain things i need to design a POC so that we can develop this concept.
There must a utility ,such that during creation of screen layout , that screen should be saved in the database(RDBMS) with a screen number.
All the Events related to that control should be saved in some other table which will be dynamically mapped during the calling of screen number by the user.
When the user call that screen ,a generic function should be invoked which'll call the screen file from the database and apply all the properties ,events,etc at runtime and the final output will be displayed to the user.
This POC will help the us to customised the screens according to our usage.also all the code will seperated which can easily be used for some other development process.
Thanks
Amit Kalra
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Iam not getting it with GUI framework supporting serialization .
The Concept should be like this .
The Developer has a utility like a Screen Painter in which developer can drag drop controls ,now this file will get saved in 2 formats ,first one is a source file and another on is the compiled one (say compiled in a .cpp format or any other format).
now on a client side ,when the user enters any transaction number ,there should be a utility which can load the file from the database ,also apply all the functions applicable to each event .
This Concept is similar to wat is there in SAP R/3.
please help me in undergoing this POC.
Thanks
If I understand your question, you are asking for a GUI framework supporting serialization. There are several ones supporting this. Two I have been using are the FOX Toolkit (C++, cross-platform) and the Windows Presentation Foundation (.NET), which is using the XAML format for serialization.
You can achieve the purpose by using the Serialization support of many popular languages. Even if there is no support for that it shouldn't not be very difficult, storing essential data in some configuration files (or as such in your case storing in a DB) will do the expected like controls details, their position etc. But standard frameworks will make your life easy in long running.