java-design-patterns/dao/README.md

---
layout: pattern
title: Data Access Object
folder: dao
permalink: /patterns/dao/
categories: Persistence Tier
tags:
 - Java
 - Difficulty-Beginner
---

## Intent
Object provides an abstract interface to some type of database or
other persistence mechanism.

![alt text](./etc/dao.png "Data Access Object")

## Applicability
Use the Data Access Object in any of the following situations

* when you want to consolidate how the data layer is accessed
* when you want to avoid writing multiple data retrieval/persistence layers

## Credits

* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00			`---`
			`layout: pattern`
			`title: Data Access Object`
			`folder: dao`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`permalink: /patterns/dao/`
Categorize and tag all patterns #213 2015-12-28 15:52:44 +02:00			`categories: Persistence Tier`
Work on #226, moved POSA reference and some J2EE design pattern references 2015-09-24 12:23:02 +05:30			`tags:`
			`- Java`
			`- Difficulty-Beginner`
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00			`---`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Intent`
			`Object provides an abstract interface to some type of database or`
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00			`other persistence mechanism.`

			`![alt text](./etc/dao.png "Data Access Object")`

Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Applicability`
			`Use the Data Access Object in any of the following situations`
Work towards #56: Splitting up the README I did the job and splitted up the readme, hopefully everything was splitted correctly... 2015-08-13 23:54:40 +02:00
			`* when you want to consolidate how the data layer is accessed`
Work towards #56: Add permalink to every pattern This makes cleaner URLs thanks to jekyll 2015-08-15 18:03:05 +02:00			`* when you want to avoid writing multiple data retrieval/persistence layers`
Work on #226, moved POSA reference and some J2EE design pattern references 2015-09-24 12:23:02 +05:30
Use headings instead of bold text in index.md #238 2016-01-03 21:14:30 +01:00			`## Credits`
Work on #226, moved POSA reference and some J2EE design pattern references 2015-09-24 12:23:02 +05:30
			`* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)`