Android ORMLite入门与高级用法详解

需积分: 9 153 浏览量更新于2024-07-24 收藏 362KB PDF 举报

本文档深入介绍了Android开发中的ORMLite技术，这是一套轻量级的对象关系映射框架，旨在简化Android应用程序与SQLite数据库之间的交互。以下是文档中涵盖的关键知识点： 1. **ORMLitePackage简介**: ORMLite是版本4.19的一个开源库，由GrayWatson在2011年4月发布，提供给开发者一个易于使用的接口来处理Android应用程序中的数据持久化。文档包含了版权信息及许可条款，强调了允许在保留版权声明和许可声明的情况下复制和分发。 2. **入门指南**: - **下载ORMLite Jar**: 提供了如何下载适合项目需求的ORMLite库，确保将其添加到项目的构建路径中。 - **配置类和DAO**: 学习如何配置要与数据库交互的类（包括添加ORM注解）和Data Access Object (DAO)。这里涉及到如何设置类的构造函数和数据类型映射。 3. **使用方法**: - **设置类和注解**: 介绍如何在类上应用ORMLite注解，以及如何利用JPA注解进行更深层次的集成。 - **连接源**: 描述了不同的数据库连接方式，如SQLite、内容提供者等。 - **DAO设置**: 明确了如何创建和配置DAO对象，以便执行CRUD操作。 - **支持的数据库**: 概述了ORMLite支持哪些类型的数据库，以及其对不同数据库的兼容性。 - **整合流程**: 展示了一个完整的使用流程，包括表和模式的创建，以及如何执行基本的数据库操作。 - **表和模式创建工具**: 强调了`TableUtils`和`TableCreator`类的作用，用于自动创建数据库表。 - **标识列处理**: 讨论了如何处理主键，包括自增ID、字段自带ID以及序列生成的ID。 - **DAO操作实践**: 包括查询、更新和执行原始SQL语句的方法。 - **索引和查询优化**: 如何为关键字段添加索引以提高查询性能。 - **高级功能**: 包含了对执行复杂查询和原生SQL命令的指导。本文档提供了详尽的教程，帮助Android开发者了解如何在项目中有效地使用ORMLite来管理和操作数据库，无论是在数据模型设计、表结构生成还是实际操作数据时，都提供了实用的指导和代码示例。通过学习这些内容，开发者可以快速上手并提升Android应用的数据管理能力。

7Chapter 2: How to Use 14 April 2011

generatedIdSequence

String name of the sequence number to be used to generate this value. Same

as generatedId but you can specify the sequence name to use. Default is

none. Only one ﬁeld can have this set in a class. This is only necessary for

databases which require sequences for generated ids. If you use generatedId

instead then the code will auto-generate a sequence name. Only one of this,

id, and generatedId can be speciﬁed. See Section 2.8.3 [GeneratedIdSequence

Column], page 21.

foreign

Boolean setting which identiﬁes this ﬁeld as corresponding to another class

that is also stored in the database. Default is false. The ﬁeld must not be a

primitive type. The other class must have an id ﬁeld (either id, generatedId,

or generatedIdSequence) which will be stored in this table. When an object

is returned from a query call, any foreign objects will just have the id ﬁeld set.

See Section 2.12 [Foreign Objects], page 26.

useGetSet

Boolean that says that the ﬁeld should be accessed with get and set methods.

Default is false which instead uses direct ﬁeld access via Java reﬂection. This

may be necessary if the object you are storing has protections around it.

NOTE: The name of the get method must match getXxx() where Xxx is the

name of the ﬁeld with the ﬁrst letter capitalized. The get must return a class

which matches the ﬁeld’s exactly. The set method must match setXxx(), have

a single argument whose class matches the ﬁeld’s exactly, and return void. For

example:

@DatabaseField(useGetSet = true)

private Integer orderCount;

public Integer getOrderCount() {

return orderCount;

}

public void setOrderCount(Integer orderCount) {

this.orderCount = orderCount;

}

unknownEnumName

If the ﬁeld is a Java enumerated type then you can specify the name of a

enumerated value which will be used if the value of a database row is not

found in the enumerated type. If this is not speciﬁed and a database row does

contain an unknown name or ordinal value then a SQLException is thrown when

the row is being read from the database. This is useful to handle backwards

compatibility when handling out-of-date database values as well as forwards

compatibility if old software is accessing up-to-date data or if you have to roll

a release back.

8Chapter 2: How to Use 14 April 2011

throwIfNull

Boolean that tells ORMLite to throw an exception if it sees a null value in a

database row and is trying to store it in a primitive ﬁeld. By default it is false.

If it is false and the database ﬁeld is null, then the value of the primitive will

be set to 0 (false, null, etc.). This can only be used on a primitive ﬁeld.

persisted

Set this to be false (default true) to not store this ﬁeld in the database. This is

useful if you want to have the annotation on all of your ﬁelds but turn oﬀ the

writing of some of them to the database.

format

This allows you to specify format information of a particular ﬁeld. Right now

this is only appplicable for the following types:

• DATE_STRING for specifying the format of the date string stored in the

database

• STRING_BYTES for specifying the Charset used to encode the string as an

array of bytes

unique

Adds a constraint to the ﬁeld that it has to be unique across all rows in the

table. This allows you to have a unique ﬁeld in the table even though it is

not the id ﬁeld. For example, you might have an Account class which has a

generated account-id but you also want the email address to be unique across

all Accounts. You can also use the uniqueIndexName to create an index for this

ﬁeld. For unique constraints across multiple ﬁelds, see the uniqueIndex below.

index

Boolean value (default false) to have the database add an index for this ﬁeld.

This will create an index with the name columnName with a " idx" suﬃx.

To specify a speciﬁc name of the index or to index multiple ﬁelds, use the

indexName ﬁeld.

uniqueIndex

Boolean value (default false) to have the database add a unique index for this

ﬁeld. Same as index but this will ensure that all of the values in the index

are unique. If you just want to make sure of unique-ness then you can use the

unique ﬁeld instead.

indexName

String value (default none) to have the database add an index for this ﬁeld

with this name. You do not need to specify the index boolean as well. To index

multiple ﬁelds together in one index, each of the ﬁelds should have the same

indexName value.

uniqueIndexName

String value (default none) to have the database add a unique index for this ﬁeld

with this name. Same as index but this will ensure that all of the values in the

index are unique. For example, this means that you can insert ("pittsburgh",

10Chapter 2: How to Use 14 April 2011

length

Speciﬁes the length (or width) of the database ﬁeld. Maybe only

applicable for Strings and only supported by certain database types.

Default for those that do is 255. Same as the width ﬁeld in the

@DatabaseField annotation.

nullable

Set to true to have a ﬁeld not be able to be inserted into the

database with a null value. Same as the canBeNull ﬁeld in the

@DatabaseField annotation.

unique

Adds a constraint to the ﬁeld that it has to be unique across all

rows in the table. Same as the unique ﬁeld in the @DatabaseField

annotation.

@Id

Used to specify a ﬁeld to be persisted to the database as a primary row-id. If

you want to have the id be auto-generated, you will need to also specify the

@GeneratedValue annotation.

@GeneratedValue

Used to deﬁne an id ﬁeld as having a auto-generated value. This is only

used in addition to the @Id annotation. See the generatedId ﬁeld in the

@DatabaseField annotation for more details.

@OneToOne or @ManyToOne

Fields with these annotations are assumed to be foreign ﬁelds. See Section 2.12

[Foreign Objects], page 26. ORMLite does not enforce the many or one rela-

tionship nor does it use any of the annotation ﬁelds. It just uses the existence

of either of these annotations to indicate that it is a foreign object.

If the @Column annotation is used on a ﬁeld that has a unknown type then it is assumed

to be a Serializable type ﬁeld and the object should implement java.io.Serializable.

See [datatype serializable], page 13.

2.1.3 Adding a No-Argument-Constructor

After you have added the class and ﬁeld annotations, you will also need to add a no-

argument constructor with at least package visibility. When an object is returned from a

query, ORMLite constructs the object using Java reﬂection and a constructor needs to be

called.

Account() {

// all persisted classes must define a no-arg constructor

// with at least package visibility

}

So your ﬁnal example Account class with annotations and constructor would look like:

剩余65页未读，继续阅读

xiaoshunzi2016

粉丝: 0
资源: 2

Android ORMLite入门与高级用法详解

android开发 ormlite

Android Ormlite数据库使用

android ORMLite源码

Android-ormlite-android.zip

Android数据库框架-----ORMLite 的基本用法

Android代码-ormlite-sqlcipher

Android数据库框架-----ORMLite关联表的使用

android-repository-ormlite:一个可以帮助您使用存储库模式在OrmLite上实现Android持久性的项目

Android快速开发--ORMLite，包含jar以及官方文档

ormlite 包涵ormlite-android-5.1和ormlite-core-5.1

最新资源