Create simple ContentProviders for Android Applications reducing boilerplate code.
Writing Content Providers in Android Applications can be really annoying. In most cases there is not much complexity in regards of the data. Still, you have to write a great deal of boilerplate code to get going. This library is intended to ease up the creation of very simple Content Providers using annotations.
Grab the latest version from Maven Central
compile 'com.github.triplet.simpleprovider:simpleprovider:1.1.0'We introduced a possibly incompatible change in version 1.1.0. See The Changelog for details.
SimpleProvider uses annotations on classes and fields to define the database structure. Everything else (database and table creation, URI matching, CRUD operations) is handled by the abstract class AbstractProvider.
To write your own ContentProvider you have to extend the AbstractProvider class and implement the abstract method getAuthority():
public class BlogProvider extends AbstractProvider {
protected String getAuthority() {
return "com.example.blog.DATA";
}
}Next you will want to define the tables and columns that make up your data.
To do so, create inner classes inside your BlogProvider and use the provided annotations @Table and @Column:
@Table
public class Post {
@Column(value = Column.FieldType.INTEGER, primaryKey = true)
public static final String KEY_ID = "_id";
@Column(Column.FieldType.TEXT)
public static final String KEY_TITLE = "title";
@Column(Column.FieldType.TEXT)
public static final String KEY_CONTENT = "content";
@Column(Column.FieldType.TEXT)
public static final String KEY_AUTHOR = "author";
}
@Table
public class Comment {
@Column(value = Column.FieldType.INTEGER, primaryKey = true)
public static final String KEY_ID = "_id";
@Column(Column.FieldType.INTEGER)
public static final String KEY_POST_ID = "post_id";
@Column(Column.FieldType.TEXT)
public static final String KEY_CONTENT = "content";
@Column(Column.FieldType.TEXT)
public static final String KEY_AUTHOR = "author";
}In the example above we create a simple data structure for a blog application that has posts and comments on posts.
The @Table-Annotation registers a class as a database table. AbstractProvider will take care of creating tables called posts and comments. Note, how we used the plural version of the class name. You can override this behaviour by providing an additional String as the table name.
The @Column-Annotation defines a database column for that table. It requires a column type (One of Column.FieldType.INTEGER, Column.FieldType.TEXT, Column.FieldType.FLOAT or Column.FieldType.BLOB). You may also add SQL extras, e.g. to define a column as the primary key for that table as we did for Post.KEY_ID.
That's all. The AbstractProvider will handle the database creation and default CRUD operations for us.
The above example creates two tables that can be accessed using the standard insert(), query(), update(), delete() operations provided by the ContentResolver class. AbstractProvider automatically handles the standard URIs that directly access a single table.
Based on the example above, and assuming your authority is something like com.example.blog.DATA, then your ContentProvider will automatically handle the following URIs:
com.example.blog.DATA/posts
com.example.blog.DATA/posts/*
com.example.blog.DATA/comments
com.example.blog.DATA/comments/*
We may find ourselves in the situation where we need to change our database schema after we have released our app. Let's assume, we want to add a column to the Posts table that holds the creation date for a post. We obviously need to update the Post class to define the additional column:
@Table
public class Post {
// ... (previously defined columns)
@Column(value = Column.FieldType.INTEGER, since = 2)
public static final String KEY_CREATION_DATE = "creation_date";
}Note, how we used the since-key of the @Column-Annotation to state that this column has been added to the database schema in version 2. To make sure all the upgrade routines are called we also have to override the getSchemaVersion() method:
@Override
protected int getSchemaVersion() {
return 2;
}SimpleProvider uses Annotations and Reflection to create the SQL tables. For example we try to use the pluralized class names of your schema classes in a CREATE TABLE statement. Please make sure to add the following lines to your project-specific proguard rules:
# The AbstractProvider searches for inner classes annotated with @Table
# but proguard flattens nested classes. This line makes sure the structure
# is preserved.
-keepattributes InnerClasses
# Don't obfuscate the FieldType enum as those values are added
# to the CREATE TABLE statement directly
-keep enum de.triplet.simpleprovider.Column$FieldType { public *; }
# Do not obfuscate anything that is annotated with @Table or @Column
# so AbstractProvider can automatically generate the table and column names.
# (This line might be optional if you're fine with a table called 'a' and columns
# called 'a', 'b', 'c', 'd' and so forth).
-keep @de.triplet.simpleprovider.Table class * { @de.triplet.simpleprovider.Column *; }
Please note that these rules have not been fully tested so use them at your own risk.
The MIT License (MIT)
Copyright (c) 2014 Christian Becker
Copyright (c) 2014 Björn Hurling
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
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