写自己的ANDROIDSDK 参考资料1

http://www.vogella.com/articles/AndroidLibraryProjects/article.html

Android Library Projects - Tutorial

Lars Vogel

Version 1.3

Copyright © 2011, 2012, 2013 Lars Vogel

03.06.2013

Revision History
Revision 0.1	16.03.2012	Lars Vogel	Created
Revision 0.2 - 1.3	16.04.2012 - 03.06.2013	Lars Vogel	bugfixes and updates

Android Library Projects
This tutorial describes how to create and use library projects in Android. The tutorial is based on Eclipse 4.2, Java 1.6 and Android 4.2.

Table of Contents

1. Android library projects
1.1. Motivation1.2. Creating and using library projects1.3. Priorities for conflicting resources
2. Using JAR files in Android3. Prerequisite4. Tutorial: Create Android library projects
4.1. Create library project4.2. RSS - Really Simple Syndication4.3. Create Model class4.4. Create instances4.5. Set as library project4.6. Use library project
5. Thank you6. Questions and Discussion7. Links and Literature
7.1. Source Code7.2. Android Resources7.3. vogella Resources

1. Android library projects

1.1. Motivation

Android library projects allow to store source code and resources which are used by several other Android projects. The Android development tools compile the content of library into the Android project by creating a JAR file.

Library projects cannot be compiled to Android applications directly.

Using library projects help you to structure your application code. Also more and more important Open Source libraries are available for Android. Understanding library projects is therefore important for every Android programmer.

1.2. Creating and using library projects

If the Android development tools build a project which uses a library project, it also builds the components of the library and adds them to the

.apk

file of the compiled application.

Therefore a library project can be considered to be a compile-time artifact. A Android library project can contain Java classes, Android components and resources. Only assets are not supported.

To create a library project, set the Mark this project as library flag in the Android project generation wizard.

To use such a library, select the generated project, right-click on it and select properties. On the Android tab add the library project to it.

The library project must declare all its components, e.g.
activities, service, etc. via the

AndroidManifest.xml

file. The application which uses the library must also declare all the used components via the

AndroidManifest.xml

file.

Other projects can now use this library project. This can also be set via the properties of the corresponding project.

1.3. Priorities for conflicting resources

The Android development tools merges the resources of a library project with the resources of the application project. In the case that a resources ID is defined several times, the tools select the resource from the application, or the library with highest
priority, and discard the other resource.

2. Using JAR files in Android

To use a Java library inside your Android project directly, you can create a folder called

libs

and place your JAR into this folder.

Tip

If you call the folder

libs

, the Android Developer Tools automatically add the JAR file to the classpath of your project.

3. Prerequisite

The following example assumes that you have created a normal Android project called
com.example.android.rssfeed based on
Android Fragments tutorial .

4. Tutorial: Create Android library projects

4.1. Create library project

Create a new Android project called com.example.android.rssfeedlibrary. Do not need to create an
activity.



Our library project will not contribute Android components but a data model and a method to get the number of instances. We will provide RSSfeed data. The following gives a short introduction into RSS.

4.2. RSS - Really Simple Syndication

An RSS document is an XML file which can be used to publish blog entries and news. The format of the XML file is specified via the RSS specification.

RSS stands for Really Simple Syndication (in version 2.0 of the RSS specification).

Typically a RSS file is provided by a web server, which RSS client read. These RSS clients parse the file and display it.

4.3. Create Model class

Create an

RssItem

class which can store data of an RSS entry.

package com.example.android.rssfeedlibrary;

public class RssItem {
private String pubDate;
private String description;
private String link;
private String title;

}

Use Eclipse code generation capabilities which can be found in the menu under
Source to generate the getters and setter, the constructor and a

toString()

method. The result should look like the following class.

package com.example.android.rssfeedlibrary;

public class RssItem {
private String pubDate;
private String description;
private String link;
private String title;

public RssItem() {
}

public RssItem(String title, String link) {
this.title = title;
this.link = link;
}

public String getPubDate() {
return pubDate;
}

public void setPubDate(String pubDate) {
this.pubDate = pubDate;
}

public String getDescription() {
return description;
}

public void setDescription(String description) {
this.description = description;
}

public String getLink() {
return link;
}

public void setLink(String link) {
this.link = link;
}

public String getTitle() {
return title;
}

public void setTitle(String title) {
this.title = title;
}

@Override
public String toString() {
return "RssItem [title=" + title + "]";
}

}

4.4. Create instances

Create a new class called

RssFeedProvider

with a static method to return a list of

RssItem

objects.

package com.example.android.rssfeedlibrary;

import java.util.ArrayList;
import java.util.List;

public class RssFeedProvider {
// Helper method to get a list
// of RssItems

public static List<RssItem> parse(String rssFeed) {

List<RssItem> list = new ArrayList<RssItem>();

// create some example data
RssItem item = new RssItem("test1", "l1");
list.add(item);
item = new RssItem("test2", "l2");
list.add(item);
// TODO Create a few more instances of RssItem

return list;
}
}

Solve the TODOs to create example instances of the

RssItem

class and add it to the list. This method does currently only return test data.

4.5. Set as library project

Right-click on the Android project and select Properties. Ensure that the
is Library flag is set.

4.6. Use library project

In your application project defines that you want to use the library project via the project properties.



Use the static method of

RssFeedProvider

to get the list of

RssItem

objects and display the number in your

DetailFragment

instead of current system time.

To send the new data change your

MyListFragment

class.

// Update the method updateDetail() {
// more code....

// reading the RSS items
List<RssItem> list = RssFeedProvider
.parse("http://www.vogella.com/article.rss");
String text = String.valueOf(list.size());
// TODO send text to the Detail fragment

5. Thank you

Please help me to support this article:

6. Questions and Discussion

If you find errors in this tutorial, please notify me (see the top of the page). Please note that due to the high volume of feedback I receive, I cannot answer questions to your implementation. Ensure you have read the

vogella FAQ as I don't respond to questions already answered there.

7. Links and Literature

7.1. Source Code

Source Code of Examples

7.2. Android Resources

Android Tutorial

Android Location API and Google Maps

Android and Networking

7.3. vogella Resources

vogella Training Android and Eclipse Training from the vogella team

Android Tutorial Introduction to Android Programming

GWT Tutorial Program in Java, compile to JavaScript and HTML

Eclipse RCP Tutorial Create native applications in Java

JUnit Tutorial Test your application

Git Tutorial Put all your files in a distributed version control system