Android应用目录（一）-----资源目录

Application List

MyApp/
AndroidManifest.xml	(required) Advertises the screens that this application provides, where they can be launched (from the main program menu or elsewhere), any content providers it implements and what kind of data they handle, where the implementation classes are, and other application-wide information. Syntax details for this file are described in The AndroidManifest.xml File.
src/ /myPackagePath/.../MyClass.java	(required) This folder holds all the source code files for your application, inside the appropriate package subfolders.
res/	(required) This folder holds all the resources for your application. Resources are external data files or description files that are compiled into your code at build time. Files in different folders are compiled differently, so you must put the proper resource into the proper folder. (See Resources for details.)
anim/ animation1.xml ...	(optional) Holds any animation XML description files that the application uses. The format of these files is described in Resources.
drawable/ some_picture.png some_stretchable.9.png some_background.xml ...	(optional) Zero or more files that will be compiled to android.graphics.drawable resources. Files can be image files (png, gif, or other) or XML files describing other graphics such as bitmaps, stretchable bitmaps, or gradients. Supported bitmap file formats are PNG (preferred), JPG, and GIF (discouraged), as well as the custom 9-patch stretchable bitmap format. These formats are described in Resources.
layout/ screen_1_layout.xml ...	(optional) Holds all the XML files describing screens or parts of screens. Although you could create a screen in Java, defining them in XML files is typically easier. A layout file is similar in concept to an HTML file that describes the screen layout and components. See User Interface for more information about designing screens, and Available Resource Types for the syntax of these files.
values/ arrays classes.xml colors.xml dimens.xml strings.xml styles.xml values.xml	(optional) XML files describing additional resources such as strings, colors, and styles. The naming, quantity, and number of these files are not enforced--any XML file is compiled, but these are the standard names given to these files. However, the syntax of these files is prescribed by Android, and described in Resources.
xml/	(optional) XML files that can be read at run time on the device.
raw/	(optional) Any files to be copied directly to the device.

       资源目录

2.Resource Types

Each of the documents in this section describe the usage, format and syntax for a certain type of application resource that you can provide in your resources directory (res/).

Here's a brief summary of each resource type:

Animation Resources

Define pre-determined animations.
Tween animations are saved in res/anim/ and accessed from the R.anim class.
Frame animations are saved in res/drawable/ and accessed from the R.drawable class.

Color State List Resource

Define a color resources that changes based on the View state.
Saved in res/color/ and accessed from the R.color class.

Drawable Resources

Define various graphics with bitmaps or XML.
Saved in res/drawable/ and accessed from the R.drawable class.

Layout Resource

Define the layout for your application UI.
Saved in res/layout/ and accessed from the R.layout class.

Menu Resource

Define the contents of your application menus.
Saved in res/menu/ and accessed from the R.menu class.

String Resources

Define strings, string arrays, and plurals (and include string formatting and styling).
Saved in res/values/ and accessed from the R.string, R.array, and R.plurals classes.

Style Resource

Define the look and format for UI elements.
Saved in res/values/ and accessed from the R.style class.

More Resource Types

Define values such as booleans, integers, dimensions, colors, and other arrays.
Saved in res/values/ but each accessed from unique R sub-classes (such as R.bool, R.integer, R.dimen, etc.).

3.More Resource Types

This page defines more types of resources you can externalize, including:

Bool

XML resource that carries a boolean value.

Color

XML resource that carries a color value (a hexadecimal color).

Dimension

XML resource that carries a dimension value (with a unit of measure).

ID

XML resource that provides a unique identifier for application resources and components.

Integer

XML resource that carries an integer value.

Integer Array

XML resource that provides an array of integers.

Typed Array

XML resource that provides a TypedArray (which you can use for an array of drawables).

Bool

A boolean value defined in XML.

Note: A bool is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine bool resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/filename.xml
The filename is arbitrary. The <bool> element's name will be used as the resource ID.

resource reference:

In Java: R.bool.bool_name
In XML: @[package:]bool/bool_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <bool
        name="bool_name"
        >[true | false]</bool>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<bool>

A boolean value: true or false.

attributes:

name

String. A name for the bool value. This will be used as the resource ID.

example:

XML file saved at res/values-small/bools.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <bool name="screen_small">true</bool>
    <bool name="adjust_view_bounds">true</bool>
</resources>

This application code retrieves the boolean:

Resources res = getResources();
boolean screenIsSmall = res.getBoolean(R.bool.screen_small);

This layout XML uses the boolean for an attribute:

<ImageView
    android:layout_height="fill_parent"
    android:layout_width="fill_parent"
    android:src="@drawable/logo"
    android:adjustViewBounds="@bool/adjust_view_bounds" />

Color

A color value defined in XML. The color is specified with an RGB value and alpha channel. You can use a color resource any place that accepts a hexadecimal color value. You can also use a color resource when a drawable resource is expected in XML (for example, android:drawable="@color/green").

The value always begins with a pound (#) character and then followed by the Alpha-Red-Green-Blue information in one of the following formats:

• #RGB
• #ARGB
• #RRGGBB
• #AARRGGBB

Note: A color is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine color resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/colors.xml
The filename is arbitrary. The <color> element's name will be used as the resource ID.

resource reference:

In Java: R.color.color_name
In XML: @[package:]color/color_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color
        name="color_name"
        >hex_color</color>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<color>

A color expressed in hexadecimal, as described above.

attributes:

name

String. A name for the color. This will be used as the resource ID.

example:

XML file saved at res/values/colors.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <color name="opaque_red">#f00</color>
   <color name="translucent_red">#80ff0000</color>
</resources>

This application code retrieves the color resource:

Resources res = getResources();
int color = res.getColor(R.color.opaque_red);

This layout XML applies the color to an attribute:

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:textColor="@color/translucent_red"
    android:text="Hello"/>

Dimension

A dimension value defined in XML. A dimension is specified with a number followed by a unit of measure. For example: 10px, 2in, 5sp. The following units of measure are supported by Android:

dp

Density-independent Pixels - an abstract unit that is based on the physical density of the screen. These units are relative to a 160 dpi (dots per inch) screen, so 160dp is always one inch regardless of the screen density. The ratio of dp-to-pixel will change with the screen density, but not necessarily in direct proportion. You should use these units when specifying view dimensions in your layout, so the UI properly scales to render at the same actual size on different screens. (The compiler accepts both "dip" and "dp", though "dp" is more consistent with "sp".)

sp

Scale-independent Pixels - this is like the dp unit, but it is also scaled by the user's font size preference. It is recommend you use this unit when specifying font sizes, so they will be adjusted for both the screen density and the user's preference.

pt

Points - 1/72 of an inch based on the physical size of the screen.

px

Pixels - corresponds to actual pixels on the screen. This unit of measure is not recommended because the actual representation can vary across devices; each devices may have a different number of pixels per inch and may have more or fewer total pixels available on the screen.

mm

Millimeters - based on the physical size of the screen.

in

Inches - based on the physical size of the screen.

Note: A dimension is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine dimension resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/filename.xml
The filename is arbitrary. The <dimen> element's name will be used as the resource ID.

resource reference:

In Java: R.dimen.dimension_name
In XML: @[package:]dimen/dimension_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <dimen
        name="dimension_name"
        >dimension</dimen>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<dimen>

A dimension, represented by a float, followed by a unit of measurement (dp, sp, pt, px, mm, in), as described above.

attributes:

name

String. A name for the dimension. This will be used as the resource ID.

example:

XML file saved at res/values/dimens.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <dimen name="textview_height">25dp</dimen>
    <dimen name="textview_width">150dp</dimen>
    <dimen name="ball_radius">30dp</dimen>
    <dimen name="font_size">16sp</dimen>
</resources>

This application code retrieves a dimension:

Resources res = getResources();
float fontSize = res.getDimension(R.dimen.font_size);

This layout XML applies dimensions to attributes:

<TextView
    android:layout_height="@dimen/textview_height"
    android:layout_width="@dimen/textview_width"
    android:textSize="@dimen/font_size"/>

ID

A unique resource ID defined in XML. Using the name you provide in the <item> element, the Android developer tools create a unique integer in your project's R.java class, which you can use as an identifier for an application resources (for example, a View in your UI layout) or a unique integer for use in your application code (for example, as an ID for a dialog or a result code).

Note: An ID is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine ID resources with other simple resources in the one XML file, under one <resources> element. Also, remember that an ID resources does not reference an actual resource item; it is simply a unique ID that you can attach to other resources or use as a unique integer in your application.

file location:

res/values/filename.xml
The filename is arbitrary.

resource reference:

In Java: R.id.name
In XML: @[package:]id/name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item
        type="id"
        name="id_name" />
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<item>

Defines a unique ID. Takes no value, only attributes.

attributes:

type

Must be "id".

name

String. A unique name for the ID.

example:

XML file saved at res/values/ids.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item type="id" name="button_ok" />
    <item type="id" name="dialog_exit" />
</resources>

Then, this layout snippet uses the "button_ok" ID for a Button widget:

<Button android:id="@id/button_ok"
    style="@style/button_style" />

Notice that the android:id value does not include the plus sign in the ID reference, because the ID already exists, as defined in the ids.xml example above. (When you specify an ID to an XML resource using the plus sign—in the format android:id="@+id/name"—it means that the "name" ID does not exist and should be created.)

As another example, the following code snippet uses the "dialog_exit" ID as a unique identifier for a dialog:

showDialog(R.id.dialog_exit);

In the same application, the "dialog_exit" ID is compared when creating a dialog:

protected Dialog onCreateDialog(int)(int id) {
    Dialog dialog;
    switch(id) {
    case R.id.dialog_exit:
        ...
        break;
    default:
        dialog = null;
    }
    return dialog;
}

Integer

An integer defined in XML.

Note: An integer is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine integer resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/filename.xml
The filename is arbitrary. The <integer> element's name will be used as the resource ID.

resource reference:

In Java: R.integer.integer_name
In XML: @[package:]integer/integer_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer
        name="integer_name"
        >integer</integer>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<integer>

An integer.

attributes:

name

String. A name for the integer. This will be used as the resource ID.

example:

XML file saved at res/values/integers.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer name="max_speed">75</integer>
    <integer name="min_speed">5</integer>
</resources>

This application code retrieves an integer:

Resources res = getResources();
int maxSpeed = res.getInteger(R.integer.max_speed);

Integer Array

An array of integers defined in XML.

Note: An integer array is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine integer array resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/filename.xml
The filename is arbitrary. The <integer-array> element's name will be used as the resource ID.

compiled resource datatype:

Resource pointer to an array of integers.

resource reference:

In Java: R.array.string_array_name
In XML: @[package:]array.integer_array_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer-array
        name="integer_array_name">
        <item
            >integer</item>
    </integer-array>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<string-array>

Defines an array of integers. Contains one or more child <item> elements.

attributes:

android:name

String. A name for the array. This name will be used as the resource ID to reference the array.

<item>

An integer. The value can be a referenced to another integer resource. Must be a child of a <integer-array> element.

No attributes.

example:

XML file saved at res/values/integers.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <integer-array name="bits">
        <item>4</item>
        <item>8</item>
        <item>16</item>
        <item>32</item>
    </integer-array>
</resources>

This application code retrieves the integer array:

Resources res = getResources();
int[] bits = res.getIntArray(R.array.bits);

Typed Array

A TypedArray defined in XML. You can use this to create an array of other resources, such as drawables. Note that the array is not required to be homogeneous, so you can create an array of mixed resource types, but you must be aware of what and where the data types are in the array so that you can properly obtain each item with the TypedArray's get...() methods.

Note: A typed array is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine typed array resources with other simple resources in the one XML file, under one <resources> element.

file location:

res/values/filename.xml
The filename is arbitrary. The <array> element's name will be used as the resource ID.

compiled resource datatype:

Resource pointer to a TypedArray.

resource reference:

In Java: R.array.array_name
In XML: @[package:]array.array_name

syntax:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array
        name="integer_array_name">
        <item>resource</item>
    </array>
</resources>

elements:

<resources>

Required. This must be the root node.

No attributes.

<array>

Defines an array. Contains one or more child <item> elements.

attributes:

android:name

String. A name for the array. This name will be used as the resource ID to reference the array.

<item>

A generic resource. The value can be a reference to a resource or a simple data type. Must be a child of an <array> element.

No attributes.

example:

XML file saved at res/values/arrays.xml:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <array name="icons">
        <item>@drawable/home</item>
        <item>@drawable/settings</item>
        <item>@drawable/logout</item>
    </array>
    <array name="colors">
        <item>#FFFF0000</item>
        <item>#FF00FF00</item>
        <item>#FF0000FF</item>
    </array>
</resources>

This application code retrieves each array and then obtains the first entry in each array:

Resources res = getResources();
TypedArray icons = res.obtainTypedArray(R.array.icons);
Drawable drawable = icons.getDrawable(0);

TypedArray colors = res.obtainTypedArray(R.array.icons);
int color = colors.getColor(0,0);