Android SDK对应没个定义在res目录下的资源都会定义一个维一的资源ID。在编译时会在gen目录下生成 R.java , 资源ID的格式为 R.[type].[id] 类型为资源类型如anim, array, attr等
可以在代码或是XML资源文件(如layout, style中）访问这些资源。
Context类提供了访问资源的方法，一是直接通过如getText, getString等来访问资源，此外一般的方法是通过getResources()来取代Resources对象，再通过Resources对象来访问资源。下图为Context的类继承图：
可以看到Application ,Service ,Activity 都是Context的子类，因此在这些类中都可以直接访问资源：
[java]
// Using the getString() conevenience method,
// retrieve a string
// resource that hapepns to have style information.
//Note the use of
// CharSequence instead of String so we don't
// lose the style info.
cs = getText(R.string.styled_text);
tv = (TextView)findViewById(R.id.styled_text);
tv.setText(cs);
// Use the same resource, but convert it to a
//string, which causes it
// to lose the style information.
str = getString(R.string.styled_text);
tv = (TextView)findViewById(R.id.plain_text);
tv.setText(str);
// You might need to do this if your code
// is not in an activity.
// For example View has a protected mContext
//field you can use.
// In this case it's just 'this' since
//Activity is a context.
Context context = this;
// Get the Resources object from our context
Resources res = context.getResources();
// Get the string resource, like above.
cs = res.getText(R.string.styled_text);
tv = (TextView)findViewById(R.id.res1);
tv.setText(cs);
// Using the getString() conevenience method,
// retrieve a string
// resource that hapepns to have style information.
//Note the use of
// CharSequence instead of String so we don't
// lose the style info.
cs = getText(R.string.styled_text);
tv = (TextView)findViewById(R.id.styled_text);
tv.setText(cs);
// Use the same resource, but convert it to a
//string, which causes it
// to lose the style information.
str = getString(R.string.styled_text);
tv = (TextView)findViewById(R.id.plain_text);
tv.setText(str);
// You might need to do this if your code
// is not in an activity.
// For example View has a protected mContext
//field you can use.
// In this case it's just 'this' since
//Activity is a context.
Context context = this;
// Get the Resources object from our context
Resources res = context.getResources();
// Get the string resource, like above.
cs = res.getText(R.string.styled_text);
tv = (TextView)findViewById(R.id.res1);
tv.setText(cs);
作者：mapdigit
