首先对LayoutInflater下一个定义吧,Layoutinflater的作用就是将一个xml布局文件实例化为View对象。
获取Layoutinflater对象的方法有三种,招不在多,管用就行,跟踪源码后发现三种方法的本质都是调用了context.getSystemService(),所以建议以后写的时候就用context.getSystemService()。具体写法如下:
[java]
LayoutInflater inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LayoutInflater inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);接下来重点介绍inflate()方法的使用:
1、返回值:
View对象,有了View对象我们就能做诸如setContentView()或者在自定义Adapter里面的getView()方法中获取item的布局。
2、参数:
[java]
public View inflate (int resource, ViewGroup root)
public View inflate (int resource, ViewGroup root)
第一个参数是一个xml文件的R索引,比如R.layout.activity_main。第二个参数如果不为null就是将得到的View对象再放入一个Viewgroup容器中,我这么说可能有的读者还不是很清楚,文章的最后会有一个例子来说明问题。
[java]
public View inflate (int resource, ViewGroup root, boolean attachToRoot)
public View inflate (int resource, ViewGroup root, boolean attachToRoot)
这里的第三个参数的意思是如果第二个参数不为null,那么为true则放入第二个参数引用的Viewgroup中,为false则不放入第二个参数的Viewgroup中。
下面用一个实例来说明问题。
布局文件有两个:
activity_main.xml
[html]
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<RelativeLayout
android:id="@+id/viewgroup"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</RelativeLayout>
</LinearLayout>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<RelativeLayout
android:id="@+id/viewgroup"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
</RelativeLayout>
</LinearLayout>inflatertest.xml
[html]
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="inflatedemo" />
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="inflatedemo" />
</LinearLayout>当Activity中如是写:
[java]
<PRE class=java name="code">@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup);
}</PRE>
<PRE></PRE>
或者
<PRE></PRE>
[java]
@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);mInflater = (LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);mInflater.inflate(R.layout.inflatertest, mViewGroup);}@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup);
}
或者
[java]
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup, true);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup, true);
}结果是这样子的:
当Activity中如是写:
[java]
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup, false);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mViewGroup = (RelativeLayout) findViewById(R.id.viewgroup);
mInflater = (LayoutInflater) getApplicationContext().getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
mInflater.inflate(R.layout.inflatertest, mViewGroup, false);
}结果是这样的:
今天就到这里,学习框架,一定要掌握函数的返回值和参数的意义,学会总结规律。