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Android中LayoutInflater的使用
来源:互联网   发布日期:2015-10-13 15:22:55   浏览:1682次  

导读: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...

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。

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