10.8 LayoutInflater(布局服务)

面演示下两种不同写法添加一个Button的例子：先写个布局文件先：activity_main.xml：<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/RelativeLayout1" android:layout_width="match_parent" android:layout_height="match_parent" > <TextView android:id="@+id/txtTitle" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="我是xml文件加载的布局"/> </RelativeLayout> 第一种不需要setContentView()加载布局文件先：public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Button btnOne = new Button(this); btnOne.setText("我是动态添加的按钮"); RelativeLayout.LayoutParams lp2 = new RelativeLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); lp2.addRule(RelativeLayout.CENTER_IN_PARENT); LayoutInflater inflater = LayoutInflater.from(this); RelativeLayout rly = (RelativeLayout) inflater.inflate( R.layout.activity_main, null) .findViewById(R.id.RelativeLayout1); rly.addView(btnOne,lp2); setContentView(rly); } } 第二种不需要setContentView()加载布局文件先：public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button btnOne = new Button(this); btnOne.setText("我是动态添加的按钮"); RelativeLayout.LayoutParams lp2 = new RelativeLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); lp2.addRule(RelativeLayout.CENTER_IN_PARENT); RelativeLayout rly = (RelativeLayout) findViewById(R.id.RelativeLayout1); rly.addView(btnOne,lp2); } } 分析总结：代码很简单,创建按钮后，我们又创建了一个LayoutParams对象，用来设置Button的大小，又通过addRule()方法设置了Button的位置!第一种方法：通过LayoutInflate的inflate()方法加载了activity_main布局，获得了外层容器，接着addView添加按钮进容器,最后setContentView();第二种方法：因为我们已经通过setContetView()方法加载了布局，此时我们就可以通过findViewById找到这个外层容器,接着addView,最后setContentView()即可!另外,关于这个setContentView( )他设置的视图节点是整个XML的根节点!2）Java代码动态加载xml布局接下来的话，我们换一个，这次加载的是xml文件!动态地添加xml文件!先写下主布局文件和动态加载的布局文件：activity_main.xml：<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/RelativeLayout1" android:layout_width="match_parent" android:layout_height="match_parent" > <Button android:id="@+id/btnLoad" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="动态加载布局"/></RelativeLayout> inflate.xml：<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:orientation="vertical" android:id="@+id/ly_inflate" > <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="我是Java代码加载的布局" /> <Button android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="我是布局里的一个小按钮" /> </LinearLayout> 接着到我们的MainActivity.java在这里动态加载xml布局：public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //获得LayoutInflater对象; final LayoutInflater inflater = LayoutInflater.from(this); //获得外部容器对象 final RelativeLayout rly = (RelativeLayout) findViewById(R.id.RelativeLayout1); Button btnLoad = (Button) findViewById(R.id.btnLoad); btnLoad.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { //加载要添加的布局对象 LinearLayout ly = (LinearLayout) inflater.inflate( R.layout.inflate, null, false).findViewById( R.id.ly_inflate); //设置加载布局的大小与位置 RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); lp.addRule(RelativeLayout.CENTER_IN_PARENT); rly.addView(ly,lp); } }); } } 运行截图：代码分析：①获取容器对象:final RelativeLayout rly = (RelativeLayout) findViewById(R.id.RelativeLayout1);②获得Inflater对象,同时加载被添加的布局的