LayoutInflate的使用

LayoutInflater作用是将layout的xml布局文件实例化为View类对象。

setContentView()一旦调用, layout就会立刻显示UI；而inflate只会把Layout形成一个以view类实现成的对象，有需要时再用setContentView(view)显示出来。一般在activity中通过setContentView()将界面显示出来，但是如果在非activity中如何对控件布局设置操作了，这就需要LayoutInflater动态加载。

LayoutInflater在Android中是“扩展”的意思，作用类似于findViewById()，不同的是LayoutInflater是用来获得布局文件对象的，而findViewById()是用来获得具体控件的。LayoutInflater经常在BaseAdapter的getView方法中用到，用来获取整个View并返回。

获取LayoutInflater有三种方法：

LayoutInflater inflate = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);LayoutInflater inflate = getLayoutInflater();//在Activity中使用LayoutInflater inflate = LayoutInflater.from(getApplicationContext());

用法举例：

user_folder.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:orientation="vertical" >    <EditText        android:id="@+id/editText1"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:ems="10" >        <requestFocus />    </EditText>    <Button        android:id="@+id/button1"        style="?android:attr/buttonStyleSmall"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="Button" /></LinearLayout>

MainActivity.java:

package com.example.hello;import android.os.Bundle;import android.os.Handler;import android.app.Activity;import android.view.LayoutInflater;import android.view.Menu;import android.view.View;import android.widget.Button;import android.widget.RelativeLayout;import android.widget.Toast;public class MainActivity extends Activity implements View.OnClickListener{private RelativeLayout frame;private View mySelfView1 = null;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                frame = (RelativeLayout) findViewById(R.id.frame);        Button btn = (Button) findViewById(R.id.button1);        btn.setOnClickListener(this);        // 第一种方式        // LayoutInflater inflate = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);        // 第二种方式        // LayoutInflater inflate = getLayoutInflater();        LayoutInflater inflate = LayoutInflater.from(getApplicationContext());        mySelfView1 = inflate.inflate(R.layout.user_folder, null);            }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.main, menu);        return true;    }@Overridepublic void onClick(View v) {// TODO Auto-generated method stub        if(mySelfView1 != null){        Toast.makeText(getApplicationContext(), "show my selfview", Toast.LENGTH_SHORT).show();        frame.addView(mySelfView1);                Handler handler = new Handler();        handler.postDelayed(new Runnable() {@Overridepublic void run() {// TODO Auto-generated method stubframe.removeView(mySelfView1);}}, 2000);        } else {        Toast.makeText(getApplicationContext(), "selfview is null", Toast.LENGTH_SHORT).show();        }}    }