android:弹出对话框及LayoutInflater的使用

LayoutInflater 类似于findViewById 只不过前者的对象是布局，后者的对象是控件，这是我的理解。

而且findViewById是View的方法，也就是说使用它必须是在要找控件的父控件下面才可以。这时候通常是用LayoutInlater的实例的findViewById方法

下面给出个代码实例:

package com.example.newadt.zhuqi.first;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {
    
    private Button btn_click;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        btn_click = (Button)findViewById(R.id.btn_click);
        btn_click.setOnClickListener(new OnClickListener() {
            
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                showCustomDialog();
                

            }

            private void showCustomDialog() {                
                AlertDialog.Builder builder;  //
                AlertDialog alertDialog;  //对话框
                Context mContext = MainActivity.this;  
                  
                //下面三种方法都可以  
                ////LayoutInflater inflater = getLayoutInflater(); 
//                LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
                LayoutInflater inflater = (LayoutInflater)mContext.getSystemService(LAYOUT_INFLATER_SERVICE);  
                View layout = inflater.inflate(R.layout.custom_dialog,null);  
                TextView text = (TextView) layout.findViewById(R.id.text);  
                text.setText("Hello, Welcome to Mr Wei's blog!");  
                Log.i("smallpig", "the text is "+text.getText());
                ImageView image = (ImageView) layout.findViewById(R.id.image);  //注意：此处findViewById的方法使用者是layout。不加会报错
                image.setImageResource(R.drawable.ic_launcher);  
                builder = new AlertDialog.Builder(mContext);  
                builder.setView(layout);  //把view加入对话框
                alertDialog = builder.create();//生成对话框
                alertDialog.show();            
                
            }
        });
    }


    @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;
    }
    
}

 布局文件为

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button 
        android:id="@+id/btn_click"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@id/tv"
        android:text="@string/clickme"
        />
</RelativeLayout>

对话框custom_dialog的布局文件：

<?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="horizontal"
    android:padding="10dp" >

    <ImageView android:id="@+id/image"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:layout_marginRight="10dp"
               android:background="@drawable/ic_launcher"
               />
    <TextView
         android:id="@+id/text"
              android:layout_width="wrap_content"  
              android:layout_height="wrap_content" 
              android:textColor="#FFF"
              android:text="@string/clickme"
              />
</LinearLayout>