LayoutInflater 的使用 ----动态改变布局；

LayoutInflater的作用类似于findViewById(),不同点是LayoutInflater是用来找layout下xml布局文件，并且实例化。

通过LayoutInflater获取布局文件根元素，并将新的UI元素添加进去，再设置Adapter和setContentView(),就可以动态的改变布局；

看一例子：

要实现的效果：屏幕中六行六列图片，只显示下三角的图片，点击任一个图片，变为上三角；

1.Activity；

package zzu.wyb.gridview;

import android.app.Activity;
import android.os.Bundle;
import android.text.Layout;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class GridViewActivity extends Activity {
	private GridView gv_sample; // GridView；
	private int[] imgids = { R.drawable.sample_0, R.drawable.sample_1,
			R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4,
			R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7,
			R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2,
			R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5,
			R.drawable.sample_6, R.drawable.sample_7, R.drawable.sample_0,
			R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3,
			R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6,
			R.drawable.sample_7, R.drawable.sample_0, R.drawable.sample_1,
			R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4,
			R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7,
			R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2,
			R.drawable.sample_3 };

	private boolean layoutIndicator = false; // 控制图片显示位置的指示器；
	private LayoutInflater inflater;	//渲染器；
	private LinearLayout rootLayout;//根布局；

	

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		/*		GridView gridv = new GridView(this);
		this.setContentView(gridv);
		gridv.setNumColumns(6);
		gridv.setAdapter( new GridViewAdapter(this, imgids, true));
		gridv.setOnItemClickListener(gridViewListener);
		
*/
		setContentView(R.layout.main_gridview);
		gv_sample = (GridView) findViewById(R.id.gv_sample);
		gv_sample.setNumColumns(6);
		setGridViewAdapter();
		gv_sample.setOnItemClickListener(gridViewListener);

	}

	/**
	 * 设置监听器,设置适配器！
	 */
	private void setGridViewAdapter() {

		GridViewAdapter adapter = new GridViewAdapter(this, imgids, layoutIndicator);// 新监听器

		gv_sample.setAdapter(adapter);

	}

	GridView.OnItemClickListener gridViewListener = new GridView.OnItemClickListener() {

		@Override
		public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
				long arg3) {

			// 改变指示器；
			layoutIndicator = !layoutIndicator;
			System.out.println("test,itemSelectedListener.");
		
			// 改变布局；
			changeView(imgids, layoutIndicator);
		}

	};

	/**
	 * 控制图片显示；
	 * 
	 * @param
	 */
	private void changeView(int[] imgs, boolean viewIndicator) {
		if (true) {
			// 获取根布局；
			inflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
			rootLayout = (LinearLayout) inflater.inflate(
					R.layout.main_gridview, null);
			
			// 移除布局文件下的所有子元素；
			rootLayout.removeView(gv_sample);
			// this.gv_sample.setVisibility(GridView.GONE);
		
			//新一个GridView，上下文环境为当前；
			gv_sample = new GridView(this);
			gv_sample.setNumColumns(6);//设置显示为六行；
			if (rootLayout != null) {
				System.out.println("convertView is not  null!!!");
				gv_sample.setAdapter(new GridViewAdapter(this, imgs, viewIndicator));
				rootLayout.addView(gv_sample);//将新的GridView添加到布局文件中；
				this.setContentView(rootLayout);//显示更改过的布局；
				gv_sample.setOnItemClickListener(gridViewListener);
				
			} else {
				System.out.println("convertView is null!!!");
			}

		}
		

	}

	

	

}

2.Adapter

package zzu.wyb.gridview;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

/**
 * 配置Adapter
 * 
 * @author BurgenWang
 * 
 */
public class GridViewAdapter extends BaseAdapter {
	private Context context;
	private int[] imgs;
	private boolean viewIndicator;

	/**
	 * 
	 * @param context GridView所要显示的上下文环境；
	 * @param imgids 数据源，图片id数组；
	 * @param viewIndicator 指示器，boolean
	 */ 
	public GridViewAdapter(Context context, int[] imgids,boolean viewIndicator) {
		this.context = context;
		this.imgs = imgids;
		this.viewIndicator = viewIndicator;
	}

	
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return imgs.length;
	}

	@Override
	/**
	 * 通过元素在GridView中的位置获得该元素的id；
	 */
	public Object getItem(int position) {
		
		return imgs[position];
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return imgs[position];
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		ImageView img = null;
		
		if(convertView == null ){
			
			img = new ImageView(this.context);
			convertView = img;
			}else{	//convertView保存上次的View；
				img = (ImageView) convertView;
			}
		
		img.setScaleType(img.getScaleType().CENTER_CROP);//设置图片显示；从图片中心向外缩放；
		img.setLayoutParams(new GridView.LayoutParams(70,70));//每个图片所占空间大小
		img.setPadding(8, 8, 8, 8);	//图片间左上右下间距；
		img.setImageResource(this.imgs[position]);//图片资源
		int x = position%6;//图片在GridView中所在行
		int y = position/6;//列；
		if(this.viewIndicator){//若为true，则显示右上半部分；
			if(x>y  ){
				img.setVisibility(ImageView.INVISIBLE);
			}
		}else{//否则显示左下半部分；
			if(x<y ){
				img.setVisibility(ImageView.INVISIBLE);
			}
		}
		
		
		return img;
	}
	
	

}

3.layout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="vertical" >

    
    <GridView
        android:id="@+id/gv_sample"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:numColumns="6"
       
        android:gravity="center">
    </GridView>

</LinearLayout>