獲取SD卡上所有的圖片

fragment_main.xml

<LinearLayout 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="com.xwy.sd.MainActivity$PlaceholderFragment" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />
    
    <GridView 
        android:id="@+id/gridView1"
        android:layout_height="match_parent"
        android:layout_width="wrap_content"
        android:layout_marginTop="10px"
        android:horizontalSpacing="3px"
        android:verticalSpacing="3px"
        android:numColumns="4" ></GridView>

</LinearLayout>

MainActivity.java

package com.xwy.sd;

import java.io.File;
import java.util.ArrayList;
import java.util.List;

import android.support.v4.app.Fragment;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

public class MainActivity extends Activity {

	private List<String> imagePath = new ArrayList<String>();
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.fragment_main);

		String sdpath = Environment.getExternalStorageDirectory() + "/";
		getFiles(sdpath);////呼叫getFiles()方法獲取SD卡上的全部圖片
		if(imagePath.size()<1){
			return;
		}
		GridView gridView = (GridView) findViewById(R.id.gridView1);
		BaseAdapter adapter = new BaseAdapter() {
			
			public View getView(int position, View convertView, ViewGroup parent) {
				ImageView imageView; // 宣告ImageView的物件
				if(convertView == null){
					imageView = new ImageView(MainActivity.this);// 例項化ImageView的物件
					/************* 設定影象的寬度和高度 ******************/
					imageView.setAdjustViewBounds(true);
					imageView.setMaxHeight(113);
					imageView.setMaxWidth(150);
					/**************************************************/
					imageView.setPadding(5, 5, 5, 5); // 設定ImageView的內邊距
				}else{
					imageView = (ImageView) convertView;
				}
				// 為ImageView設定要顯示的圖片
				Bitmap bm = BitmapFactory.decodeFile(imagePath.get(position));
				imageView.setImageBitmap(bm);
				return imageView;
			}
			
			public long getItemId(int position) {
				// TODO Auto-generated method stub
				return position;
			}
			
			public Object getItem(int position) {
				// TODO Auto-generated method stub
				return position;
			}
			
			public int getCount() {
				// TODO Auto-generated method stub
				return imagePath.size();
			}
		};
		gridView.setAdapter(adapter); // 將介面卡與GridView關聯
	}

	//遍歷指定的路徑
	private void getFiles(String url) {
		File files = new File(url);	//建立檔案物件
		File[] file = files.listFiles();
		try {
			for(File f : file){//通過for迴圈遍歷獲取到的檔案陣列
				if(f.isDirectory()){//如果是目錄，也就是資料夾
					getFiles(f.getAbsolutePath());// 遞迴呼叫
				}else{
					if(isImageFile(f.getParent())){//如果是圖片檔案
						imagePath.add(f.getPath());	//將檔案的路徑新增到list集合中
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static String[] imageFormatSet = new String[]{"jpg","png","gif"};//合法的檔案格式
	private static boolean isImageFile(String path) {
		for(String format : imageFormatSet){
			if(path.contains(format)){//判斷是否為有合法的圖片檔案
				return true;
			}
		}
		return false;
	}

	
	
	
	
	@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;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}

	/**
	 * A placeholder fragment containing a simple view.
	 */
	public static class PlaceholderFragment extends Fragment {

		public PlaceholderFragment() {
		}

		@Override
		public View onCreateView(LayoutInflater inflater, ViewGroup container,
				Bundle savedInstanceState) {
			View rootView = inflater.inflate(R.layout.fragment_main, container,
					false);
			return rootView;
		}
	}

}