最近闲来无聊，决定写一个小小的android ImageView应用学习下。在写的过程中，出现了一些小问题，希望能够得到大家的帮助。这个应用大致的功能是，读取sdcard上的图片，然后使用gallery和ImageSwitcher显示出来。我刚开始完成了基本功能，现在想给应用加一个删除图片功能的时候，遇到了问题，现来看看的代码吧
- Java code
package com.alan.android;import java.io.File;import java.util.ArrayList;import java.util.HashMap;import android.app.Activity;import android.app.AlertDialog;import android.app.AlertDialog.Builder;import android.content.Context;import android.content.DialogInterface;import android.content.DialogInterface.OnClickListener;import android.content.res.TypedArray;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.drawable.Drawable;import android.net.Uri;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.View;import android.view.ViewGroup;import android.view.animation.AnimationUtils;import android.widget.Adapter;import android.widget.AdapterView;import android.widget.AdapterView.OnItemLongClickListener;import android.widget.AdapterView.OnItemSelectedListener;import android.widget.BaseAdapter;import android.widget.Gallery;import android.widget.Gallery.LayoutParams;import android.widget.ImageSwitcher;import android.widget.ImageView;import android.widget.ViewSwitcher.ViewFactory;public class ImageViewerActivity extends Activity implements ViewFactory, OnItemSelectedListener { private ImageSwitcher mImgSwitcher; private Gallery mGallery; private ImageAdapter adapter; private ArrayList<String> mImgPathList; //private String[] mImgPath; //sdcard Path private String mSdcardPath; //cache for the Bitmap res private HashMap<Integer, Bitmap> imgCache = new HashMap<Integer, Bitmap>(); private static final String LOG_TAG="ImageViewer"; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); mImgPathList = new ArrayList<String>(); mSdcardPath = Environment.getExternalStorageDirectory().toString(); saveImagePathToList(mImgPathList, mSdcardPath); ////////////////////////////////////////////// //print all the imgPath and see whether it's right //for(int i = 0 ; i < mImgPathList.size() ; i++){ // Log.e("ImagePath",mImgPathList.get(i)); //} ////////////////////////////////////////////// //set ImageSwitcher mImgSwitcher = (ImageSwitcher)findViewById(R.id.imgswitcher); mImgSwitcher.setFactory(this); mImgSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_in)); mImgSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,android.R.anim.fade_out)); //set Gallery mGallery = (Gallery)findViewById(R.id.imgallery); adapter = new ImageAdapter(this, mImgPathList); mGallery.setAdapter(adapter); mGallery.setOnItemSelectedListener(this); mGallery.setOnItemLongClickListener(new OnItemLongClickListener(){ public boolean onItemLongClick(AdapterView<?> arg0, View arg1, final int position, long id) { // TODO Auto-generated method stub AlertDialog.Builder build = new Builder(ImageViewerActivity.this); build.setTitle("你想执行下列哪个操作？") .setPositiveButton("删除选中文件", new OnClickListener(){ public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub onDelBtnDown(position); } }) .setNegativeButton("重命名该图片", new OnClickListener(){ public void onClick(DialogInterface dialog, int which) { // TODO Auto-generated method stub onRenameBtnDown(); } }); build.create().show(); return false; } }); } //button down callbacks private void onRenameBtnDown() { // TODO Auto-generated method stub } private void onDelBtnDown(int pos) { // TODO Auto-generated method stub Log.d(LOG_TAG,"the pos will deleted is " + pos); File current = new File(mImgPathList.get(pos)); current.delete(); mImgPathList.clear(); saveImagePathToList(mImgPathList, mSdcardPath);// for(int i = 0 ; i < mImgPathList.size() ; i++){// Log.e(LOG_TAG, mImgPathList.get(i));// } adapter = new ImageAdapter(this, mImgPathList); mGallery.setAdapter(adapter); mGallery.requestLayout(); RefreshView(); } private void RefreshView(){ for(int i = 0 ; i < mImgPathList.size() ; i++){ Log.e("ImagePath",mImgPathList.get(i)); } } //get image path recursively private void saveImagePathToList(ArrayList<String> list, String filePath) { // TODO Auto-generated method stub File mFile = new File(filePath); File[] listFile = mFile.listFiles(); if(listFile != null){ for(int i = 0 ; i < listFile.length ; i++){ File file = listFile[i]; if(isAnImageFile(file.getAbsolutePath())){ list.add(file.getAbsolutePath()); }else if(file.isDirectory() && !file.getAbsolutePath().contains("DCIM")){ //get image path recursively this.saveImagePathToList(mImgPathList, file.getAbsolutePath()); } continue; } } } //check the fils's suffix and tell whether it's an image private boolean isAnImageFile(String fileName){ String fileNameLowerCase = fileName.toLowerCase(); if(fileNameLowerCase.endsWith("jpg") || fileNameLowerCase.endsWith("gif") || fileNameLowerCase.endsWith("bmp") || fileNameLowerCase.endsWith("jpeg") || fileNameLowerCase.endsWith("png")){ return true; } return false; } public View makeView() { // TODO Auto-generated method stub ImageView iv = new ImageView(this); //iv.setBackgroundColor(0xFF000000); iv.setScaleType(ImageView.ScaleType.FIT_CENTER); iv.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.MATCH_PARENT,LayoutParams.MATCH_PARENT)); return iv; } public class ImageAdapter extends BaseAdapter{ private Context mContext; private int mGalleryBackground; private ArrayList<String> mArrayList; public ImageAdapter(Context c, ArrayList<String> list){ mContext = c; mArrayList = list; //use attrs.xml to specify the Gallery's attributes TypedArray mTypeArray = obtainStyledAttributes(R.styleable.Gallery); mGalleryBackground = mTypeArray.getResourceId(R.styleable.Gallery_android_galleryItemBackground, 0); mTypeArray.recycle(); } public int getCount() { // TODO Auto-generated method stub return mArrayList.size(); } public Object getItem(int position) { // TODO Auto-generated method stub //just return position, will use it later return position; } public long getItemId(int position) { // TODO Auto-generated method stub //just return position will use it later return position; } public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub //new a ImageView for the image displaying Log.d(LOG_TAG,"getView--->"); ImageView imgView = new ImageView(mContext); //check the cache first Bitmap current = imgCache.get(position); if(current == null){ current = BitmapFactory.decodeFile(mArrayList.get(position)); imgCache.put(position, current); } imgView.setImageBitmap(current); imgView.setScaleType(ImageView.ScaleType.FIT_XY); imgView.setLayoutParams(new Gallery.LayoutParams(136, 88)); imgView.setBackgroundResource(mGalleryBackground); return imgView; } } public void onItemSelected(AdapterView<?> arg0, View arg1, int pos, long id) { // TODO Auto-generated method stub String imgPath = mImgPathList.get(pos); Log.e(LOG_TAG,"Selected Img Path is " + imgPath); Drawable drawadle = Drawable.createFromPath(imgPath); mImgSwitcher.setImageDrawable(drawadle); //release Bitmap resource releaseBitmap(); } //just keep the bitmap in Visible range, release the rest private void releaseBitmap() { // TODO Auto-generated method stub int begin = mGallery.getFirstVisiblePosition(); int end = mGallery.getLastVisiblePosition(); for(int i = 0 ; i < begin ; i++){ Bitmap delBitmap = imgCache.get(i); if(delBitmap != null){ imgCache.remove(i); delBitmap.recycle(); } } for(int i = end + 1 ; i < imgCache.size() ; i++){ Bitmap delBitmap = imgCache.get(i); if(delBitmap != null){ imgCache.remove(i); delBitmap.recycle(); } } }}