折腾了好多天，遇到 N 多让人崩溃无语的问题，不过今天终于有些收获了，这是实验的第一版，有些混乱，下一步进行改造细分，先把代码记录在这儿吧。
网上查了很多资料，发现都千篇一律，抄来抄去，很多细节和完整实例都没看到，只有自己一点点研究了，总体感觉 android 下面要显示个图片真不容易埃
项目主要实现的功能：
异步加载图片图片内存缓存、异步磁盘文件缓存解决使用 viewHolder 后出现的图片错位问题优化列表滚动性能，仅显示可见子项中的图片无需固定图片显示高度，对高度进行缓存使列表滚动时不会因图片高度变化而闪动，使滚动体验更加流畅图片动画展示效果，新加载的图片显示透明渐变动画
没有涉及到下拉加载和刷新数据，目前还没接触到这些，而且已发现自定义 ListView 中如果有添加 顶部和底部 的拉动加载更多数据提示的 view ，将会导致 ListView 的 child 数量和 position 混乱，所以只有先简单使用 ListView 来做个效果。
核心主要是三个文件：MainActivity.java,ZAsyncImageLoader.java, DiaryListAdapter.java
下面贴代码：
MainActivity.java
package com.ai9475.meitian;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.charset.Charset;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import android.content.Intent;
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.os.Handler;
import android.os.Looper;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBar;
import android.support.v7.app.ActionBarActivity;
import android.util.JsonReader;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
import com.ai9475.meitian.adapter.DiaryListAdapter;
import com.ai9475.util.ZAsyncImageLoader;
import com.ai9475.util.ZHttpRequest;
import com.ai9475.util.ZLog;
import com.ai9475.widget.PullToRefreshListView;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.protocol.HTTP;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.json.JSONStringer;
import org.w3c.dom.Text;
public class MainActivity extends ActionBarActivity
{
private static final String TAG = "MainActivity";
private ListView mDiaryListView;
private DiaryListAdapter mDiaryListAdapter;
private ZAsyncImageLoader mAsyncImageLoader;
private Handler handler = new Handler();
private int endId = 0;
private boolean isScrolling = false;
@Override
protected void onCreate(Bundle savedInstanceState)
{
Log.d("main activity", "start");
// 执行父级初始化方法
super.onCreate(savedInstanceState);
// 让 ActionBar 浮动在 Activity 上方进行半透明遮盖
//this.supportRequestWindowFeature(Window.FEATURE_ACTION_BAR_OVERLAY);
// 解析视图数据
this.setContentView(R.layout.activity_main);
AppManager.getInstance().addActivity(this);
this.mAsyncImageLoader = new ZAsyncImageLoader();
this.mAsyncImageLoader.setIsUseDiskCache(true);
this.mAsyncImageLoader.setCacheDir(AppConfig.IMAGE_CACHE_PATH);
// 配置 ActionBar 相关
final ActionBar bar = this.getSupportActionBar();
// 标题
bar.setTitle("Bar");
// 返回按钮
//bar.setDisplayHomeAsUpEnabled(true);
// 应用徽标控制
//bar.setDisplayUseLogoEnabled(false);
// 应用图标控制
//bar.setDisplayShowHomeEnabled(true);
// 标题栏控制
//bar.setDisplayShowTitleEnabled(true);
// 设置 TABS 导航模式
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
/*
bar.getHeight();
final ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
ViewTreeObserver scvto = scrollView.getViewTreeObserver();
if (scvto != null) {
scvto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
scrollView.setPadding(
scrollView.getPaddingLeft(),
bar.getHeight(),
scrollView.getPaddingRight(),
scrollView.getPaddingBottom()
);
return true;
}
});
}*/
/*Fragment fragmentA = new FragmentTab();
Fragment fragmentB = new FragmentTab();
Fragment fragmentC = new FragmentTab();
tabA.setTabListener(new MyTabsListener(fragmentA));
tabB.setTabListener(new MyTabsListener(fragmentB));
tabC.setTabListener(new MyTabsListener(fragmentC));*/
bar.addTab(bar.newTab().setText("ATab").setTabListener(new MyTabsListener()));
bar.addTab(bar.newTab().setText("BTab").setTabListener(new MyTabsListener()));
bar.addTab(bar.newTab().setText("CTab").setTabListener(new MyTabsListener()));
/*//bar.setDisplayShowHomeEnabled(false);
//bar.setDisplayShowTitleEnabled(false);
// 顶部帧布局操作栏
final FrameLayout topActBar = (FrameLayout) findViewById(R.id.topActionBar);
// 底部帧布局操作栏
final FrameLayout bottomActBar = (FrameLayout) findViewById(R.id.bottomActionBar);
// 列表滚动视图
final ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
// 顶部操作栏绑定事件：同步设置滚动视图顶部内边距
topActBar
.getViewTreeObserver()
.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
scrollView.setPadding(
scrollView.getPaddingLeft(),
topActBar.getHeight(),
scrollView.getPaddingRight(),
scrollView.getPaddingBottom()
);
return true;
}
});
// 底部操作栏绑定事件：同步设置滚动视图底部内边距
bottomActBar
.getViewTreeObserver()
.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
scrollView.setPadding(
scrollView.getPaddingLeft(),
scrollView.getPaddingTop(),
scrollView.getPaddingRight(),
bottomActBar.getHeight()
);
return true;
}
});
*/
//AppContext context = (AppContext) getApplicationContext();
//context.test();
/*
ZAsyncImageLoader loader = new ZAsyncImageLoader();
String url1 = "http://img.ai9475.com/data/attachment/images/meitian/c5/e4/59/c5e459f00dce21480c9941eefbb88f90_200.jpg";
String url2 = "http://img.ai9475.com/data/attachment/images/meitian/f9/29/ee/f929ee1dd6af7b805744b9fb3f4f99b5_200.jpg";
loader.loadDrawable(url1, new ZAsyncImageLoader.OnImageLoadListener() {
@Override
public void onLoaded(Drawable imageDrawable, String imageUrl) {
ImageView img = (ImageView) findViewById(R.id.showPic1);
img.setImageDrawable(imageDrawable);
}
});
loader.loadDrawable(url2, new ZAsyncImageLoader.OnImageLoadListener() {
@Override
public void onLoaded(Drawable imageDrawable, String imageUrl) {
ImageView img = (ImageView) findViewById(R.id.showPic2);
img.setImageDrawable(imageDrawable);
}
});*/
// 找到日记列表视图对象
this.mDiaryListView = (ListView) findViewById(R.id.diaryListCt);
new Thread(){
@Override
public void run() {
Runnable runnable = new Runnable() {
@Override
public void run() {
loadDiaryListData();
}
};
handler.post(runnable);
}
}.start();
}
/**
* 日记列表初始化
*/
protected void initDiaryList(JSONArray diaryList)
{
Log.d("initDiaryList", "start");
// 列表单元与数据的适配器生成
this.mDiaryListAdapter = new DiaryListAdapter(this, this.mDiaryListView, this.mAsyncImageLoader, diaryList);
// 绑定列表数据单元适配器
Log.d("initDiaryList", "setAdapter");
this.mDiaryListView.setAdapter(this.mDiaryListAdapter);
Log.d("bindListViewEvents", "start");
// 绑定日记列表事件
this.bindListViewEvents();
Log.d("DiaryListAdapter", "end");
}
static int j = 0;
/**
* 绑定日记列表事件
*/
public void bindListViewEvents()
{
// 列表滚动事件
this.mDiaryListView.setOnScrollListener(new AbsListView.OnScrollListener(){
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState)
{
switch (scrollState) {
case AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:
ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_TOUCH_SCROLL");
mDiaryListAdapter.setIsSCrolling(true);
break;
case AbsListView.OnScrollListener.SCROLL_STATE_FLING:
ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_FLING");
mDiaryListAdapter.setIsSCrolling(true);
break;
case AbsListView.OnScrollListener.SCROLL_STATE_IDLE:
// 第一个可见 item 的 position
int first = mDiaryListView.getFirstVisiblePosition();
// 最后一个可见 item 的 position
int last = mDiaryListView.getLastVisiblePosition();
// 屏幕上可见 item 的总数
int onScreenCount = mDiaryListView.getChildCount();
int total = first + last;
ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_IDLE => " + (j++) +", first: "+ first +", last: "+ last +", total: "+ total +", onScreenCount:"+ onScreenCount);
mDiaryListAdapter.setIsSCrolling(false);
mDiaryListAdapter.setPositionRange(first, last);
View child;
int position;
for (int i = 0; i" + (j++) +", first: "+ first +", last: "+ last +", total:"+ total);
}
});
// 列表单元点击事件
ZLog.i(TAG, "diaryListInit : setOnItemClickListener");
this.mDiaryListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView> adapterView, View view, int i, long l) {
getSupportActionBar().setTitle("点击了: "+ i);
}
});
ZLog.i("DiaryListAdapter", "setOnRefreshListener");
// 当向下拉动刷新时触发列表更新事件
/*this.mDiaryListView.setOnRefreshListener(new PullToRefreshListView.OnRefreshListener() {
@Override
public void onRefresh() {
getSupportActionBar().setTitle("执行加载…");
loadDiaryListData();
mDiaryListView.onRefreshComplete();
}
});*/
}
public void loadDiaryListData()
{
ZLog.i(TAG, "loadDiaryListData : start");
try {
ZHttpRequest httpRequset = new ZHttpRequest(new ZHttpRequest.OnHttpRequestListener() {
@Override
public void onRequest(ZHttpRequest request) {
ZLog.i(TAG, "request data : start");
}
@Override
public void onSucceed(int statusCode, ZHttpRequest request) {
// 创建每行数据的集合
ZLog.i(TAG, "request onSucceed : start");
try {
String content = request.getInputStream();
if (content == null) {
Toast.makeText(getApplicationContext(), "数据请求失败", Toast.LENGTH_SHORT).show();
return;
}
JSONArray diaryList = new JSONArray(content);
/*if (asyncImageLoader.getMaxPosition() " + content;
} else {
content = post.post("http://192.168.1.6/test.php");
content = "POST数据：isPost" + (post.isPost() ? "yes" : "no") + " =>" + content;
}
} catch (IOException e) {
content = "IO异常：" + e.getMessage();
} catch (Exception e) {
content = "异常：" + e.getMessage();
}
textView.setText(content);
}
public void doPhoto(View view)
{
destoryBimap();
String state = Environment.getExternalStorageState();
if (state.equals(Environment.MEDIA_MOUNTED)) {
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
startActivityForResult(intent, 1);
} else {
Toast.makeText(MainActivity.this, "没有SD卡", Toast.LENGTH_LONG).show();
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
Uri uri = data.getData();
if (uri != null) {
this.photo = BitmapFactory.decodeFile(uri.getPath());
}
if (this.photo == null) {
Bundle bundle = data.getExtras();
if (bundle != null) {
this.photo = (Bitmap) bundle.get("data");
} else {
Toast.makeText(MainActivity.this, "拍照失败", Toast.LENGTH_LONG).show();
return;
}
}
FileOutputStream fileOutputStream = null;
try {
// 获取 SD 卡根目录
String saveDir = Environment.getExternalStorageDirectory() + "/meitian_photos";
// 新建目录
File dir = new File(saveDir);
if (! dir.exists()) dir.mkdir();
// 生成文件名
SimpleDateFormat t = new SimpleDateFormat("yyyyMMddssSSS");
String filename = "MT" + (t.format(new Date())) + ".jpg";
// 新建文件
File file = new File(saveDir, filename);
// 打开文件输出流
fileOutputStream = new FileOutputStream(file);
// 生成图片文件
this.photo.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream);
// 相片的完整路径
this.picPath = file.getPath();
ImageView imageView = (ImageView) findViewById(R.id.showPhoto);
imageView.setImageBitmap(this.photo);
} catch (Exception e) {
e.printStackTrace();
} finally {
if (fileOutputStream != null) {
try {
fileOutputStream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
/**
* 销毁图片文件
*
private void destoryBimap()
{
if (photo != null && ! photo.isRecycled()) {
photo.recycle();
photo = null;
}
}*/
}
其中涉及到 scroll 滚动相关的事件，我一开始在这里折腾了好久，可以去看看我这篇文章：
Android 关于 OnScrollListener 事件顺序次数的简要分析
ZAsyncImageLoader.java
package com.ai9475.util;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.Message;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.ref.SoftReference;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Date;
import java.util.HashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
/**
* 异步多线程加载图片
*
* Created by ZHOUZ on 14-2-7.
*/
public class ZAsyncImageLoader
{
private static final String TAG = "ZAsyncImageLoader";
/**
* 线程池中的线程数量
*/
private int mThreadSize = 5;
/**
* 是否使用 SD 卡缓存图片
*/
private boolean mIsUseDiskCache = false;
/**
* SD 卡上缓存的图片有效期（单位:秒）
*/
private int mExpireTime = 86400;
/**
* 图片缓存文件目录
*/
private String mCachePath = null;
/**
* 同步缓存已加载过的图片，使用软引用优化内存
*/
private HashMap> mImageCaches = new HashMap>();
/**
* 使用线程池，根据 CPU 数量来动态决定可用线程数量
*/
private ExecutorService mExecutorService = null;
/**
* 设置 SD 卡中的图片缓存有效时长（单位:秒）
*
* @param time
*/
public void setExpireTime(int time) {
this.mExpireTime = time;
}
/**
* 设置线程数量
*
* @param size
*/
public void setThreadSize(int size) {
this.mThreadSize = size;
}
/**
* 设置是否使用 SD 卡缓存图片
*
* @param isUse
*/
public void setIsUseDiskCache(Boolean isUse) {
this.mIsUseDiskCache = isUse;
}
/**
* 设置缓存目录
*
* @param path
*/
public void setCacheDir(String path) {
this.mCachePath = path;
}
/**
* 获取线程池管理器
*
* @return
*/
public ExecutorService getExecutorService() {
if (this.mExecutorService == null) {
if (this.mThreadSizesoftReference = this.mImageCaches.get(imageUrl);
if (softReference != null) {
Drawable drawable = softReference.get();
if (drawable != null) {
return drawable;
}
}
}
// 异步多线程加载图片后的数据传递处理
final Handler handler = new Handler() {
@Override
public void handleMessage(Message message) {
if (message.what == 1) {
listener.onLoaded((Drawable) message.obj, imageUrl, tag);
} else {
listener.onFailed((IOException) message.obj, imageUrl, tag);
}
}
};
// 通过线程池来控制管理图片加载
this.getExecutorService().submit(new Runnable() {
@Override
public void run() {
Message msg;
try {
Drawable drawable = loadImageFromUrl(imageUrl);
mImageCaches.put(imageUrl, new SoftReference(drawable));
msg = handler.obtainMessage(1, drawable);
} catch (IOException e) {
msg = handler.obtainMessage(0, e);
}
handler.sendMessage(msg);
}
});
return null;
}
/**
* 加载远程图片或本地图片缓存文件
*
* @param imageUrl
* @return
* @throws IOException
*/
public Drawable loadImageFromUrl(String imageUrl) throws IOException
{
// 检查 SD 卡是否可用并将图片缓存到 SD 卡上
if (mIsUseDiskCache && mCachePath != null)
{
File d = new File(mCachePath);
if (! d.exists()) {
d.mkdirs();
}
final File f = new File(mCachePath + ZHelper.md5(imageUrl));
long time = (new Date()).getTime();
long expire = time - (mExpireTime * 1000L);
// 文件存在且在有效期内则直接读取
if (f.exists() && f.lastModified() > expire) {
FileInputStream fis = new FileInputStream(f);
return Drawable.createFromStream(fis, "src");
}
// 远程加载图片后写入到 SD 卡上
InputStream i = this.getImageInputStream(imageUrl);
if (i == null) {
return null;
}
final Drawable drawable = Drawable.createFromStream(i, "src");
// 将图片异步写入到本地 SD 卡中缓存, 避免阻塞UI线程, 导致图片不能显示
new Thread(new Runnable() {
@Override
public void run() {
try {
InputStream i = ZFormat.drawable2InputStream(drawable);
DataInputStream in = new DataInputStream(i);
FileOutputStream out = new FileOutputStream(f);
byte[] buffer = new byte[1024];
int byteRead;
while ((byteRead = in.read(buffer)) != -1) {
out.write(buffer, 0, byteRead);
}
in.close();
out.close();
} catch (IOException e) {
ZLog.d("write image cache IOException", e.getMessage());
e.printStackTrace();
}
}
}).start();
return drawable;
}
// 只读取远程图片不缓存
else {
InputStream i = this.getImageInputStream(imageUrl);
return Drawable.createFromStream(i, "src");
}
}
/**
* 远程加载图片数据
*
* @param imageUrl
* @return
* @throws IOException
*/
public InputStream getImageInputStream(String imageUrl) throws IOException
{
URL m = new URL(imageUrl);
HttpURLConnection conn = (HttpURLConnection) m.openConnection();
conn.setRequestMethod("GET");
conn.setUseCaches(false);
conn.setDoInput(true);
conn.setConnectTimeout(5000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
return conn.getInputStream();
}
/**
* 加载图片的事件监听器
*/
public interface OnImageLoadListener {
/**
* 图片加载完成事件处理
*
* @param imageDrawable
* @param imageUrl
* @param tag
*/
public void onLoaded(Drawable imageDrawable, String imageUrl, String tag);
/**
* 图片加载失败的事件处理
*
* @param e
* @param imageUrl
* @param tag
*/
public void onFailed(IOException e, String imageUrl, String tag);
}
protected void finalize()
{
this.mExecutorService.shutdown();
}
}
DiaryListAdapter.java
package com.ai9475.meitian.adapter;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AlphaAnimation;
import android.widget.AbsListView;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.ai9475.meitian.R;
import com.ai9475.util.ZAsyncImageLoader;
import com.ai9475.util.ZHelper;
import com.ai9475.util.ZLog;
import com.ai9475.util.ZUI;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
/**
* Created by ZHOUZ on 14-2-8.
*/
public class DiaryListAdapter extends BaseAdapter implements AbsListView.RecyclerListener
{
private static final String TAG = "DiaryListAdapter";
private Context mContext;
private ListView mDiaryListView;
public View mConvertView;
private ZAsyncImageLoader mAsyncImageLoader;
private JSONArray mDiaryDataList = null;
private boolean mIsScrolling = false;
private int mFirstPosition = 0;
private int mLastPosition = 0;
private int mPrevFirstPosition = 0;
private int mPrevLastPosition = 0;
private HashMap mImagesHeight = new HashMap();
public DiaryListAdapter(Context context, ListView listView, ZAsyncImageLoader imageLoader, JSONArray diaryList)
{
this.mContext = context;
this.mAsyncImageLoader = imageLoader;
this.mDiaryDataList = diaryList;
this.mDiaryListView = listView;
}
public void setIsSCrolling(boolean flag)
{
this.mIsScrolling = flag;
}
/**
* 当前列表加载到的日记总数
*
* @return
*/
public int getCount() {
return this.mDiaryDataList == null ? 0 : this.mDiaryDataList.length();
}
/**
* 可见单元位置对比是否处在在上次滚动可是范围内
*
* @param position
* @return
*/
public boolean isInPrevPositionRange(int position) {
// 初始化时直接返回 false
if (this.mPrevLastPosition == 0) return false;
// 检测当前 item 的位置是否在上次滚动范围内, 是则表示该 item 正处于屏幕可见状态中无需重新加载
return (position >= this.mPrevFirstPosition && position = mFirstPosition && positionmaxHeight) {
height = maxHeight;
} else if (height
代码相关的一些类方法，以及涉及到的其他方面问题的相关博文：
android 一些数据转换方法
Android实现图片宽度100%ImageView宽度且高度按比例自动伸缩
