&&&&android 加载json数据到listview
android 加载json数据到listview
通过读取网络的json数据，并显示到listview中，并具有加载更多的功能
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+ ListView+Json解析、简单的上滑下拉刷新的实现
+ ListView+Json解析、简单的上滑下拉刷新的实现
+ ListView+Json解析、简单的上滑下拉刷新的实现。。。。
若举报审核通过，可奖励20下载分
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+ ListView+Json解析、简单的上滑下拉刷新的实现
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+ ListView+Json解析、简单的上滑下拉刷新的实现
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你的VIP会员已过期VIP会员享免积分 . 专属通道极速下载，请继续开通VIP会员iOS怎样通过这样的JSON数据，实现上下拉刷新加载更多_问答_ThinkSAAS
iOS怎样通过这样的JSON数据，实现上下拉刷新加载更多
iOS怎样通过这样的JSON数据，实现上下拉刷新加载更多
"count": 87,
"next":"",
"posts": [
"author":"",
"body":"u66f4u597dua73u9a73u4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0du4e0d",
"body_html": null,
"body_title": null,
"comment_count": 0,
"comments":"",
"timestamp":"Wed, 24 Jun :03 GMT",
"author":"",
"body":"u770bu770bu770bu770bu61u60u60u",
"body_html": null,
"body_title": null,
"comment_count": 0,
"comments":"",
"timestamp":"Wed, 24 Jun :31 GMT",
"author":"",
"body":"uuuuuuuuuuuuuuuuuuuu6de1u6de1uu6de1uu6de1uu6de1uu6de1uu6de1uu6de1u7684",
"body_html": null,
"body_title": null,
"comment_count": 0,
"comments":"",
"timestamp":"Wed, 24 Jun :44 GMT",
"prev": null
请问怎样通过这样的JSON数据，实现下拉刷新加载更多，是要判断id吗？还是创建时间？或者输出怎样的JSON数据更方便一些？
next字段可以不需要，客户端可以通过count字段计算出下一次请求的页码。
count字段只需要在获取第一页数据时返回。
下拉刷新：清空本地所有数据，加载第一页。
上拉加载：使用当前页码加载数据。
下拉刷新和上拉加载加载网络数据成功后的共同逻辑：加载成功后通过count和获取到的数据总条数对比，如果还有数据，那么页码变量要加一。
下拉刷新上拉加载有一个很好用的库推荐
添加你想要问的问题
PHP开发框架
开发工具/编程工具
服务器环境
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ThinkSAAS将为商业授权用户提供二次开发指导和技术支持
让ThinkSAAS更好，把建议拿来。
开发客服微信随便扯扯1，我比较喜欢把判断写成 常量在前，变量在后的形式，主要是由于这样可以规避粗心引起的错误。
例如 &0 == mLength ,可以规避不小心写成mLength = 0;因为书写成 0= mLength会报错，而mLength = 0 不会报错。
若引起阅读不便，请包涵。
今天我们计划要实现一个装满数据的ListView，并且在顶部下拉可以刷新，下滑到底部可以加载更多。分析需求，第一件事就是要将ListView装满数据，那么这个数据从哪里来？从网络来，所以第一件事就是将网络数据下载下来。因此先添加权限：
&uses-permission android:name=&android.permission.INTERNET&/&
&!-- 硬盘缓存--&
&!-- 在SDCard中创建与删除文件权限 --&
&uses-permission android:name=&android.permission.MOUNT_UNMOUNT_FILESYSTEMS& /&
&!-- 往SDCard写入数据权限 --&
&uses-permission android:name=&android.permission.WRITE_EXTERNAL_STORAGE& /&
&!-- 从SDCard读取数据权限 --&
&uses-permission android:name=&android.permission.READ_EXTERNAL_STORAGE& /&
把后面三个也一起添加了吧，因为本例最终的效果要实现双缓存，所以对SD的读写权限也是必须的。
然后进入正题：加载网络数据：
package com.example.asynctaskdemo;
import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;
import com.example.asynctaskdemo.NewsAdapter.IRefereshListener;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity {
private final static String TAG = &zxt/MainActivity&;
private final String Url = &/api/teacher?type=4&num=30&;
List&NewsBean& mNewsDatas =
private RefreshListView mListView ;
private TextView mNoDatas;
//下拉数据刷新 改写数组为集合
//public static String[]
public static List&String& urls;
//下拉数据刷新
private NewsAdapter mNewsAdapter;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListView = (RefreshListView) findViewById(R.id.listView1);
(TextView) findViewById(R.id.tv_nodatas);
new NewTask().execute(Url);
//下拉刷新数据
/* public interface IRefreshCompleteListener{
public void onRefreshComplete();
private IRefreshCompleteListener mRefreshC
public void IRefreshCompleteListener(IRefreshCompleteListener listener){
mRefreshComplete =
public void refreshData(RefreshListView listview){
//获取最新数据
setReflashData();
//?????????
//mRefreshComplete.onRefreshComplete();
//下拉刷新
private int newDataslength ;
private void setReflashData() {
new DownPullTask().execute(Url);
//执行更新 start
/*NewsBean bean = new NewsBean();
bean.NewsNo = &31&;
bean.NewsName = &new Name&;
bean.NewsDescription = &new Des&;
bean.NewsPicResUrl = Math.random()&0.5? &/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png& :
&http://img.my.csdn.net/uploads//_6518.jpg&;*/
//执行更新 end
private void showList(List&NewsBean& apk_list) {
//NewsAdapter adapter = (NewsAdapter) mListView.getAdapter();
/*if (adapter == null) {
listview = (ReFlashListView) findViewById(R.id.listview);
listview.setInterface(this);
adapter = new MyAdapter(this, apk_list);
listview.setAdapter(adapter);
} else {*/
if(mNewsAdapter!=null)
mNewsAdapter.onDateChange(apk_list);
private class DownPullTask extends AsyncTask&String,Void,List&NewsBean&&{
protected List&NewsBean& doInBackground(String... params) {
Log.i(TAG,&NewTask:doInBackground&);
return getDataByUrl(params[0]);
protected void onPostExecute(List&NewsBean& newsBeens) {
super.onPostExecute(newsBeens);
//fix bug if first nodata
//更新了几条数据
if(null!=newsBeens){
newDataslength = newsBeens.size();
if(null==mNewsDatas ){
mNewsDatas = new ArrayList&NewsBean&();
mNewsDatas.addAll(0,newsBeens);
showList(mNewsDatas);
//??listview ??????????
newDataslength = 0;
mNewsAdapter.refreshComplete(newDataslength);
setHintVisibility(newsBeens);
Log.i(TAG,&NewTask:onPostExecute:&+newDataslength);
Toast.makeText(MainActivity.this,&成功更新&+newDataslength+&条新闻&,Toast.LENGTH_SHORT).show();
//下拉刷新 end
class NewTask extends AsyncTask&String, Void, List&NewsBean&& {
protected List&NewsBean& doInBackground(String... params) {
return getDataByUrl(params[0]);
protected void onPostExecute(List&NewsBean& result) {
super.onPostExecute(result);
//下拉刷新
mNewsAdapter= new NewsAdapter(MainActivity.this, result,mListView);
//下拉刷新
mListView.setAdapter(mNewsAdapter);
mListView.setOnScrollListener(mNewsAdapter);
// 处理下拉刷新
mListView.setOnTouchListener(mNewsAdapter);
mNewsDatas = result;
// 处理下拉刷新
//刷新回调
mNewsAdapter.setIRefereshListener(new IRefereshListener() {
public void onRefresh() {
mListView.postDelayed(new Runnable() {
public void run() {
refreshData(mListView);
//刷新回调
setHintVisibility(result);
//加载更多begin
mNewsAdapter.setIOnScrollBottomListener(new NewsAdapter.IOnScrollBottomListener() {
public void onScrollBottom() {
mListView.postDelayed(new Runnable() {
public void run() {
//加载数据
loadMoreData();
mNewsAdapter.bottomDataLoadComplete();
//加载更多end
//加载更多begin
private int index =100;
private void loadMoreData(){
NewsBean bean = new NewsBean();
bean.NewsNo = &&+index++;
bean.NewsPicResUrl = &/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png&;
/*List&NewsBean& datas = mNewsAdapter.getDatas();
datas.add(-1,bean);*/
mNewsAdapter.setData(-1,bean);
mNewsAdapter.notifyDataSetChanged();
//加载更多end
private void setHintVisibility(List&NewsBean& result) {
mNoDatas.setVisibility(result==null? View.VISIBLE:View.GONE);
public List&NewsBean& getDataByUrl(String url) {
List&NewsBean& datas =
String jsonString = readStream(new URL(url).openStream());
datas = parseJson(jsonString);
//Log.i(&zxt&, &jsonString:&+jsonString);
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
return datas;
private List&NewsBean& parseJson(String jsonString) {
JSONObject jsonObject = new JSONObject(jsonString);
JSONArray jsonArray = jsonObject.getJSONArray(&data&);
JSONObject data =
List&NewsBean& datas =
new ArrayList&NewsBean&();
NewsBean bean =
//处理下拉刷新加入
if(null==urls){
urls = new ArrayList&String&();
List&String& tempUrls = new ArrayList&String&();
//处理下拉刷新加入
for (int i = 0; i & jsonArray.length(); i++) {
data = (JSONObject) jsonArray.get(i);
bean = new NewsBean();
bean.NewsPicResUrl = data.getString(&picSmall&);
//处理下拉刷新加入
tempUrls.add(bean.NewsPicResUrl);
//处理下拉刷新加入
bean.NewsName = data.getString(&name&);
bean.NewsDescription = data.getString(&description&);
bean.NewsNo = data.getString(&id&);
//加载大图加入
bean.NewsPicBigResUrl = data.getString(&picBig&);
//加载大图加入
datas.add(bean);
//处理下拉刷新加入
将新的url 加入到最上方
urls.addAll(0,tempUrls);
//处理下拉刷新加入
return datas;
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
private String readStream(InputStream is) {
StringBuilder jsonString = new StringBuilder();
String line = &&;
InputStreamReader isr = new InputStreamReader(is, &utf-8&);
BufferedReader br = new BufferedReader(isr);
if (null != (line = br.readLine())) {
jsonString.append(line);
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return jsonString.toString();
package com.example.asynctaskdemo;
import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ValueAnimator;
import android.animation.ValueAnimator.AnimatorUpdateListener;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import java.util.List;
public class NewsAdapter extends BaseAdapter implements OnScrollListener,
OnTouchListener {
private static final String TAG = &zxt/NewsAdapter&;
private volatile List&NewsBean& mDatas;
private LayoutInflater mInflater;
private RefreshListView mListView;
private Context mContext;
// 网络图片加载
public List&NewsBean& getDatas() {
return mDatas;
public void setDatas(List&NewsBean& mDatas) {
this.mDatas = mDatas;
public void setData(int pos, NewsBean bean) {
if (-1 != pos) {
mDatas.add(pos, bean);
MainActivity.urls.add(pos, bean.NewsPicResUrl);
mDatas.add(bean);
MainActivity.urls.add(bean.NewsPicResUrl);
private ImageLoader mImageLoader;
public NewsAdapter(Context context, List&NewsBean& mDatas, RefreshListView listView) {
mContext = context;
this.mDatas = mDatas;
this.mInflater = LayoutInflater.from(context);
//抽象成单例后改写 begin
//mImageLoader = new ImageLoader(listView);
mImageLoader = ImageLoader.getInstance(context);
mImageLoader.setmListView(listView);
//抽象成单例后改写 end
mListView = listView;
initHeaderView();
initFooterView();
private void initFooterView() {
mFooterView = mListView.getFooterView();
//下拉刷新数据
public void onDateChange(List&NewsBean& mDatas) {
this.mDatas = mDatas;
this.notifyDataSetChanged();
//下拉刷新数据
private void initHeaderView() {
headerView = mListView.findViewById(R.id.headerview);
// 获取View高度
headerHeight = mListView.getHeaderHeight();
mTipView = (TextView) headerView.findViewById(R.id.tip);
mTimeView = (TextView) headerView.findViewById(R.id.lastupdate_time);
mArrowView = (ImageView) headerView.findViewById(R.id.arrow);
mBar = (ProgressBar) headerView.findViewById(R.id.progress);
public int getCount() {
if (mDatas != null)
return mDatas.size();
public Object getItem(int position) {
// TODO Auto-generated method stub
return mDatas.get(position);
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder =
if (convertView == null) {
//Log.i(TAG, &getView-&缓存为空:& + position);
holder = new ViewHolder();
convertView = mInflater.inflate(R.layout.item, parent, false);
holder.pic = (ImageView) convertView.findViewById(R.id.iv_pic);
holder.no = (TextView) convertView.findViewById(R.id.tv_no);
holder.name = (TextView) convertView.findViewById(R.id.tv_name);
holder.description = (TextView) convertView
.findViewById(R.id.tv_description);
convertView.setTag(holder);
//Log.i(TAG, &getView-&缓存过:& + position);
holder = (ViewHolder) convertView.getTag();
NewsBean bean = mDatas.get(position);
// 加载网络图片
holder.pic.setTag(bean.NewsPicResUrl);
// mImageLoader.getImageByAsyncTask(holder.pic, bean.NewsPicResUrl);
holder.pic.setImageResource(R.drawable.ic_launcher);
// 滑动优化 如果有缓存，则加载 否则不加载
final Bitmap pBitmap = mImageLoader.setDefaultBitmap(holder.pic, bean.NewsPicResUrl);
// /滑动优化
holder.name.setText(bean.NewsName);
holder.description.setText(bean.NewsDescription);
holder.no.setText(bean.NewsNo);
//添加事件点击
final String urlBig = bean.NewsPicBigResUrl;
final String urlSmall = bean.NewsPicResUrl;
holder.pic.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
Toast.makeText(v.getContext(), &bean.NewsNo:& + urlBig, Toast.LENGTH_SHORT).show();
Intent intent = new Intent(mContext, BigImageActivity.class);
intent.putExtra(&urlBig&, urlBig);
intent.putExtra(&urlSmall&, urlSmall);
mContext.startActivity(intent);
return convertView;
class ViewHolder {
public ImageView pic;
public TextView name;
public TextView description;
public TextView no;
// 滚动时的优化 begin
private int mStart, mEnd;
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (scrollState == SCROLL_STATE_IDLE) {
Log.i(TAG, &scrollState:& + mStart + &-& + mEnd);
loadImages();
Log.i(TAG, &scrollState cancel:&);
mImageLoader.cancelAllTasks();
private void loadImages() {
if (null != mDatas && mDatas.size() & 0) {
//修复bug 滑动时边缘不加载 begin
int start = mStart != 0 ? mStart - 1 : 0;
int end = mEnd != mDatas.size() ? mEnd + 1 : mEnd;
//修复bug 滑动时边缘不加载 end
mImageLoader.loadImages(start, end);
private boolean isInit =
//加载更多 begin
private boolean isLoading =
private View mFooterView;
public interface IOnScrollBottomListener {
void onScrollBottom();
private IOnScrollBottomListener mIOnScrollBottomListener;
public void setIOnScrollBottomListener(IOnScrollBottomListener onScrollBottomListener) {
mIOnScrollBottomListener = onScrollBottomListener;
public void bottomDataLoadComplete() {
//隐藏view 加载数据 改变flag
mFooterView.setVisibility(View.GONE);
isLoading =
//加载更多 end
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
Log.i(TAG, &onScroll():totalItemCount& + totalItemCount + &
,isLoading:& + isLoading + &,
firstVisibleItem:&
+ firstVisibleItem + &
,visibleItemCount:& + visibleItemCount + &, totalItemCount:& + totalItemCount);
mStart = firstVisibleItem;
//其实现在的listview看不到那么多 应该-1 否则最后会空指针
(因为我们add了一个headerview进去)
add 了 footview 所以再-1
mEnd = mStart + visibleItemCount - 1 - 1;
if (visibleItemCount != 0 && isInit) {
loadImages();
//处理滑动加载更多: 2 != totalItemCount 防止没有数据一直在加载更多
if (2 != totalItemCount && firstVisibleItem + visibleItemCount == totalItemCount && !isLoading) {
isLoading =
mFooterView.setVisibility(View.VISIBLE);
//执行加载更多操作
if (null != mIOnScrollBottomListener) {
mIOnScrollBottomListener.onScrollBottom();
// 滚动时的优化 end
// 处理下拉刷新
private int lastY;
private View headerView;
private TextView mTipView;
private TextView mTimeView;
private ImageView mArrowView;
private ProgressBar mBar;
private int headerHeight;
private int gap;
public interface IRefereshListener {
public void onRefresh();
private IRefereshListener mRefereshListener;
public void setIRefereshListener(IRefereshListener listener) {
this.mRefereshListener = listener;
//监听执行完毕 继续滚动
public void refreshComplete(int length) {
Log.i(TAG, &refreshComplete()&);
//其实这里的mStarat =0的
mImageLoader.loadImages(mStart, mStart + length);
rollToInit(1);
public boolean onTouch(View v, MotionEvent event) {
if (mStart == 0 && isMoveEnable) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
lastY = (int) event.getY();
//初始化 几个view的状态显示
mTipView.setText(&下拉可以刷新&);
mArrowView.setVisibility(View.VISIBLE);
mBar.setVisibility(View.GONE);
//初始化 几个view的状态显示
case MotionEvent.ACTION_MOVE:
gap = (int) (event.getY() - lastY);
Log.i(TAG, & ACTION_MOVE gap:& + gap);
//移动View
setPaddingTop(-headerHeight + gap);
//下拉可以刷新（超过宽度）-》松开可以刷新-》
if (gap & headerHeight) {
mTipView.setText(&松开可以刷新&);
//下拉可以刷新（超过宽度）-》松开可以刷新-》
case MotionEvent.ACTION_UP:
//松开-》滑动到View宽度-》
if (gap & headerHeight) {
rollToInit(0);
//正在刷新-》
mTipView.setText(&正在刷新&);
mArrowView.setVisibility(View.GONE);
mBar.setVisibility(View.VISIBLE);
//执行刷新操作
if (mRefereshListener != null) {
mRefereshListener.onRefresh();
//执行刷新操作
//松开-》滑动到View宽度-》
//恢复初始。
rollToInit(1);
Log.i(TAG, &lastY:& + lastY + &headerHeight:& + headerHeight);
private boolean isMoveEnable =
private void rollToInit(int endTop) {
//回去的动画：//使用ObjectAnimator 不好实现， 打算用ValueAnimator
/*ObjectAnimator animator = ObjectAnimator.ofFloat(mListView, &Y&,-(headerView.getPaddingTop()+headerHeight));
animator.setDuration(500).start();*/
isMoveEnable =
int top = headerView.getPaddingTop();
//解决 拖动不超过headerheight 不会滑动回去的bug
int end = top & 0 ? -(top + headerHeight) : -(top + headerHeight + headerHeight);
Log.i(TAG, &rollToInit:& + endTop + &
,top:& + top + &, -(top+headerHeight)
& + (-(top + headerHeight)));
ValueAnimator animator = ValueAnimator.ofInt(top, endTop == 1 ? end : endTop);
animator.addUpdateListener(new AnimatorUpdateListener() {
public void onAnimationUpdate(ValueAnimator animation) {
Integer paddingTop = (Integer) animation.getAnimatedValue();
setPaddingTop(paddingTop);
//添加动画完成监听器
animator.addListener(new AnimatorListenerAdapter() {
public void onAnimationEnd(Animator animation) {
super.onAnimationEnd(animation);
isMoveEnable =
//添加动画完成监听器
animator.setDuration(500).start();
private void setPaddingTop(int top) {
if (null != headerView) {
headerView.setPadding(headerView.getPaddingLeft(), top, headerView.getPaddingRight(), headerView.getPaddingBottom());
package com.example.asynctaskdemo;
public class NewsBean {
public String NewsPicResUrl;
public String NewsPicBigResUrl;
public String NewsName;
public String NewsDescription;
public String NewsNo;
package com.example.asynctaskdemo;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class RefreshListView extends android.widget.ListView {
private final static String TAG =&zxt/refreshListView&;
private View headerView ;
private View footerView;
public View getFooterView() {
return footerView;
/*public void bottomDataLoadComplete(){
//隐藏view 加载数据 改变flag
footerView.setVisibility(View.GONE);
private int headerHeight;
public int getHeaderHeight() {
return headerHeight;
public RefreshListView(Context context) {
this(context, null);
public RefreshListView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
public RefreshListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
initView(context);
private void initView(Context context) {
headerView = LayoutInflater.from(context).inflate(R.layout.header,null);
this.addHeaderView(headerView);
// 测量View
headerView.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
// 获取View高度
headerHeight = headerView.getMeasuredHeight();
Log.d(TAG, &headerHeight:&+headerHeight);
//设置默认隐藏
setPaddingTop(-headerHeight);
//上啦刷新
View footerView = LayoutInflater.from(context).inflate(R.layout.footer_layout,this,false);
this.addFooterView(footerView);
this.footerView = footerView.findViewById(R.id.load_layout);
this.footerView.setVisibility(View.GONE);
private void setPaddingTop(int top){
if(null!=headerView){
headerView.setPadding(headerView.getPaddingLeft(), top, headerView.getPaddingRight(), headerView.getPaddingBottom());
package com.example.asynctaskdemo;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.support.annotation.Nullable;
import android.support.v4.util.LruCache;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.ProgressBar;
import com..mcxtzhang.utils.FileUtils;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;
import libcore.io.DiskLruCache;
public class ImageLoader {
private static final String TAG = &zxt/ImageLoader&;
//抽象成单例 begin
private static class ImageLoaderHolder {
private static final ImageLoader mImageLoader = new ImageLoader();
private static Context mContext;
public static ImageLoader getInstance(Context context){
mContext = context.getApplicationContext();
return ImageLoaderHolder.mImageLoader;
private ImageLoader() {
Log.i(&TAG&,&ImageLoader&);
int maxMemory = (int) Runtime.getRuntime().maxMemory();
mCache = new LruCache&String, Bitmap&(maxMemory / 20) {
protected int sizeOf(String key, Bitmap value) {
return value.getByteCount();
//硬盘缓存 begin
//初始化工作
File cacheDir = FileUtils.getFileCache(mContext, &disk_caches&);
if (!cacheDir.exists()) {
cacheDir.mkdirs();
mDiskCache = DiskLruCache.open(cacheDir, 1, 1, 10 * 1024 * 1024);
} catch (IOException e) {
e.printStackTrace();
//硬盘缓存 end
mSets = new HashSet&NewsImageAsyncTask&();
//抽象成单例 end
//图片缓存 start
private LruCache&String,Bitmap& mCache;
//硬盘缓存
private DiskLruCache mDiskCache;
public Bitmap getBitmapFromCache(String url){
Log.i(TAG, &getBitmapFromCache&);
return mCache.get(url);
public void putBitmapToCache(String url,Bitmap bitmap){
Log.i(TAG, &putBitmapToCache&);
if(null == getBitmapFromCache(url)){
mCache.put(url, bitmap);
//图片缓存 end
public void getImageByAsyncTask(ImageView imageView,String url){
//图片缓存 start
Bitmap bitmap = getBitmapFromCache(url);
if(null == bitmap)
new NewsImageAsyncTask(/*imageView,*/url).execute();
imageView.setImageBitmap(bitmap);
//图片缓存 end
//每次加载一张图片
private class NewsImageAsyncTask extends AsyncTask&Void,Void,Bitmap&{
//private ImageView mImageV
private String mUrl;
public NewsImageAsyncTask(/*ImageView mImageView,*/String url) {
//this.mImageView = mImageV
mUrl = url;
protected Bitmap doInBackground(Void... params) {
//硬盘缓存
// 用了二级缓存 所以要改写获取图片的流程：
/*Bitmap result = getBitmapByUrl(mUrl);
Log.i(TAG, &isCancelled:&+isCancelled());
//内存缓存 start
putBitmapToCache(mUrl, result);
//内存缓存end*/
return getBitmapAndSaveToCacheByUrl(mUrl);
protected void onPostExecute(Bitmap result) {
super.onPostExecute(result);
//设置图片 防止错位
/*if(mUrl.equals(mImageView.getTag())){
mImageView.setImageBitmap(result);
//滑动优化
ImageView imageView = (ImageView) mListView.findViewWithTag(mUrl);
if(imageView!=null && null != result)
imageView.setImageBitmap(result);
mSets.remove(this);
//滑动优化
public Bitmap getBitmapByUrl(String string) {
InputStream is1=null/*,is2 = null*/;
Bitmap result =
HttpURLConnection conn = (HttpURLConnection) new URL(string).openConnection();
is1 = new BufferedInputStream(conn.getInputStream());
//优化图片加载 begin
/*ByteArrayOutputStream out = new ByteArrayOutputStream();
ImageUtils.copy(is1,out);
is2 = new ByteArrayInputStream(out.toByteArray());*/
result = BitmapFactory.decodeStream(is1);
= ImageUtils.decodeSuitableBitmap(is,60,60);
//result = ImageUtils.decodeSuitableBitmap(string,1,1);
//Log.i(TAG,&resutl size:&+result.getByteCount());
//result = ImageUtils.decodeSampledBitmapFromInputStream(is1,is2,1,1);
Log.i(TAG,&resutl size:&+(result !=null?result.getByteCount():&null&));
/*if (result==null){
Log.i(TAG,&result==null&);
//Log.i(TAG,&result=&+result);
//优化图片加载 end
conn.disconnect();
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
if(is1!=null){
is1.close();
/*if(is2!=null){
is2.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
return result;
//滚动时的优化 begin
private static Set&NewsImageAsyncTask& mSets ;
private ListView mListView;
public ListView getmListView() {
return mListView;
public void setmListView(ListView mListView) {
this.mListView = mListView;
public void loadImages(int mStart, int mEnd) {
Log.i(TAG, &loadImages:& + mStart+&-&+mEnd);
for (int i = mStart; i & mEnd; i++) {
Log.i(TAG, &loadImages:&+i);
String url = MainActivity.urls.get(i);
Bitmap bm = getBitmapFromCache(url);
ImageView mImageView = (ImageView)mListView.findViewWithTag(url);
if(null!=bm && null!= mImageView){
mImageView.setImageBitmap(bm);
else{//重新下载
NewsImageAsyncTask task = new NewsImageAsyncTask(url);
mSets.add(task);
task.execute();
public void cancelAllTasks() {
if(mSets!=null){
for (NewsImageAsyncTask task : mSets) {
task.cancel(false);
//看缓存中是否有 有则设置 没有则默认图片不管
public Bitmap setDefaultBitmap(ImageView pic, String newsPicResUrl) {
Bitmap bm = getBitmapFromCache(newsPicResUrl);
if(null!=bm){
pic.setImageBitmap(bm);
return bm;
//滚动时的优化 end
//硬盘缓存 加载图片方法(不返回bitmap，为了通用，不仅仅保存图片) 并写入硬缓存 begin
private static boolean getBitmapUrlToStream(String urlString, OutputStream outputStream) {
HttpURLConnection urlConnection =
BufferedOutputStream out =
BufferedInputStream in =
final URL url = new URL(urlString);
urlConnection = (HttpURLConnection) url.openConnection();
in = new BufferedInputStream(urlConnection.getInputStream(), 8 * 1024);
out = new BufferedOutputStream(outputStream, 8 * 1024);
while ((b = in.read()) != -1) {
out.write(b);
} catch (final IOException e) {
e.printStackTrace();
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
if (out != null) {
out.close();
if (in != null) {
in.close();
} catch (final IOException e) {
e.printStackTrace();
//硬盘缓存 加载图片方法 end
//硬盘缓存
下载图片 存入缓存（SD ,内存都存入）方法 begin
private Bitmap getBitmapAndSaveToCacheByUrl(String mUrl) {
String key = FileUtils.toMD5String(mUrl);
FileDescriptor fileDescriptor =
FileInputStream fileInputStream =
DiskLruCache.Snapshot snapShot =
//尝试获取硬缓存里的数据
snapShot = mDiskCache.get(key);
//如果没有缓存
if (snapShot == null) {
//尝试读从网络取并写入
DiskLruCache.Editor editor = mDiskCache.edit(key);
if (editor != null) {
OutputStream outputStream = editor.newOutputStream(0);
if (getBitmapUrlToStream(mUrl, outputStream)) {
editor.abort();
//再次读取
snapShot = mDiskCache.get(key);
if (snapShot != null) {
fileInputStream = (FileInputStream) snapShot.getInputStream(0);
fileDescriptor = fileInputStream.getFD();
//利用读取的硬盘数据，生成bitmap
Bitmap bitmap =
if (fileDescriptor != null) {
bitmap = BitmapFactory.decodeFileDescriptor(fileDescriptor);
//利用bitmap 存入内存缓存
if (bitmap != null) {
putBitmapToCache(mUrl, bitmap);
//返回bitmap
return bitmap;
} catch (IOException e) {
e.printStackTrace();
} finally {
if (fileDescriptor == null && fileInputStream != null) {
fileInputStream.close();
} catch (IOException e) {
//加载大图
public void loadBigBitmap(String url, ImageView imageView, ProgressBar mProgressBar){
if(imageView!=null && null!= url){
new BigImageAsyncTask(imageView,mProgressBar).execute(url);
private class BigImageAsyncTask extends AsyncTask&String,Void,Bitmap& {
private ImageView mImageView;
private ProgressBar mProgressBar;
public BigImageAsyncTask(ImageView imageView, ProgressBar progressBar) {
mImageView = imageView;
mProgressBar = progressBar;
protected Bitmap doInBackground(String... params) {
return getBitmapByUrl(params[0]);
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
if(bitmap!=null)
mImageView.setImageBitmap(bitmap);
if(null!=mProgressBar){
mProgressBar.setVisibility(View.GONE);
package com.example.asynctaskdemo;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;
import android.widget.ProgressBar;
* Created by zhangxutong on .
public class BigImageActivity extends Activity{
private ImageView mBigImageView;
private ProgressBar mProgressBar;
private ImageLoader mImageLoader;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bigimage);
initView();
mImageLoader = ImageLoader.getInstance(BigImageActivity.this);
Intent intent = getIntent() ;
String urlBig = intent.getStringExtra(&urlBig&);
String urlSmall = intent.getStringExtra(&urlSmall&);
//设置初始值
if(null!=urlSmall) {
Bitmap bitmap = mImageLoader.getBitmapFromCache(urlSmall);
Log.i(&TAG&,&urlSmall:&+urlSmall+&, bitmap:&+bitmap);
if(null!=bitmap){
mBigImageView.setImageBitmap(bitmap);
//加载大图
mImageLoader.loadBigBitmap(urlBig,mBigImageView,mProgressBar);
private void initView() {
mBigImageView = (ImageView) findViewById(R.id.iv_bigimage);
mProgressBar = (ProgressBar) findViewById(R.id.pb);
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