问题描述

安卓，子线程获取网络图片，发消息给主线程，主线程用图片填充listview，出错

先上logcat:

我的xml布局就是一个按钮，和一个listview，listview里就一个imageview，按下按钮开始从网络获取图片，然后发消息到主线程，然后listview就填充数据。xml代码就不贴了。

以下是mainactivity

 public class MainActivity extends AppCompatActivity implements View.OnClickListener{    Button but;    Bitmap bitmap;    ListView listView;    Bitmap mainBitmap;    MainHandler mainHandler=new MainHandler();    List<Map<StringBitmap>> list=new ArrayList<>();    Map<StringBitmap> map;    Message sendMsg;    List<Bitmap> bitmapList=new ArrayList<>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);        setSupportActionBar(toolbar);        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);        fab.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                Snackbar.make(viewReplace with your own action"" Snackbar.LENGTH_LONG)                        .setAction(""Action"" null).show();            }        });        but=(Button)super.findViewById(R.id.but);        img=(ImageView)super.findViewById(R.id.img);        listView=(ListView)super.findViewById(R.id.listview);        but.setOnClickListener(this);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.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();        //noinspection SimplifiableIfStatement        if (id == R.id.action_settings) {            return true;        }        return super.onOptionsItemSelected(item);    }    public void onClick(View v)    {        new Thread() {            public void run() {               List<String> imageList=new ArrayList<>();                imageList.add(""http://i1.hdslb.com/u_user/ed5c9f35b1311b3606c29d633793690b.png"");                imageList.add(""http://i1.hdslb.com/u_user/cfdf3c751a554873ecf4687616e1f858.jpg"");                imageList.add(""http://i1.hdslb.com/u_user/1462ad43f88a4b6e8b32da2447479f23.jpg"");                try                {                    Looper.prepare();                    for(int i=0;i<imageList.size();i++) {                        URL uri = new URL(imageList.get(i));                        HttpURLConnection httpURLConnection = (HttpURLConnection) uri.openConnection();                        httpURLConnection.setConnectTimeout(5000);                        httpURLConnection.setUseCaches(false);                        httpURLConnection.setDoInput(true);                        InputStream inputStream = httpURLConnection.getInputStream();                        bitmap = BitmapFactory.decodeStream(inputStream);                        bitmapList.add(bitmap);                       }                    Message sendFinishMessage=Message.obtain();                    sendFinishMessage.what=2;                    mainHandler.sendMessage(sendFinishMessage);                    Looper.loop();                } catch (Exception e)                {                    Log.e(""this""获取网络图片失败"" + e);                }            }        }.start();    }    class MainHandler extends Handler    {        public void handleMessage(Message msg)        {            if(msg.what ==2)            {                for(int i=0;i<bitmapList.size();i++)                {                    map=new HashMap<>();                    map.put(""image""bitmapList.get(i));                    list.add(map);                }                initListView();            }        }    }    public void initListView()    {        SimpleAdapter simpleAdapter=new SimpleAdapter(thislistR.layout.listviewnew String[]{""image""}new int[]{R.id.imageview2});        listView.setAdapter(simpleAdapter);    }}

代码如上，请问是哪里出了问题？

解决方案

看到 日志输出 说找不到文件 应该是在获取网络的图片decode 成bitmap的时候出错
URL uri = new URL(imageList.get(i));
HttpURLConnection httpURLConnection = (HttpURLConnection) uri.openConnection();
httpURLConnection.setConnectTimeout(5000);
httpURLConnection.setUseCaches(false);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
bitmap = BitmapFactory.decodeStream(inputStream);
bitmapList.add(bitmap);

看来应该是这片代码的问题

解决方案二：
for(int i=0;i<imageList.size();i++) {
URL uri = new URL(imageList.get(i));
HttpURLConnection httpURLConnection = (HttpURLConnection) uri.openConnection();
httpURLConnection.setConnectTimeout(5000);
httpURLConnection.setUseCaches(false);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
bitmap = BitmapFactory.decodeStream(inputStream);
bitmapList.add(bitmap);
}

                                        循环里面加载图片错误                                         不是图片地址不能访问 就是 以上代码有问题  你可以参考楼上的代码