问题描述

使用 Bitmap 时，图片不能显示

请大家帮我看看下面的代码，为什么图像不能在list中显示，然而空间和图像的其他描述却能看得见。

public class Test extends ListActivity  {      Prefs myprefs = null;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.listplaceholder);        this.myprefs = new Prefs(getApplicationContext());        // install handler for processing gui update messages        ArrayList<HashMap<String Object>> mylist = new ArrayList<HashMap<String Object>>();        JSONObject json = JSONfunctions.getJSONfromURL(""http://midsweden.gofreeserve.com/proj/androidjson.php?identifier="" +         Test.this.myprefs.getPersonalno());        try{            JSONArray  earthquakes = json.getJSONArray(""services"");            for(int i=0;i<earthquakes.length();i++){                                        HashMap<String Object> map = new HashMap<String Object>();                 JSONObject e = earthquakes.getJSONObject(i);                map.put(""id"" e.getString(""taskid""));                map.put(""pic""Service name : "" + e.getString(""employeepic""));                map.put(""serviceinfo""" +  e.getString(""employeename"")+ "" : ""+ e.getString(""starttime"")                        +"" To "" +  e.getString(""endtime""));                  BmpFromURL  myBmpFromURL = new BmpFromURL(""http://midsweden.gofreeserve.com/proj/admin/pictures/file87619.jpg"");                  Bitmap myBitmap = myBmpFromURL.getMyBitmap();                    map.put(""img""myBitmap);                mylist.add(map);                        }               }catch(JSONException e)        {             Log.e(""log_tag""Error parsing data ""+e.toString());        }        SimpleAdapter adapter = new SimpleAdapter(this mylist  R.layout.testnew String[] {""img""servicename""serviceinfo"" }                         new int[] {  R.id.image R.id.item_title R.id.item_subtitle });        setListAdapter(adapter);        final ListView lv = getListView();        lv.setTextFilterEnabled(true);          lv.setOnItemClickListener(new OnItemClickListener() {            public void onItemClick(AdapterView<?> parent View view int position long id) {                              @SuppressWarnings(""unchecked"")                HashMap<String String> o = (HashMap<String String>) lv.getItemAtPosition(position);                                   Toast.makeText(Test.thisID '"" + o.get(""id"") + ""' was clicked."" Toast.LENGTH_SHORT).show();             }        });    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        MenuInflater inflater = getMenuInflater();        inflater.inflate(R.menu.menu menu);        return true;    }      @Override    public boolean onOptionsItemSelected(MenuItem item) {        switch (item.getItemId()) {            case R.id.settings:                     Intent intent = new Intent(this ShowSettings.class);                  startActivity(intent);            break;            case R.id.web:                     Intent intent4 = new Intent(this MenuActivity.class);                  startActivity(intent4);            break;            case R.id.services:                     Intent intent2 = new Intent(this Test.class);                startActivity(intent2);              break;            case R.id.Quit:                Intent intent3 = new Intent(this ServicesDemo.class);                startActivity(intent3);                   break;            default:                break;        }        return true;    }}

Bitmap class

    public class BmpFromURL {    private Bitmap myBitmap;    public BmpFromURL(String imageURL){    URL myImageURL = null;    try {    myImageURL = new URL(imageURL);    } catch (MalformedURLException error) {    error.printStackTrace();    }    try {    HttpURLConnection connection = (HttpURLConnection)myImageURL .openConnection();    connection.setDoInput(true);    connection.connect();    InputStream input = connection.getInputStream();    myBitmap = BitmapFactory.decodeStream(input);    } catch (IOException e) {   e.printStackTrace();    }    }   public Bitmap getMyBitmap() {    return myBitmap;    }}

xml 文件

<?xml version=""1.0"" encoding=""utf-8""?><LinearLayout xmlns:android=""http://schemas.android.com/apk/res/android""    android:orientation=""vertical""    android:layout_width=""fill_parent""    android:layout_height=""fill_parent""    android:cacheColorHint=""#55000000""    android:background=""#55000000""    >      <ImageView      android:id=""@+id/image""      android:layout_width=""50dip""      android:layout_height=""50dip""      /><TextView      android:id=""@+id/item_title""    android:layout_width=""fill_parent""     android:layout_height=""wrap_content""     android:textAppearance=""?android:attr/textAppearanceMedium""    android:padding=""2dp""    android:textSize=""20dp"" />    <TextView      android:id=""@+id/item_subtitle""    android:layout_width=""fill_parent""     android:layout_height=""wrap_content""     android:padding=""2dp""    android:textSize=""18dp"" /></LinearLayout>

解决方案

请使用下面 ListView 的图片延迟加载
请看这里： http://open-pim.com/tmp/LazyList.zip
GitHub: https://github.com/thest1/LazyList