使用AsyncTask异步加载图片

主要看看AsyncTask如何使用:

MainActivity.java

1. public class MainActivity extends Activity {  
2. private static final String TAG = "MainActivity";  
3. private List<String>  datas;  
4. private LayoutInflater inflater;  
5. private Context context;  
6. private MyAdapter adapter;  
7. private ListView listview;  
8. private List<String> imgUrls;  
9. private List<TextView> list = new ArrayList<TextView>();  
10. private List<String> sortUrl = new ArrayList<String>();  
11. @Override  
12. protected void onCreate(Bundle savedInstanceState) {  
13. super.onCreate(savedInstanceState);  
14.         requestWindowFeature(Window.FEATURE_NO_TITLE);  
15.         setContentView(R.layout.activity_main);  
16. this);  
17. this;  
18.         listview = (ListView) findViewById(R.id.listview);  
19.         initData();  
20. new MyAdapter();  
21.         listview.setAdapter(adapter);  
22.     }  
23.   
24. private void initData() {  
25. new ArrayList<String>();  
26. "http://img5.douban.com/view/movie_poster_cover/mpst/public/p2199507156.jpg");  
27. "http://img5.douban.com/lpic/s27397768.jpg");  
28. "http://img3.douban.com/lpic/s27505695.jpg");  
29. "http://img3.douban.com/lpic/s27461340.jpg");  
30. "http://img3.douban.com/lpic/s27451442.jpg");  
31. "http://img5.douban.com/lpic/s27453059.jpg");  
32. "http://img3.douban.com/lpic/s27452925.jpg");  
33. "http://img5.douban.com/lpic/s27452846.jpg");  
34. "http://img3.douban.com/lpic/s27325332.jpg");  
35. "http://img3.douban.com/lpic/s27325315.jpg");  
36. "http://img5.douban.com/lpic/s27389537.jpg");  
37. "http://img3.douban.com/view/movie_poster_cover/mpst/public/p2199638985.jpg");  
38. "http://img3.douban.com/view/movie_poster_cover/mpst/public/p2199637691.jpg");  
39. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2195768476.jpg");  
40. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2180002996.jpg");  
41. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2182978810.jpg");  
42. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2164841498.jpg");  
43. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2161445839.jpg");  
44. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2183221886.jpg");  
45. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2164383301.jpg");  
46. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2199638985.jpg");  
47. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2199407040.jpg");  
48. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2176900061.jpg");  
49. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2180405730.jpg");  
50. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2197059721.jpg");  
51. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2196353608.jpg");  
52. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2187391526.jpg");  
53. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2185073849.jpg");  
54. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2196328516.jpg");  
55. "http://img5.douban.com/view/movie_poster_cover/lpst/public/p2166850749.jpg");  
56. "http://img3.douban.com/view/movie_poster_cover/lpst/public/p2183957412.jpg");  
57. "http://img3.douban.com/spic/s27459164.jpg");  
58. "http://img3.douban.com/spic/s27480483.jpg");  
59. "http://img3.douban.com/spic/s27460951.jpg");  
60. "http://img3.douban.com/spic/s27453772.jpg");  
61. "http://img3.douban.com/spic/s27410904.jpg");  
62. "http://img5.douban.com/spic/s27466008.jpg");  
63. "http://img3.douban.com/spic/s3259484.jpg");  
64. "http://img3.douban.com/spic/s3081692.jpg");  
65. "http://img3.douban.com/spic/s1400630.jpg");  
66. "http://img5.douban.com/spic/s4715377.jpg");  
67. "http://img3.douban.com/spic/s6201192.jpg");  
68. "http://img5.douban.com/spic/s2650727.jpg");  
69. "http://img3.douban.com/spic/s3636124.jpg");  
70. "http://img5.douban.com/spic/s3595798.jpg");  
71. "http://img3.douban.com/spic/s27078194.jpg");  
72. "http://img3.douban.com/view/event_poster/large/public/2a35a85a873e8e7.jpg");  
73. "http://img3.douban.com/view/event_poster/large/public/ce66e0569742fd7.jpg");  
74. "http://img3.douban.com/view/event_poster/large/public/4c44752e83900d9.jpg");  
75. "http://img3.douban.com/view/event_poster/large/public/d22f7b9e5c8c92c.jpg");  
76.     } 
77. 
78. private class MyAdapter extends BaseAdapter{  
79. @Override  
80. public int getCount() {  
81. return imgUrls.size();  
82.         }  
83. @Override  
84. public Object getItem(int position) {  
85. return imgUrls.get(position);  
86.         }  
87. @Override  
88. public long getItemId(int position) {  
89. return position;  
90.         }  
91. @Override  
92. public View getView(int position, View convertView, ViewGroup arg2) {  
93. null;  
94. if(convertView == null){  
95. new ViewHolder();  
96. null);  
97.                 viewHolder.image = (ImageView) convertView.findViewById(R.id.img);  
98.                 convertView.setTag(viewHolder);  
99. else{  
100.                 viewHolder = (ViewHolder) convertView.getTag();  
101.             }  
102. new ImageTask(viewHolder.image);  
103.             iamgeTask.execute(imgUrls.get(position));  
104. return convertView;  
105.         }  
106. class ViewHolder{  
107.             ImageView image;  
108.         }  
109.     }  
110. }

加载图片的类：

ImageTask.java

1. public class ImageTask extends AsyncTask<String, Void, Bitmap> {  
2. private ImageView iv;  
3. publicImageTask(ImageView iv){  
4. this.iv = iv;  
5.     }  
6. @Override  
7. protected Bitmap doInBackground(String... param) {  
8. 0];  
9. try {  
10. new URL(imgUrl);  
11. try {  
12.                 HttpURLConnection conn = (HttpURLConnection) url.openConnection();  
13.                 InputStream in = conn.getInputStream();  
14.                 Bitmap bitmap = BitmapFactory.decodeStream(in);  
15. if(bitmap!=null){  
16. return bitmap;  
17.                 }  
18. catch (IOException e) {  
19. // TODO Auto-generated catch block  
20.                 e.printStackTrace();  
21.             }  
22. catch (MalformedURLException e) {  
23. // TODO Auto-generated catch block  
24.             e.printStackTrace();  
25.         }  
26. return null;  
27.     }  
28.   
29. @Override  
30. protected void onPostExecute(Bitmap result) {  
31. super.onPostExecute(result);  
32. if(result != null){  
33.             iv.setImageBitmap(result);  
34.         }  
35.     }  
36.   
37. @Override  
38. protected void onPreExecute() {  
39. super.onPreExecute();  
40.     }  
41. }