Android（java）学习笔记204：自定义SmartImageView（继承自ImageView，扩展功能为自动获取网络路径图片）

 1 package com.himi.smart;
 2 
 3 import java.io.InputStream;
 4 import java.net.HttpURLConnection;
 5 import java.net.URL;
 6 
 7 import android.content.Context;
 8 import android.graphics.Bitmap;
 9 import android.graphics.BitmapFactory;
10 import android.os.Handler;
11 import android.os.Message;
12 import android.util.AttributeSet;
13 import android.widget.ImageView;
14 
15 /**
16  * 实现一个子类，扩展系统的ImageView
17  * @author Administrator
18  *
19  */
20 public class SmartImageView extends ImageView {
21     
22     private static final int SUCCESS = 1;
23     private Handler handler = new Handler() {
24         public void handleMessage(android.os.Message msg) {
25             switch (msg.what) {
26             case SUCCESS:
27                 Bitmap bitmap = (Bitmap) msg.obj;
28                 setImageBitmap(bitmap);
29                 break;
30 
31             default:
32                 //其他消息，都是获取图片失败
33                 break;
34             }
35 
36         };
37     };
38 
39     public SmartImageView(Context context, AttributeSet attrs, int defStyle) {
40         super(context, attrs, defStyle);
41         // TODO 自动生成的构造函数存根
42     }
43 
44     public SmartImageView(Context context, AttributeSet attrs) {
45         super(context, attrs);
46         // TODO 自动生成的构造函数存根
47     }
48 
49     public SmartImageView(Context context) {
50         super(context);
51         // TODO 自动生成的构造函数存根
52     }
53     
54     /**
55      * 设置一个网络的路径给imageview,imageview会自动的把这个路径对应的图片下载下来
56      * @param path 图片的路径
57      */
58 
59     public void  setImageUrl(final String path) {
60         new Thread() {
61             public void run() {
62                 try {
63                     URL url = new URL(path);
64                     HttpURLConnection conn = (HttpURLConnection) url.openConnection();
65                     conn.setConnectTimeout(5000);
66                     conn.setReadTimeout(5000);
67                     conn.setRequestMethod("GET");
68                     int code = conn.getResponseCode();
69                     if(code ==200) {
70                         InputStream is = conn.getInputStream();//获得服务器端的图片文件的输入流
71                         Bitmap bitmap = BitmapFactory.decodeStream(is);//将服务器端的图片文件的输入流 转化为 Bitmap图片文件
72                         //setImageBitmap(bitmap);子线程不能更新UI,这里要使用消息机制
73                         Message msg = Message.obtain();
74                         msg.obj = bitmap;
75                         msg.what = SUCCESS;
76                         handler.sendMessage(msg);
77                     }
78                 } catch (Exception e) {
79                     e.printStackTrace();
80                     handler.sendEmptyMessage(0);
81                 }
82             
83                 
84             };
85         }.start();
86     }
87     
88 }

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.himi.smart.MainActivity" >

    <com.himi.smart.SmartImageView
        android:id="@+id/iv"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

</RelativeLayout>

package com.himi.smart;

import com.himi.hebao.R;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageView;

public class MainActivity extends Activity {
    
    private SmartImageView iv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        iv = (SmartImageView) findViewById(R.id.iv);
        iv.setImageUrl("http://a.hiphotos.baidu.com/image/pic/item/cf1b9d16fdfaaf51ebc1c2be8e5494eef01f7a94.jpg");
        
    }

}