Android开发中常常有用户头像显示，似乎大多数都是圆形显示，如果每次加载网络头像，会频繁的请求网络，所以本文主要说的是登录时的头像网络加载和缓存到本地，以便于下次加载时直接从本地获取即可。
效果图
自定义控件实现圆形头像显示请看， Android自定义ImageView实现图片圆形 ，椭圆和矩形圆角显示 这篇博客即可。
代码：
public class MainActivity extends Activity implements OnClickListener {
private ImageView mImageView, mImageView2;
String url = " http://avatar.csdn.net/8/6/0/1_dickyqie.jpg";
private String mFileName;
private String mSaveMessage;
Util util = new Util();
private Bitmap mBitmap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
// TODO Auto-generated method stub
mImageView = (ImageView) findViewById(R.id.personal_image);
mImageView2 = (ImageView) findViewById(R.id.personal_image2);
findViewById(R.id.button1).setOnClickListener(this);
findViewById(R.id.button2).setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.button1:
new Thread(connectNet).start();
break;
case R.id.button2:
Bitmap ben = BitmapFactory.decodeFile(Util.ALBUM_PATH + mFileName);
mImageView2.setImageBitmap(ben);
break;
default:
break;
}
}
private Runnable saveFileRunnable = new Runnable() {
@Override
public void run() {
try {
util.saveFile(mBitmap, mFileName);
mSaveMessage = "图片保存成功！";
} catch (IOException e) {
mSaveMessage = "图片保存失败！";
e.printStackTrace();
}
messageHandler.sendMessage(messageHandler.obtainMessage());
}
};
private Handler messageHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
Toast.makeText(MainActivity.this, mSaveMessage, 1).show();
}
};
/*
* 连接网络 由于在4.0中不允许在主线程中访问网络，所以需要在子线程中访问
*/
private Runnable connectNet = new Runnable() {
@Override
public void run() {
try {
String filePath = url;
mFileName = "test.jpg";
// 以下是取得图片的两种方法
// 方法1：取得的是byte数组, 从byte数组生成bitmap
byte[] data = util.getImage(filePath);
if (data != null) {
mBitmap = BitmapFactory.decodeByteArray(data, 0,
data.length);
} else {
Toast.makeText(MainActivity.this, "Image error!", 1).show();
}
// ******** 方法2：取得的是InputStream，直接从InputStream生成bitmap
// mBitmap =
// BitmapFactory.decodeStream(util.getImageStream(filePath));
// 发送消息，通知handler在主线程中更新UI
connectHanlder.sendEmptyMessage(0);
} catch (Exception e) {
Toast.makeText(MainActivity.this, "无法链接网络！", 1).show();
e.printStackTrace();
}
}
};
private Handler connectHanlder = new Handler() {
@Override
public void handleMessage(Message msg) {
// 更新UI，显示图片
if (mBitmap != null) {
mImageView.setImageBitmap(mBitmap);// display image
new Thread(saveFileRunnable).start();
}
}
};
}
不要忘记在AndroidManifest.xml加权限哦！
由于代码太多，完整代码未给出，源码直接下载即可