登录圆形头像之网络加载与缓存到本地

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！

    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"></uses-permission>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"></uses-permission>

由于代码太多，完整代码未给出，源码直接下载即可

源码点击下载：https://github.com/DickyQie/android-cache