Android之查看网络图片和网页HTML

网络编程是Android应用中很重要的一部分，本文主要讲述了利用HttpURLConnection获取网络图片和HTML的方法。

获取网络图片

public class MainActivity extends Activity implements OnClickListener {

    private static final String TAG = "MainActivity";
    protected static final int ERROR = 1;
    private EditText etUrl;
    private ImageView ivIcon;
    private final int SUCCESS = 0;

    private Handler handler = new Handler() {

        /**
         * 接收消息
         */
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            Log.i(TAG, "what = " + msg.what);
            if(msg.what == SUCCESS) {   // 当前是访问网络, 去显示图片
                ivIcon.setImageBitmap((Bitmap) msg.obj);        // 设置imageView显示的图片
            } else if(msg.what == ERROR) {
                Toast.makeText(MainActivity.this, "抓去失败", 0).show();
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ivIcon = (ImageView) findViewById(R.id.iv_icon);
        etUrl = (EditText) findViewById(R.id.et_url);

        findViewById(R.id.btn_submit).setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        final String url = etUrl.getText().toString();

        new Thread(new Runnable() {

            @Override
            public void run() {
                Bitmap bitmap = getImageFromNet(url);

//              ivIcon.setImageBitmap(bitmap);      // 设置imageView显示的图片
                if(bitmap != null) {
                    Message msg = new Message();
                    msg.what = SUCCESS;
                    msg.obj = bitmap;
                    handler.sendMessage(msg);
                } else {
                    Message msg = new Message();
                    msg.what = ERROR;
                    handler.sendMessage(msg);
                }
            }}).start();

    }

    /**
     * 根据url连接取网络抓去图片返回
     * @param url
     * @return url对应的图片
     */
    private Bitmap getImageFromNet(String url) {
        HttpURLConnection conn = null;
        try {
            URL mURL = new URL(url);    // 创建一个url对象

            // 得到http的连接对象
            conn = (HttpURLConnection) mURL.openConnection();

            conn.setRequestMethod("GET");       // 设置请求方法为Get
            conn.setConnectTimeout(10000);      // 设置连接服务器的超时时间, 如果超过10秒钟, 没有连接成功, 会抛异常
            conn.setReadTimeout(5000);      // 设置读取数据时超时时间, 如果超过5秒, 抛异常

            conn.connect();     // 开始链接

            int responseCode = conn.getResponseCode(); // 得到服务器的响应码
            if(responseCode == 200) {
                // 访问成功
                InputStream is = conn.getInputStream(); // 获得服务器返回的流数据

                Bitmap bitmap = BitmapFactory.decodeStream(is); // 根据 流数据 创建一个bitmap位图对象

                return bitmap;
            } else {
                Log.i(TAG, "访问失败: responseCode = " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(conn != null) {
                conn.disconnect();      // 断开连接
            }
        }
        return null;
    }
}

不能子线程中改变主线程页面，故需要使用Handler

上面的方法较为烦琐，使用github上的开源库，android-smart-image-view可以有效的实现相同的功能，同时简化操作，使用方法是将开源库src文件夹下的内容复制一份到工程中,同时在布局文件中，使用全类名使用自定义控件SmartImageView即可.

android-smart-image-view实现

public class MainActivity2 extends Activity implements OnClickListener {

    private EditText etUrl;
    private SmartImageView mImageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);

        etUrl = (EditText) findViewById(R.id.et_url);
        mImageView = (SmartImageView) findViewById(R.id.iv_icon);

        findViewById(R.id.btn_submit).setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {

        // 1. 取出url, 抓取图片
        String url = etUrl.getText().toString();

        mImageView.setImageUrl(url);
    }
}

查看网页HTML实现

public class MainActivity extends Activity {

    private static final String TAG = "MainActivity";
    private static final int SUCCESS = 0;
    protected static final int ERROR = 1;
    private EditText etUrl;
    private TextView tvHtml;

    private Handler handler = new Handler() {

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
            case SUCCESS:
                 tvHtml.setText((String) msg.obj);
                break;
            case ERROR:
                Toast.makeText(MainActivity.this, "访问失败", 0).show();
                break;
            default:
                break;
            }
        }

    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        etUrl = (EditText) findViewById(R.id.et_url);
        tvHtml = (TextView) findViewById(R.id.tv_html);

    }

    public void getHtml(View v) {
        final String url = etUrl.getText().toString();

        new Thread(new Runnable() {

            @Override
            public void run() {
                // 请求网络
                String html = getHtmlFromInternet(url);

                if(!TextUtils.isEmpty(html)) {
                    // 更新textview的显示了
                    Message msg = new Message();
                    msg.what = SUCCESS;
                    msg.obj = html;
                    handler.sendMessage(msg);
                } else {
                    Message msg = new Message();
                    msg.what = ERROR;
                    handler.sendMessage(msg);
                }
            }
        }).start();
    }

    /**
     * 根据给定的url访问网络, 抓去html代码
     * @param url
     * @return
     */
    protected String getHtmlFromInternet(String url) {

        try {
            URL mURL = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) mURL.openConnection();

            conn.setRequestMethod("GET");
            conn.setConnectTimeout(10000);
            conn.setReadTimeout(5000);

//          conn.connect();

            int responseCode = conn.getResponseCode();

            if(responseCode == 200) {
                InputStream is = conn.getInputStream();
                String html = getStringFromInputStream(is);
                return html;
            } else {
                Log.i(TAG, "访问失败: " + responseCode);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 根据流返回一个字符串信息
     * @param is
     * @return
     * @throws IOException
     */
    private String getStringFromInputStream(InputStream is) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = -1;

        while((len = is.read(buffer)) != -1) {
            baos.write(buffer, 0, len);
        }
        is.close();

        String html = baos.toString();  // 把流中的数据转换成字符串, 采用的编码是: utf-8

        String charset = "utf-8";
        if(html.contains("gbk") || html.contains("gb2312")
                || html.contains("GBK") || html.contains("GB2312")) {       // 如果包含gbk, gb2312编码, 就采用gbk编码进行对字符串编码
            charset = "gbk";
        }

        html = new String(baos.toByteArray(), charset); // 对原有的字节数组进行使用处理后的编码名称进行编码
        baos.close();
        return html;
    }
}

使用这种方法HTML有时会产生乱码，解决方法如上

完成