Bootstrap

Android Http基础:图片下载并显示和WebView的应用

<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"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<ImageView
    android:id="@+id/image"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"></ImageView>
<WebView
    android:id="@+id/wedView"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_below="@id/image"></WebView>

MainActivity:


/**

  • 在Android上发送HTTP请求的方式一般有两种,HttpURLConnection和HttpClient

*/

public class MainActivity extends ActionBarActivity {

private WebView webView;
private ImageView imageView;
public static final int SHOW_WEDVIEW = 0;
private Handler handler = new Handler();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    webView = (WebView) findViewById(R.id.wedView);
    imageView = (ImageView) findViewById(R.id.image);
    //通过网络加载图片
    new ImageThread("http://gb.cri.cn/mmsource/images/2013/02/22/35/14607758026320856623.jpg",imageView,handler).start();
    //在WebView中显示百度主页
    new HttpThread("http://www.baidu.com",webView,handler).start();
}

}

ImageThread(加载图片的线程):


public class ImageThread extends Thread {

//声明要传递的参数
private String url;
private ImageView imageView;
private Handler handler;
//创建构造方法,对参数进行初始化
public ImageThread(String url, ImageView imageView, Handler handler) {
    this.url = url;
    this.imageView = imageView;
    this.handler = handler;
}
@Override
public void run() {
    try {
        //定义一个URL对象
        URL httpUrl = new URL(url);
        //获取HttpURLConnection的实例,表示到URL所引用的远程对象的连接
        HttpURLConnection connection = (HttpURLConnection) httpUrl.openConnection();
        //设置读取超时时间
        connection.setReadTimeout(5000);
        //设置请求方法,GET表示希望从服务器那里获取数据,而POST则表示提交数据给服务器
        connection.setRequestMethod("GET");
        //设置该URLConnection的doOutput请求头字段的值
        connection.setDoInput(true);
        //用时间作为下载的图片的文件名
        String fileName = String.valueOf(System.currentTimeMillis());
        File downloadFile = null;
        InputStream inputStream = connection.getInputStream();
        //要把文件写到SD卡,所以用FileOutputStream
        FileOutputStream fileOutputStream = null;
        //判断SD卡是否存在,存在就创建文件
        if (Environment.getExternalStorageState().equals(
                Environment.MEDIA_MOUNTED)) {
            File parent = Environment.getExternalStorageDirectory();
            downloadFile = new File(parent,fileName);
            fileOutputStream = new FileOutputStream(downloadFile);
        }
        //创建一个2K的缓冲区
        byte[] bytes = new byte[2 * 1024];
        int length;
        if (fileOutputStream != null) {
            while ((length = inputStream.read(bytes)) != -1) {
                fileOutputStream.write(bytes,0,length);
            }
        }
        final Bitmap bitmap = BitmapFactory.decodeFile(downloadFile.getAbsolutePath());
        //通过handler去更新UI
        handler.post(new Runnable() {
            @Override
            public void run() {
                imageView.setImageBitmap(bitmap);
            }
        });
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

}

HttpThread(加载WebView的线程):


public class HttpThread extends Thread {

//声明要传递的参数
private String url;
private WebView webView;
private Handler handler;
//创建构造方法,对参数进行初始化
public HttpThread(String url, WebView webView, Handler handler) {
    this.url = url;
    this.webView = webView;
    this.handler = handler;
}
@Override
public void run() {
    try {
        //定义一个URL对象
        URL httpUrl = new URL(url);
        //获取HttpURLConnection的实例,表示到URL所引用的远程对象的连接
        HttpURLConnection connection = (HttpURLConnection) httpUrl.openConnection();
        //设置读取超时时间
        connection.setReadTimeout(5000);
        //设置请求方法,GET表示希望从服务器那里获取数据,而POST则表示提交数据给服务器
        connection.setRequestMethod("GET");
        final StringBuffer stringBuffer = new StringBuffer();
        /*  getInputStream():返回该URLConnection对应的输入流,用于获取URLConnection响应的内容
;