Android之网络操作 - 从网络获取图片或网页

1.在Java中操作显示网络图片

public class ImageRequest 
{
	/**
	 * @param args
	 */
	public static void main(String[] args) throws Exception 
	{
		//构造一个URL对象
		URL url = new URL("http://www.baidu.com/img/baidu_sylogo1.gif");
		//使用openConnection打开URL对象
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		//使用Http协议，设置请求方式为GET
		conn.setRequestMethod("GET");
		//设置链接超时异常，5s
		conn.setConnectTimeout(5 * 1000);
		//通过输入流获取图片数据
		InputStream inStream = conn.getInputStream();
		//获取到图片的二进制数据
		byte[] data = readInputStream(inStream);
		//构造一个文件，保存图片到项目的根目录下
		File imageFile = new File("baidu_logo.jpg");
		//构造一个文件输出流FileOutputStream
		FileOutputStream outStream = new FileOutputStream(imageFile);
		//把文件数据写入到输出流
		outStream.write(data);
		outStream.close();
	}
	
	/**
	 * 从输入流里面得到返回为二进制的数据
	 * @param inStream 输入流
	 * @return byte[] 二进制数据
	 * @throws Exception
	 */
	public static byte[] readInputStream(InputStream inStream) throws Exception
	{
		//构造一个ByteArrayOutputStream
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		//设置一个缓冲区
		byte[] buffer = new byte[1024];
		int len = 0;
		//判断输入流长度是否等于-1，即非空
		while( (len=inStream.read(buffer)) != -1 )
		{
			//把缓冲区的内容写入到输出流中，从0开始读取，长度为len
			outStream.write(buffer, 0, len);
		}
		//关闭输入流
		inStream.close();
		return outStream.toByteArray();
	}
}

2.Android中显示图片：

(1)ImageShowActivity.java

public class ImageShowActivity extends Activity 
{
	private static final String TAG = "ImageShowActivity";
    private EditText pathText;
    private ImageView imageView;
    
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //得到EditText，ImageView与Button
        pathText = (EditText) this.findViewById(R.id.urlpath);
        imageView = (ImageView) this.findViewById(R.id.imageView);        
        Button button = (Button)this.findViewById(R.id.button);
        //设置Button监听
        button.setOnClickListener(new View.OnClickListener() 
        {
			@Override
			public void onClick(View v) 
			{
				//获取EditText里面的地址
				String path = pathText.getText().toString();
				try 
				{
					//得到图片的二进制数据
					byte[] data = ImageService.getImage(path);
					//图片处理
					Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);//生成位图
					//显示图片	
					imageView.setImageBitmap(bitmap);				
				} 
				catch (Exception e) 
				{
					//出错的时候提示错误信息
					Toast.makeText(ImageShowActivity.this, R.string.error, 1).show();
					//Log里面打印错误信息
					Log.e(TAG, e.toString());
				}
			}
		});
    }
}

(2)编写一个流处理工具类，StreamTool.java

public class StreamTool 
{
	/**
	 * 从输入流里面得到返回为二进制的数据
	 * @param inStream 输入流
	 * @return byte[] 二进制数据
	 * @throws Exception
	 */
	public static byte[] readInputStream(InputStream inStream) throws Exception
	{
		//构造一个ByteArrayOutputStream
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		//设置一个缓冲区
		byte[] buffer = new byte[1024];
		int len = 0;
		//判断输入流长度是否等于-1，即非空
		while( (len=inStream.read(buffer)) != -1 )
		{
			//把缓冲区的内容写入到输出流中，从0开始读取，长度为len
			outStream.write(buffer, 0, len);
		}
		//关闭输入流
		inStream.close();
		return outStream.toByteArray();
	}
}

(3)编写一个图片处理类，打开URL,获取输入流等操作

public class ImageService 
{	
	public static byte[] getImage(String path) throws Exception 
	{
		//构造一个URL对象
		URL url = new URL("http://www.baidu.com/img/baidu_sylogo1.gif");
		//使用openConnection打开URL对象
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		//使用Http协议，设置请求方式为GET
		conn.setRequestMethod("GET");
		//设置链接超时异常，5s
		conn.setConnectTimeout(5 * 1000);
		//通过输入流获取图片数据
		InputStream inStream = conn.getInputStream();
		//返回图片的二进制数据
		return StreamTool.readInputStream(inStream);
	}
}

注意别忘记在AndroidManifest.xml文件中添加访问网络的权限：

<uses-permission android:name="android.permission.INTERNET"/>

3.在Android中显示网页代码：通过滚动条视图(ScrollView)工具显示代码

（1）main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
    <ScrollView
     android:layout_width="fill_parent"
     android:layout_height="fill_parent">
		<TextView  
		    android:layout_width="fill_parent" 
		    android:layout_height="wrap_content" 
		    android:id="@+id/textView"
		/>
    </ScrollView>
</LinearLayout>

(2)与上面显示图片类似

public class MainActivity extends Activity 
{
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        TextView textView = (TextView)this.findViewById(R.id.textView);
        try 
        {
        	textView.setText(HtmlService.getHtml("http://www.sohu.com"));
		} 
        catch (Exception e) 
        {
			Log.e("MainActivity", e.toString());
			Toast.makeText(MainActivity.this, "网络连接失败", 1).show();
		}
    }
}

public class HtmlService 
{
	public static String getHtml(String path) throws Exception 
	{
		URL url = new URL(path);
		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
		conn.setRequestMethod("GET");
		conn.setConnectTimeout(5 * 1000);
		//通过输入流获取html数据
		InputStream inStream = conn.getInputStream();
		//得到html的二进制数据
		byte[] data = StreamTool.readInputStream(inStream);
		String html = new String(data, "gb2312");
		return html;
	}
}

public class StreamTool 
{
	/**
	 * 从输入流中获取数据
	 * @param inStream 输入流
	 * @return
	 * @throws Exception
	 */
	public static byte[] readInputStream(InputStream inStream) throws Exception
	{
		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
		byte[] buffer = new byte[1024];
		int len = 0;
		while( (len=inStream.read(buffer)) != -1 )
		{
			outStream.write(buffer, 0, len);
		}
		inStream.close();
		return outStream.toByteArray();
	}
}