小案例

网络图片查看器

1.布局文件

<LinearLayout 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:orientation="vertical"

    tools:context=".MainActivity" >

 

    <ImageView

        android:id="@+id/iv_beauty"

        android:layout_width="match_parent"

        android:layout_height="match_parent"

        android:layout_weight="100" />

 

    <EditText

        android:id="@+id/et_path"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:singleLine="true"

        android:text="http://a.hiphotos.baidu.com/album/w%3D2048/sign=0a938b00d53f8794d3ff4f2ee6230cf4/faedab64034f78f06fe0f24b78310a55b2191c9a.jpg" />

 

    <Button

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:onClick="watch"

        android:text="浏览" />

 

</LinearLayout>

2.Activity 

public class MainActivity extends Activity {

 

private ImageView iv_beauty;

private EditText et_path;

 

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

this.iv_beauty = (ImageView) this.findViewById(R.id.iv_beauty);

this.et_path = (EditText) this.findViewById(R.id.et_path);

}

 

public void watch(View view) {

String path = this.et_path.getText().toString().trim();

if (TextUtils.isEmpty(path)) {

Toast.makeText(this, "路径不能为空", 0).show();

} else {

try {

URL url = new URL(path);

HttpURLConnection connection = (HttpURLConnection) url

.openConnection();

// 设置请求方式

connection.setRequestMethod("GET");

// 设置超时时间

connection.setConnectTimeout(10000);

 

// connection.setRequestProperty(field, newValue)

 

int code = connection.getResponseCode();

if (code == 200) {

InputStream is = connection.getInputStream();

Bitmap bitmap = BitmapFactory.decodeStream(is);

this.iv_beauty.setImageBitmap(bitmap);

 

} else {

Toast.makeText(this, "获取图片失败", 0).show();

}

} catch (Exception e) {

e.printStackTrace();

Toast.makeText(this, "读取图片失败", 0).show();

}

 

}

}

}

 

3.授权

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

代码只能在4.0以下运行，4.0以上会抛 android.os.NetworkOnMainThreadException

 

从 Android 2.3 开始提供了一个新的类 StrictMode，该类可以用于捕捉发生在应用程序主线程中耗时的磁盘、网络访问或函数调用，可以帮助开发者改进程序，使主线程处理 UI 和动画在磁盘读写和网络操作时变得更平滑，避免主线程被阻塞。

 

 

网络html查看器

1.布局文件

<LinearLayout 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:orientation="vertical"

    tools:context=".MainActivity" >

 

    <EditText

        android:id="@+id/et_path"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:hint="请输入网址" />

 

    <Button

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:hint="确定"

        android:onClick="click" />

 

    <ScrollView

        android:layout_width="match_parent"

        android:layout_height="match_parent" >

 

        <TextView

            android:id="@+id/tv_content"

            android:layout_width="wrap_content"

            android:layout_height="wrap_content" />

    </ScrollView>

 

</LinearLayout>

2.Activity

public class MainActivity extends Activity {

 

protected static final int ERROR = 0;

protected static final int SHOW_CONTENT = 1;

private EditText et_path;

private TextView tv_content;

 

private Handler handler = new Handler() {

public void handleMessage(android.os.Message msg) {

switch (msg.what) {

case ERROR:

Toast.makeText(MainActivity.this, "获取网页信息失败",

Toast.LENGTH_SHORT).show();

break;

case SHOW_CONTENT:

tv_content.setText((String) msg.obj);

break;

}

 

};

 

};

 

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

this.et_path = (EditText) this.findViewById(R.id.et_path);

this.tv_content = (TextView) this.findViewById(R.id.tv_content);

}

 

public void click(View view) {

final String path = this.et_path.getText().toString().trim();

if (TextUtils.isEmpty(path)) {

Toast.makeText(this, "路径不能为空！", Toast.LENGTH_SHORT).show();

} else {

new Thread() {

 

public void run() {

try {

URL url = new URL(path);

HttpURLConnection conn = (HttpURLConnection) url

.openConnection();

conn.setRequestMethod("GET");

conn.setReadTimeout(5000);

int code = conn.getResponseCode();

if (code == 200) {

InputStream is = conn.getInputStream();

String result = StreamTool.readInputStream(is);

Message msg = new Message();

msg.what = SHOW_CONTENT;

msg.obj = result;

handler.sendMessage(msg);

} else {

Message msg = new Message();

msg.what = ERROR;

handler.sendMessage(msg);

}

} catch (Exception e) {

e.printStackTrace();

Message msg = new Message();

msg.what = ERROR;

handler.sendMessage(msg);

}

};

 

}.start();

}

}

 

}

 

3.工具类

public class StreamTool {

 

public static String readInputStream(InputStream is) {

try {

 

ByteArrayOutputStream out = new ByteArrayOutputStream();

int length = 0;

byte[] buffer = new byte[1024];

if ((length = is.read(buffer)) != -1) {

out.write(buffer, 0, length);

}

byte[] result = out.toByteArray();

return new String(result);

} catch (Exception e) {

// TODO: handle exception

}

return "转换失败";

}

 

}

 

4.授权

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