【移动应用开发技术】利用HTTP从网络下载图片并显示

【移动应用开发技术】利用HTTP从网络下载图片并显示

利用Http从指定地址下载图片并显示出来/**

*

简单的封装一个http下载类

*

*/

public

class

HttpUtils

{

//指定一张图片

private

String

URL_PATH

=

"/files/RemoteFiles/20140420/095185001.jpg";

public

HttpUtils(){

}

//返回一个byte类型的数组

public

byte[]

getData(){

HttpClient

httpClient

=

new

DefaultHttpClient();

HttpGet

httpGet

=

new

HttpGet(URL_PATH);

HttpResponse

httpResponse

=

null;

try

{

httpResponse

=

httpClient.execute(httpGet);

if

(httpResponse.getStatusLine().getStatusCode()

==

200)

{

byte[]

data

=

EntityUtils.toByteArray(httpResponse

.getEntity());

return

data;

}

}

catch

(Exception

e)

{

e.printStackTrace();

}

return

null;

}

}//用于调用的avtivity

public

class

MainActivity

extends

Activity

{

private

Button

btnDown;

private

ImageView

img;

private

ProgressDialog

dialog;

@Override

protected

void

onCreate(Bundle

savedInstanceState)

{

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

btnDown

=

(Button)

findViewById(R.id.button1);

img

=

(ImageView)

findViewById(R.id.p_w_picpathView1);

dialog

=

new

ProgressDialog(this);

dialog.setTitle("提示信息");

dialog.setMessage("正在下载中，请稍后...");

dialog.setCancelable(false);

btnDown.setOnClickListener(new

View.OnClickListener()

{

@Override

public

void

onClick(View

v)

{

new

Thread(mRunnable).start();

dialog.show();

}

});

}

private

Runnable

mRunnable

=

new

Runnable()

{

@Override

public

void

run()

{

//

TODO

Auto-generated

method

stub

byte[]

data

=

new

HttpUtils().getData();

Message

msg

=

Message.obtain();

msg.obj

=

data;

msg.what

=

0x001;

handler.sendMessage(msg);

}

};

private

Handler

handler

=

new

Handler()

{

//

在Handler中获取消息，重写handleMessage()方法

@Override

public

void

handleMessage(Message

msg)

{

//

判断消息码是否为0x001

if(msg.what

==

0x001){

byte[]

data=(byte[])msg.obj;

Bitmap

bmp=BitmapFactory.decodeByteArray(data,

0,

data.length);

img.setImageBitmap(bmp);

dialog.dismiss();

}

}

};

}//布局

.xml

很简单只有两个控件

<RelativeLayout

xmlns:android="/apk/res/android"

xmlns:tools="/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingBottom="@dimen/activity_vertical_margin"

android:paddingLeft="@dimen/activity_horizontal_margin"

android:paddingRight="@dimen/activity_horizontal_margin"

android:paddingTop="@dimen/activity_vertical_margin"

tools:context=".MainActivity"

>

<Button

android:id="@+id/button1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentBottom="true"

android:layout_centerHorizontal="true"

android:layout_marginBottom="54dp"

android:text="下载"

/>

<ImageView

android:id="@+id/p_w_picpathView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentTop="true"

android:layout_centerHorizontal="true"

android:layout_marginTop="79d