加载网络图片

1.主工程

package com.fsg.thinkpad.myapplication;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.TextView;

import java.net.URL;

public class NetworkActivity extends AppCompatActivity {
TextView textView;
EditText editText;
Button button;
ImageView mImageView;

String mImageUrl;

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

textView=(TextView)findViewById(R.id.textView4);
editText=(EditText)findViewById(R.id.editText2);
button=(Button)findViewById(R.id.buttonGet);
mImageView=(ImageView)findViewById(R.id.imageView);

mImageUrl="http://img4.douban.com/view/photo/photo/public/p2266866059.jpg";

/* button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new Thread(new Runnable() {
@Override
public void run() {
final Drawable drawable=loadImageFromNetwork("http://img4.douban.com/view/photo/photo/public/p2266866059.jpg");
mImageView.post(new Runnable() {
@Override
public void run() {
mImageView.setImageDrawable(drawable);
}
});

}
}).start();
}
});
*/
new DownloadImageTask().execute(mImageUrl);
}

private Drawable loadImageFromNetwork(String imageUrl) {
Drawable drawable=null;
try {
drawable=Drawable.createFromStream(new URL(imageUrl).openStream(),"p2266866059.jpg");
}catch (Exception e){
Log.d("GetImageFromNetWork", e.getMessage());
}
if (drawable==null){
Log.d("GetImageFromNetWork", "null drawable");
}else {
Log.d("GetImageFromNetWork", "success");
}
return drawable;
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_network, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();

//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}

return super.onOptionsItemSelected(item);
}

private class DownloadImageTask extends AsyncTask<String,Void,Drawable> {

@Override
protected Drawable doInBackground(String... urls) {
return loadImageFromNetwork(urls[0]);
}
protected void onPostExecute(Drawable result) {
mImageView.setImageDrawable(result);
}

}
}
2.布局文件
<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="com.fsg.thinkpad.myapplication.NetworkActivity">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:id="@+id/textView4"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />

<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="textPostalAddress"
android:ems="10"
android:id="@+id/editText2"
android:layout_below="@+id/textView4"
android:layout_alignRight="@+id/textView4"
android:layout_alignEnd="@+id/textView4" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="获取"
android:id="@+id/buttonGet"
android:layout_alignTop="@+id/editText2"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />

<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imageView"
android:src="@mipmap/b"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true" />

</RelativeLayout>