AsyncTask下载网络图片的简单应用

1、imageTest

package lpc.com.asynctaskdemo;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;
import android.widget.ProgressBar;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;

/**
 * Created by Administrator on 2015/12/8.
 */
public class ImageTest extends Activity {

    private ImageView mImageView;
    private ProgressBar mProgressBar;
    private String URL = "http://cdnq.duitang.com/uploads/item/201409/14/20140914172442_sjXYv.jpeg";

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

        mImageView = (ImageView) findViewById(R.id.image);
        mProgressBar = (ProgressBar) findViewById(R.id.progress);
        new MyAsycTask().execute(URL);
    }
    class MyAsycTask extends AsyncTask<String,Void,Bitmap>{

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            mProgressBar.setVisibility(View.VISIBLE);
        }

        @Override
        protected void onPostExecute(Bitmap bitmap) {
            super.onPostExecute(bitmap);
            mProgressBar.setVisibility(View.GONE);
            mImageView.setImageBitmap(bitmap);
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            String url = params[0];
            Bitmap bitmap = null;
            URLConnection connection;
            InputStream is;

            try {
                connection = new URL(url).openConnection();
                is = connection.getInputStream();
                BufferedInputStream bis = new BufferedInputStream(is);
                bitmap = BitmapFactory.decodeStream(bis);

                is.close();
                bis.close();

            } catch (IOException e) {
                e.printStackTrace();
            }
            return bitmap;
        }
    }
}

2、布局文件 image.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/image"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <ProgressBar
        android:id="@+id/progress"
        android:visibility="gone"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

3、Manifest文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="lpc.com.asynctaskdemo">
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".ImageTest">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>

    </application>

</manifest>

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