http://blog.csdn.net/forlong401/article/details/7737571
1.定義handler
private static final int DOWNLOAD_IMAGE_SUCCESS = 0;
private static final int DOWNLOAD_IMAGE_FAILURE = 1;
private ImageView mDetailImageView;
private String mImageUrl;
private Thread mDownloadImageThread;
private Bitmap mDownloadImageBitmap;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(final Message msg) {
switch (msg.what) {
case DOWNLOAD_IMAGE_SUCCESS:{
if (mDownloadImageBitmap != null) {
mDetailImageView.setImageBitmap(mDownloadImageBitmap);
mDetailImageView.setVisibility(View.VISIBLE);
}
break;
}
case DOWNLOAD_IMAGE_FAILURE:{
if (mDownloadImageBitmap != null) {
mDownloadImageBitmap.recycle();
mDownloadImageBitmap = null;
// TODO: should set default image to notice user download failure.
mDetailImageView.setVisibility(View.VISIBLE);
}
break;
}
}
}
};
2.定義runnable
private class DownloadImageRunner implements Runnable {
public void run() {
Message msg = new Message();
msg.what = DOWNLOAD_IMAGE_SUCCESS;
try {
URL url;
url = new URL(mImageUrl);
HttpURLConnection conn;
conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(6000);
conn.setDoInput(true);
conn.setUseCaches(false);
InputStream is = conn.getInputStream();
mDownloadImageBitmap = BitmapFactory.decodeStream(is);
is.close();
} catch (IOException e) {
msg.what = DOWNLOAD_IMAGE_FAILURE;
e.printStackTrace();
} catch (Exception e) {
msg.what = DOWNLOAD_IMAGE_FAILURE;
e.printStackTrace();
}
mHandler.sendMessage(msg);
}
}
3.使用線程
DownloadImageRunner downloadImageRunner = new DownloadImageRunner();
mDownloadImageThread = new Thread(downloadImageRunner);
mDownloadImageThread.start();
4.Activity銷毀時清理記憶體
@Override
public void onDestroy() {
super.onDestroy();
if (mDownloadImageBitmap != null) {
mDownloadImageBitmap.recycle();
mDownloadImageBitmap = null;
}
}
ps:
MainActivity.java
package com.example.newtest;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import org.apache.http.util.ByteArrayBuffer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
public class MainActivity extends Activity {
public Button bTest,bTest2;
private static final int DOWNLOAD_IMAGE_SUCCESS = 0;
private static final int DOWNLOAD_IMAGE_FAILURE = 1;
private ImageView mDetailImageView;
private String mImageUrl="http://lh5.ggpht.com/_mrb7w4gF8Ds/TCpetKSqM1I/AAAAAAAAD2c/Qef6Gsqf12Y/s144-c/_DSC4374%20copy.jpg";
private Thread mDownloadImageThread;
private Bitmap mDownloadImageBitmap;
private Handler mHandler = new Handler() {
@Override
public void handleMessage(final Message msg) {
switch (msg.what) {
case DOWNLOAD_IMAGE_SUCCESS:{
if (mDownloadImageBitmap != null) {
mDetailImageView.setImageBitmap(mDownloadImageBitmap);
mDetailImageView.setVisibility(View.VISIBLE);
}
break;
}
case DOWNLOAD_IMAGE_FAILURE:{
if (mDownloadImageBitmap != null) {
mDownloadImageBitmap.recycle();
mDownloadImageBitmap = null;
// TODO: should set default image to notice user download failure.
mDetailImageView.setVisibility(View.VISIBLE);
}
break;
}
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDetailImageView = (ImageView) findViewById(R.id.imageViewDownload);
bTest = (Button) findViewById(R.id.button1);
bTest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
mImageUrl="http://lh5.ggpht.com/_mrb7w4gF8Ds/TCpetKSqM1I/AAAAAAAAD2c/Qef6Gsqf12Y/s144-c/_DSC4374%20copy.jpg";
DownloadImageRunner downloadImageRunner = new DownloadImageRunner();
mDownloadImageThread = new Thread(downloadImageRunner);
mDownloadImageThread.start();
}
});
bTest2 = (Button) findViewById(R.id.button2);
bTest2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v)
{
mImageUrl="http://lh3.ggpht.com/_lLj6go_T1CQ/TCD8PW09KBI/AAAAAAAAQdc/AqmOJ7eg5ig/s144-c/Juvenile%20Gannet%20despute.jpg";
DownloadImageRunner downloadImageRunner = new DownloadImageRunner();
mDownloadImageThread = new Thread(downloadImageRunner);
mDownloadImageThread.start();
}
});
}
@Override
protected void onDestroy()
{
// TODO Auto-generated method stub
super.onDestroy();
if (mDownloadImageBitmap != null) {
mDownloadImageBitmap.recycle();
mDownloadImageBitmap = null;
}
}
private class DownloadImageRunner implements Runnable {
public void run() {
Message msg = new Message();
msg.what = DOWNLOAD_IMAGE_SUCCESS;
try {
URL url;
url = new URL(mImageUrl);
HttpURLConnection conn;
conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(6000);
conn.setDoInput(true);
conn.setUseCaches(false);
InputStream is = conn.getInputStream();
mDownloadImageBitmap = BitmapFactory.decodeStream(is);
is.close();
} catch (IOException e) {
msg.what = DOWNLOAD_IMAGE_FAILURE;
e.printStackTrace();
} catch (Exception e) {
msg.what = DOWNLOAD_IMAGE_FAILURE;
e.printStackTrace();
}
mHandler.sendMessage(msg);
}
}
}
activity_main.xml:
<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: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_below="@+id/textView1"
android:layout_marginLeft="150dp"
android:layout_marginTop="156dp"
android:layout_toRightOf="@+id/textView1"
android:text="button1" />
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/button1"
android:layout_alignBottom="@+id/button1"
android:layout_centerHorizontal="true"
android:text="button2" />
<ImageView
android:id="@+id/imageViewDownload"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_marginLeft="132dp"
android:layout_toRightOf="@+id/button2"
android:src="@android:drawable/btn_plus" />
</RelativeLayout>
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.newtest"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="17"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_CORSE_LOCATION"/>
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.READ_USER_DICTIONARY" />
<uses-permission android:name="android.permission.WRITE_USER_DICTIONARY" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.CHANGE_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.GET_TASKS"/>
<uses-permission android:name="android.permission.READ_LOGS" />
<uses-permission android:name="android.permission.DISABLE_KEYGUARD" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
<uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.newtest.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>