android 下载保存图片

引用：http://www.linuxidc.com/Linux/2011-06/37233.htm

1.java代码，下载图片的主程序

先实现显示图片，然后点击下载图片按钮，执行下载功能。

从网络上取得的图片，生成Bitmap时有两种方法，一种是先转换为byte[]，再生成bitmap；一种是直接用InputStream生成bitmap。

publicclassAndroidTest2_3_3extendsActivity{
privatefinalstaticStringTAG="AndroidTest2_3_3";
privatefinalstaticStringALBUM_PATH
=Environment.getExternalStorageDirectory()+"/download_test/";
privateImageViewimageView;
privateButtonbtnSave;
privateProgressDialogmyDialog=null;
privateBitmapbitmap;
privateStringfileName;
privateStringmessage;
@Override
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
imageView=(ImageView)findViewById(R.id.imgSource);
btnSave=(Button)findViewById(R.id.btnSave);
StringfilePath="http://hi.csdn.net/attachment/201105/21/134671_13059532779c5u.jpg";
fileName="test.jpg";
try{
////////////////取得的是byte数组,从byte数组生成bitmap
byte[]data=getImage(filePath);
if(data!=null){
bitmap=BitmapFactory.decodeByteArray(data,0,data.length);//bitmap
imageView.setImageBitmap(bitmap);//displayimage
}else{
Toast.makeText(AndroidTest2_3_3.this,"Imageerror!",1).show();
}
////////////////////////////////////////////////////////
//********取得的是InputStream，直接从InputStream生成bitmap***********/
bitmap=BitmapFactory.decodeStream(getImageStream(filePath));
if(bitmap!=null){
imageView.setImageBitmap(bitmap);//displayimage
}
//********************************************************************/
Log.d(TAG,"setimage...");
}catch(Exceptione){
Toast.makeText(AndroidTest2_3_3.this,"Newworkerror!",1).show();
e.printStackTrace();
}
//下载图片
btnSave.setOnClickListener(newButton.OnClickListener(){
publicvoidonClick(Viewv){
myDialog=ProgressDialog.show(AndroidTest2_3_3.this,"保存图片","图片正在保存中，请稍等...",true);
newThread(saveFileRunnable).start();
}
});
}
/**
*Getimagefromnewwork
*@parampathThepathofimage
*@returnbyte[]
*@throwsException
*/
publicbyte[]getImage(Stringpath)throwsException{
URLurl=newURL(path);
HttpURLConnectionconn=(HttpURLConnection)url.openConnection();
conn.setConnectTimeout(5*1000);
conn.setRequestMethod("GET");
InputStreaminStream=conn.getInputStream();
if(conn.getResponseCode()==HttpURLConnection.HTTP_OK){
returnreadStream(inStream);
}
returnnull;
}
/**
*Getimagefromnewwork
*@parampathThepathofimage
*@returnInputStream
*@throwsException
*/
publicInputStreamgetImageStream(Stringpath)throwsException{
URLurl=newURL(path);
HttpURLConnectionconn=(HttpURLConnection)url.openConnection();
conn.setConnectTimeout(5*1000);
conn.setRequestMethod("GET");
if(conn.getResponseCode()==HttpURLConnection.HTTP_OK){
returnconn.getInputStream();
}
returnnull;
}
/**
*Getdatafromstream
*@paraminStream
*@returnbyte[]
*@throwsException
*/
publicstaticbyte[]readStream(InputStreaminStream)throwsException{
ByteArrayOutputStreamoutStream=newByteArrayOutputStream();
byte[]buffer=newbyte[1024];
intlen=0;
while((len=inStream.read(buffer))!=-1){
outStream.write(buffer,0,len);
}
outStream.close();
inStream.close();
returnoutStream.toByteArray();
}
/**
*保存文件
*@parambm
*@paramfileName
*@throwsIOException
*/
publicvoidsaveFile(Bitmapbm,StringfileName)throwsIOException{
FiledirFile=newFile(ALBUM_PATH);
if(!dirFile.exists()){
dirFile.mkdir();
}
FilemyCaptureFile=newFile(ALBUM_PATH+fileName);
BufferedOutputStreambos=newBufferedOutputStream(newFileOutputStream(myCaptureFile));
bm.compress(Bitmap.CompressFormat.JPEG,80,bos);
bos.flush();
bos.close();
}
privateRunnablesaveFileRunnable=newRunnable(){
@Override
publicvoidrun(){
try{
saveFile(bitmap,fileName);
message="图片保存成功！";
}catch(IOExceptione){
message="图片保存失败！";
e.printStackTrace();
}
messageHandler.sendMessage(messageHandler.obtainMessage());
}
};
privateHandlermessageHandler=newHandler(){
@Override
publicvoidhandleMessage(Messagemsg){
myDialog.dismiss();
Log.d(TAG,message);
Toast.makeText(AndroidTest2_3_3.this,message,Toast.LENGTH_SHORT).show();
}
};
}

2.main.xml文件，只有一个button和一个ImageView

<?xmlversion="1.0"encoding="utf-8"?>
<LinearLayoutxmlns:Android="http://schemas.android.com/apk/res/android"
Android:orientation="vertical"
Android:layout_width="fill_parent"
Android:layout_height="fill_parent"
>
<Button
Android:id="@+id/btnSave"
Android:layout_width="wrap_content"
Android:layout_height="wrap_content"
Android:text="保存图片"
/>
<ImageView
Android:id="@+id/imgSource"
Android:layout_width="wrap_content"
Android:layout_height="wrap_content"
Android:adjustViewBounds="true"
/>
</LinearLayout>

3.在mainfest文件中增加互联网权限和写sd卡的权限

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

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