Sharedpreferences (3)-accessing images

Mainactivity is as follows:

Package CC. SP; import Java. io. bytearrayinputstream; import Java. io. bytearrayoutputstream; import android. OS. bundle; import android. util. base64; import android. view. view; import android. view. view. onclicklistener; import android. widget. button; import android. widget. imageview; import android. app. activity; import android. content. context; import android. content. sharedpreferences; import android. content. sharedpreferences. editor; import android. graphics. bitmap; import android. graphics. bitmap. compressformat; import android. graphics. bitmapfactory;/*** demo Description: * using sharedpreferences to access images *** references: * 1 http://blog.csdn.net/tangnengwu/article/details/37881087 * 2 http://blog.csdn.net/lfdfhl/article/details/37742775 * 3 http://blog.csdn.net/lfdfhl/article/details/17998469 * 4 http://blog.csdn.net/lfdfhl/article/details/10961459 * Thank you very much */public class mainactivity extends activity {private button msavebutton; private button mgetbutton; private imageview mimageview; @ overrideprotected void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. main); Init ();} private void Init () {msavebutton = (button) findviewbyid (R. id. savebutton); msavebutton. setonclicklistener (New onclicklistener () {@ overridepublic void onclick (view) {savebitmaptosharedpreferences () ;}}); mgetbutton = (button) findviewbyid (R. id. getbutton); mgetbutton. setonclicklistener (New onclicklistener () {@ overridepublic void onclick (view) {getbitmapfromsharedpreferences () ;}}); mimageview = (imageview) findviewbyid (R. id. imageview);}/*** convert bitmap to a string and save it to sharedpreferences. ** Note: * do not select compressformat when compressing an image to the output stream. JPEG and PNG. Otherwise, the image has a black background. * For details, see reference 2 */private void savebitmaptosharedpreferences () {Bitmap bitmap = bitmapfactory. decoderesource (getresources (), R. drawable. ic_launcher); // Step 1: compress bitmap to bytearrayoutputstreambytearrayoutputstream bytearrayoutputstream (); bitmap. compress (compressformat. PNG, 80, bytearrayoutputstream); // Step 2: Convert the data in the byte array output stream to the string stringbyte [] bytearray = bytearrayoutputstream. tobytearray (); string imagestring = new string (base64.encodetostring (bytearray, base64.default); // Step 3: Keep the string to inclusharedpreferences = getsharedpreferences ("testsp", context. mode_private); Editor editor = sharedpreferences. edit (); Editor. putstring ("image", imagestring); Editor. commit ();}/*** retrieve bitmap */private void getbitmapfromsharedpreferences () {sharedpreferences = getsharedpreferences ("testsp", context. mode_private); // Step 1: Obtain the bitmapstring imagestring = sharedpreferences in the string format. getstring ("image", ""); // Step 2: Use base64 to convert the string to bytearrayinputstreambyte [] bytearray = base64.decode (imagestring, base64.default ); bytearrayinputstream = new bytearrayinputstream (bytearray); // Step 3: Use bytearrayinputstream to generate bitmapbitmap bitmap = bitmapfactory. decodestream (bytearrayinputstream); mimageview. setimagebitmap (Bitmap );}}

Main. XML is as follows:

<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"> <button Android: id = "@ + ID/savebutton" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: text = "Save the image to sharedpreferences" Android: layout_centerhorizontal = "true" Android: layout_margintop = "25dip"/> <button Android: Id = "@ + ID/getbutton" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: text = "get an image from sharedpreferences" Android: layout_centerhorizontal = "true" Android: layout_margintop = "80dip"/> <imageview Android: id = "@ + ID/imageview" Android: layout_width = "wrap_content" Android: layout_height = "wrap_content" Android: layout_centerinparent = "true"/> </relativelayout>