我使用“Android Studio”构建一个Android应用程序，在压缩后上传图像并使用base64对其进行编码，并以字符串格式将其保存在服务器上，然后下载（PHP使用JSON发送图像字符串）。解码图像后，某些图像正常显示，但其他图像不显示（大多数图像不显示）。
我搜索并尝试了许多已发布的解决方案，但没有任何正常工作，请任何帮助。
这是我的android java代码：
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final int RESULT_LOAD_IMAGE = 1;
ImageView imagetoupload, imagetodownload;
Button up_bt, dw_bt;
EditText etuploadname, etdownname;
String get_etdownname, down_user_pic, encodedImage;
Bitmap decodedByte;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imagetoupload = (ImageView) findViewById(R.id.imagetoupload);
imagetodownload = (ImageView) findViewById(R.id.imagetodownload);
up_bt = (Button) findViewById(R.id.up_bt);
dw_bt = (Button) findViewById(R.id.dw_bt);
etuploadname = (EditText) findViewById(R.id.etuploadname);
etdownname = (EditText) findViewById(R.id.etdownname);
up_bt.setOnClickListener(this);
dw_bt.setOnClickListener(this);
imagetoupload.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.imagetoupload:
Intent galleryIntent = new Intent(Intent.ACTION_PICK, MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
startActivityForResult(galleryIntent, RESULT_LOAD_IMAGE);
break;
case R.id.up_bt:
Bitmap image = ((BitmapDrawable) imagetoupload.getDrawable()).getBitmap();
new UploadImage(image, etuploadname.getText().toString()).execute();
break;
case R.id.dw_bt:
get_etdownname = etdownname.getText().toString();
DownloadBackGround b = new DownloadBackGround();
b.execute(get_etdownname);
break;
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && data != null) {
Uri selectedimage = data.getData();
imagetoupload.setImageURI(selectedimage);
}
}
private class UploadImage extends AsyncTask<Void, Void, Void> {
Bitmap image;
String name;
public UploadImage(Bitmap image, String name) {
this.image = image;
this.name = name;
}
@SuppressWarnings("ResourceType")
@Override
protected Void doInBackground(Void... params) {
String data = "";
int tmp;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.PNG, 100, byteArrayOutputStream);
encodedImage = Base64.encodeToString(byteArrayOutputStream.toByteArray(), Base64.DEFAULT);
Log.d("Me", encodedImage);
try {
URL url = new URL("------ my url -------");
String urlParams = "image=" + encodedImage + "&name=" + name;
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setDoOutput(true);
OutputStream os = httpURLConnection.getOutputStream();
os.write(urlParams.getBytes());
os.flush();
os.close();
InputStream is = httpURLConnection.getInputStream();
while ((tmp = is.read()) != -1) {
data += (char) tmp;
}
is.close();
httpURLConnection.disconnect();
Log.e("Me", data + "");
// return data;
} catch (IOException e) {
e.printStackTrace();
// return "Exception: " + e.getMessage();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
Toast.makeText(getApplicationContext(), "image uploaded", Toast.LENGTH_LONG).show();
byte[] decodedString = Base64.decode(encodedImage.getBytes(), Base64.DEFAULT);
Bitmap decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
imagetodownload.setImageBitmap(decodedByte);
imagetodownload.setImageBitmap(decodedByte);
}
}
////////////////////////////download /////////////////////////////
class DownloadBackGround extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... params) {
String name_pic = params[0];
try {
URL url = new URL("------ my url ------");
String urlParams = "name=" + name_pic;
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setDoOutput(true);
OutputStream os = httpURLConnection.getOutputStream();
os.write(urlParams.getBytes());
os.flush();
os.close();
InputStream is = httpURLConnection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
StringBuilder buffer = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line);
}
is.close();
httpURLConnection.disconnect();
return buffer.toString();
} catch (MalformedURLException e) {
e.printStackTrace();
return "Exception: " + e.getMessage();
} catch (IOException e) {
e.printStackTrace();
return "Exception: " + e.getMessage();
}
}
@Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (result.equals("2")) {
Log.e("Me", "No picture in this name");
} else {
Log.e("Me", result);
try {
JSONObject parentObject = new JSONObject(result);
JSONArray parentArray = parentObject.getJSONArray("result");
JSONObject finalObject = parentArray.getJSONObject(0);
down_user_pic = finalObject.getString("pic_byte");
} catch (JSONException e) {
e.printStackTrace();
}
//// decode picture and set here
Log.d("Me", down_user_pic);
byte[] decodedString = Base64.decode(down_user_pic.getBytes(), Base64.DEFAULT);
decodedByte = BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
imagetodownload.setImageBitmap(decodedByte);
}
}
}
///////////////////////////////下载/////////////// ///////////
这是我上传的php代码：
<?php require "init.php";
// Check connection
if (!$con) {
die("Connection failed: " . mysqli_connect_error());
}
$image = $_REQUEST["image"];
$name = $_POST["name"];
$image = str_replace(" ", "+", $image);
$id= uniqid();
//$decodedImage = base64_decode("$image");
$sql = "INSERT INTO `pictures` (`id`, `pic_id`, `pic_byte`) VALUES ('".$id."', '".$name."', '".$image."');";
if(!mysqli_query($con, $sql)){
}
?>
这是我下载的PHP代码：
<?php
require "init.php";
// Check connection
if (!$con) {
die("Connection failed: " . mysqli_connect_error());
}
$name = $_POST["name"];
$id= uniqid();
$sql = "SELECT * FROM pictures WHERE `pic_id`='".$name."'";
$res = mysqli_query($con,$sql);
$result = array();
while($row = mysqli_fetch_array($res)){
array_push($result,
array('pic_byte'=>$row[2]));
}
$string1 = '{"result":[]}';
$string2 = json_encode(array("result"=>$result));
$pos = strspn($string1 ^ $string2, "\0");
if($string1[$pos]=="" && $string2[$pos] == ""){
echo "2";
}else {
echo $string2;
}
?>
这个logcat显示：
04-20 11:39:31.184 18472-18472/com.example.aly.updownpic D/dalvikvm: GC_FOR_ALLOC freed 1765K, 44% free 7473K/13340K, paused 17ms, total 21ms
04-20 11:39:31.184 18472-18472/com.example.aly.updownpic I/dalvikvm-heap: Grow heap (frag case) to 13.192MB for 4080016-byte allocation
04-20 11:39:31.234 18472-18472/com.example.aly.updownpic D/skia: --- decoder->decode returned false
更新
我使用的是JPEG，但不到一半的图片显示
