android图片上传

最近项目上需要图片上传功能，所以开始查询相关资料，并终于实现。

android这边使用得是android studio,后台处理这边使用得是eclipse中servlet

首先是布局：（比较简单）

<?xml version="1.0" encoding="utf-8"?>

然后是activity

相册和拍照2种方式

 final CharSequence[] items = {"相册", "拍照"};        AlertDialog.Builder dlg = new AlertDialog.Builder(UploadActivity.this);        dlg.setTitle("添加图片");        dlg.setTitle("添加图片");        dlg.setItems(items, new DialogInterface.OnClickListener() {             public void onClick(DialogInterface dialog, int item) {                 // 这里item是根据选择的方式，                 if (item == 0) {                     Intent galleryIntent = new Intent(Intent.ACTION_PICK,                             android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);                     startActivityForResult(galleryIntent, RESULT_LOAD_IMG);                     } else {                       try {                         Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);                         startActivityForResult(intent, 0);                         } catch (Exception e) {                         e.printStackTrace();                         }                      }              }         }).create();                 dlg.show();

重写onActivityResult方法

@Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        super.onActivityResult(requestCode, resultCode, data);        try {            if (requestCode == RESULT_LOAD_IMG && resultCode == RESULT_OK && null != data) {                Uri selectedImage = data.getData();                String[] filePathColumn = { MediaStore.Images.Media.DATA };                // 获取游标                Cursor cursor = getContentResolver().query(selectedImage, filePathColumn, null, null, null);                cursor.moveToFirst();                int columnIndex = cursor.getColumnIndex(filePathColumn[0]);                imgPath = cursor.getString(columnIndex);                cursor.close();                ImageView imgView = (ImageView) findViewById(R.id.imageView);                imgView.setImageBitmap(BitmapFactory.decodeFile(imgPath));            } else if(requestCode ==0){                Bundle bundle = data.getExtras();                bitmap = (Bitmap) bundle.get("data");                ImageView imgView = (ImageView) findViewById(R.id.imageView);                imgView.setImageBitmap(bitmap);                encodeImagetoString(bitmap);            } else{                Toast.makeText(this, "You haven't picked Image",                        Toast.LENGTH_LONG).show();            }        } catch (Exception e) {            Toast.makeText(this, "Something went wrong", Toast.LENGTH_LONG).show();        }    }

将图片转64编码

private void encodeImagetoString( Bitmap b) {        new AsyncTask() {            protected void onPreExecute() {            };            @Override            protected String doInBackground(Void... params) {                ByteArrayOutputStream stream = new ByteArrayOutputStream();                // 压缩图片                bitmap.compress(Bitmap.CompressFormat.PNG, 50, stream);                byte[] byte_arr = stream.toByteArray();                // Base64图片转码为String                encodedString = Base64.encodeToString(byte_arr, 0);                return "";            }            @Override            protected void onPostExecute(String msg) {                prgDialog.setMessage("Calling Upload");                // 将转换后的图片添加到上传的参数中                params.put("image", encodedString);                Toast.makeText(getApplicationContext(), encodedString.length()+"", Toast.LENGTH_LONG).show();                params.put("filename", "bbb");                // 上传图片                imageUpload();            }        }.execute(null, null, null);    }

上传图片

public void imageUpload() {        prgDialog.setMessage("Invoking JSP");        String url = AppConfig.URLS.UPLOADPIC;        AsyncHttpClient client = new AsyncHttpClient();        client.post(url, params, new AsyncHttpResponseHandler() {            @Override            public void onSuccess(int statusCode, Header[] headers, byte[] bytes) {                prgDialog.hide();                Toast.makeText(getApplicationContext(), "upload success", Toast.LENGTH_LONG).show();            }            @Override            public void onFailure(int statusCode, Header[] headers, byte[] bytes, Throwable throwable) {                prgDialog.hide();                if (statusCode == 404) {                    Toast.makeText(getApplicationContext(),                            "Requested resource not found", Toast.LENGTH_LONG).show();                }                // 当 Http 响应码'500'                else if (statusCode == 500) {                    Toast.makeText(getApplicationContext(),                            "Something went wrong at server end", Toast.LENGTH_LONG).show();                }                // 当 Http 响应码 404, 500                else {                    Toast.makeText(                            getApplicationContext(), "Error Occured n Most Common Error: n1. Device " +                                    "not connected to Internetn2. Web App is not deployed in App servern3." +                                    " App server is not runningn HTTP Status code : "                                    + statusCode, Toast.LENGTH_LONG).show();                }            }        });    }

这段代码使用到了android-async-http-1.4.8.jar,其中使用时，一个Header[]类找不到，因此，经过查询后，解决办法如下：

useLibrary 'org.apache.http.legacy'  此段代码加build.gradle到配置文件中即可

最后，这个所使用到的权限：

这样，android端就完成了，就差java后台接受上传至服务器中。

接下来是Java后台，我这里的后台在Tomcat中运行

UploadImage(servlet)

@WebServlet("/UploadImage")public class UploadImage extends HttpServlet {private static final long serialVersionUID = 1L;           /**     * @see HttpServlet#HttpServlet()     */    public UploadImage() {        super();        // TODO Auto-generated constructor stub    }/** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubSystem.out.println("get");}/** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// TODO Auto-generated method stubrequest.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");String imgEncodedStr = request.getParameter("image");String fileName = request.getParameter("filename");System.out.println("Filename: "+ fileName);//System.out.println(imgEncodedStr);if(imgEncodedStr != null){  convertStringtoImage(imgEncodedStr, fileName);  System.out.print("Image upload complete, Please check your directory"); } else{  System.out.print("图片为空"); }} public  void convertStringtoImage(String encodedImageStr, String fileName) {   try {   // Base64解码图片   byte[] imageByteArray = Base64.decodeBase64(encodedImageStr);    //   FileOutputStream imageOutFile = new FileOutputStream("D:/jhglpic/uploads/" + fileName+".jpg");   imageOutFile.write(imageByteArray);    imageOutFile.close();    System.out.println("成功");  } catch (FileNotFoundException fnfe) {   System.out.println("Image Path not found" + fnfe);  } catch (IOException ioe) {   System.out.println("Exception while converting the Image " + ioe);  } }}

这样就完成了，在测试时发现几个问题

使用了jar包后，有个Header[]类找不到，已经在文章种提到解决办法
测试时，使用相册中微信保存得照片、截图都可以成功上传，但是使用本机拍摄得照片时，后台接受不到图片信息。对比2两者得区别，发现本机拍摄得照片有4M大小左右，可能就是太大了，需要对图片进行处理，如下：

 options = new BitmapFactory.Options();                options.inJustDecodeBounds = true; // 只获取图片的大小信息，而不是将整张图片载入在内存中，避免内存溢出                BitmapFactory.decodeFile(imgPath, options);                int inSampleSize = 2;                int height = options.outHeight;                int width= options.outWidth;                int minLen = Math.min(height, width); // 原图的最小边长                if(minLen > 100) { // 如果原始图像的最小边长大于100dp（此处单位我认为是dp，而非px）                    float ratio = (float)minLen / 100.0f; // 计算像素压缩比例                    inSampleSize = (int)ratio;                }                options.inJustDecodeBounds = false;                options.inSampleSize = inSampleSize; // 设置为刚才计算的压缩比例                bitmap = BitmapFactory.decodeFile(imgPath,                        options);                ByteArrayOutputStream stream = new ByteArrayOutputStream();                // 压缩图片                bitmap.compress(Bitmap.CompressFormat.PNG, 50, stream);                byte[] byte_arr = stream.toByteArray();                // Base64图片转码为String                encodedString = Base64.encodeToString(byte_arr, 0);                bitmap.recycle();

最后附有 UploadActivity类

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