Java 在 JSON 请求中发送图像

Send Image in JSON request

提问by reiley

I'm using JSONwith RESTapi for using web service.

我使用的是JSON与RESTAPI使用Web服务。

Now I also need to send Images in request. Is it possible?

现在我还需要在请求中发送图像。是否可以？

If yes, what changes do I need to do on client/server side.

如果是，我需要在客户端/服务器端做哪些更改。

And in my Java code, how should I send the image content (do I need to set a content type separately)?

在我的 Java 代码中，我应该如何发送图像内容（是否需要单独设置内容类型）？

回答by Boris Strandjev

You should not send the image itself, but url from which it can be downloaded.

您不应该发送图像本身，而是可以从中下载图像的 url。

Otherwise:

除此以外：

• you make the request too big
• usually you would like to load the images asynchronously, which can only be achieved if the contents are separated from the other data.
• you most probably would not be able to make use of automatic JSON parsing libraries like GSON, Hymanson, or the integrated in the Adnroid SDKAndroidObject

• 你的要求太大了
• 通常您希望异步加载图像，这只有在内容与其他数据分开时才能实现。
• 您很可能无法使用自动 JSON 解析库，例如 GSON、Hymanson 或集成在 Adnroid SDK 中的库AndroidObject

回答by fida1989

Sample app side code that worked for me. You can send image in one valuepair and the json in another valuepair: (Here "uploadedfile" tag defines the valuepair as the path of the image file in sd card during checking in post function, other tags will be considered as text data)

对我有用的示例应用程序端代码。您可以在一个valuepair中发送图像，在另一个valuepair中发送json：（这里“uploadedfile”标签将valuepair定义为检查post功能时sd卡中图像文件的路径，其他标签将被视为文本数据）

List<NameValuePair> values; values = new ArrayList<NameValuePair>();

        System.out.println(Constants.all_datas.get(pos).getBookName());

        values.add(new NameValuePair("uploadedfile",
                Constants.book_image_path
                        + Constants.all_datas.get(pos).getImage()));

        values.add(new NameValuePair("id", Constants.all_datas.get(pos)
                .getBookid() + ""));
        values.add(new NameValuePair("bookname", Constants.all_datas
                .get(pos).getBookName()));
        values.add(new NameValuePair("price", Constants.all_datas.get(
                pos).getPrice()));
        values.add(new NameValuePair("writtername", Constants.all_datas
                .get(pos).getWritterName()));
        values.add(new NameValuePair("publishername",
                Constants.all_datas.get(pos).getPublisherName()));

        post(values);

// Post Function

// 发布功能

public void post(final List<NameValuePair> nameValuePairs) {
        // Setting progressDialog properties
        progressDialog = ProgressDialog.show(CustomBookActivity.this, "",
                "Syncing Book Data...");

        mHandler = new Handler();
        // Function to run after thread
        mUpdateResults = new Runnable() {
            public void run() {

                progressDialog.dismiss();

                // Something

            }
        };
        new Thread() {
            @Override
            public void run() {

                HttpClient httpClient = new DefaultHttpClient();
                HttpContext localContext = new BasicHttpContext();
                HttpPost httpPost = new HttpPost(URL);

                try {
                    MultipartEntity entity = new MultipartEntity(
                            HttpMultipartMode.BROWSER_COMPATIBLE);

                    for (int index = 0; index < nameValuePairs.size(); index++) {
                        if (nameValuePairs.get(index).getName()
                                .equalsIgnoreCase("uploadedfile")) {
                            // If the key equals to "uploadedfile", we use FileBody
                            // to transfer the data
                            entity.addPart(
                                    nameValuePairs.get(index).getName(),
                                    new FileBody(new File(nameValuePairs.get(
                                            index).getValue())));
                        } else {
                            // Normal string data
                            entity.addPart(nameValuePairs.get(index).getName(),
                                    new StringBody(nameValuePairs.get(index)
                                            .getValue()));
                        }
                    }

                    httpPost.setEntity(entity);

                    HttpResponse response = httpClient.execute(httpPost,
                            localContext);
                    HttpEntity result_entity = response.getEntity();
                    String htmlResponse = EntityUtils.toString(result_entity);
                    result = htmlResponse;
                    System.out.println("SYNC:::" + result);
                    // server = true;
                } catch (IOException e) {
                    e.printStackTrace();
                    // server = false;
                }

                // dismiss the progress dialog

                // Calling post function
                mHandler.post(mUpdateResults);

            }
        }.start();

    }

Apache Mime4J, HTTPCore, HTTPMime libary jars need to be added to project

需要将 Apache Mime4J、HTTPCore、HTTPMime 库 jar 添加到项目中

回答by user3483525

The way to do that would be to send it as content inside a HttpPost request as below

这样做的方法是将其作为内容发送到 HttpPost 请求中，如下所示

HttpClient client = new DefaultHttpClient();
HttpPost postRequest = new HttpPost(url);
String body = getMessageBody();
try
{
    postRequest.setEntity(new StringEntity(body, "UTF8"));
    postRequest.setHeader("Content-Type", "application/x-www-form-urlencoded");
    HttpResponse response = client.execute(postRequest);
    return response;
} catch (UnsupportedEncodingException e)
{
    e.printStackTrace();
} catch (ClientProtocolException e)
{
    e.printStackTrace();
} catch (IOException e)
{
    e.printStackTrace();
}

The way you would string encode the image would be to do the following.

您对图像进行字符串编码的方式是执行以下操作。

BufferedImage img = ImageIO.read(new File("filename.jpg"));             
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(img, "jpg", baos);
baos.flush();
Base64 base = new Base64(false);
String encodedImage = base.encodeToString(baos.toByteArray());
baos.close();
encodedImage = java.net.URLEncoder.encode(encodedImage, "ISO-8859-1");

Good luck

祝你好运

回答by Francesco verheye

I use this code in my AsyncTask:

我在 AsyncTask 中使用此代码：

@Override
protected String doInBackground(String... str) {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
    String encodedImage = bitmapToString(mBitmap);

    ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
    nameValuePairs.add(new BasicNameValuePair("data", encodedImage));

    try {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(
                "http://192.168.0.107:8300/upload/upload");
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse response = httpclient.execute(httppost);
        String the_string_response = convertResponseToString(response);
        return the_string_response;
    } catch (Exception e) {
        System.out.println("Error in http connection " + e.toString());
        return "error";
    }
}

public String bitmapToString(Bitmap bitmap) {
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
    byte[] b = baos.toByteArray();
    String temp = null;
    try {
        System.gc();
        temp = Base64.encodeToString(b, Base64.DEFAULT);
    } catch (Exception e) {
        e.printStackTrace();
    } catch (OutOfMemoryError e) {
        baos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 50, baos);
        b = baos.toByteArray();
        temp = Base64.encodeToString(b, Base64.DEFAULT);
        Log.e("PictureDemo", "Out of memory error catched");
    }
    return temp;
}

private String convertResponseToString(HttpResponse response)
        throws IllegalStateException, IOException {

    String res = "";
    StringBuffer buffer = new StringBuffer();
    inputStream = response.getEntity().getContent();
    int contentLength = (int) response.getEntity().getContentLength();
    if (contentLength < 0) {
    } else {
        byte[] data = new byte[512];
        int len = 0;
        try {
            while (-1 != (len = inputStream.read(data))) {
                buffer.append(new String(data, 0, len));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            inputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        res = buffer.toString();
    }
    return res;
}