android - 如何将 HTTP 多部分请求正文放在一起以便与图像一起发送一些字符串参数

Question

我正在尝试构建 http 请求正文，它将图像连同一些参数从 android 设备发送到服务器。

现在发送图像的工作正常，这是为此目的构建 http 请求正文的代码部分

conn.setDoInput(true); // Allow Inputs
            conn.setDoOutput(true); // Allow Outputs
            conn.setUseCaches(false); // Don't use a Cached Copy
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Connection", "Keep-Alive");
            conn.setRequestProperty("ENCTYPE", "multipart/form-data");
            conn.setRequestProperty("Content-Type",
                    "multipart/form-data;boundary=" + boundary);
            conn.setRequestProperty("uploaded_file", fileName);

            dos = new DataOutputStream(conn.getOutputStream());

            dos.writeBytes(twoHyphens + boundary + lineEnd);
            dos.writeBytes("Content-Disposition: form-data; name=\"uploaded_file\"; filename=\""
                    + fileName + "\"" + lineEnd);

我每次尝试添加我将从 POST 数组检索的参数时都没有成功，但通常我尝试添加的是:

dos.writeBytes(twoHyphens + boundary + lineEnd);
dos.writeBytes("Content-Disposition: form-data; name=\"param1\"");
dos.writeBytes(lineEnd);

无论如何，这是朝着正确方向迈出的一步吗？

Answer 1

    HashMap<String, String> formValues = new HashMap<String, String>();
        HashMap<String, String> fileValues = new HashMap<String, String>(); 

        formValues.put("text_request_parameter", f_name);       
            fileValues.put("file_request_parameter", file_path);

                WebServiceUtil wUtil = new WebServiceUtil(this, serverUri, formValues,true, fileValues);
            /*if you want to request text only
                /WebServiceUtil wUtil = new WebServiceUtil(this, serverUri, formValues,false, fileValues);*/

        wUtil.execute();

// WebServiceUtil.java 

    import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;

public class WebServiceUtil extends AsyncTask<String, Integer, String> {

    HashMap<String, String> formValues;
    HashMap<String, String> fileValues;

    Boolean uploadFile;
    String reqUrl;
    String result;
    ProgressDialog dialog;
    Context context;

    public WebServiceUtil(Context context, String reqUrl,
            HashMap<String, String> formValues, Boolean uploadFile,
            HashMap<String, String> fileValues) {

        this.context = context;
        this.reqUrl = reqUrl;
        this.formValues = formValues;

        this.uploadFile = uploadFile;
        if (uploadFile) {

            this.fileValues = fileValues;
        }
    }

    @Override
    protected void onPreExecute() {

        super.onPreExecute();

    }

    //

    @Override
    protected String doInBackground(String... URLs) {

        List<String> response = null;
        try {
            MultipartUtility mu = new MultipartUtility(context, reqUrl, "UTF-8");

            for (Map.Entry<String, String> entry : formValues.entrySet()) {
                String key = entry.getKey();

                String value = entry.getValue();

                mu.addFormField(key, value);

            }

            if (uploadFile) {

                for (Map.Entry<String, String> entry : fileValues.entrySet()) {
                    String key = entry.getKey();

                    String value = entry.getValue();

                    File file = new File(value);
                    mu.addFilePart(key, file);

                }

            }

            response = mu.finish();

        } catch (IOException e) {

            e.printStackTrace();
        }

        return response.toString();

    }

    protected void onPostExecute(String result) {

    }

}

MultipartUtility.java 改编自 codejava.net

import java.io.BufferedReader;
 
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.List;
import android.app.ProgressDialog;
import android.content.Context;

/**
 * This utility class provides an abstraction layer for sending multipart HTTP
 * POST requests to a web server. 
 * @author www.codejava.net
 *
 */
public class MultipartUtility {
    private final String boundary;
    private static final String LINE_FEED = "\r\n";
    private HttpURLConnection httpConn;
    private String charset;
    private OutputStream outputStream;
    private PrintWriter writer;
    ProgressDialog dialog;

    /**
     * This constructor initializes a new HTTP POST request with content type
     * is set to multipart/form-data
     * @param requestURL
     * @param charset
     * @throws IOException
     */
    public MultipartUtility(Context context,String requestURL, String charset)
            throws IOException {
        //dialog = new ProgressDialog(context);
        this.charset = charset;

        // creates a unique boundary based on time stamp
        boundary = "===" + System.currentTimeMillis() + "===";

        URL url = new URL(requestURL);
        httpConn = (HttpURLConnection) url.openConnection();
        httpConn.setUseCaches(false);
        httpConn.setDoOutput(true); // indicates POST method
        httpConn.setDoInput(true);
        httpConn.setRequestProperty("Content-Type",
                "multipart/form-data; boundary=" + boundary);
        httpConn.setRequestProperty("User-Agent", "CodeJava Agent");
        httpConn.setRequestProperty("Test", "Bonjour");
        outputStream = httpConn.getOutputStream();
        writer = new PrintWriter(new OutputStreamWriter(outputStream, charset),
                true);
    }

    /**
     * Adds a form field to the request
     * @param name field name
     * @param value field value
     */
    public void addFormField(String name, String value) {
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append("Content-Disposition: form-data; name=\"" + name + "\"")
                .append(LINE_FEED);
        writer.append("Content-Type: text/plain; charset=" + charset).append(
                LINE_FEED);
        writer.append(LINE_FEED);
        writer.append(value).append(LINE_FEED);
        writer.flush();
    }

    /**
     * Adds a upload file section to the request
     * @param fieldName name attribute in <input type="file" name="..." />
     * @param uploadFile a File to be uploaded
     * @throws IOException
     */
    public void addFilePart(String fieldName, File uploadFile)
            throws IOException {
        String fileName = uploadFile.getName();
        writer.append("--" + boundary).append(LINE_FEED);
        writer.append(
                "Content-Disposition: form-data; name=\"" + fieldName
                        + "\"; filename=\"" + fileName + "\"")
                .append(LINE_FEED);
        writer.append(
                "Content-Type: "
                        + URLConnection.guessContentTypeFromName(fileName))
                .append(LINE_FEED);
        writer.append("Content-Transfer-Encoding: binary").append(LINE_FEED);
        writer.append(LINE_FEED);
        writer.flush();

        FileInputStream inputStream = new FileInputStream(uploadFile);
        byte[] buffer = new byte[4096];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        outputStream.flush();
        inputStream.close();

        writer.append(LINE_FEED);
        writer.flush();    
    }

    /**
     * Adds a header field to the request.
     * @param name - name of the header field
     * @param value - value of the header field
     */
    public void addHeaderField(String name, String value) {
        writer.append(name + ": " + value).append(LINE_FEED);
        writer.flush();
    }

    /**
     * Completes the request and receives response from the server.
     * @return a list of Strings as response in case the server returned
     * status OK, otherwise an exception is thrown.
     * @throws IOException
     */
    public List<String> finish() throws IOException {


        List<String> response = new ArrayList<String>();

        writer.append(LINE_FEED).flush();
        writer.append("--" + boundary + "--").append(LINE_FEED);
        writer.close();

        // checks server's status code first
        int status = httpConn.getResponseCode();
        if (status == HttpURLConnection.HTTP_OK) {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    httpConn.getInputStream()));
            String line = null;
            while ((line = reader.readLine()) != null) {
                response.add(line);
            }
            reader.close();
            httpConn.disconnect();
        } else {
            throw new IOException("Server returned non-OK status: " + status);
        }


        return response;
    }
}