android中的文件（圖片）上傳

android中的文件（圖片）上傳其實沒什麼複雜的，主要是對 multipart/form-data 協議要有所瞭解。

關於 multipart/form-data 協議，在 RFC文檔中有詳細的描述 RFC 2388 - Returning Values from Forms: multipart/form-data

大家有興趣的話可以去看看，這裡有一篇非常好的文章進行了介紹：Http協議中的數據傳送之多重表單提交--multipart/form-data

那麼在Android中如何實現呢？這裡寫了一個簡單的工具類，供大家使用

UploadUtil

package com.atwal.util;

import android.util.Log;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
import java.util.Map;
import java.util.UUID;

/**
 * Created by atwal on 2016/3/11.
 */
public class UploadUtil {
    private static final String TAG = "uploadFile";
    private static final int TIME_OUT = 10 * 1000;   //超時時間
    private static final String CHARSET = "utf-8";
    private static final String BOUNDARY = UUID.randomUUID().toString();  //邊界標識隨機生成
    private static final String PREFIX = "--";
    private static final String LINE_END = "\r\n";
    private static final String CONTENT_TYPE = "multipart/form-data";   //內容類型

    /**
     * 上傳文件
     * @param file 文件
     * @param RequestURL post地址
     * @param params 除文件外其他參數
     * @param uploadFieldName 上傳文件key
     * @return
     */
    public static String uploadFile(File file, String RequestURL, Map<String, String> params, String uploadFieldName) {
        String result = null;

        try {
            URL url = new URL(RequestURL);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(TIME_OUT);
            conn.setConnectTimeout(TIME_OUT);
            conn.setDoInput(true);
            conn.setDoOutput(true);
            conn.setUseCaches(false);
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Charset", CHARSET);
            conn.setRequestProperty("connection", "keep-alive");
            conn.setRequestProperty("Content-Type", CONTENT_TYPE + ";boundary=" + BOUNDARY);

            DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
            StringBuffer sb = new StringBuffer();
            sb.append(getRequestData(params));

            if (file != null) {
                sb.append(PREFIX);
                sb.append(BOUNDARY);
                sb.append(LINE_END);
                sb.append("Content-Disposition: form-data; name=\"" + uploadFieldName + "\"; filename=\"" + file.getName() + "\"" + LINE_END);
                sb.append("Content-Type: application/octet-stream; charset=" + CHARSET + LINE_END);
                sb.append(LINE_END);
            }
            dos.write(sb.toString().getBytes());
            if (file != null) {
                InputStream is = new FileInputStream(file);
                byte[] bytes = new byte[1024];
                int len = 0;
                while ((len = is.read(bytes)) != -1) {
                    dos.write(bytes, 0, len);
                }
                is.close();
                dos.write(LINE_END.getBytes());
                byte[] end_data = (PREFIX + BOUNDARY + PREFIX + LINE_END).getBytes();
                dos.write(end_data);
            }
            dos.flush();

            int res = conn.getResponseCode();
            Log.e(TAG, "response code:" + res);
            if (res == 200) {
                Log.e(TAG, "request success");
                InputStream input = conn.getInputStream();
                StringBuffer sb1 = new StringBuffer();
                int ss;
                while ((ss = input.read()) != -1) {
                    sb1.append((char) ss);
                }
                result = sb1.toString();
                Log.i(TAG, "result : " + result);
            } else {
                Log.e(TAG, "request error");
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }

    /**
     * 對post參數進行編碼處理
     * @param params post參數
     * @return
     */
    private static StringBuffer getRequestData(Map<String, String> params) {
        StringBuffer stringBuffer = new StringBuffer();
        try {
            for (Map.Entry<String, String> entry : params.entrySet()) {
                stringBuffer.append(PREFIX);
                stringBuffer.append(BOUNDARY);
                stringBuffer.append(LINE_END);
                stringBuffer.append("Content-Disposition: form-data; name=\"" + entry.getKey() + "\"" + LINE_END);
                stringBuffer.append(LINE_END);
                stringBuffer.append(URLEncoder.encode(entry.getValue(), CHARSET));
                stringBuffer.append(LINE_END);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return stringBuffer;
    }
}

代碼比較簡單，就不細說了，主要就是把參數及文件按協議進行拼接。

註：本類代碼參考了android上傳文件到伺服器 一文，做了優化修改

調用

調用代碼比較簡單，這裡需要註意的是，文件上傳是一個網路操作，要另開線程處理。另外要給應用網路和SD卡讀寫許可權。

String requestURL = "伺服器地址";
String picPath = "圖片地址";
File file = new File(picPath);
Log.i("upload", "file exists:" + file.exists());
if (file.exists()) {
    Map<String, String> params = new HashMap<>();
    params.put("id", "1");
    //...如果有其他參數添加到這裡
    String request = UploadUtil.uploadFile(file, requestURL, params, "image");
    Log.i("upload", request);
}

當然，此工具類對異常信息並未處理，大家可根據自己的情況進行優化。