从app上传图片到php，再上传到java后端服务器的方法一条龙服务

　　在现在的网络开发中，上传图片类的需求实在是太普通不过了，但是对于怎么样做到上传图片，对于刚开始建立项目的时候，还是有点不知所措的。也许有幸，我们做的项目是之前已经有人写过类似的用例了，那么我们只需要依葫芦画瓢就行了。

　　好好了解下图片上传（文件上传）的方式，对于认知的提升还是有好处的。而且说不定哪天你就有个这样的需求呢，这里是一条龙上传。

　　本文就一个从app到php层，再到java层的流程，演译下整个上传图片的流程吧。

一、app端获取用户选择的图片，转化为输入流，上传至php前端接口：

package com.dia.ration;

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.util.HashMap;
import java.util.Map;
import java.util.UUID;

/**
 * 上传文件到服务器类
 */
public class UploadUtil {
    private static final String TAG = "uploadFile";
    private static final int TIME_OUT = 10 * 1000; // 超时时间
    private static final String CHARSET = "utf-8"; // 设置编码
    /**
     * Android上传文件到服务端
     *
     * @param file 需要上传的文件
     * @param RequestURL 请求的rul
     * @return 返回响应的内容
     */
    public static String uploadFile(File file, String RequestURL) {
        String result = null;
        String BOUNDARY = UUID.randomUUID().toString(); // 边界标识 随机生成
        String PREFIX = "--", LINE_END = "
";
        String CONTENT_TYPE = "multipart/form-data"; // 内容类型
        try {
            URL url = new URL(RequestURL);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(TIME_OUT);
            conn.setConnectTimeout(TIME_OUT);
            conn.setDoInput(true);          // 允许输入流
            conn.setDoOutput(true);         // 允许输出流
            conn.setUseCaches(false);       // 不允许使用缓存
            conn.setRequestMethod("POST"); // 请求方式
            conn.setRequestProperty("Charset", CHARSET); // 设置编码
            conn.setRequestProperty("connection", "keep-alive");
            conn.setRequestProperty("Content-Type", CONTENT_TYPE + ";boundary=" + BOUNDARY);
            if (file != null) {
                DataOutputStream dos = new DataOutputStream(conn.getOutputStream());
                StringBuffer sb = new StringBuffer();
                sb.append(PREFIX);
                sb.append(BOUNDARY);
                sb.append(LINE_END);
                /**
                 * 这里重点注意： name里面的值为服务端需要key 只有这个key 才可以得到对应的文件
                 * filename是文件的名字，包含后缀名的 比如:abc.png
                 */
                sb.append("Content-Disposition: form-data; name="uploadfile"; 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());
                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();
                InputStream input = conn.getInputStream();
                StringBuffer sb1 = new StringBuffer();
                int ss;
                while ((ss = input.read()) != -1) {
                    sb1.append((char) ss);
                }
                result = sb1.toString();
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }
    /**
     * 通过拼接的方式构造请求内容，实现参数传输以及文件传输
     *
     * @param url Service net address
     * @param params text content
     * @param files pictures
     * @return String result of Service response
     * @throws IOException
     */
    public static String post(String url, Map<String, String> params, Map<String, File> files)
            throws IOException {
        String BOUNDARY = UUID.randomUUID().toString();
        String PREFIX = "--", LINEND = "
";
        String MULTIPART_FROM_DATA = "multipart/form-data";
        String CHARSET = "UTF-8";
        URL uri = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) uri.openConnection();
        conn.setReadTimeout(10 * 1000); // 缓存的最长时间
        conn.setDoInput(true);          // 允许输入
        conn.setDoOutput(true);         // 允许输出
        conn.setUseCaches(false);       // 不允许使用缓存
        conn.setRequestMethod("POST");
        conn.setRequestProperty("connection", "keep-alive");
        conn.setRequestProperty("Charsert", "UTF-8");
        conn.setRequestProperty("Content-Type", MULTIPART_FROM_DATA + ";boundary=" + BOUNDARY);
        // 首先组拼文本类型的参数
        StringBuilder sb = new StringBuilder();
        for (Map.Entry<String, String> entry : params.entrySet()) {
            sb.append(PREFIX);
            sb.append(BOUNDARY);
            sb.append(LINEND);
            sb.append("Content-Disposition: form-data; name="" + entry.getKey() + """ + LINEND);
            sb.append("Content-Type: text/plain; charset=" + CHARSET + LINEND);
            sb.append("Content-Transfer-Encoding: 8bit" + LINEND);
            sb.append(LINEND);
            sb.append(entry.getValue());
            sb.append(LINEND);
        }
        DataOutputStream outStream = new DataOutputStream(conn.getOutputStream());
        outStream.write(sb.toString().getBytes());
        // 发送文件数据
        if (files != null)
            for (Map.Entry<String, File> file : files.entrySet()) {
                StringBuilder sb1 = new StringBuilder();
                sb1.append(PREFIX);
                sb1.append(BOUNDARY);
                sb1.append(LINEND);
                sb1.append("Content-Disposition: form-data; name="uploadfile"; filename=""
                        + file.getValue().getName() + """ + LINEND);
                sb1.append("Content-Type: application/octet-stream; charset=" + CHARSET + LINEND);
                sb1.append(LINEND);
                outStream.write(sb1.toString().getBytes());
                InputStream is = new FileInputStream(file.getValue());
                byte[] buffer = new byte[1024];
                int len = 0;
                while ((len = is.read(buffer)) != -1) {
                    outStream.write(buffer, 0, len);
                }
                is.close();
                outStream.write(LINEND.getBytes());
            }
        byte[] end_data = (PREFIX + BOUNDARY + PREFIX + LINEND).getBytes();
        outStream.write(end_data);
        outStream.flush();
        int res = conn.getResponseCode();
        InputStream in = conn.getInputStream();
        StringBuilder sb2 = new StringBuilder();
        if (res == 200) {
            int ch;
            while ((ch = in.read()) != -1) {
                sb2.append((char) ch);
            }
        }
        outStream.close();
        conn.disconnect();
        return sb2.toString();
    }
    // 测试
    public static void main(String[] args) throws IOException {
        String requestURL = "sss";
        final Map<String, String> params = new HashMap<String, String>();
        params.put("send_userId", String.valueOf(1));
        params.put("send_email", "ss@ss.com");
        final Map<String, File> files = new HashMap<String, File>();
        files.put("uploadfile", new File("/var/data/de.jpg"));
        final String result = UploadUtil.post(requestURL, params, files);
        System.out.println("result is: " + result);
    }
}

二、php服务端接收文件，临时保存并继续上传至java后端：

　　1. 接收文件类

<?php
namespace AppController;

use ActionRestAction;
use ApiUploadApi;

class UserController extends RestAction
{
    /**
     * 用户头像上传
     */
    public function set_avatar_post($code)
    {
        $uploadApi = new UploadApi();
        $res = $uploadApi->uploads('avatar');
        $filename = $res['data'];

        $result = $uploadApi->uploadAvatar($code, $filename);
        @unlink($filename);            //删除图片
        if (!$result['status']) {
            $this->response($result);
        }
        $avatar = A("Personal", "Api")->getAvatar($code);
        $this->response($avatar);
    }
}

　　2. 上传类

<?php
namespace ApiAction;

class UploadApi
{   
    public function __construct()
    {
        //...
    }

    public function curlGet($url, $param = array(), $timeout = 30, $ajaxResponseImmediately = true)
    {
        $opts = array(
            CURLOPT_TIMEOUT => $timeout,
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_SSL_VERIFYHOST => false,
            CURLOPT_HTTPHEADER => $header
        );
        switch (strtoupper($method)) {
            // case 'POST':
                // $opts[CURLOPT_URL] = $url;
                // $opts[CURLOPT_POST] = 1;
                // $opts[CURLOPT_POSTFIELDS] = $param;
                // break;
            default:
                $opts[CURLOPT_URL] = $url . '?' . http_build_query($param);
                break;
        }

        $ch = curl_init();
        curl_setopt_array($ch, $opts);
        $result = curl_exec($ch);

        //记录请求日志
        curl_close($ch);
        return $result;
    }

    public function curlPost($url, $param = array(), $timeout = 30, $ajaxResponseImmediately = true)
    {
        $opts = array(
            CURLOPT_TIMEOUT => $timeout,
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_SSL_VERIFYPEER => false,
            CURLOPT_SSL_VERIFYHOST => false,
            CURLOPT_HTTPHEADER => $header
        );
        switch (strtoupper($method)) {
            case 'POST':
            default:
                $opts[CURLOPT_URL] = $url;
                $opts[CURLOPT_POST] = 1;
                $opts[CURLOPT_POSTFIELDS] = $param;
                break;
                // $opts[CURLOPT_URL] = $url . '?' . http_build_query($param);
                // break;
        }

        $ch = curl_init();
        curl_setopt_array($ch, $opts);
        $result = curl_exec($ch);

        $log_data['result'] = $result;
        if (!empty($param)) $log_data['param'] = $param;
        curl_close($ch);
        return $result;
    }

    public function uploads($param = '')
    {
        if ($param == '') {
            $param = 'imgFile';
        }
        // 文件保存目录路径
        $save_url = dirname(dirname(dirname(__FILE__))) . DIRECTORY_SEPARATOR . "Uploads" . DIRECTORY_SEPARATOR;
        // 定义允许上传的文件扩展名
        $ext_arr = array(
            'image' => array('gif', 'jpg', 'jpeg', 'png', 'bmp'),
        );
        // 最大文件大小
        $max_size = 20 * 1024;
        // PHP上传失败
        if (!empty ($_FILES [$param] ['error'])) {
            switch ($_FILES [$param] ['error']) {
                case '1' :
                    $error = '超过php.ini允许的大小。';
                    break;
                case '2' :
                    $error = '超过表单允许的大小。';
                    break;
                case '3' :
                    $error = '图片只有部分被上传。';
                    break;
                case '4' :
                    $error = '请选择图片。';
                    break;
                case '6' :
                    $error = '找不到临时目录。';
                    break;
                case '7' :
                    $error = '写文件到硬盘出错。';
                    break;
                case '8' :
                    $error = 'File upload stopped by extension。';
                    break;
                case '999' :
                default :
                    $error = '未知错误。';
            }
            $result = array('status' => '0', 'error' => '111111', 'msg' => $error);

        }
        // 有上传文件时
        if (empty ($_FILES) === false) {
            $file_name = $_FILES [$param] ['name'];// 原文件名
            $tmp_name = $_FILES [$param] ['tmp_name'];// 服务器上临时文件名
            $file_size = $_FILES [$param] ['size'];// 文件大小
            // 检查文件名
            if (!$file_name) {
                $result = array('status' => '0', 'error' => '111111', 'msg' => '请选择文件');
            }
            // 检查是否已上传
            if (@is_uploaded_file($tmp_name) === false) {
                $result = array('status' => '0', 'error' => '111111', 'msg' => '上传失败');
            }
            // 检查文件大小
            if ($file_size > $max_size) {
                $result = array('status' => '0', 'error' => '111111', 'msg' => '');
            }
            // 检查目录名
            $dir_name = empty ($_GET ['dir']) ? 'image' : trim($_GET ['dir']);
            if (empty ($ext_arr [$dir_name])) {
                $result = array('status' => '0', 'error' => '111111', 'msg' => '目录名不正确');
            }
            // 获得文件扩展名
            $temp_arr = explode('.', $file_name);
            $file_ext = array_pop($temp_arr);
            $file_ext = trim($file_ext);
            $file_ext = strtolower($file_ext);
            // 检查扩展名
            if (in_array($file_ext, $ext_arr [$dir_name]) === false) {
                $result = array('status' => '0', 'error' => '111111', 'msg' => '上传文件扩展名是不允许的扩展名');
            }
            // 创建文件夹
            if ($dir_name !== '') {
                if (!file_exists($save_url)) {
                    mkdir($save_url);
                }
            }
            $new_file_name = date('YmdHis') . '_' . rand(10000, 99999) . '.' . $file_ext;
            $file_path = $save_url . $new_file_name;
            if (move_uploaded_file($tmp_name, $file_path) === false) {
                $result['msg'] = '上传文件失败';
                $result = array('status' => '0', 'error' => '111111', 'msg' => '上传文件失败');
            } else {
                $result = array('status' => '1', 'error' => '000000', 'data' => $file_path);
            }
            @chmod($file_path, 0644);
            return $result;
        }
    }

    public function uploadAvatar($code, $avatarImageName) {
        $url = $this->getApiUrl(__METHOD__);
        $data = array(
            "code" => $code,
            "ip" => $this->params['ip'],
            "avatar" => !empty($avatarImageName) ? '@' . $avatarImageName : '',
        );
        $result = $this->curlPost($url, $data);
        return $result;
    }
}

　　这样，php就已经接收到了来自客户端的 图片上传了，并且已经上传到java后端服务器。

　　注意：这里有个坑，即php版本大于5.6以后，直接使用 @ 符号无法上传文件了，需要 加上一个安全选项：CURLOPT_SAFE_UPLOAD => false 才可以，或者使用5.6以的高级上传类上传文件：

curl_setopt(ch, CURLOPT_POSTFIELDS, [
    'file' => new CURLFile(realpath('image.png')), 
]); 

三、java后端接收php上传的图片

package com.xx.c.action;

import com.xx.core.pojo.Constants;
import com.xx.core.pojo.MicroException;
import com.xx.core.pojo.ResponseEntity;
import com.xx.core.web.spring.bind.annotation.ClientIP;
import com.xx.core.web.spring.bind.annotation.SessionUserId;
import com.xx.c.pojo.user.UpFileUrlBean;
import com.xx.c.service.user.UserService;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import java.util.Iterator;

@Controller
@RequestMapping(value = "upload")
public class UploadAction {

    @Resource(name = "userService")
    private UserService userService;

    @RequestMapping(value = "/uploadAvatar", method = RequestMethod.POST, produces = "application/json")
    @ResponseBody
    public Object uploadAvatar(@RequestParam String code, @ClientIP String addIp, @SessionUserId Long userId, 
            @ModelAttribute UpFileUrlBean bean, HttpServletRequest request) throws MicroException {
        bean.setAddIp(addIp);
        bean.setUserId(userId);
        
        try {
            // 转型为MultipartHttpRequest：
            MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
            // 从其中取出一个文件 后续可使用spring 上传文件方法：file.transferTo(destFile);
            MultipartFile file = null;
            for (Iterator<String> it = multipartRequest.getFileNames(); it.hasNext();) {
                file = multipartRequest.getFile((String) it.next());
            }
            userService.uploadAvatar(file, bean);
        } catch (Exception e) {
            throw new MicroException(Constants.ErrCode.UPLOAD_AVATAR_TO_SERVER_FAILED, Constants.ErrMsg.UPLOAD_AVATAR_TO_SERVER_FAILED, e);
        }

        ResponseEntity ret = new ResponseEntity(Constants.System.OK);
        return ret;
    }

}

　　至此，上传流程已经完成了。（当然，后续还可能使用其他上传，比如dubbo调用文件系统上传文件，调用第三方sdk上传到文件服务器。。。， 原理大抵一样，使用字节流进行传输，然后读取出来存储到文件）

　　一般为app写的接口中，都会涉及到加解密问题，此时，文件不应该算作加密的范畴，而应单独给一个字段。