java实现后台图片跨域上传功能的实例讲解

@ResponseBody
 @RequestMapping(value="/imgUpLoadNewOneKuaYu")
 public String imgUpLoadNewOneKuaYu(HttpServletRequest request) throws IOException {
   String urlStr = "http://localhost:9080/no-js/admin/upload";
   Map<String, String> textMap = new HashMap<String, String>(); 
   MultipartHttpServletRequest multiRequest = (MultipartHttpServletRequest) request;//流的数据*
   //取得request中的所有文件名 
    Iterator<String> iter = multiRequest.getFileNames(); 
    Map<String, InputStream> fileMap = new HashMap<String, InputStream>();
    if(iter.hasNext()){ 
     //取得上传文件 
     MultipartFile file = multiRequest.getFile(iter.next()); 
     if(file != null){ 
      //取得当前上传文件的文件名称 
      String myFileName = file.getOriginalFilename();
      InputStream fileInputStream=file.getInputStream(); 
      fileMap.put(myFileName, fileInputStream); 
     }
    }
   String ret = FileUpLoadNew.formUpload(urlStr, textMap, fileMap);
   System.out.println(ret);
   return ret;
 }

package net.sahv.bdyz.util;

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Iterator;
import java.util.Map;

public class FileUpLoadNew {

 /**
  * @param urlStr
  * @param textMap
  * @param fileMap
  * @return
  */
 public static String formUpload(String urlStr, Map<String, String> textMap, Map<String, InputStream> fileMap) {
  String res = "";
  HttpURLConnection conn = null;
  String BOUNDARY = "---------------------------123821742118716"; //boundary就是request头和上传文件内容的分隔符
  try {
   URL url = new URL(urlStr);
   conn = (HttpURLConnection) url.openConnection();
   conn.setConnectTimeout(5000);
   conn.setReadTimeout(30000);
   conn.setDoOutput(true);
   conn.setDoInput(true);
   conn.setUseCaches(false);
   conn.setRequestMethod("POST");
   conn.setRequestProperty("Connection", "Keep-Alive");
   conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
   conn.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);
   OutputStream out = new DataOutputStream(conn.getOutputStream());
   // textMap：如果传送的是文本内容
   if (textMap != null) {
    StringBuffer strBuf = new StringBuffer();
    Iterator<Map.Entry<String, String>> iter = textMap.entrySet().iterator();
    while (iter.hasNext()) {
     Map.Entry<String, String> entry = iter.next();
     String inputName = (String) entry.getKey();
     String inputValue = (String) entry.getValue();
     if (inputValue == null) {
      continue;
     }
     strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
     strBuf.append("Content-Disposition: form-data; name=\"" + inputName + "\"\r\n\r\n");
     strBuf.append(inputValue);
    }
    out.write(strBuf.toString().getBytes());
   }
   //fileMap：如果传送的是文件流
   if (fileMap != null) {
    Iterator<Map.Entry<String, InputStream>> iter = fileMap.entrySet().iterator();
    while (iter.hasNext()) {
     Map.Entry<String, InputStream> entry = iter.next();
     String inputName = (String) entry.getKey();
     FileInputStream inputValue = (FileInputStream) entry.getValue();
     if (inputValue == null) {
      continue;
     }
     String contentType = "image/png";
     StringBuffer strBuf = new StringBuffer();
     strBuf.append("\r\n").append("--").append(BOUNDARY).append("\r\n");
     strBuf.append("Content-Disposition: form-data; name=\"" + inputName + "\"; filename=\"" + inputName + "\"\r\n");
     strBuf.append("Content-Type:" + contentType + "\r\n\r\n");
     out.write(strBuf.toString().getBytes());
     DataInputStream in = new DataInputStream(inputValue);
     int bytes = 0;
     byte[] bufferOut = new byte[1024];
     while ((bytes = in.read(bufferOut)) != -1) {
      out.write(bufferOut, 0, bytes);
     }
     in.close();
    }
   }
   byte[] endData = ("\r\n--" + BOUNDARY + "--\r\n").getBytes();
   out.write(endData);
   out.flush();
   out.close();
   // 读取返回数据
   StringBuffer strBuf = new StringBuffer();
   BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
   String line = null;
   while ((line = reader.readLine()) != null) {
    strBuf.append(line).append("\n");
   }
   res = strBuf.toString();
   reader.close();
   reader = null;
  } catch (Exception e) {
   System.out.println("发送POST请求出错。" + urlStr);
   e.printStackTrace();
  } finally {
   //最后关闭链接
   if (conn != null) {
    conn.disconnect();
    conn = null;
   }
  }
  return res;
 }
}

package com.lyc.noJs.controller;

import com.google.common.base.Splitter;
import com.lyc.noJs.util.ImgMD5Util;
import lombok.extern.slf4j.Slf4j;
import org.joda.time.DateTime;
import org.springframework.stereotype.Controller;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;

import java.io.*;
import java.security.NoSuchAlgorithmException;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

@Controller
@RequestMapping("/admin")
@Slf4j
public class UploadController {

 @ResponseBody
 @RequestMapping(value = "/upload",method= RequestMethod.POST)
 public String upload(MultipartHttpServletRequest multiRequest) throws UnsupportedEncodingException {
  //图片文件夹根路径
  //TODO
  //这里的父路径暂时是target路径，在真实上线后，应该将其改成其它路径。
  String uploadFilePath = multiRequest.getServletContext().getRealPath("/upload/");
  //图片文件夹日期路径
  String datePath = getDateFolderName() + "\\";
  //图片名称
  String imagePath = saveImage(multiRequest,uploadFilePath,datePath);
  log.info(imagePath);
  return imagePath;
 }

 /**
  * 保存图片
  * @param multiRequest
  * @param uploadFilePath
  * @param datePath
  * @return
  * @throws UnsupportedEncodingException
  */
 public String saveImage(MultipartHttpServletRequest multiRequest,String uploadFilePath,String datePath) throws UnsupportedEncodingException {
  String imageNameHead = createImageNameHead();
  String imageName = "";
  //设置图片的浏览为utf-8格式，防止图片名称乱码
  multiRequest.setCharacterEncoding("utf-8");
  MultiValueMap<String, MultipartFile> multiFileMap = multiRequest.getMultiFileMap();
  Set<Map.Entry<String, List<MultipartFile>>> set = multiFileMap.entrySet();
  Iterator<Map.Entry<String, List<MultipartFile>>> iterator = set.iterator();
  while(iterator.hasNext()){
   Map.Entry<String, List<MultipartFile>> entry = iterator.next();
   String imageNameEnd = getImageNameEnd(entry);
   imageName = imageNameHead + "." + imageNameEnd;
   List<MultipartFile> multipartFileList = entry.getValue();
   MultipartFile multipartFile = multipartFileList.get(0);
   //图片文件的包路径
   String imagePath = uploadFilePath + datePath;
   //如果文件夹创建失败，则返回null
   if(makeParentFolder(imagePath)){  //如果文件夹创建失败，则返回false，否则返回true
    //图片文件的路径
    String imgFile = imagePath + imageName;
    //如果文件创建失败，则返回null
    if(!makeImage(multipartFile,imgFile)){ //当文件创建失败时，返回false，否则返回true
     return null;
    }
   } else {
    return null;
   }
  }
  return datePath + imageName;
 }

 /**
  * 创建图片
  * @param multipartFile
  * @param imgFile
  * @return
  */
 public boolean makeImage(MultipartFile multipartFile,String imgFile){
  File tempFile = new File(imgFile);
  if(tempFile != null){
   //如果原图片不存在，则生成图片
   if(!tempFile.exists()){
    try {
     log.info("1");
     multipartFile.transferTo(tempFile);
    } catch (IOException e) {
     e.printStackTrace();
    }
   }
   return true;
  }
  return false;
 }

 /**
  * 创建父文件路径
  * @param imagePath
  * @return
  */
 public boolean makeParentFolder(String imagePath){
  File parentFile = new File(imagePath);
  if(parentFile != null){
   while (!parentFile.exists()){
    //批量生成全部的父文件路径
    parentFile.mkdirs();
   }
   return true;
  }
  return false;
 }

 /**
  * 文件夹生成规则
  */
 public String getDateFolderName(){
  DateTime dataTime = new DateTime();
  String currentDate = dataTime.toString("yyyy\\MM\\dd");
  return currentDate;
 }

 /**
  * 创建图片文件的文件名
  * @return
  */
 public String createImageNameHead(){
  DateTime dataTime = new DateTime();
  return String.valueOf(dataTime.getMillis());
 }
}