java实现文件上传、下载（包含下载网络图片上传到服务器上）

拿去直接用就好：
1、文件上传

package com.myproject.aiplatform.core.utils;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

import org.apache.commons.io.FileUtils;
import org.springframework.web.multipart.MultipartFile;

/**
* 上传文件
* @version
*/
public class FileUpload {

/**上传文件
* @param file          //文件对象
* @param filePath      //上传路径
* @param fileName      //文件名
* @return  文件名
*/
public static String fileUp(MultipartFile file, String filePath, String fileName){
String extName = ""; // 扩展名格式：
try {
if (file.getOriginalFilename().lastIndexOf(".") >= 0){
extName = file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
}
copyFile(file.getInputStream(), filePath, fileName+extName).replaceAll("-", "");
} catch (IOException e) {
System.out.println(e);
}
return fileName+extName;
}

/**
* 写文件到当前目录的upload目录中
* @param in
* @param fileName
* @throws IOException
*/
public static String copyFile(InputStream in, String dir, String realName)
throws IOException {
File file = mkdirsmy(dir,realName);
FileUtils.copyInputStreamToFile(in, file);
in.close();
return realName;
}

/**判断路径是否存在，否：创建此路径
* @param dir  文件路径
* @param realName  文件名
* @throws IOException
*/
public static File mkdirsmy(String dir, String realName) throws IOException{
File file = new File(dir, realName);
if (!file.exists()) {
if (!file.getParentFile().exists()) {
file.getParentFile().mkdirs();
}
file.createNewFile();
}
return file;
}

/**下载网络图片上传到服务器上
* @param httpUrl 图片网络地址
* @param filePath  图片保存路径
* @param myFileName  图片文件名(null时用网络图片原名)
* @return  返回图片名称
*/
public static String getHtmlPicture(String httpUrl, String filePath , String myFileName) {

URL url;                        //定义URL对象url
BufferedInputStream in;         //定义输入字节缓冲流对象in
FileOutputStream file;          //定义文件输出流对象file
try {
String fileName = null == myFileName?httpUrl.substring(httpUrl.lastIndexOf("/")).replace("/", ""):myFileName; //图片文件名(null时用网络图片原名)
url = new URL(httpUrl);     //初始化url对象
in = new BufferedInputStream(url.openStream());                                 //初始化in对象，也就是获得url字节流
//file = new FileOutputStream(new File(filePath +"\\"+ fileName));
file = new FileOutputStream(mkdirsmy(filePath,fileName));
int t;
while ((t = in.read()) != -1) {
file.write(t);
}
file.close();
in.close();
return fileName;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;

}
}

2、文件下载

package com.myproject.aiplatform.core.utils;

import java.io.BufferedOutputStream;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.http.HttpServletResponse;

/**
* 下载文件
* @version
*/
public class FileDownload {

/**
* @param response
* @param filePath      //文件完整路径(包括文件名和扩展名)
* @param fileName      //下载后看到的文件名
* @return  文件名
*/
public static void fileDownload(final HttpServletResponse response, String filePath, String fileName) throws Exception{
byte[] data = FileUtil.toByteArray2(filePath);
fileName = URLEncoder.encode(fileName, "UTF-8");
response.reset();
response.setHeader("Content-Disposition", "attachment; filename=" + fileName );
response.addHeader("Content-Length", "" + data.length);
response.setContentType("application/octet-stream;charset=UTF-8");
OutputStream outputStream = new BufferedOutputStream(response.getOutputStream());
outputStream.write(data);
outputStream.flush();
outputStream.close();
response.flushBuffer();
}

}