本文介绍了JAVA通过HttpURLConnection 上传和下载文件的方法，分享给大家，具体如下：

HttpURLConnection文件上传

HttpURLConnection采用模拟浏览器上传的数据格式，上传给服务器

上传代码如下：

package com.util;

import java.io.BufferedInputStream;

import java.io.BufferedReader;

import java.io.DataOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLConnection;

import java.util.Iterator;

import java.util.Map;

/**

* Java原生的API可用于发送HTTP请求，即java.net.URL、java.net.URLConnection，这些API很好用、很常用，

* 但不够简便；

*

* 1.通过统一资源定位器(java.net.URL)获取连接器(java.net.URLConnection) 2.设置请求的参数 3.发送请求

* 4.以输入流的形式获取返回内容 5.关闭输入流

*

* @author H__D

*

*/

public class HttpConnectionUtil {

/**

* 多文件上传的方法

*

* @param actionUrl：上传的路径

* @param uploadFilePaths：需要上传的文件路径，数组

* @return

*/

@SuppressWarnings("finally")

public static String uploadFile(String actionUrl, String[] uploadFilePaths) {

String end = "\r\n";

String twoHyphens = "--";

String boundary = "*****";

DataOutputStream ds = null;

InputStream inputStream = null;

InputStreamReader inputStreamReader = null;

BufferedReader reader = null;

StringBuffer resultBuffer = new StringBuffer();

String tempLine = null;

try {

// 统一资源

URL url = new URL(actionUrl);

// 连接类的父类，抽象类

URLConnection urlConnection = url.openConnection();

// http的连接类

HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;

// 设置是否从httpUrlConnection读入，默认情况下是true;

httpURLConnection.setDoInput(true);

// 设置是否向httpUrlConnection输出

httpURLConnection.setDoOutput(true);

// Post 请求不能使用缓存

httpURLConnection.setUseCaches(false);

// 设定请求的方法，默认是GET

httpURLConnection.setRequestMethod("POST");

// 设置字符编码连接参数

httpURLConnection.setRequestProperty("Connection", "Keep-Alive");

// 设置字符编码

httpURLConnection.setRequestProperty("Charset", "UTF-8");

// 设置请求内容类型

httpURLConnection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);

// 设置DataOutputStream

ds = new DataOutputStream(httpURLConnection.getOutputStream());

for (int i = 0; i < uploadFilePaths.length; i++) {

String uploadFile = uploadFilePaths[i];

String filename = uploadFile.substring(uploadFile.lastIndexOf("//") + 1);

ds.writeBytes(twoHyphens + boundary + end);

ds.writeBytes("Content-Disposition: form-data; " + "name=\"file" + i + "\";filename=\"" + filename

+ "\"" + end);

ds.writeBytes(end);

FileInputStream fStream = new FileInputStream(uploadFile);

int bufferSize = 1024;

byte[] buffer = new byte[bufferSize];

int length = -1;

while ((length = fStream.read(buffer)) != -1) {

ds.write(buffer, 0, length);

}

ds.writeBytes(end);

/* close streams */

fStream.close();

}

ds.writeBytes(twoHyphens + boundary + twoHyphens + end);

/* close streams */

ds.flush();

if (httpURLConnection.getResponseCode() >= 300) {

throw new Exception(

"HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());

}

if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {

inputStream = httpURLConnection.getInputStream();

inputStreamReader = new InputStreamReader(inputStream);

reader = new BufferedReader(inputStreamReader);

tempLine = null;

resultBuffer = new StringBuffer();

while ((tempLine = reader.readLine()) != null) {

resultBuffer.append(tempLine);

resultBuffer.append("\n");

}

}

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

} finally {

if (ds != null) {

try {

ds.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if (reader != null) {

try {

reader.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if (inputStreamReader != null) {

try {

inputStreamReader.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

if (inputStream != null) {

try {

inputStream.close();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

return resultBuffer.toString();

}

}

public static void main(String[] args) {

// 上传文件测试

String str = uploadFile("http://127.0.0.1:8080/image/image.do",new String[] { "/Users//H__D/Desktop//1.png","//Users/H__D/Desktop/2.png" });

System.out.println(str);

}

}

HttpURLConnection文件下载

下载代码如下：

package com.util;

import java.io.BufferedInputStream;

import java.io.BufferedReader;

import java.io.DataOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.OutputStreamWriter;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLConnection;

import java.util.Iterator;

import java.util.Map;

/**

* Java原生的API可用于发送HTTP请求，即java.net.URL、java.net.URLConnection，这些API很好用、很常用，

* 但不够简便；

*

* 1.通过统一资源定位器(java.net.URL)获取连接器(java.net.URLConnection) 2.设置请求的参数 3.发送请求

* 4.以输入流的形式获取返回内容 5.关闭输入流

*

* @author H__D

*

*/

public class HttpConnectionUtil {

/**

*

* @param urlPath

* 下载路径

* @param downloadDir

* 下载存放目录

* @return 返回下载文件

*/

public static File downloadFile(String urlPath, String downloadDir) {

File file = null;

try {

// 统一资源

URL url = new URL(urlPath);

// 连接类的父类，抽象类

URLConnection urlConnection = url.openConnection();

// http的连接类

HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;

// 设定请求的方法，默认是GET

httpURLConnection.setRequestMethod("POST");

// 设置字符编码

httpURLConnection.setRequestProperty("Charset", "UTF-8");

// 打开到此 URL 引用的资源的通信链接(如果尚未建立这样的连接)。

httpURLConnection.connect();

// 文件大小

int fileLength = httpURLConnection.getContentLength();

// 文件名

String filePathUrl = httpURLConnection.getURL().getFile();

String fileFullName = filePathUrl.substring(filePathUrl.lastIndexOf(File.separatorChar) + 1);

System.out.println("file length---->" + fileLength);

URLConnection con = url.openConnection();

BufferedInputStream bin = new BufferedInputStream(httpURLConnection.getInputStream());

String path = downloadDir + File.separatorChar + fileFullName;

file = new File(path);

if (!file.getParentFile().exists()) {

file.getParentFile().mkdirs();

}

OutputStream out = new FileOutputStream(file);

int size = 0;

int len = 0;

byte[] buf = new byte[1024];

while ((size = bin.read(buf)) != -1) {

len += size;

out.write(buf, 0, size);

// 打印下载百分比

// System.out.println("下载了-------> " + len * 100 / fileLength +

// "%\n");

}

bin.close();

out.close();

} catch (MalformedURLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} finally {

return file;

}

}

public static void main(String[] args) {

// 下载文件测试

downloadFile("http://localhost:8080/images/1467523487190.png", "/Users/H__D/Desktop");

}

}

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