JAVA通过HttpURLConnection 上传和下载文件

Posted 2020-08-02 H__D

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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：

  1 package com.util;
  2 
  3 import java.io.BufferedInputStream;
  4 import java.io.BufferedReader;
  5 import java.io.DataOutputStream;
  6 import java.io.File;
  7 import java.io.FileInputStream;
  8 import java.io.FileOutputStream;
  9 import java.io.IOException;
 10 import java.io.InputStream;
 11 import java.io.InputStreamReader;
 12 import java.io.OutputStream;
 13 import java.io.OutputStreamWriter;
 14 import java.net.HttpURLConnection;
 15 import java.net.MalformedURLException;
 16 import java.net.URL;
 17 import java.net.URLConnection;
 18 import java.util.Iterator;
 19 import java.util.Map;
 20 
 21 /**
 22  * 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，
 23  * 但不够简便；
 24  * 
 25  * 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
 26  * 4.以输入流的形式获取返回内容 5.关闭输入流
 27  * 
 28  * @author H__D
 29  *
 30  */
 31 public class HttpConnectionUtil {
 32 
 33 
 34     /**
 35      * 多文件上传的方法
 36      * 
 37      * @param actionUrl：上传的路径
 38      * @param uploadFilePaths：需要上传的文件路径，数组
 39      * @return
 40      */
 41     @SuppressWarnings("finally")
 42     public static String uploadFile(String actionUrl, String[] uploadFilePaths) {
 43         String end = "\\r\\n";
 44         String twoHyphens = "--";
 45         String boundary = "*****";
 46 
 47         DataOutputStream ds = null;
 48         InputStream inputStream = null;
 49         InputStreamReader inputStreamReader = null;
 50         BufferedReader reader = null;
 51         StringBuffer resultBuffer = new StringBuffer();
 52         String tempLine = null;
 53 
 54         try {
 55             // 统一资源
 56             URL url = new URL(actionUrl);
 57             // 连接类的父类，抽象类
 58             URLConnection urlConnection = url.openConnection();
 59             // http的连接类
 60             HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
 61 
 62             // 设置是否从httpUrlConnection读入，默认情况下是true;
 63             httpURLConnection.setDoInput(true);
 64             // 设置是否向httpUrlConnection输出
 65             httpURLConnection.setDoOutput(true);
 66             // Post 请求不能使用缓存
 67             httpURLConnection.setUseCaches(false);
 68             // 设定请求的方法，默认是GET
 69             httpURLConnection.setRequestMethod("POST");
 70             // 设置字符编码连接参数
 71             httpURLConnection.setRequestProperty("Connection", "Keep-Alive");
 72             // 设置字符编码
 73             httpURLConnection.setRequestProperty("Charset", "UTF-8");
 74             // 设置请求内容类型
 75             httpURLConnection.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
 76 
 77             // 设置DataOutputStream
 78             ds = new DataOutputStream(httpURLConnection.getOutputStream());
 79             for (int i = 0; i < uploadFilePaths.length; i++) {
 80                 String uploadFile = uploadFilePaths[i];
 81                 String filename = uploadFile.substring(uploadFile.lastIndexOf("//") + 1);
 82                 ds.writeBytes(twoHyphens + boundary + end);
 83                 ds.writeBytes("Content-Disposition: form-data; " + "name=\\"file" + i + "\\";filename=\\"" + filename
 84                         + "\\"" + end);
 85                 ds.writeBytes(end);
 86                 FileInputStream fStream = new FileInputStream(uploadFile);
 87                 int bufferSize = 1024;
 88                 byte[] buffer = new byte[bufferSize];
 89                 int length = -1;
 90                 while ((length = fStream.read(buffer)) != -1) {
 91                     ds.write(buffer, 0, length);
 92                 }
 93                 ds.writeBytes(end);
 94                 /* close streams */
 95                 fStream.close();
 96             }
 97             ds.writeBytes(twoHyphens + boundary + twoHyphens + end);
 98             /* close streams */
 99             ds.flush();
100             if (httpURLConnection.getResponseCode() >= 300) {
101                 throw new Exception(
102                         "HTTP Request is not success, Response code is " + httpURLConnection.getResponseCode());
103             }
104 
105             if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
106                 inputStream = httpURLConnection.getInputStream();
107                 inputStreamReader = new InputStreamReader(inputStream);
108                 reader = new BufferedReader(inputStreamReader);
109                 tempLine = null;
110                 resultBuffer = new StringBuffer();
111                 while ((tempLine = reader.readLine()) != null) {
112                     resultBuffer.append(tempLine);
113                     resultBuffer.append("\\n");
114                 }
115             }
116 
117         } catch (Exception e) {
118             // TODO Auto-generated catch block
119             e.printStackTrace();
120         } finally {
121             if (ds != null) {
122                 try {
123                     ds.close();
124                 } catch (IOException e) {
125                     // TODO Auto-generated catch block
126                     e.printStackTrace();
127                 }
128             }
129             if (reader != null) {
130                 try {
131                     reader.close();
132                 } catch (IOException e) {
133                     // TODO Auto-generated catch block
134                     e.printStackTrace();
135                 }
136             }
137             if (inputStreamReader != null) {
138                 try {
139                     inputStreamReader.close();
140                 } catch (IOException e) {
141                     // TODO Auto-generated catch block
142                     e.printStackTrace();
143                 }
144             }
145             if (inputStream != null) {
146                 try {
147                     inputStream.close();
148                 } catch (IOException e) {
149                     // TODO Auto-generated catch block
150                     e.printStackTrace();
151                 }
152             }
153 
154             return resultBuffer.toString();
155         }
156     }
157 
158 
159     public static void main(String[] args) {
160 
161         // 上传文件测试
162          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" });
163          System.out.println(str);
164 
165 
166     }
167 
168 }

uploadFile

HttpURLConnection文件下载

　　下载代码如下：

  1 package com.util;
  2 
  3 import java.io.BufferedInputStream;
  4 import java.io.BufferedReader;
  5 import java.io.DataOutputStream;
  6 import java.io.File;
  7 import java.io.FileInputStream;
  8 import java.io.FileOutputStream;
  9 import java.io.IOException;
 10 import java.io.InputStream;
 11 import java.io.InputStreamReader;
 12 import java.io.OutputStream;
 13 import java.io.OutputStreamWriter;
 14 import java.net.HttpURLConnection;
 15 import java.net.MalformedURLException;
 16 import java.net.URL;
 17 import java.net.URLConnection;
 18 import java.util.Iterator;
 19 import java.util.Map;
 20 
 21 /**
 22  * 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，
 23  * 但不够简便；
 24  * 
 25  * 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
 26  * 4.以输入流的形式获取返回内容 5.关闭输入流
 27  * 
 28  * @author H__D
 29  *
 30  */
 31 public class HttpConnectionUtil {
 32 
 33 
 34     /**
 35      * 
 36      * @param urlPath
 37      *            下载路径
 38      * @param downloadDir
 39      *            下载存放目录
 40      * @return 返回下载文件
 41      */
 42     public static File downloadFile(String urlPath, String downloadDir) {
 43         File file = null;
 44         try {
 45             // 统一资源
 46             URL url = new URL(urlPath);
 47             // 连接类的父类，抽象类
 48             URLConnection urlConnection = url.openConnection();
 49             // http的连接类
 50             HttpURLConnection httpURLConnection = (HttpURLConnection) urlConnection;
 51             // 设定请求的方法，默认是GET
 52             httpURLConnection.setRequestMethod("POST");
 53             // 设置字符编码
 54             httpURLConnection.setRequestProperty("Charset", "UTF-8");
 55             // 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）。
 56             httpURLConnection.connect();
 57 
 58             // 文件大小
 59             int fileLength = httpURLConnection.getContentLength();
 60 
 61             // 文件名
 62             String filePathUrl = httpURLConnection.getURL().getFile();
 63             String fileFullName = filePathUrl.substring(filePathUrl.lastIndexOf(File.separatorChar) + 1);
 64 
 65             System.out.println("file length---->" + fileLength);
 66 
 67             URLConnection con = url.openConnection();
 68 
 69             BufferedInputStream bin = new BufferedInputStream(httpURLConnection.getInputStream());
 70 
 71             String path = downloadDir + File.separatorChar + fileFullName;
 72             file = new File(path);
 73             if (!file.getParentFile().exists()) {
 74                 file.getParentFile().mkdirs();
 75             }
 76             OutputStream out = new FileOutputStream(file);
 77             int size = 0;
 78             int len = 0;
 79             byte[] buf = new byte[1024];
 80             while ((size = bin.read(buf)) != -1) {
 81                 len += size;
 82                 out.write(buf, 0, size);
 83                 // 打印下载百分比
 84                 // System.out.println("下载了-------> " + len * 100 / fileLength +
 85                 // "%\\n");
 86             }
 87             bin.close();
 88             out.close();
 89         } catch (MalformedURLException e) {
 90             // TODO Auto-generated catch block
 91             e.printStackTrace();
 92         } catch (IOException e) {
 93             // TODO Auto-generated catch block
 94             e.printStackTrace();
 95         } finally {
 96             return file;
 97         }
 98 
 99     }
100 
101     public static void main(String[] args) {
102 
103         // 下载文件测试
104         downloadFile("http://localhost:8080/images/1467523487190.png", "/Users/H__D/Desktop");
105 
106     }
107 
108 }

downloadFile

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