这篇文章主要介绍了Java中http下载文件客户端和上传文件客户端的示例分析，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。
一、下载客户端代码
package javadownload; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; public class GetVM { public static void main(String[] args) { String url = "http://192.168.5.102:8845/xx"; byte[] btImg = getVMFromNetByUrl(url); if(null != btImg && btImg.length > 0){ System.out.println("读取到：" + btImg.length + " 字节"); String fileName = "ygserver"; writeImageToDisk(btImg, fileName); }else{ System.out.println("没有从该连接获得内容"); } } public static void writeImageToDisk(byte[] vm, String fileName){ try { File file = new File("./" + fileName); FileOutputStream fops = new FileOutputStream(file); fops.write(vm); fops.flush(); fops.close(); System.out.println("下载完成"); } catch (Exception e) { e.printStackTrace(); } } public static byte[] getVMFromNetByUrl(String strUrl){ try { URL url = new URL(strUrl); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5 * 1000); InputStream inStream = conn.getInputStream();//通过输入流获取数据 byte[] btImg = readInputStream(inStream);//得到的二进制数据 return btImg; } catch (Exception e) { e.printStackTrace(); } return null; } public static byte[] readInputStream(InputStream inStream) throws Exception{ ByteArrayOutputStream outStream = new ByteArrayOutputStream(); byte[] buffer = new byte[1024]; int len = 0; while( (len=inStream.read(buffer)) != -1 ){ outStream.write(buffer, 0, len); } inStream.close(); return outStream.toByteArray(); } }上述代码只适合下载小文件，如果下载大文件则会出现 Exception in thread "main" java.lang.OutOfMemoryError: Java heap space 错误，所以如果下载大文件需要对上述代码进行改造，代码如下：
package javadownload; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; public class GetBigFile { public static void main(String[] args) { String url = "http://192.168.5.76:8080/export?uuid=123"; String fileName="yserver"; getVMFromNetByUrl(url,fileName); } public static void getVMFromNetByUrl(String strUrl,String fileName){ try { URL url = new URL(strUrl); HttpURLConnection conn = (HttpURLConnection)url.openConnection(); conn.setRequestMethod("GET"); conn.setConnectTimeout(5 * 1000); InputStream inStream = conn.getInputStream();//通过输入流获取数据 byte[] buffer = new byte[4096]; int len = 0; File file = new File("./" + fileName); FileOutputStream fops = new FileOutputStream(file); while( (len=inStream.read(buffer)) != -1 ){ fops.write(buffer, 0, len); } fops.flush(); fops.close(); } catch (Exception e) { e.printStackTrace(); } } }二、上传文件客户端：
package javadownload; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.OutputStream; import java.net.HttpURLConnection; import java.net.URL; public class FileUpload { public int send(String url, String filePath) throws IOException { File file = new File(filePath); if (!file.exists() || !file.isFile()) { return -1; } URL urlObj = new URL(url); HttpURLConnection con = (HttpURLConnection) urlObj.openConnection(); con.setRequestMethod("POST"); // 以Post方式提交表单，默认get方式 con.setDoInput(true); con.setDoOutput(true); con.setUseCaches(false); // post方式不能使用缓存 // 设置请求头信息 con.setRequestProperty("Connection", "close");//Keep-Alive con.setRequestProperty("Charset", "UTF-8"); // 设置边界 String BOUNDARY = "----------" + System.currentTimeMillis(); con.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY); // 请求正文信息 // 第一部分： StringBuilder sb = new StringBuilder(); sb.append("--"); // ////////必须多两道线 sb.append(BOUNDARY); sb.append("\r\n"); sb.append("Content-Disposition: form-data;name=\"file_name\";filename=\"" + file.getName() + "\"\r\n"); sb.append("Content-Type:application/octet-stream\r\n\r\n"); sb.append("Connection:close\r\n\r\n"); byte[] head = sb.toString().getBytes("utf-8"); // 获得输出流 OutputStream out = new DataOutputStream(con.getOutputStream()); out.write(head); // 文件正文部分 DataInputStream in = new DataInputStream(new FileInputStream(file)); int bytes = 0; byte[] bufferOut = new byte[1024]; while ((bytes = in.read(bufferOut)) != -1) { out.write(bufferOut, 0, bytes); } in.close(); // 结尾部分 byte[] foot = ("\r\n--" + BOUNDARY + "--\r\n").getBytes("utf-8");// 定义最后数据分隔线 out.write(foot); out.flush(); out.close(); return con.getResponseCode(); // try { // // 定义BufferedReader输入流来读取URL的响应 // BufferedReader reader = new BufferedReader(new InputStreamReader( // con.getInputStream())); // String line = null; // while ((line = reader.readLine()) != null) { // System.out.println(line); // } // } catch (Exception e) { // System.out.println("发送POST请求出现异常！" + e); // e.printStackTrace(); // } } public static void main(String[] args) throws IOException { FileUpload up = new FileUpload(); System.out.println(up.send("http://192.168.5.102:8845/xx", "./vif.xml")); ; } }感谢你能够认真阅读完这篇文章，希望小编分享的“Java中http下载文件客户端和上传文件客户端的示例分析”这篇文章对大家有帮助，同时也希望大家多多支持编程网，关注编程网行业资讯频道，更多相关知识等着你来学习!
