Java下http下载文件客户端和上传文件客户端实例代码

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("rn"); 
    sb.append("Content-Disposition: form-data;name="file_name";filename="" 
 + file.getName() + ""rn"); 
    sb.append("Content-Type:application/octet-streamrnrn"); 
    sb.append("Connection:closernrn"); 
    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 = ("rn--" + BOUNDARY + "--rn").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")); 
    ; 
  } 
} 

总结

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