Java下http下载文件客户端和上传文件客户端实例代码

时间:2022-08-26 21:27:43

一、下载客户端代码

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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;
/**
 * @说明 导出虚拟机
 * @author wxt
 * @version 1.0
 * @since
 */
public class GetVM {
  /**
   * 测试
   * @param args
   */
  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");
    }
  }
  /**
   * 将vm 写入到磁盘
   * @param vm 数据流
   * @param fileName 文件保存时的名称
   */
  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();
    }
  }
  /**
   * 根据地址获得数据的字节流
   * @param strUrl 网络连接地址
   * @return
   */
  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;
  }
  /**
   * 从输入流中获取数据
   * @param inStream 输入流
   * @return
   * @throws Exception
   */
  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:

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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;
/**
 * @说明 导出虚拟机
 * @author wxt
 * @version 1.0
 * @since
 */
public class GetBigFile {
  /**
   * 测试
   * @param args
   */
  public static void main(String[] args) {
    String url = "http://192.168.5.76:8080/export?uuid=123";
    String fileName="yserver"
    getVMFromNetByUrl(url,fileName);
  }
  /**
   * 根据地址获下载文件
   * @param strUrl 网络连接地址
   * @param fileName 下载文件的存储名称
   */
  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:

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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 {
  /**
   * 发送请求
   *
   * @param url
   *      请求地址
   * @param filePath
   *      文件在服务器保存路径(这里是为了自己测试方便而写,可以将该参数去掉)
   * @return
   * @throws IOException
   */
  public int send(String url, String filePath) throws IOException {
    File file = new File(filePath);
    if (!file.exists() || !file.isFile()) {
      return -1;
    }
    /**
     * 第一部分
     */
    URL urlObj = new URL(url);
    HttpURLConnection con = (HttpURLConnection) urlObj.openConnection();
    /**
     * 设置关键值
     */
    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();
    /**
     * 读取服务器响应,必须读取,否则提交不成功
     */
    return con.getResponseCode();
    /**
     * 下面的方式读取也是可以的
     */
    // 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

以上所述是小编给大家介绍的Java下http下载文件客户端和上传文件客户端实例代码,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持!

原文链接:http://blog.csdn.net/chenyulancn/article/details/45562119