java - 如何使用简单的 HttpClient 示例下载文件？

Question

我是 Java 和 HttpClient 新手，我正在尝试从 Dropbox 文件进行简单下载，但出现以下异常:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
    at org.apache.http.impl.client.AbstractHttpClient.<init>(AbstractHttpClient.java:187)
    at org.apache.http.impl.client.DefaultHttpClient.<init>(DefaultHttpClient.java:146)
    at downlaodtest.DownlaodTest.main(DownlaodTest.java:23)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    ... 3 more
Java Result: 1

为什么会抛出异常？

public class DownlaodTest {
  public static void main(String[] args) throws IOException {
    HttpClient httpclient = new DefaultHttpClient();
    HttpGet httpget = new HttpGet("https://dl.dropbox.com/s/ex4clsfmiu142dy/test.zip");
    HttpResponse response = httpclient.execute(httpget);
    System.out.println(response.getStatusLine());
    HttpEntity entity = response.getEntity();
    if (entity != null) {
      InputStream instream = entity.getContent();
      try {
        BufferedInputStream bis = new BufferedInputStream(instream);
        String filePath = "C:/@Victor";
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(new File(filePath)));
        int inByte;
        while ((inByte = bis.read()) != -1 ) {
          bos.write(inByte);
        }
        bis.close();
        bos.close();
      } catch (IOException ex) {
        throw ex;
      } catch (RuntimeException ex) {
        httpget.abort();
        throw ex;
      } finally {
        instream.close();
      }
      httpclient.getConnectionManager().shutdown();
    }
  }
}

Answer 1

如果我将文件路径更改为有效路径并将其所需的所有库添加到类路径中，它在我的计算机上工作正常。

String filePath = "d:\\test.zip";

图书馆:

commons-codec-1.6.jar
commons-logging-1.1.1.jar
fluent-hc-4.2.3.jar
httpclient-4.2.3.jar
httpclient-cache-4.2.3.jar
httpcore-4.2.2.jar
httpmime-4.2.3.jar