0

我是 Java 和 HttpClient 的新手，我正在尝试从 Dropbox 文件中进行简单下载，但我得到以下异常：

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();
    }
  }
}
4

3 回答 3

3

如果我将文件路径更改为有效路径并将它需要的所有库添加到类路径中，它在我的机器上工作正常。

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
于 2013-01-26T17:32:58.963 回答
0

我认为你必须添加下面的行来保存你的文件。

response.addHeader(“Content-Disposition”, “attachment;filename=\”" + file.getName() + “\”");
response.addHeader(“Content-Transfer-Encoding”, “binary”);`
response.setContentType(“application/octet-stream”);`
response.setContentLength((int) file.length());`
response.getOutputStream().write(buffer);`
response.getOutputStream().flush();`
于 2013-01-26T17:32:08.917 回答
0

首先，如果您是 Java 新手，您必须了解管理 Java 依赖项。

要么下载带有依赖项的二进制发行版，然后将它们全部复制到项目中并添加到 Eclipse，要么学习使用maven。

例如，您添加依赖项：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.0-alpha4</version>
</dependency>

并且 maven 正在为您做所有其他事情（下载所有依赖项及其依赖项）。

于 2013-01-26T18:21:08.413 回答