hadoop下载文件出现的问题java.lang.NullPointerException

快来打我* 2023-06-30 13:53 11阅读 0赞

hadoop下载文件 代码如下：

package week01;
    
    import java.io.FileInputStream;
    
    import java.io.IOException;
    import java.net.URI;
    import java.net.URISyntaxException;
    
    import org.apache.commons.io.IOUtils;
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.FSDataOutputStream;
    import org.apache.hadoop.fs.FileSystem;
    import org.apache.hadoop.fs.Path;
    import org.junit.Before;
    import org.junit.Test;
    
    public class HdfsUtil {
    
    	
    	
    	FileSystem fs = null;
    	
    	@Before
    	public void init() throws IOException, InterruptedException, URISyntaxException{
    		
    		Configuration conf = new Configuration();
    		conf.set("fs.defaultFS", "hdfs://week01:9000");
    		
    		//fs = FileSystem.get(conf);
    		fs = FileSystem.get(new URI("hdfs://week01:9000"), conf, "hadoop");
    
    	}
    	
    	
    	
    	/**
    	 * 下载文件  使用封装好的方法  
    	 * @throws Exception 
    	 * @throws IllegalArgumentException 
    	 */
    	@Test
    	public void download() throws Exception{
    		fs.copyToLocalFile(new Path("hdfs://week01:9000/aa/test2.txt"), new Path("c:/test2.txt"));
    	}
    	
    	
    }

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确实如很多网友说的：  
出现原因：缺少hadoop.dll或winutils.exe

解决办法：缺少哪个，就在本地的E:\\hadoop\\hadoop-2.6.4\\bin下加上哪个。  
而这个方法，貌似不好使，经过亲自测试，解决方法如下所示：  
在你的bin目录里面加上这两个文件，然后呢，在你的C:\\Windows\\System32加上hadoop.dll就可以解决上面出现的错误。

资源链接：[https://download.csdn.net/download/qq\_31090095/10883609][https_download.csdn.net_download_qq_31090095_10883609]

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[https_download.csdn.net_download_qq_31090095_10883609]: https://download.csdn.net/download/qq_31090095/10883609