java.lang.NullPointerException at java.lang.ProcessBuilder.start(Unkn...
1：问题出现的原因，部署好的hadoop-2.6.4进行window10操作hadoop api出现的错误，具体错误是我向hdfs上传文件，还好点，之前解决过，这里不叙述，这里说一下从hdfs下载文件出现的错误：
详细错误如下所示：
java.lang.NullPointerException at java.lang.ProcessBuilder.start(Unknown Source) at org.apache.hadoop.util.Shell.runCommand(Shell.java:482) at org.apache.hadoop.util.Shell.run(Shell.java:455) at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:715) at org.apache.hadoop.util.Shell.execCommand(Shell.java:808) at org.apache.hadoop.util.Shell.execCommand(Shell.java:791) at org.apache.hadoop.fs.RawLocalFileSystem.setPermission(RawLocalFileSystem.java:659) at org.apache.hadoop.fs.FilterFileSystem.setPermission(FilterFileSystem.java:490) at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:462) at org.apache.hadoop.fs.ChecksumFileSystem.create(ChecksumFileSystem.java:428) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:908) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:889) at org.apache.hadoop.fs.FileSystem.create(FileSystem.java:786) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:365) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:338) at org.apache.hadoop.fs.FileUtil.copy(FileUtil.java:289) at org.apache.hadoop.fs.FileSystem.copyToLocalFile(FileSystem.java:1970) at org.apache.hadoop.fs.FileSystem.copyToLocalFile(FileSystem.java:1939) at org.apache.hadoop.fs.FileSystem.copyToLocalFile(FileSystem.java:1915) at com.bie.lesson01.HdfsClientTest.downloadFile(HdfsClientTest.java:64) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26) at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229) at org.junit.runners.ParentRunner.run(ParentRunner.java:309) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
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。
而且可以完成你想要完成的操作：
资源下载地址：http://download.csdn.net/download/biexiansheng/10132712
停更......
2017-11-25 17:28:05
