Java 从HDFS读取文件时出现格式错误的异常
我有下面的测试程序从HDFS读取一个文件Java 从HDFS读取文件时出现格式错误的异常,java,hadoop,Java,Hadoop,我有下面的测试程序从HDFS读取一个文件 public class FileReader { public static final String NAMENODE_IP = "172.32.17.209"; public static final String FILE_PATH = "/notice.html"; public static void main(String[] args) throws MalformedURLException,
public class FileReader {
public static final String NAMENODE_IP = "172.32.17.209";
public static final String FILE_PATH = "/notice.html";
public static void main(String[] args) throws MalformedURLException,
IOException {
String url = "hdfs://" + NAMENODE_IP + FILE_PATH;
InputStream is = new URL(url).openStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = br.readLine();
while(line != null) {
System.out.println(line);
line = br.readLine();
}
}
}
它给出了java.net.MalformedURLException
Exception in thread "main" java.net.MalformedURLException: unknown protocol: hdfs
at java.net.URL.<init>(URL.java:592)
at java.net.URL.<init>(URL.java:482)
at java.net.URL.<init>(URL.java:431)
at in.ksharma.hdfs.FileReader.main(FileReader.java:29)
线程“main”java.net.MalformedURLException中的异常:未知协议:hdfs
位于java.net.URL。(URL.java:592)
位于java.net.URL。(URL.java:482)
在java.net.URL.(URL.java:431)
位于in.ksharma.hdfs.FileReader.main(FileReader.java:29)
注册Hadoop的Url处理程序。标准Url处理程序不知道如何处理hdfs://scheme 试试这个:
public static void main(String[] args) throws MalformedURLException,
IOException {
URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory());
String url = "hdfs://" + NAMENODE_IP + FILE_PATH;
InputStream is = new URL(url).openStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line = br.readLine();
while(line != null) {
System.out.println(line);
line = br.readLine();
}
}
我在Hadoop2.6上编写一个Java应用程序来读取hdfs时遇到了同样的问题。 我的解决方案是:添加
hadoop-2.X/share/hadoop/hdfs/hadoop-hdfs-2.X.jar to your classpath.
在我们的案例中,我们必须将其与其他答案结合起来:
因此,首先在我们的HDFS设置类(
Scala code
)中:
后来,就像在公认的答案中:旁注: 我们已经:
“org.apache.hadoop”%“hadoop hdfs”%“2.8.0”
在我们的依赖项中,它没有帮助。我尝试了此代码,但仍然得到异常:未知协议:hdfs
。请告诉我您是如何解决此问题的。这是删除错误所必需的步骤。我看不出有什么理由否决这项议案。为我工作。
val hadoopConfig: Configuration = new Configuration()
hadoopConfig.set("fs.hdfs.impl", classOf[DistributedFileSystem].getName)
hadoopConfig.set("fs.file.impl", classOf[LocalFileSystem].getName)
URL.setURLStreamHandlerFactory(new FsUrlStreamHandlerFactory)
Try(new URL(path))