我在没有命令的情况下运行访问hdfs的代码时遇到问题：

hadoop jar

下面是我尝试运行的代码：

package com.infotel.mycompany.testhdfs;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
/**
 * Hello world!
 *
 */
public class App
{
    public static void main( String[] args ) throws IOException
    {
        Configuration config = new Configuration();
        config.addResource("/opt/hadoop-2.2.0/etc/hadoop/core-site.xml");
        config.set("fs.defaultFS", "hdfs://192.168.2.164/");
        FileSystem dfs = FileSystem.get(config);
        Path pt = new Path("/path/to/myfile");
        BufferedReader br = new BufferedReader(new InputStreamReader(dfs.open(pt)));
        String line;
        line = br.readLine();
        while(line != null) {
                System.out.println(line);
                line = br.readLine();
        }
    }
}

我使用maven和以下pom.xml构建代码：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mycompany.bigdata</groupId>
    <artifactId>testhdfs</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>testhdfs</name>
    <url>http://maven.apache.org</url>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>3.8.1</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-core</artifactId>
            <version>0.20.2</version>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.infotel.bigdata.testhdfs.App</mainClass>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

使用此命令运行代码时：

hadoop jar target/testhdfs-0.0.1-SNAPSHOT.jar com.infotel.mycompany.testhdfs.App

很好用。但是如果我用这个命令或从eclipse运行代码：

mvn exec:java

我得到以下错误：

java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:293)
        at java.lang.Thread.run(Thread.java:744)
Caused by: java.io.FileNotFoundException: File /path/to/myfile does not exist.
        at org.apache.hadoop.fs.RawLocalFileSystem.getFileStatus(RawLocalFileSystem.java:361)
        at org.apache.hadoop.fs.FilterFileSystem.getFileStatus(FilterFileSystem.java:245)
        at org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSInputChecker.<init>(ChecksumFileSystem.java:125)
        at org.apache.hadoop.fs.ChecksumFileSystem.open(ChecksumFileSystem.java:283)
        at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:356)
        at com.infotel.bigdata.testhdfs.App.main(App.java:30)

这是我的core-site.xml：

<configuration>    
    <property>
         <name>fs.defaultFS</name>   
         <value>hdfs://chef</value>
         <description>NameNode URI </description>
    </property> 
    <property>       
        <name>hadoop.http.staticuser.user</name>  
        <value>hdfs</value>  
    </property>
    <property>
        <name>hadoop.tmp.dir</name>
        <value>/opt/hadoop-2.2.0/tmp</value>
    </property>
</configuration>

我在尝试运行mapreduce时遇到了同样的问题，我必须使用hadoopjar命令，而不是从eclipse运行它。我正在使用hadoop2.2.0。看起来我完全错过了什么或不明白什么，谷歌没有帮助我。
如果有人有解决办法，我会非常感激。最终的目标是从servlet中的hdfs中检索文件，这就是为什么我不能使用 hadoop jar