Java 无法找到或加载主类org.apache.hadoop.mapreduce.v2.app.MRAppMaster mapred-site.xml的内容： mapreduce.framework.name 纱线 warn.app.mapreduce.am.env HADOOP\u MAPRED\u HOME=/HOME/admin/HADOOP-3.1.0 mapreduce.map.env HADOOP\u MAPRED\u HOME=/HOME/admin/HADOOP-3.1.0 mapreduce.reduce.env HADOOP\u MAPRED\u HOME=/HOME/admin/HADOOP-3.1.0 mapreduce.application.classpath $HADOOP\u MAPRED\u HOME/share/HADOOP/mapreduce/*，$HADOOP\u MAPRED\u HOME/share/HADOOP/mapreduce/lib/*

虽然我已经设置了warn.app.mapreduce.am.env和其他参数；我无法找到或加载主类org.apache.hadoop.mapreduce.v2.app.MRAppMaster错误。 我试图在linux机器上安装hadoop的地方远程运行map reduce程序，并在windows机器上运行它。 以下是我的作业配置设置

public class WordCount {
  public static void main(String[] args)
      throws IOException, ClassNotFoundException, InterruptedException {
    //
    UserGroupInformation ugi = UserGroupInformation.createRemoteUser("admin");
    ugi.doAs(new PrivilegedExceptionAction<Void>() {

      public Void run() throws Exception {
        try {
          Configuration configuration = new Configuration();

          configuration.set("yarn.resourcemanager.address", "192.168.33.75:50001"); // see step 3
          configuration.set("mapreduce.framework.name", "yarn");
          // configuration.set("yarn.app.mapreduce.am.env",
          // "HADOOP_MAPRED_HOME=/home/admin/hadoop-3.1.0");
          // configuration.set("mapreduce.map.env", "HADOOP_MAPRED_HOME=/home/admin/hadoop-3.1.0");
          // configuration.set("mapreduce.reduce.env",
          // "HADOOP_MAPRED_HOME=/home/admin/hadoop-3.1.0");
          configuration.set("fs.defaultFS", "hdfs://192.168.33.75:54310"); // see step 2
          configuration.set("mapreduce.app-submission.cross-platform", "true");
          configuration.set("mapred.remote.os", "Linux");
          configuration.set("yarn.application.classpath",
              "$HADOOP_CONF_DIR:$HADOOP_COMMON_HOME/*:$HADOOP_COMMON_HOME/lib/*:"
                  + "$HADOOP_HDFS_HOME/*:$HADOOP_HDFS_HOME/lib/*:"
                  + "$HADOOP_YARN_HOME/*:$HADOOP_YARN_HOME/lib/*:"
                  + "$HADOOP_MAPRED_HOME/*:$HADOOP_MAPRED_HOME/lib/*");

          Job job = Job.getInstance(configuration);

          job.setJarByClass(WordCount.class); // use this when uploaded the Jar to the server and
                                              // running the job directly and locally on the server
          job.setOutputKeyClass(Text.class);
          job.setOutputValueClass(IntWritable.class);
          job.setMapperClass(MapForWordCount.class);
          job.setReducerClass(ReduceForWordCount.class);

          Path input = new Path("/user/admin/wordCountInput.txt");
          Path output = new Path("/user/admin/output");
          FileInputFormat.addInputPath(job, input);
          FileOutputFormat.setOutputPath(job, output);
          System.exit(job.waitForCompletion(true) ? 0 : 1);
        } catch (Exception e) {
          e.printStackTrace();
        }
        return null;
      }

    });


  }

公共类字数{
公共静态void main（字符串[]args）
抛出IOException、ClassNotFoundException、InterruptedException{
//
UserGroupInformation ugi=UserGroupInformation.createRemoteUser（“admin”）；
ugi.doAs（新特权接受行动）{
public Void run（）引发异常{
试一试{
配置=新配置（）；
configuration.set（“warn.resourcemanager.address”，“192.168.33.75:50001”）；//参见步骤3
set（“mapreduce.framework.name”、“纱线”）；
//configuration.set（“warn.app.mapreduce.am.env”，
//“HADOOP_MAPRED_HOME=/HOME/admin/HADOOP-3.1.0”）；
//set（“mapreduce.map.env”、“HADOOP\u MAPRED\u HOME=/HOME/admin/HADOOP-3.1.0”）；
//configuration.set（“mapreduce.reduce.env”，
//“HADOOP_MAPRED_HOME=/HOME/admin/HADOOP-3.1.0”）；
configuration.set（“fs.defaultFS”hdfs://192.168.33.75:54310“”；//参见步骤2
set（“mapreduce.app submission.cross-platform”、“true”）；
set（“mapred.remote.os”、“Linux”）；
configuration.set（“warn.application.classpath”，
“$HADOOP_CONF_DIR:$HADOOP_COMMON_HOME/*：$HADOOP_COMMON_HOME/lib/*：”
+“$HADOOP\u HDFS\u HOME/*：$HADOOP\u HDFS\u HOME/lib/*：”
+“$HADOOP\u Thread\u HOME/*：$HADOOP\u Thread\u HOME/lib/*：”
+“$HADOOP\u MAPRED\u HOME/*：$HADOOP\u MAPRED\u HOME/lib/*”；
Job Job=Job.getInstance（配置）；
job.setJarByClass（WordCount.class）；//将Jar上载到服务器并
//直接在服务器上本地运行作业
job.setOutputKeyClass（Text.class）；
job.setOutputValueClass（IntWritable.class）；
setMapperClass（MapForWordCount.class）；
job.setReducerClass（reduceForDorCount.class）；
路径输入=新路径（“/user/admin/wordCountInput.txt”）；
路径输出=新路径（“/user/admin/output”）；
addInputPath（作业，输入）；
setOutputPath（作业，输出）；
系统退出（作业等待完成（真）？0:1；
}捕获（例外e）{
e、 printStackTrace（）；
}
返回null；
}
});
}

请帮帮我。我在过去6天一直在解决这个问题。提前谢谢。

---

Hadoop版本：3.1.0

我也遇到了同样的问题，通过在mapred site.xml中添加这个解决了（因此编辑mapreduce.application.classpath属性）

mapreduce.application.classpath
$HADOOP\u MAPRED\u HOME/share/HADOOP/mapreduce/*，$HADOOP\u MAPRED\u HOME/share/mapreduce/lib/*，$HADOOP\u MAPRED\u HOME/share/HADOOP/common/*，$HADOOP\u MAPRED\u HOME/share/HADOOP/share/*，$HADOOP\u MAPRED\u HOME/share/share/lib/*，$HADOOP\u MAPRED\u HOME/HADOOP/share/*，$HADOOP\share/HADOOP/HADOOP/HADOOP/share/*/*

我在warn-site.xml中添加了以下属性

<property>
  <name>yarn.application.classpath</name>
  <value> $HADOOP_CONF_DIR,$HADOOP_COMMON_HOME/share/hadoop/common/*,$HADOOP_COMMON_HOME/share/hadoop/common/lib/*,$HADOOP_HDFS_HOME/share/hadoop/hdfs/*,$HADOOP_HDFS_HOME/share/hadoop/hdfs/lib/*,$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/*,$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/lib/*,
    $HADOOP_YARN_HOME/share/hadoop/yarn/*,$HADOOP_YARN_HOME/share/hadoop/yarn/lib/* 
  </value>
</property>

---

我的程序现在运行顺利。请随时询问详细信息。

问题是您的资源管理器（Thread）无法加载Hadoop库（JAR）。 我通过更新配置解决了这个问题。 将此添加到warn-site.xml：

.application.classpath
C:/hadoop-2.8.0/share/hadoop/mapreduce/*，C:/hadoop-2.8.0/share/hadoop/mapreduce/lib/*，C:/hadoop-2.8.0/share/hadoop/common/*，C:/hadoop-2.8.0/share/hadoop/common/lib/*，
C:/hadoop-2.8.0/share/hadoop/hdfs/*，C:/hadoop-2.8.0/share/hadoop/hdfs/lib/*，C:/hadoop-2.8.0/share/hadoop/warn/*，C:/hadoop-2.8.0/share/hadoop/warn/lib/*

---

请注意，此处使用的路径可以是相对的，具体取决于您的系统。

只需编辑mapred site.xml文件：

添加以下属性：

mapreduce.framework.name
纱线

warn.app.mapreduce.am.env
HADOOP\u MAPRED\u HOME=/Users/adityaatri/Applications/HADOOP-3.1.3

mapreduce.map.env
HADOOP\u MAPRED\u HOME=/Users/adityaatri/Applications/HADOOP-3.1.3

mapreduce.reduce.env
HADOOP\u MAPRED\u HOME=/Users/adityaatri/Applications/HADOOP-3.1.3

现在，对于上述4个属性，将路径

/Users/adityaatri/Applications/hadoop-3.1.3

替换为您的hadoop家庭地址

现在添加第5个属性：

mapreduce.application.classpath

在终端中执行以下命令后，必须用内容填充

元素：

export HADOOP\u CLASSPATH=$（HADOOP CLASSPATH）

echo$HADOOP\u类路径

我的终端的输出：

/Users/adityaatri/Applications/hadoop-3.1.3/etc/hadoop:/Users/adityaatri/Applications/hadoop-3.1.3/share/hadoop/common/lib/*：/Users/adityaatri/Applications/hadoop-3.1.3/share/hadoop/common/*：/Users/adityaatri Applications/hadoop/hadoop/hdfs:/Users/adityaatri/Applications/hadoop-3.1.1。
<property> 
    <name>mapreduce.application.classpath</name>
    <value>$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/*,$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/lib/*,$HADOOP_MAPRED_HOME/share/hadoop/common/*,$HADOOP_MAPRED_HOME/share/hadoop/common/lib/*,$HADOOP_MAPRED_HOME/share/hadoop/yarn/*,$HADOOP_MAPRED_HOME/share/hadoop/yarn/lib/*,$HADOOP_MAPRED_HOME/share/hadoop/hdfs/*,$HADOOP_MAPRED_HOME/share/hadoop/hdfs/lib/*</value>
</property>

<property>
  <name>yarn.application.classpath</name>
  <value> $HADOOP_CONF_DIR,$HADOOP_COMMON_HOME/share/hadoop/common/*,$HADOOP_COMMON_HOME/share/hadoop/common/lib/*,$HADOOP_HDFS_HOME/share/hadoop/hdfs/*,$HADOOP_HDFS_HOME/share/hadoop/hdfs/lib/*,$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/*,$HADOOP_MAPRED_HOME/share/hadoop/mapreduce/lib/*,
    $HADOOP_YARN_HOME/share/hadoop/yarn/*,$HADOOP_YARN_HOME/share/hadoop/yarn/lib/* 
  </value>
</property>

  configuration.set("yarn.application.classpath",
              "{{HADOOP_CONF_DIR}},{{HADOOP_COMMON_HOME}}/share/hadoop/common/*,{{HADOOP_COMMON_HOME}}/share/hadoop/common/lib/*,"
                  + " {{HADOOP_HDFS_HOME}}/share/hadoop/hdfs/*,{{HADOOP_HDFS_HOME}}/share/hadoop/hdfs/lib/*,"
                  + "{{HADOOP_MAPRED_HOME}}/share/hadoop/mapreduce/*,{{HADOOP_MAPRED_HOME}}/share/hadoop/mapreduce/lib/*,"
                  + "{{HADOOP_YARN_HOME}}/share/hadoop/yarn/*,{{HADOOP_YARN_HOME}}/share/hadoop/yarn/lib/*");

<property>
<name>yarn.application.classpath</name>
<value>C:/hadoop-2.8.0/share/hadoop/mapreduce/*,C:/hadoop-2.8.0/share/hadoop/mapreduce/lib/*,C:/Hadoop-2.8.0/share/hadoop/common/*,C:/Hadoop-2.8.0/share/hadoop/common/lib/*,
    C:/hadoop-2.8.0/share/hadoop/hdfs/*,C:/hadoop-2.8.0/share/hadoop/hdfs/lib/*,C:/hadoop-2.8.0/share/hadoop/yarn/*,C:/hadoop-2.8.0/share/hadoop/yarn/lib/*</value>
</property>