一次失败的尝试hdfs的java客户端编写（在linux下使用eclipse）
给centOS安装图形界面
GNOME桌面环境
https://blog.csdn.net/wh211212/article/details/52937299
在linux下安装eclipse开发hadoop的配置
file -> properties -> java build path -> add libiary -> user libiary
点击按钮 user libiary -> new 取名叫 hdfslib
选中 hdfslib 的状态下点击 Add External JARs ，在安装路径下找到
- hdfs 的核心jar包：hadoop-3.0.0/share/hadoop/hdfs/hadoop-hdfs-3.0.0.jar，点OK。及其依赖：hadoop-3.0.0/share/hadoop/hdfs/lib，全选然后 OK
- commons 的核心jar包：hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar，ok，及其依赖：hadoop-3.0.0/share/hadoop/common/lib，全选然后 OK
然后在eclipse中创建一个工程，新建一个class，把core-site.xml和hdfs-site.xml两个配置文件拷贝到src中。
代码部分
写一段代码完成下载操作：开一个hdfs输入流，在本地开一个输出流，把输入流拷贝到输出流里就完成了下载
FileSystem（org.apache.hadoop.fs）：访问hdfs的核心入口类 是一个抽象类，用静态方法 get() 拿到它的对象，这个对象就是hdfs的一个客户端
Configuration（org.apache.hadoop.conf）：读配置文件，保存配置文件中的各种key-value
package cn.hadoop.hdfs;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
public class HdfsUtil {
public static void main(String[] args) throws IOException {
Configuration conf = new Configuration();
FileSystem fs = FileSystem.get(conf);
Path src = new Path("hdfs://node01:9000/jdk-8u161-linux-x64.tar.gz");
//打开输入流
FSDataInputStream inputStream = fs.open(src);
//本地输出流
FileOutputStream outputStream = new FileOutputStream("/home/app/download/jdk.tgz");
//将输入流写入输出流
IOUtils.copy(inputStream, outputStream);
}
}
运行报错 1
hadoop 3.0.0 No FileSystem for scheme "hdfs"
参照：https://blog.csdn.net/u013281331/article/details/17992077
在core-site.xml中加入
<property>
<name>fs.hdfs.impl</name>
<value>org.apache.hadoop.hdfs.DistributedFileSystem</value>
<description>The FileSystem for hdfs: uris.</description>
</property>
（或者在代码中写一行 conf.set("fs.hdfs.impl",org.apache.hadoop.hdfs.DistributedFileSystem.class.getName()); ）
运行报错 2
Class org.apache.hadoop.hdfs.DistributedFileSystem not found
去官网下载导入了hadoop-core-1.2.1.jar之后好了
运行报错 3
之前的报错是没有了，但再次GG了
Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Exception in thread "main" java.lang.NoSuchMethodError: org.apache.hadoop.hdfs.server.namenode.NameNode.getAddress(Ljava/lang/String;)Ljava/net/InetSocketAddress;
看到有说是hadoop本地库是32位的，而在64位的服务器上就会有问题（估计是老版本）。但是查看本地库
cd hadoop-2.4.1/lib/native
file libhadoop.so.1.0.0
看到就是64-bit的，说明不是这个问题。
命令行运行如下代码打印错误信息（参照：https://blog.csdn.net/znb769525443/article/details/51507283）
export HADOOP_ROOT_LOGGER=DEBUG,console
hadoop fs -text /test/data/origz/access.log.gz
打印出来一大堆
2018-03-25 15:35:15,338 DEBUG util.Shell: setsid exited with exit code 0
2018-03-25 15:35:15,379 DEBUG conf.C8onfiguration: parsing URL jar:file:/home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar!/core-default.xml
2018-03-25 15:35:15,393 DEBUG conf.Configuration: parsing input stream sun.net.www.protocol.jar.JarURLConnection(JarURLInputStream@26653222 2018-03-25 15:35:16,054 DEBUG conf.Configuration: parsing URL file:/home/thousfeet/app/hadoop-3.0.0/etc/hadoop/core-site.xml 2018-03-25 15:35:16,054 DEBUG conf.Configuration: parsing input stream java.io.BufferedInputStream@5a8e6209 2018-03-25 15:35:17,071 DEBUG core.Tracer: sampler.classes = ; loaded no samplers 2018-03-25 15:35:17,173 DEBUG core.Tracer: span.receiver.classes = ; loaded no span receivers 2018-03-25 15:35:18,565 DEBUG lib.MutableMetricsFactory: field org.apache.hadoop.metrics2.lib.MutableRate org.apache.hadoop.security.UserGroupInformation)UgiMetrics.loginSuccess with annotation @org.apache.hadoop.metrics2.annotation.Metric(about=, sampleName=Ops, always=false, type=DEFAULT, valueName=Time, value=[Rate of successful kerberos logins and latency (milliseconds)])
2018-03-25 15:35:18,570 DEBUG lib.MutableMetricsFactory: field org.apache.hadoop.metrics2.lib.MutableRate org.apache.hadoop.security.UserGroupInformation(UgiMetrics.loginFailure with annotation @org.apache.hadoop.metrics2.annotation.Metric(about=, sampleName=Ops, always=false, type=DEFAULT, valueName=Time, value=[Rate of failed kerberos logins and latency (milliseconds)]) 2018-03-25 15:35:18,570 DEBUG lib.MutableMetricsFactory: field org.apache.hadoop.metrics2.lib.MutableRate org.apache.hadoop.security.UserGroupInformation)UgiMetrics.getGroups with annotation @org.apache.hadoop.metrics2.annotation.Metric(about=, sampleName=Ops, always=false, type=DEFAULT, valueName=Time, value=[GetGroups])
2018-03-25 15:35:18,571 DEBUG lib.MutableMetricsFactory: field private org.apache.hadoop.metrics2.lib.MutableGaugeLong org.apache.hadoop.security.UserGroupInformation(UgiMetrics.renewalFailuresTotal with annotation @org.apache.hadoop.metrics2.annotation.Metric(about=, sampleName=Ops, always=false, type=DEFAULT, valueName=Time, value=[Renewal failures since startup]) 2018-03-25 15:35:18,571 DEBUG lib.MutableMetricsFactory: field private org.apache.hadoop.metrics2.lib.MutableGaugeInt org.apache.hadoop.security.UserGroupInformation)UgiMetrics.renewalFailures with annotation @org.apache.hadoop.metrics2.annotation.Metric(about=, sampleName=Ops, always=false, type=DEFAULT, valueName=Time, value=[Renewal failures since last successful login])
2018-03-25 15:35:18,572 DEBUG impl.MetricsSystemImpl: UgiMetrics, User and group related metrics
2018-03-25 15:35:18,651 DEBUG security.SecurityUtil: Setting hadoop.security.token.service.use_ip to true
2018-03-25 15:35:18,738 DEBUG security.Groups: Creating new Groups object
2018-03-25 15:35:18,740 DEBUG util.NativeCodeLoader: Trying to load the custom-built native-hadoop library...
2018-03-25 15:35:18,868 DEBUG util.NativeCodeLoader: Loaded the native-hadoop library
2018-03-25 15:35:18,869 DEBUG security.JniBasedUnixGroupsMapping: Using JniBasedUnixGroupsMapping for Group resolution
2018-03-25 15:35:18,869 DEBUG security.JniBasedUnixGroupsMappingWithFallback: Group mapping impl=org.apache.hadoop.security.JniBasedUnixGroupsMapping
2018-03-25 15:35:19,088 DEBUG security.Groups: Group mapping impl=org.apache.hadoop.security.JniBasedUnixGroupsMappingWithFallback; cacheTimeout=300000; warningDeltaMs=5000
2018-03-25 15:35:19,157 DEBUG security.UserGroupInformation: hadoop login
2018-03-25 15:35:19,157 DEBUG security.UserGroupInformation: hadoop login commit
2018-03-25 15:35:19,256 DEBUG security.UserGroupInformation: using local user:UnixPrincipal: thousfeet
2018-03-25 15:35:19,256 DEBUG security.UserGroupInformation: Using user: "UnixPrincipal: thousfeet" with name thousfeet
2018-03-25 15:35:19,257 DEBUG security.UserGroupInformation: User entry: "thousfeet"
2018-03-25 15:35:19,257 DEBUG security.UserGroupInformation: UGI loginUser:thousfeet (auth:SIMPLE)
2018-03-25 15:35:19,258 DEBUG core.Tracer: sampler.classes = ; loaded no samplers
2018-03-25 15:35:19,258 DEBUG core.Tracer: span.receiver.classes = ; loaded no span receivers
2018-03-25 15:35:19,258 DEBUG fs.FileSystem: Loading filesystems
2018-03-25 15:35:19,304 DEBUG fs.FileSystem: file:// = class org.apache.hadoop.fs.LocalFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,339 DEBUG fs.FileSystem: viewfs:// = class org.apache.hadoop.fs.viewfs.ViewFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,343 DEBUG fs.FileSystem: ftp:// = class org.apache.hadoop.fs.ftp.FTPFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,349 DEBUG fs.FileSystem: har:// = class org.apache.hadoop.fs.HarFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,368 DEBUG fs.FileSystem: http:// = class org.apache.hadoop.fs.http.HttpFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,395 DEBUG fs.FileSystem: https:// = class org.apache.hadoop.fs.http.HttpsFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/common/hadoop-common-3.0.0.jar
2018-03-25 15:35:19,450 DEBUG fs.FileSystem: hdfs:// = class org.apache.hadoop.hdfs.DistributedFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/hdfs/hadoop-hdfs-client-3.0.0.jar
2018-03-25 15:35:20,568 DEBUG fs.FileSystem: webhdfs:// = class org.apache.hadoop.hdfs.web.WebHdfsFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/hdfs/hadoop-hdfs-client-3.0.0.jar
2018-03-25 15:35:20,569 DEBUG fs.FileSystem: swebhdfs:// = class org.apache.hadoop.hdfs.web.SWebHdfsFileSystem from /home/thousfeet/app/hadoop-3.0.0/share/hadoop/hdfs/hadoop-hdfs-client-3.0.0.jar
2018-03-25 15:35:20,569 DEBUG fs.FileSystem: Looking for FS supporting hdfs
2018-03-25 15:35:20,569 DEBUG fs.FileSystem: looking for configuration option fs.hdfs.impl
2018-03-25 15:35:20,654 DEBUG fs.FileSystem: Looking in service filesystems for implementation class
2018-03-25 15:35:20,655 DEBUG fs.FileSystem: FS for hdfs is class org.apache.hadoop.hdfs.DistributedFileSystem
2018-03-25 15:35:20,760 DEBUG impl.DfsClientConf: dfs.client.use.legacy.blockreader.local = false
2018-03-25 15:35:20,761 DEBUG impl.DfsClientConf: dfs.client.read.shortcircuit = false
2018-03-25 15:35:20,761 DEBUG impl.DfsClientConf: dfs.client.domain.socket.data.traffic = false
2018-03-25 15:35:20,761 DEBUG impl.DfsClientConf: dfs.domain.socket.path =
2018-03-25 15:35:20,823 DEBUG hdfs.DFSClient: Sets dfs.client.block.write.replace-datanode-on-failure.min-replication to 0
2018-03-25 15:35:20,928 DEBUG retry.RetryUtils: multipleLinearRandomRetry = null
2018-03-25 15:35:20,989 DEBUG ipc.Server: rpcKind=RPC_PROTOCOL_BUFFER, rpcRequestWrapperClass=class org.apache.hadoop.ipc.ProtobufRpcEngine(RpcProtobufRequest, rpcInvoker=org.apache.hadoop.ipc.ProtobufRpcEngine)Server$ProtoBufRpcInvoker@272113c4
2018-03-25 15:35:21,060 DEBUG ipc.Client: getting client out of cache: org.apache.hadoop.ipc.Client@2794eab6
2018-03-25 15:35:23,045 DEBUG unix.DomainSocketWatcher: org.apache.hadoop.net.unix.DomainSocketWatcher$2@4b4bda67: starting with interruptCheckPeriodMs = 60000
2018-03-25 15:35:23,115 DEBUG util.PerformanceAdvisory: Both short-circuit local reads and UNIX domain socket are disabled.
2018-03-25 15:35:23,123 DEBUG sasl.DataTransferSaslUtil: DataTransferProtocol not using SaslPropertiesResolver, no QOP found in configuration for dfs.data.transfer.protection
2018-03-25 15:35:23,329 DEBUG ipc.Client: The ping interval is 60000 ms.
2018-03-25 15:35:23,331 DEBUG ipc.Client: Connecting to node01/192.168.216.100:9000
2018-03-25 15:35:24,267 DEBUG ipc.Client: IPC Client (2146338580) connection to node01/192.168.216.100:9000 from thousfeet: starting, having connections 1
2018-03-25 15:35:24,381 DEBUG ipc.Client: IPC Client (2146338580) connection to node01/192.168.216.100:9000 from thousfeet sending #0 org.apache.hadoop.hdfs.protocol.ClientProtocol.getFileInfo
2018-03-25 15:35:24,427 DEBUG ipc.Client: IPC Client (2146338580) connection to node01/192.168.216.100:9000 from thousfeet got value #0
2018-03-25 15:35:24,427 DEBUG ipc.ProtobufRpcEngine: Call: getFileInfo took 1193ms
text: `/text/data/origz/access.log.gz': No such file or directory
2018-03-25 15:35:24,575 DEBUG ipc.Client: stopping client from cache: org.apache.hadoop.ipc.Client@2794eab6
2018-03-25 15:35:24,576 DEBUG ipc.Client: removing client from cache: org.apache.hadoop.ipc.Client@2794eab6
2018-03-25 15:35:24,576 DEBUG ipc.Client: stopping actual client because no more references remain: org.apache.hadoop.ipc.Client@2794eab6
2018-03-25 15:35:24,576 DEBUG ipc.Client: Stopping client
2018-03-25 15:35:24,598 DEBUG ipc.Client: IPC Client (2146338580) connection to node01/192.168.216.100:9000 from thousfeet: closed
2018-03-25 15:35:24,598 DEBUG ipc.Client: IPC Client (2146338580) connection to node01/192.168.216.100:9000 from thousfeet: stopped, remaining connections 0
2018-03-25 15:35:24,699 DEBUG util.ShutdownHookManager: ShutdownHookManger complete shutdown.
感觉问题出在
Both short-circuit local reads and UNIX domain socket are disabled.
查了一大堆的的博客教程都不对，直接找到官网去了 http://hadoop.apache.org/docs/current/hadoop-project-dist/hadoop-hdfs/ShortCircuitLocalReads.html
给hdfs-site.xml配置加上
<property>
<name>dfs.client.read.shortcircuit</name>
<value>true</value>
</property>
<property>
<name>dfs.client.use.legacy.blockreader.local</name>
<value>true</value>
</property>
<property>
<name>dfs.datanode.data.dir.perm</name>
<value>750</value>
</property>
<property>
<name>dfs.block.local-path-access.user</name>
<value>foo,bar</value>
</property>
还是不行
参考 https://www.cnblogs.com/dandingyy/archive/2013/03/08/2950696.html ，在run configuration中 Arguments/VM arguments加上 -Djava.library.path=/home/thousfeet/app/hadoop-3.0.0/lib/native
运行报错 4
之前报错的第一行unable xxx不见了...但第二行的报错还在
Exception in thread "main" java.lang.NoSuchMethodError: org.apache.hadoop.hdfs.server.namenode.NameNode.getAddress(Ljava/lang/String;)Ljava/net/InetSocketAddress;
参考 https://blog.csdn.net/yzl_8877/article/details/53216923
java.net.URL urlOfClass = NameNode.class.getClassLoader().getResource("com/sun/jndi/dns/NameNode.class"); //InsertProgarm是该语句所在的类
System.out.println(urlOfClass);
输出
jar:file:/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/jre/lib/rt.jar!/com/sun/jndi/dns/NameNode.class
但是我总不能把 rt.jar 移除了吧！甚至都有点想修改rt.jar把这个class的getAddress()方法给去了，但是动了JRE的标准API后续不知道的某些地方有牵连就会很爆炸（）
到这里瓶颈了，还没解决
猜测可能最好还是用maven直接配置（？）...打算再折腾半天，如果还解决不了就算了，反正现在的需求来看暂时不会用上这个。