idea中Exception in thread “main“ java.lang.UnsatisfiedLinkError: org.apache.hadoop.io.nativeio.Native

这个困扰了我三天的问题，之前已经不想解决了，直到再一次遇到，决定彻底干它，之前也在网上搜了一些解决它的办法，什么改变环境还有加入NativeIO，都没有用，不过最后还是使用了NativeIO的方法解决了，之前一直没有用的原因是，没有把文件放对位置

正确的位置应该是放在java包下，和项目包并行，而且必须是这个包名org.apache.hadoop.io.nativeio和NativeIO这个类名，不然不能覆盖原来的这个类

下面附上NativeIO的源码，有的包可能要自己引一下，细节上应该不用说了

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.io.nativeio;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.fs.HardLink;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.io.SecureIOUtils.AlreadyExistsException;
import org.apache.hadoop.util.NativeCodeLoader;
import org.apache.hadoop.util.Shell;
import org.apache.hadoop.util.PerformanceAdvisory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import sun.misc.Unsafe;

import com.google.common.annotations.VisibleForTesting;

/**
 * JNI wrappers for various native IO-related calls not available in Java. These
 * functions should generally be used alongside a fallback to another more
 * portable mechanism.
 */
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class NativeIO {
    public static class POSIX {
        // Flags for open() call from bits/fcntl.h
        public static final int O_RDONLY = 00;
        public static final int O_WRONLY = 01;
        public static final int O_RDWR = 02;
        public static final int O_CREAT = 0100;
        public static final int O_EXCL = 0200;
        public static final int O_NOCTTY = 0400;
        public static final int O_TRUNC = 01000;
        public static final int O_APPEND = 02000;
        public static final int O_NONBLOCK = 04000;
        public static final int O_SYNC = 010000;
        public static final int O_ASYNC = 020000;
        public static final int O_FSYNC = O_SYNC;
        public static final int O_NDELAY = O_NONBLOCK;

        // Flags for posix_fadvise() from bits/fcntl.h
        /* No further special treatment. */
        public static final int POSIX_FADV_NORMAL = 0;
        /* Expect random page references. */
        public static final int POSIX_FADV_RANDOM = 1;
        /* Expect sequential page references. */
        public static final int POSIX_FADV_SEQUENTIAL = 2;
        /* Will need these pages. */
        public static final int POSIX_FADV_WILLNEED = 3;
        /* Don't need these pages. */
        public static final int POSIX_FADV_DONTNEED = 4;
        /* Data will be accessed once. */
        public static final int POSIX_FADV_NOREUSE = 5;

        /*
         * Wait upon writeout of all pages in the range before performing the write.
         */
        public static final int SYNC_FILE_RANGE_WAIT_BEFORE = 1;
        /*
         * Initiate writeout of all those dirty pages in the range which are not
         * presently under writeback.
         */
        public static final int SYNC_FILE_RANGE_WRITE = 2;

        /*
         * Wait upon writeout of all pages in the range after performing the write.
         */
        public static final int SYNC_FILE_RANGE_WAIT_AFTER = 4;

        private static final Log LOG = LogFactory.getLog(NativeIO.class);

        private static boolean nativeLoaded = false;
        private static boolean fadvisePossible = true;
        private static boolean syncFileRangePossible = true;

        static final String WORKAROUND_NON_THREADSAFE_CALLS_KEY = "hadoop.workaround.non.threadsafe.getpwuid";
        static final boolean WORKAROUND_NON_THREADSAFE_CALLS_DEFAULT = true;

        private static long cacheTimeout = -1;

        private static CacheManipulator cacheManipulator = new CacheManipulator();

        public static CacheManipulator getCacheManipulator() {
            return cacheManipulator;
        }

        public static void setCacheManipulator(CacheManipulator cacheManipulator) {
            POSIX.cacheManipulator = cacheManipulator;
        }

        /**
         * Used to manipulate the operating system cache.
         */
        @VisibleForTesting
        public static class CacheManipulator {
            public void mlock(String identifier, ByteBuffer buffer, long len) throws IOException {
                POSIX.mlock(buffer, len);
            }

            public long getMemlockLimit() {
                return NativeIO.getMemlockLimit();
            }

            public long getOperatingSystemPageSize() {
                return NativeIO.getOperatingSystemPageSize();
            }

            public void posixFadviseIfPossible(String identifier, FileDescriptor fd, long offset, long len, int flags)
                    throws NativeIOException {
                NativeIO.POSIX.posixFadviseIfPossible(identifier, fd, offset, len, flags);
            }

            public boolean verifyCanMlock() {
                return NativeIO.isAvailable();
            }
        }

        /**
         * A CacheManipulator used for testing which does not actually call mlock. This
         * allows many tests to be run even when the operating system does not allow
         * mlock, or only allows limited mlocking.
         */
        @VisibleForTesting
        public static class NoMlockCacheManipulator extends CacheManipulator {
            public void mlock(String identifier, ByteBuffer buffer, long len) throws IOException {
                LOG.info("mlocking " + identifier);
            }

            public long getMemlockLimit() {
                return 1125899906842624L;
            }

            public long getOperatingSystemPageSize() {
                return 4096;
            }

            public boolean verifyCanMlock() {
                return true;
            }
        }

        static {
            if (NativeCodeLoader.isNativeCodeLoaded()) {
                try {
                    Configuration conf = new Configuration();
                    workaroundNonThreadSafePasswdCalls = conf.getBoolean(WORKAROUND_NON_THREADSAFE_CALLS_KEY,
                            WORKAROUND_NON_THREADSAFE_CALLS_DEFAULT);

                    initNative();
                    nativeLoaded = true;

                    cacheTimeout = conf.getLong(CommonConfigurationKeys.HADOOP_SECURITY_UID_NAME_CACHE_TIMEOUT_KEY,
                            CommonConfigurationKeys.HADOOP_SECURITY_UID_NAME_CACHE_TIMEOUT_DEFAULT) * 1000;
                    LOG.debug("Initialized cache for IDs to User/Group mapping with a " + " cache timeout of "
                            + cacheTimeout / 1000 + " seconds.");