ubtuntu安装java

          

            在Ubtuntu下安装hadoop集群，安装java环境

             主要参考  http://www.linuxidc.com/Linux/2015-01/112030.htm

         1、   首先从官网上下载对应版本的jdk，我下载的是jdk-7u79-linux-x64.tar.gz，放到home主目录下

         2、   打开终端 Ctrl+Alt+T，创建java的目录，输入密码

            master@ubuntu:~$ sudo mkdir /usr/local/java
             [sudo] password for master: 

         3、   把压缩包复制到java目录下：
             master@ubuntu:~$ cp jdk-7u79-linux-x64.tar.gz/usr/local/java
            可能会提示权限不足，前面加上sudo即可，

            cp: cannot create regular file '/usr/local/java/jdk-7u79-linux-x64.tar.gz': Permission denied
            master@ubuntu:~$ sudo cp jdk-7u79-linux-x64.tar.gz /usr/local/java

        4、    定位到java目录下，
            master@ubuntu:~$ cd /usr/local/java

        5、  解压压缩包，等待完成

           master@ubuntu:/usr/local/java$ sudo tar xvf jdk-7u79-linux-x64.tar.gz

          可以删除压缩包，

          master@ubuntu:/usr/local/java$ sudo rm jdk-7u79-linux-x64.tar.gz

        6、  编辑jdk环境变量，用全局设置方法，它是是所有用户的共用的环境变量

          master@ubuntu:/usr/local/java$ sudo gedit ~/.bashrc

        7、 打开文件，在最后添加下面的代码，注意更改自己jdk的版本号，后面不要多空格

          export JAVA_HOME=/usr/local/java/jdk1.7.0_79
          export JRE_HOME=${JAVA_HOME}/jre
          export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib
          export PATH=${JAVA_HOME}/bin:$PATH

         8、 查看是否安装成功
          master@ubuntu:~$ java -version
          java version "1.7.0_79"
         Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
         Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)

http://www.cnblogs.com/kinglau/p/3794433.html

安装Hadoop过程如下：

1、下载hadoop，放在home目录，解压，在local下面创建hadoop文件夹

master@ubuntu:~$ sudo cp hadoop-2.5.2.tar.gz /usr/local         //复制到local下面

master@ubuntu:~$ sudo tar -zxf hadoop-2.5.2.tar.gz -C /usr/local      //解压
master@ubuntu:~$ cd /usr/local/
master@ubuntu:/usr/local$ sudo mv ./hadoop-2.5.2/ ./hadoop  //改名
master@ubuntu:/usr/local$ sudo chown -R master ./hadoop   //赋予文件夹权限
2、配置hadoop，输入java环境

 master@ubuntu:~$ sudo gedit /usr/local/hadoop/etc/hadoop/hadoop-env.sh 
[sudo] password for master:
master@ubuntu:~$ sudo gedit ~/.bashrc   //上面配置过java环境，打开查看java的路径

找到JAVA_HOME变量，修改此变量如下

  export JAVA_HOME=/usr/local/java/jdk1.7.0_79
 3、利用Wordcount，测试hadoop
master@ubuntu:~$ cd /usr/local/hadoop   
master@ubuntu:/usr/local/hadoop$ sudo mkdir input //当前目录新建一个input文件夹
master@ubuntu:/usr/local/hadoop$ sudo cp  README.txt input  //copy txt文件进去
master@ubuntu:/usr/local/hadoop$ bin/hadoop jar share/hadoop/mapreduce/sources/hadoop-mapreduce-examples-2.5.2-sources.jar org.apache.hadoop.examples.WordCount input output       //根据自己的hadoop版本修改

成功后返回如下：

17/03/23 20:26:48 INFO mapreduce.Job: Counters: 33
 File System Counters
  FILE: Number of bytes read=547402
  FILE: Number of bytes written=1013492
  FILE: Number of read operations=0
  FILE: Number of large read operations=0
  FILE: Number of write operations=0
 Map-Reduce Framework
  Map input records=31
  Map output records=179
  Map output bytes=2055
  Map output materialized bytes=1836
  Input split bytes=104
  Combine input records=179
  Combine output records=131
  Reduce input groups=131
  Reduce shuffle bytes=1836
  Reduce input records=131
  Reduce output records=131
  Spilled Records=262
  Shuffled Maps =1
  Failed Shuffles=0
  Merged Map outputs=1
  GC time elapsed (ms)=48
  CPU time spent (ms)=0
  Physical memory (bytes) snapshot=0
  Virtual memory (bytes) snapshot=0
  Total committed heap usage (bytes)=240787456
 Shuffle Errors
  BAD_ID=0
  CONNECTION=0
  IO_ERROR=0
  WRONG_LENGTH=0
  WRONG_MAP=0
  WRONG_REDUCE=0
 File Input Format Counters
  Bytes Read=1366
 File Output Format Counters
  Bytes Written=1326