java代码cdh 在线运行JAVA代码

java: jsp中用url调用.do 的action报错 Operation is not defined for controller queryPvpAccpAccount

你的URL是不是拼错了,'emp:url action="queryPvpAccpAccount.do"/?'+paramStr+'cdh='+cdh;,这个paramStr没有参数,然后你就cdh啦

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现有 java web程序，如何去连接hadoop？

看你用什么版本的hadoop，推荐使用cdh版的

jar包导入web工程

调用HBase接口

如：

hbaseConfig = new Configuration();

conf = HBaseConfiguration.create(hbaseConfig);

admin = new HBaseAdmin(conf);

this.setTableName(tableName);

如何解决CDH5中找不到JAVA

找不到JAVA_HOME 说明JDK环境变量没有配置正确,建议查看一下是否有安装JDK,再查看一下path里有没有增加JAVA_HOME的环境变量. eoch path 即可查看。

在安装presudo版本的CDH5中，第一次需要格式化HDFS，执行：

$ sudo -u hdfs hdfs namenode -format

但是会出现：

[root@AY1312280620257702e0Z conf]# sudo -u hdfs hdfs namenode -format

Error: JAVA_HOME is not set and could not be found.

[root@AY1312280620257702e0Z conf]# echo $JAVA_HOME

/usr/qiuxin/software/jdk1.7.0_25

[root@AY1312280620257702e0Z conf]# echo $JAVA_HOME

/usr/qiuxin/software/jdk1.7.0_25

[root@AY1312280620257702e0Z conf]# sudo -u hdfs hdfs namenode -format

Error: JAVA_HOME is not set and could not be found.

[root@AY1312280620257702e0Z conf]# java -version

java version "1.7.0_25"

Java(TM) SE Runtime Environment (build 1.7.0_25-b15)

Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)

[root@AY1312280620257702e0Z conf]#

[root@AY1312280620257702e0Z ~]# for x in `cd /etc/init.d ; ls hadoop-hdfs-*` ; do sudo service $x start ; done

Starting Hadoop datanode:[  OK  ]

Error: JAVA_HOME is not set and could not be found.

Starting Hadoop namenode:[  OK  ]

Error: JAVA_HOME is not set and could not be found.

Starting Hadoop secondarynamenode:[  OK  ]

Error: JAVA_HOME is not set and could not be found.

需要进行如下配置，即可解决如上问题：

在/etc/sudores 的最后一行增加：

On systems on which

sudo

clears or restricts environment variables, you also need to add the following line to the

/etc/sudoers

file:

Defaults env_keep+=JAVA_HOME

同时需要配置：

If your JDK is located at one of the standard locations, it's detected by the script (using this component called bigtop-utils). However, if it's not, you'd have to go to /etc/default/bigtop-utils and set and export JAVA_HOME ( to /usr/qiuxin/software/jdk1.7.0_25) there. You only need to do it once and all CDH components would use that variable to figure out where JDK is.

[root@AY1312280620257702e0Z ~]# vi /etc/default/bigtop-utils

增加：export JAVA_HOME=/usr/qiuxin/software/jdk1.7.0_25

[root@AY1312280620257702e0Z ~]# source /etc/default/bigtop-utils