Dissecting The Nutch Crawler - Command "inject": net.nutch.db.WebDBInjector

英文原文出处：DissectingTheNutchCrawler
转载本文请注明出处：http://blog.csdn.net/pwlazy

Command "inject": net.nutch.db.WebDBInjector

> "inject: inject new urls into the database"
> Usage: WebDBInjector <db_dir> (-urlfile <url_file> | -dmozfile <dmoz_file>) [-subset <subsetDenominator>] [-includeAdultMaterial] [-skew skew] [-noDmozDesc] [-topicFile <topic list file>] [-topic <topic> [-topic <topic> [...]]]

WebDBInjector.main() accepts two input-type options. "-urlfile" parses a simple list ofURLs with oneURL per line. "-dmozfile" is for parsingDMOZRDF files, which is useful for bootstrapping a whole-web database.

Let's see how it works. Create a file with oneURL, then run "bin/nutch inject":

$ vi spam_url.txt 
$ bin/nutch inject spam -urlfile spam_url.txt
$ find spam -type file | xargs ls -l
-rw-r--r--  1 kangas  users    0 Oct 25 18:57 spam/dbreadlock
-rw-r--r--  1 kangas  users    0 Oct 25 18:57 spam/dbwritelock
-rw-r--r--  1 kangas  users   16 Oct 25 18:57 spam/webdb/linksByMD5/data
-rw-r--r--  1 kangas  users   16 Oct 25 18:57 spam/webdb/linksByMD5/index
-rw-r--r--  1 kangas  users   16 Oct 25 18:57 spam/webdb/linksByURL/data
-rw-r--r--  1 kangas  users   16 Oct 25 18:57 spam/webdb/linksByURL/index
-rw-r--r--  1 kangas  users   89 Oct 25 18:57 spam/webdb/pagesByMD5/data
-rw-r--r--  1 kangas  users   97 Oct 25 18:57 spam/webdb/pagesByMD5/index
-rw-r--r--  1 kangas  users  115 Oct 25 18:57 spam/webdb/pagesByURL/data
-rw-r--r--  1 kangas  users   58 Oct 25 18:57 spam/webdb/pagesByURL/index
-rw-r--r--  1 kangas  users   17 Oct 25 18:57 spam/webdb/stats

We can see that a new "stats" file was created, and the data/index files in the "pagesBy..." directories were modified.

命令：inject 对应net.nutch.db.WebDBInjector类
inject 将新的urls插入到数据库
调用方式：WebDBInjector <db_dir> (-urlfile <url_file> | -dmozfile <dmoz_file>) [-subset <subsetDenominator>] [-includeAdultMaterial] [-skew skew] [-noDmozDesc] [-topicFile <topic list file>] [-topic <topic> [-topic <topic> [...]]]

WebDBInjector.main()方法接受两个输入选项。"-urlfile"以每行一个url的方式解析一个简单url列表。 "-dmozfile"用于解析DMOZRDF文件，后者用于启动基于整个web的数据库

然我看看命令是如何工作的，产生一个文件，填入url,然后运行bin/nutch inject


$ vi spam_url.txt


$ bin/nutch inject spam -urlfile spam_url.txt


$ find spam -type file | xargs ls -l


-rw-r--r-- 1 kangas users 0 Oct 25 18:57 spam/dbreadlock


-rw-r--r-- 1 kangas users 0 Oct 25 18:57 spam/dbwritelock


-rw-r--r-- 1 kangas users 16 Oct 25 18:57 spam/webdb/linksByMD5/data


-rw-r--r-- 1 kangas users 16 Oct 25 18:57 spam/webdb/linksByMD5/index


-rw-r--r-- 1 kangas users 16 Oct 25 18:57 spam/webdb/linksByURL/data


-rw-r--r-- 1 kangas users 16 Oct 25 18:57 spam/webdb/linksByURL/index


-rw-r--r-- 1 kangas users 89 Oct 25 18:57 spam/webdb/pagesByMD5/data


-rw-r--r-- 1 kangas users 97 Oct 25 18:57 spam/webdb/pagesByMD5/index


-rw-r--r-- 1 kangas users 115 Oct 25 18:57 spam/webdb/pagesByURL/data


-rw-r--r-- 1 kangas users 58 Oct 25 18:57 spam/webdb/pagesByURL/index


-rw-r--r-- 1 kangas users 17 Oct 25 18:57 spam/webdb/stats

我们能看出一个新的stats文件产生了，而且在"pagesBy..."目录下的名为data和index的文件被修改了