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【solr专题之四】关于VelocityResponseWriter

發布時間：2024/1/23 编程问答 36 豆豆

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一、關于Velocity的基本配置

? ? 在Solr中，可以以多種方式返回搜索結果，如單純的文本回復（XML、JSON、CSV等），也可以返回velocity，js等格式。而VelocityResponseWriter就是用于將返回velocity類型文本，以便直接用于結果呈現。

? ? ?在Solr提供的example，其中的一個RequestHandler--/browse，使用了VelocityResponseWriter。其配置如下：

? ??

<requestHandler name="/browse" class="solr.SearchHandler"><lst name="defaults"><str name="echoParams">explicit</str><str name="wt">velocity</str><str name="v.template">browse</str><str name="v.layout">layout</str><str name="title">Solritas_test</str><str name="defType">edismax</str><str name="qf">text^0.5 features^1.0 name^1.2 sku^1.5 id^10.0 manu^1.1 cat^1.4title^10.0 description^5.0 keywords^5.0 author^2.0 resourcename^1.0</str><str name="df">text</str><str name="mm">100%</str><str name="q.alt">*:*</str><str name="rows">10</str><str name="fl">*,score</str><str name="mlt.qf">text^0.5 features^1.0 name^1.2 sku^1.5 id^10.0 manu^1.1 cat^1.4title^10.0 description^5.0 keywords^5.0 author^2.0 resourcename^1.0</str><str name="mlt.fl">text,features,name,sku,id,manu,cat,title,description,keywords,author,resourcename</str><int name="mlt.count">3</int><str name="facet">on</str><str name="facet.field">cat</str><str name="facet.field">manu_exact</str><str name="facet.field">content_type</str><str name="facet.field">author_s</str><str name="facet.query">ipod</str><str name="facet.query">GB</str><str name="facet.mincount">1</str><str name="facet.pivot">cat,inStock</str><str name="facet.range.other">after</str><str name="facet.range">price</str><int name="f.price.facet.range.start">0</int><int name="f.price.facet.range.end">600</int><int name="f.price.facet.range.gap">50</int><str name="facet.range">popularity</str><int name="f.popularity.facet.range.start">0</int><int name="f.popularity.facet.range.end">10</int><int name="f.popularity.facet.range.gap">3</int><str name="facet.range">manufacturedate_dt</str><str name="f.manufacturedate_dt.facet.range.start">NOW/YEAR-10YEARS</str><str name="f.manufacturedate_dt.facet.range.end">NOW</str><str name="f.manufacturedate_dt.facet.range.gap">+1YEAR</str><str name="f.manufacturedate_dt.facet.range.other">before</str><str name="f.manufacturedate_dt.facet.range.other">after</str><str name="hl">on</str><str name="hl.fl">content features title name</str><str name="hl.encoder">html</str><str name="hl.simple.pre"><b></str><str name="hl.simple.post"></b></str><str name="f.title.hl.fragsize">0</str><str name="f.title.hl.alternateField">title</str><str name="f.name.hl.fragsize">0</str><str name="f.name.hl.alternateField">name</str><str name="f.content.hl.snippets">3</str><str name="f.content.hl.fragsize">200</str><str name="f.content.hl.alternateField">content</str><str name="f.content.hl.maxAlternateFieldLength">750</str><str name="spellcheck">on</str><str name="spellcheck.extendedResults">false</str><str name="spellcheck.count">5</str><str name="spellcheck.alternativeTermCount">2</str><str name="spellcheck.maxResultsForSuggest">5</str><str name="spellcheck.collate">true</str><str name="spellcheck.collateExtendedResults">true</str><str name="spellcheck.maxCollationTries">5</str><str name="spellcheck.maxCollations">3</str></lst><arr name="last-components"><str>spellcheck</str></arr></requestHandler>

關于velocity這個writer的定義如下：

<queryResponseWriter name="velocity" class="solr.VelocityResponseWriter" startup="lazy"/>

處理一個流程的步驟如下：

1、根據請求url查找相關的配置請求的url為：http://localhost:8983/solr/browse 則在solrConfig.xml中查找 ?/browse的配置，可以得出上述所示的結果。
2、其中有關velocity的內容如下： <requestHandler name="/browse" class="solr.SearchHandler"><lst name="defaults"><str name="echoParams">explicit</str><str name="wt">velocity</str><str name="v.template">browse</str><str name="v.layout">layout</str><str name="title">Solritas_test</str>
從上述定義中開始分別查找顯示層的內容(vm文件)與處理類的內容(wt的實現類。)
3、定位顯示內容模板根據v.template屬性，定義到文件browse.vm，注意在配置中省略了后綴名vm。由于存在v.layout屬性，因此，此屬性的值將作為模板，而v.template中的內容將作為$content的內容。

v.layout: Template name that wraps main template (v.template). Main template renders to a $content that can be used in layout template.

layout.vm的內容如下： #*** Overall HTML page layout*#<html> <head>#parse("head.vm") </head><body><div id="admin"><a href="#url_root/#/#core_name">Solr Admin</a></div><div id="header">#parse("header.vm")</div><div id="tabs">#parse("tabs.vm")</div><div id="content">$content</div><div id="footer">#parse("footer.vm")</div></body> </html>
4、定位ResponseWriter? 從第2步的結果知道，使用的velocity，然后查找這個wt的定義，可以得到 <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter" startup="lazy"/> 即VelocityResponseWriter實現類，其定義如下： public class VelocityResponseWriter extends Object implements QueryResponseWriter
與Solr返回Velocity相關的類只有4個：

PageTool
SolrParamResourceLoader
SolrVelocityResourceLoader
VelocityResponseWriter

以下是關于VelocityResponseWriter的官方說明：http://wiki.apache.org/solr/VelocityResponseWriter

Introduction

VelocityResponseWriter (aka?Solritas) enables Solr to respond with content generated from?Velocity?templates. Along with technologies like SolrJS, this makes Solr itself capable of driving sophisticated search interfaces without the need for an intermediate application server between the browser and Solr.

See?SOLR-620?for more information.

Contents

Introduction

Instructions to use, Solr 1.4+

Sample Usage

Using the VelocityResponseWriter in Solr Core

Instructions to use, Solr 4.0+

Sample Usage

Options (All Versions)

Velocity Context

TODO

Instructions to use, Solr 1.4+

These steps will get you up and running for the examples below:

Download and install Solr 1.4.x
Fire up Solr: cd example; java -Dsolr.solr.home=../contrib/velocity/src/main/solr/ -jar start.jar
Index sample docs: cd example/exampledocs; java -jar post.jar *.xml
Hit the examples below...

Sample Usage

http://localhost:8983/solr/itas

Renders browse.vm from conf/velocity. Faceted navigation included.

http://localhost:8983/solr/itas?v.template.header=Custom%20Header

Renders browse.vm, but overrides the header.vm from conf/velocity with the specified value.

http://localhost:8983/solr/itas?debugQuery=true

Renders browse.vm, adding in explanation views per hit, and a Velocity context dump at the end.

Using the VelocityResponseWriter in Solr Core

The VelocityResponseWriter is still a contrib component in Solr 1.4.x. In order to use it with the core distributions the following steps need to be followed:

The following jars need to be copied from contrib/velocity/src/main/solr/lib/ to $SOLR_HOME/lib:

apache-solr-velocity-1.4-dev.jar
velocity-1.6.1.jar
velocity-tools-2.0-beta3.jar
commons-beanutils-1.7.0.jar
commons-collections-3.2.1.jar

The VelocityResponseWriter uses a more recent version of the commons lang jar than the current version of Solr core, so the jar commons-lang-2.4.jar from .../contrib/velocity/src/main/solr/lib/ should replace $SOLR_HOME/lib/commons-lang-2.1.jar

Add some configuration for this?ResponseWriter?to solrconfig.xml like this:

Set up a?RequestHandler?in solrconfig.xml:

<requestHandler name="/itas" class="solr.SearchHandler"> <lst name="defaults"> <str name="v.template">browse</str> <str name="v.properties">velocity.properties</str> <str name="v.contentType">text/html;charset=UTF-8</str> <str name="title">Solritas</str> <str name="wt">velocity</str> <str name="defType">dismax</str> <str name="q.alt">*:*</str> <str name="rows">10</str> <str name="fl">*,score</str> <str name="facet">on</str> <str name="facet.field">title</str> <str name="facet.mincount">1</str> <str name="qf"> text^0.5 title^1.5 </str> </lst>    </requestHandler>

Copy the .../contrib/velocity/src/main/solr/conf/velocity directory to $SOLR_HOME/conf/. This directory contains the Velocity templates that will be needed by the VelocityResponseWriter, and also a style sheet, main.css. The templates and style sheet can be edited to customize the display.

Instructions to use, Solr 4.0+

These steps will get you up and running for the examples below:

Check out Solr trunk: svn co?http://svn.apache.org/viewvc/lucene/dev/branches/branch_4x/
Build Solr: ant clean example
Fire up Solr: cd example; java -jar start.jar
Index sample docs: cd example/exampledocs; java -jar post.jar *.xml
Hit the examples below...

Sample Usage

http://localhost:8983/solr/browse

Renders browse.vm from conf/velocity. Faceted navigation included.

http://localhost:8983/solr/browse?v.template.header=Custom%20Header

Renders browse.vm, but overrides the header.vm from conf/velocity with the specified value.

http://localhost:8983/solr/browse?debugQuery=true

Renders browse.vm, adding in explanation views per hit, and a Velocity context dump at the end.

Options (All Versions)

v.template: template name to use, without the .vm suffix. If not specified, "default"[.vm] will be used.
v.template.<name>: overrides a file system template
debugQuery: if true, default view displays explanations for each hit and additional debugging information in the footer.
v.json: Escapes and wraps Velocity generated response with v.json parameter as a?JavaScript?function.
v.layout: Template name that wraps main template (v.template). Main template renders to a $content that can be used in layout template.
v.base_dir: overwrites default template load path (conf/velocity/).
v.properties: specifies a Velocity properties file to be applied, found using the Solr resource loader mechanism. If not specified, no .properties file is loaded. Example: v.properties=velocity.properties where velocity.properties can be found using Solr's resource loader mechanism, for example in the conf/ directory (not conf/velocity which is for templates only). The .properties file could also be located inside a JAR in the lib/ directory, or other locations.
v.contentType: sets the value of the HTTP response's Content-Type header (in case (x)html pages should be UTF-8 (instead of ISO-8859-1) encoded, make sure you set this option to?text/xml;charset=UTF-8?(for XHTML) and?text/html;charset=UTF-8?(for HTML), respectively)

Velocity Context

esc: a Velocity?EscapeTool?instance
date: a Velocity?ComparisonDateTool?instance
list: a Velocity?ListTool?instance
math: a Velocity?MathTool?instance
number: a Velocity?NumberTool?instance
page: a?PageTool?instance. page only is added to the context when response is a?QueryResponse.
request: a?SolrQueryRequest
response: a?QueryResponse?most of the time, but in some cases where?QueryResponse?doesn't like the request handlers output (AnalysisRequestHandler, for example, causes a?ClassCastException?parsing "response") the response will be a?SolrResponseBase?object.
sort: a Velocity?SortTool?instance

TODO

Ajax suggest
Integrate/adapt to SolrJS
Tie in SIMILE Timeline and SIMILE Exhibit
Add links in default footer to this wiki page, the Solr request as XML format, and SOLR-620
Fix multi-valued fields issue, and fl parameter usage.
Work on "dist" target so this works easily with a nightly build.
Make Velocity tools and engine configuration pluggable

二、Velocity文件定位過程

1、根據上述分析，首先定位layout.xml

<html> <head>#parse("head.vm") </head><body><div id="admin"><a href="#url_root/#/#core_name">Solr Admin</a></div><div id="header">#parse("header.vm")</div><div id="tabs">#parse("tabs.vm")</div><div id="content">$content</div><div id="footer">#parse("footer.vm")</div></body> </html>
2、其中content的內容即為browse.vm

<div class="pagination">#parse("pagination_top.vm") </div>## Show Error Message, if any <div class="error">#parse("error.vm") </div>## Render Results, actual matching docs <div class="results">#parse("results_list.vm") </div><div class="pagination">#parse("pagination_bottom.vm") </div>
3、browse.vm中最主要的搜索結果為results_list.vm

#*** Render the main Results List*### Usually displayed inside <div class="results">#if($response.response.get('grouped'))#foreach($grouping in $response.response.get('grouped'))#parse("hit_grouped.vm")#end#else#foreach($doc in $response.results)#parse("hit.vm")## Can get an extremely simple view of the doc## which might be nicer for debugging##parse("hit_plain.vm")#end#end

一般情況下使用hit.vm作呈現，它對頁面作了一些美工。

在某些情況下，如debug的時候，就使用hit_plain.vm進行呈現，此時將所有的屬性呈現出來。

二者的對比效果如下：

4、先查看hit_plain.vm

#*** An extremely plain / debug version of hit.vm*#<table>## For each field#foreach( $fieldName in $doc.fieldNames )## For each value#foreach( $value in $doc.getFieldValues($fieldName) )<tr>## Field Name<th align="right" valign="top">#if( $foreach.count == 1 )$fieldName:#end</th>## Field Value(s)<td align="left" valign="top">$esc.html($value) <br/></td></tr>#end ## end for each value#end ## end for each field </table> <hr/>就是將屬性名與屬性值呈現出來。

5、再看看hit.vm

#*** Called for each matching document but then* calls one of product_doc, join_doc or richtext_doc* depending on which fields the doc has*##set($docId = $doc.getFieldValue('id'))<div class="result-document">## Has a "name" field ?#if($doc.getFieldValue('name'))#parse("product_doc.vm")## Has a "compName_s" field ?#elseif($doc.getFieldValue('compName_s'))#parse("join_doc.vm")## Fallback to richtext_doc#else#parse("richtext_doc.vm")#end</div>

6、可以直接看richtest_doc.vm
#*** Render a complex document in the results list*### Load Mime-Type List and Mapping #parse('mime_type_lists.vm') ## Sets: ## * supportedMimeTypes, AKA supportedtypes ## * mimeExtensionsMap, AKA extMap## Title #if($doc.getFieldValue('title'))#set($title = $esc.html($doc.getFirstValue('title'))) #else#set($title = "["+$doc.getFieldValue('id')+"]") #end## URL #if($doc.getFieldValue('url'))#set($url = $doc.getFieldValue('url')) #elseif($doc.getFieldValue('resourcename'))#set($url = "file:///$doc.getFieldValue('resourcename')") #else#set($url = "$doc.getFieldValue('id')") #end## Sort out Mime-Type #set($ct = $list.get($doc.getFirstValue('content_type').split(";"),0)) #set($filename = $doc.getFieldValue('resourcename')) #set($filetype = false) #set($filetype = $mimeExtensionsMap.get($ct))## TODO: falling back to file extension is convenient, ## except when you don't have an icon for that extension ## example "application/vnd.openxmlformats-officedocument.wordprocessingml.document" ## document with a .docx extension. ## It'd be nice to fall back to an "unknown" or the existing "file" type ## We sort of do this below, but only if the filename has no extension ## (anything after the last dot).#if(!$filetype)#set($filetype = $filename.substring($filename.lastIndexOf(".")).substring(1)) #end## #if(!$filetype) ## #set($filetype = "file") ## #end ## #if(!$supportedMimeTypes.contains($filetype)) ## #set($filetype = "file") ## #end## Row 1: Icon and Title and mlt link <div class="result-title">## Icon## Small file type icons from http://www.splitbrain.org/projects/file_icons (public domain)<img src="#{url_root}/img/filetypes/${filetype}.png" align="center">## Title, hyperlinked<a href="${url}" target="_blank"><b>$title</b></a>## Link for MLT / More Like This / Find Similar<span class="mlt">#if($params.getBool('mlt', false) == false)<a href="#lensNoQ&q=id:%22$docId%22&mlt=true">More Like This</a>#end</span></div>## Row 2?: ID / URL <div>#Id: #field('id')##自己修改##Time: #field('tstamp') </div>## Resource Name <div>#if($doc.getFieldValue('resourcename'))Resource name: $filename #elseif($url)URL: $url#end#if($ct)($ct)#end </div>## Author #if($doc.getFieldValue('author'))<div>Author: #field('author')</div> #end## Last_Modified Date #if($doc.getFieldValue('last_modified'))<div>last-modified:#field('last_modified')</div> #end## Main content of doc <div class="result-body">#field('content') </div>## Display Similar Documents / MLT = More Like This <div class="mlt">#set($mlt = $mltResults.get($docId))#set($mltOn = $params.getBool('mlt'))#if($mltOn == true)<div class="field-name">Similar Items</div>#end## If has MLT enabled An Entries to show#if ($mltOn && $mlt && $mlt.size() > 0)<ul>#foreach($mltHit in $mlt)#set($mltId = $mltHit.getFieldValue('id'))<li><div><a href="#url_for_home?q=id:$mltId">$mltId</a></div><div><span class="field-name">Title:</span>$mltHit.getFieldValue('title')</div><div><span class="field-name">Author:</span>$mltHit.getFieldValue('author')<span class="field-name">Description:</span>$mltHit.getFieldValue('description')</div></li>#end ## end for each mltHit in $mlt</ul>## Else MLT Enabled but no mlt results for this query#elseif($mltOn && $mlt.size() == 0)<div>No Similar Items Found</div>#end </div> ## div class=mlt#parse('debug.vm') 由于本文件是example自帶的呈現文件，其屬性也按照自帶的schemal.xml定義，并不適用于nutch的schema。

因此，若要改變呈現的內容，可以直接修改此文件。如將

## Row 2?: ID / URL <div>#Id: #field('id') </div>改為：

## Row 2?: ID / URL <div>##自己修改#Time: #field('tstamp') </div>則在頁面不再顯示id，而是顯示時間。

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