solr源码入门1

在本文中，solr作为一个封装了lucene的web服务我们首先看一下solr的web.xml

<env-entry>

<env-entry-name>solr/home</env-entry-name>

<env-entry-type>java.lang.String</env-entry-type>

<env-entry-value>E:\\solr_home</env-entry-value>

</env-entry>

<filter>

<filter-name>SolrRequestFilter</filter-name>

<filter-class>org.apache.solr.servlet.SolrDispatchFilter</filter-class>

<init-param>

<param-name>excludePatterns</param-name>

<param-value>/css/*,/js/*,/img/*,/tpl/*</param-value>

</init-param>

</filter>

<filter-mapping>

<filter-name>SolrRequestFilter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<servlet>

<servlet-name>Zookeeper</servlet-name>

<servlet-class>org.apache.solr.servlet.ZookeeperInfoServlet</servlet-class>

</servlet>

。。。。。。

。。。。。。

可以看出solr的请求首先发到了filter进行处理在org.apache.solr.servlet.SolrDispatchFilter.java文件中

这个filter做的第一件事是初始化，主要是去solrhome里面解析solr.xml以及加载所有的core

@Override

public void init(FilterConfig config) throws ServletException

{

log.info("SolrDispatchFilter.init()" + this.getClass().getClassLoader());

String exclude = config.getInitParameter("excludePatterns");

if(exclude != null) { //排除一些不被filter的请求

String[] excludeArray = exclude.split(",");

excludePatterns = new ArrayList<>();

for (String element : excludeArray) {

excludePatterns.add(Pattern.compile(element));

}

}

try {

Properties extraProperties = (Properties) config.getServletContext().getAttribute(PROPERTIES_ATTRIBUTE);

if (extraProperties == null)

extraProperties = new Properties();

String solrHome = (String) config.getServletContext().getAttribute(SOLRHOME_ATTRIBUTE);

if (solrHome == null)

//从web.xml中获取solrhome的地址

solrHome = SolrResourceLoader.locateSolrHome();

//利用solrhome生成CoreContainer把所有的core状态维护起来

this.cores = createCoreContainer(solrHome, extraProperties);

if (this.cores.getAuthenticationPlugin() != null) {

HttpClientConfigurer configurer = this.cores.getAuthenticationPlugin().getDefaultConfigurer();

if (configurer != null) {

configurer.configure((DefaultHttpClient)httpClient, new ModifiableSolrParams());

}

}

log.info("user.dir=" + System.getProperty("user.dir"));

}

catch( Throwable t ) {

// catch this so our filter still works

log.error( "Could not start Solr. Check solr/home property and the logs");

SolrCore.log( t );

if (t instanceof Error) {

throw (Error) t;

}

}

log.info("SolrDispatchFilter.init() done");

}

每一次不被排除的查询都会执行具体的filter：

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain, boolean retry) throws IOException, ServletException {

if (!(request instanceof HttpServletRequest)) return;

AtomicReference<ServletRequest> wrappedRequest = new AtomicReference();

//进行一些验证，并填充wrappedRequest

if (!authenticateRequest(request, response, wrappedRequest)) { // the response and status code have already been sent

return;

}

if (wrappedRequest.get() != null) {

request = wrappedRequest.get();

}

if (cores.getAuthenticationPlugin() != null) {

log.debug("User principal: "+((HttpServletRequest)request).getUserPrincipal());

}

// No need to even create the HttpSolrCall object if this path is excluded.

if(excludePatterns != null) {

String servletPath = ((HttpServletRequest) request).getServletPath().toString();

for (Pattern p : excludePatterns) {

Matcher matcher = p.matcher(servletPath);

if (matcher.lookingAt()) {

chain.doFilter(request, response);

return;

}

}

}

HttpSolrCall call = getHttpSolrCall((HttpServletRequest) request, (HttpServletResponse) response, retry);

try {

Action result = call.call();

switch (result) {

case PASSTHROUGH:

chain.doFilter(request, response);

break;

case RETRY:

doFilter(request, response, chain, true);

break;

case FORWARD:

request.getRequestDispatcher(call.getPath()).forward(request, response);

break;

}

} finally {

call.destroy();

}

}

在 HttpSolrCall call = getHttpSolrCall((HttpServletRequest) request, (HttpServletResponse) response, retry);中solr做了大量的处理，具体是什么，下一篇文章来分析