[:de]Manchmal braucht man neben den MVC Mechanismen von Spring-Web auch ein ganz normales Servlet, welches nicht einem Handler entspricht, der ModelAndView zur\u00fcckgibt. Leider ist so ein Servlet dann aber selbst keine Spring-Bean, sondern muss sich selbst des Spring-Contexts bedienen, um an die Spring-Beans heranzukommen und Dependencies zu setzen.<\/p>\n
Ein generisches Spring-Servlet, welches auf eine Servlet-Spring-Bean delegiert, schafft Abhilfe …<\/p>\n
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Alles was es braucht ist eine Servlet-Deklaration in der web.xml:<\/p>\n
\n<servlet> <servlet-name>test<\/servlet-name> <servlet-class> com.rinke.solutions.spring.servlet.GenericSpringServlet <\/servlet-class> <\/servlet> <\/span><\/pre>\n<\/blockquote>\neine Bean Definition im Spring-Context:<\/p>\n
\n<!-- define a servlet a spring bean, will be called from generic spring servlet --> <bean id=\"test\" class=\"com.rinke.solutions.TestServlet\" scope=\"prototype\"> <property name=\"..\" ref=\"..\"\/> <\/bean> <\/span><\/pre>\n<\/blockquote>\nUnd ein Servlet wie dieses:<\/p>\n
\npackage <\/span>com.rinke.solutions.spring.servlet; <\/span>import <\/span>java.io.IOException; <\/span>import <\/span>javax.servlet.ServletConfig; <\/span>import <\/span>javax.servlet.ServletException; <\/span>import <\/span>javax.servlet.ServletRequest; <\/span>import <\/span>javax.servlet.ServletResponse; <\/span>import <\/span>javax.servlet.http.HttpServlet; <\/span>import <\/span>org.springframework.web.context.support.WebApplicationContextUtils; <\/span>\/** * generic servlet class that holds the springs WebApplicationContext in * its init method. it delegates to another servlet defines in the spring * context and injected through spring. * a servlet used a delegate should defined with scope 'prototype' otherwise when * the container tries to instanciate more than one instance of the generic * servlet the delegate still remain one singleton. * * <\/span>@author <\/span>ster *\/ <\/span>public class <\/span>GenericSpringServlet <\/span>extends <\/span>HttpServlet <\/span>{ <\/span>private <\/span>HttpServlet delegate; <\/span>\/** * just delegate to the \"spring\" servlet. * <\/span>@inheritDoc <\/span>* <\/span>@see <\/span>javax.servlet.Servlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse) *\/ <\/span>@Override <\/span>public <\/span>void <\/span>service<\/span>(<\/span>ServletRequest req, ServletResponse res<\/span>) <\/span>throws <\/span>ServletException, IOException <\/span>{ <\/span>delegate.service<\/span>(<\/span>req,res<\/span>)<\/span>; <\/span>} <\/span>\/** * retrieves a servlet bean from the context with the same name that the generic * servlet is configured. if one instance of the generic servlet is named 'test', * a spring bean with id 'test' is searched and used as delegate. * <\/span>@inheritDoc <\/span>* <\/span>@see <\/span>javax.servlet.Servlet#init(javax.servlet.ServletConfig) *\/ <\/span>@Override <\/span>public <\/span>void <\/span>init<\/span>() <\/span>throws <\/span>ServletException <\/span>{ <\/span>ServletConfig config = getServletConfig<\/span>()<\/span>; delegate = <\/span>(<\/span>HttpServlet<\/span>) <\/span>WebApplicationContextUtils .getRequiredWebApplicationContext<\/span>(<\/span>config.getServletContext<\/span>())<\/span>.getBean<\/span>( <\/span>config.getServletName<\/span>())<\/span>; delegate.init<\/span>(<\/span>config<\/span>)<\/span>; delegate.init<\/span>()<\/span>; <\/span>} }<\/span><\/tt><\/pre>\n<\/blockquote>\nPer Konvention wird als Servlet “Bean” immer eine Bean, die so hei\u00dft wie der ServletName als Delegate benutzt.
\n[:en]<\/p>\n
Sometimes you need a simple servlet, which does not use spring mvc of the spring web package that does not deal with "ModelAndView". Unfortunately such a servlet isn’t itself a spring bean and hence must use the WebApplicationContext to resolve dependencies and get to its "worker" spring beans.<\/p>\n
A generic spring servlet, which delegates to a spring bean, puts things right …<\/p>\n
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All you need is a servlet declaration in web.xml:<\/p>\n
\n<servlet>\r\n <servlet-name>test<\/servlet-name>\r\n <servlet-class>\r\n com.rinke.solutions.spring.servlet.GenericSpringServlet\r\n <\/servlet-class>\r\n<\/servlet>\r\n<\/span><\/pre>\n<\/blockquote>\na bean definition in the spring context:<\/p>\n
\n<!-- define a servlet a spring bean, \r\n will be called from generic spring servlet -->\r\n<bean id="test" class="com.rinke.solutions.TestServlet" scope="prototype">\r\n <property name=".." ref=".."\/>\r\n<\/bean>\r\n<\/span><\/pre>\n<\/blockquote>\n\nand a servlet like this:\n<\/p>\n
\npackage <\/span>com.rinke.solutions.spring.servlet;\r\n\r\n<\/span>import <\/span>java.io.IOException;\r\n\r\n<\/span>import <\/span>javax.servlet.ServletConfig;\r\n<\/span>import <\/span>javax.servlet.ServletException;\r\n<\/span>import <\/span>javax.servlet.ServletRequest;\r\n<\/span>import <\/span>javax.servlet.ServletResponse;\r\n<\/span>import <\/span>javax.servlet.http.HttpServlet;\r\n\r\n<\/span>import <\/span>org.springframework.web.context.support.WebApplicationContextUtils;\r\n\r\n<\/span>\/**\r\n * generic servlet class that holds the springs WebApplicationContext in\r\n * its init method. it delegates to another servlet defines in the spring\r\n * context and injected through spring.\r\n * a servlet used a delegate should defined with scope 'prototype' otherwise when\r\n * the container tries to instanciate more than one instance of the generic\r\n * servlet the delegate still remain one singleton.\r\n *\r\n * <\/span>@author <\/span>ster\r\n *\/\r\n<\/span>public class <\/span>GenericSpringServlet <\/span>extends <\/span>HttpServlet <\/span>{\r\n\r\n <\/span>private <\/span>HttpServlet delegate;\r\n <\/span>\/**\r\n * just delegate to the "spring" servlet.\r\n * <\/span>@inheritDoc\r\n <\/span>* <\/span>@see <\/span>javax.servlet.Servlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse)\r\n *\/\r\n <\/span>@Override\r\n <\/span>public <\/span>void <\/span>service<\/span>(<\/span>ServletRequest req, ServletResponse res<\/span>) <\/span>throws <\/span>ServletException, IOException <\/span>{\r\n <\/span>delegate.service<\/span>(<\/span>req,res<\/span>)<\/span>;\r\n <\/span>}\r\n\r\n <\/span>\/**\r\n * retrieves a servlet bean from the context with the same name that the generic\r\n * servlet is configured. if one instance of the generic servlet is named 'test',\r\n * a spring bean with id 'test' is searched and used as delegate.\r\n * <\/span>@inheritDoc\r\n <\/span>* <\/span>@see <\/span>javax.servlet.Servlet#init(javax.servlet.ServletConfig)\r\n *\/\r\n <\/span>@Override\r\n <\/span>public <\/span>void <\/span>init<\/span>() <\/span>throws <\/span>ServletException <\/span>{\r\n <\/span>ServletConfig config = getServletConfig<\/span>()<\/span>;\r\n delegate = <\/span>(<\/span>HttpServlet<\/span>) <\/span>WebApplicationContextUtils\r\n .getRequiredWebApplicationContext<\/span>(<\/span>config.getServletContext<\/span>())<\/span>.getBean<\/span>(\r\n <\/span>config.getServletName<\/span>())<\/span>;\r\n delegate.init<\/span>(<\/span>config<\/span>)<\/span>;\r\n delegate.init<\/span>()<\/span>;\r\n <\/span>}\r\n\r\n}<\/span><\/tt>\r\n<\/pre>\n<\/blockquote>\n\nThe convention is simple: use a spring "servlet" bean with the same name as the servlet name as delegate.<\/p>\n","protected":false},"excerpt":{"rendered":"
[:de]Manchmal braucht man neben den MVC Mechanismen von Spring-Web auch ein ganz normales Servlet, welches nicht einem Handler entspricht, der ModelAndView zur\u00fcckgibt. Leider ist so ein Servlet dann aber selbst keine Spring-Bean, sondern muss sich selbst des Spring-Contexts bedienen, um … Weiterlesen