Java 如何将web.xml servlet init param外部化?Spring DelegatingFilterProxy用于servlet?
我有一个无法修改的第三方servlet。它接受我想要外部化的Java 如何将web.xml servlet init param外部化?Spring DelegatingFilterProxy用于servlet?,java,spring,servlets,Java,Spring,Servlets,我有一个无法修改的第三方servlet。它接受我想要外部化的init参数(来自web.xml) 我可以使用外部化servlet过滤器init param。这有效地将servlet过滤器定义移动到Spring中,在Spring中有更强大的外部化工具(例如:PropertyPlaceHolderConfigure、环境变量等) 我怎样才能为servlet做到这一点呢?听起来这正是您所需要的 Spring控制器实现 包装一个servlet实例,该实例 内部管理。这样一个包袱 除此之外,还不知道serv
init参数
(来自web.xml)
我可以使用外部化servlet过滤器init param
。这有效地将servlet过滤器定义移动到Spring中,在Spring中有更强大的外部化工具(例如:PropertyPlaceHolderConfigure、环境变量等)
我怎样才能为servlet做到这一点呢?听起来这正是您所需要的
Spring控制器实现
包装一个servlet实例,该实例
内部管理。这样一个包袱
除此之外,还不知道servlet
控制器;它的整个生命周期是
这里有
/WEB-INF/struts-config.xml
这将使您能够像对待其他Spring控制器一样对待遗留servlet,因此您可以使用普通的Spring MVC处理程序映射来路由到它。看起来您需要一个
DelegatingServletProxy
类,尽管Spring中不存在这个类,但我认为编写代码非常简单,使用DelegatingFilterProxy作为起点
servlet只实现少数几个具体方法,因此委派应该是简单的
好吧,我把钱放在嘴边了!
编辑:下面是DelegatingServletProxy
的基本实现
您可以这样使用它:
<bean name="myInitParams" class="java.util.Properties">
<constructor-arg>
<props>
<prop key="initParamName">initParamValue</prop>
</props>
</constructor-arg>
</bean>
下面是servlet代码,它相当长,但大部分是委托ServletContext
——有趣的事情发生在顶部。这是未经测试的-应该被视为一个起点
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Set;
public class DelegatingServletProxy extends HttpServlet implements WebApplicationContextAware
{
private HttpServlet delegate;
private Properties initParams;
private String delegateName;
public void setDelegateName(String delegateName)
{
this.delegateName = delegateName;
}
public void init(ServletConfig config) throws ServletException
{
super.init(config);
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
delegate = wac.getBean(delegateName, HttpServlet.class);
delegate.init(new WrapServletConfig(config));
}
@Override
public void destroy()
{
delegate.destroy();
}
@Override
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException
{
delegate.service(req, res);
}
public void setInitParams(Properties initParams)
{
this.initParams = initParams;
}
private class WrapServletConfig implements ServletConfig, ServletContext
{
// we override ServletContext also because it exposes getInitParameterNames()/getInitParemter()
private ServletConfig delegate;
private ServletContext delegateContext;
public WrapServletConfig(ServletConfig config)
{
this.delegate = config;
this.delegateContext = config.getServletContext();
}
@Override
public String getServletName()
{
return delegate.getServletName();
}
@Override
public ServletContext getServletContext()
{
return delegate.getServletContext();
}
@Override
public String getInitParameter(String s)
{
return initParams.getProperty(s);
}
@Override
public Enumeration getInitParameterNames()
{
return initParams.propertyNames();
}
@Override
public Object getAttribute(String s)
{
return delegateContext.getAttribute(s);
}
@Override
public Enumeration getAttributeNames()
{
return delegateContext.getAttributeNames();
}
@Override
public void setAttribute(String s, Object o)
{
delegateContext.setAttribute(s, o);
}
@Override
public void removeAttribute(String s)
{
delegateContext.removeAttribute(s);
}
@Override
public String getServletContextName()
{
return delegateContext.getServletContextName();
}
// the remainer is just straight delegation to ServletContext
@Override
public ServletContext getContext(String s)
{
return delegateContext.getContext(s);
}
@Override
public int getMajorVersion()
{
return delegateContext.getMajorVersion();
}
@Override
public int getMinorVersion()
{
return delegateContext.getMinorVersion();
}
@Override
public String getMimeType(String s)
{
return delegateContext.getMimeType(s);
}
@Override
public Set getResourcePaths(String s)
{
return delegateContext.getResourcePaths(s);
}
@Override
public URL getResource(String s)
throws MalformedURLException
{
return delegateContext.getResource(s);
}
@Override
public InputStream getResourceAsStream(String s)
{
return delegateContext.getResourceAsStream(s);
}
@Override
public RequestDispatcher getRequestDispatcher(String s)
{
return delegateContext.getRequestDispatcher(s);
}
@Override
public RequestDispatcher getNamedDispatcher(String s)
{
return delegateContext.getNamedDispatcher(s);
}
@Override
public Servlet getServlet(String s)
throws ServletException
{
return delegateContext.getServlet(s);
}
@Override
public Enumeration getServlets()
{
return delegateContext.getServlets();
}
@Override
public Enumeration getServletNames()
{
return delegateContext.getServletNames();
}
@Override
public void log(String s)
{
delegateContext.log(s);
}
@Override
public void log(Exception e, String s)
{
delegateContext.log(e, s);
}
@Override
public void log(String s, Throwable throwable)
{
delegateContext.log(s, throwable);
}
@Override
public String getRealPath(String s)
{
return delegateContext.getRealPath(s);
}
@Override
public String getServerInfo()
{
return delegateContext.getServerInfo();
}
}
}
你如何使用这个作为替代品?它似乎没有实现Servlet接口。@mdma:没有,它是一个Spring控制器。servlet部分由标准的Spring
DispatcherServlet
处理,它将请求转发给控制器,然后控制器调用Spring管理的servlet。我一直在想为什么Spring不提供这样一个类。通常他们有很好的理由。。。
<servlet>
<servlet-name>...</servlet-name>
<servlet-class>
acme.DelegatingServletProxy
</servlet-class>
<init-param>
<param-name>proxyServletClass</param-name>
<param-value>your.original.servlet.ServletClass</param-value>
</init-param>
<init-param>
<param-name>proxyServletParams</param-name>
<param-value>myServletParams</param-value>
<!-- name of bean in spring context -->
</init-param>
</servlet>
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import javax.servlet.*;
import javax.servlet.http.HttpServlet;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Properties;
import java.util.Set;
public class DelegatingServletProxy extends HttpServlet implements WebApplicationContextAware
{
private HttpServlet delegate;
private Properties initParams;
private String delegateName;
public void setDelegateName(String delegateName)
{
this.delegateName = delegateName;
}
public void init(ServletConfig config) throws ServletException
{
super.init(config);
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
delegate = wac.getBean(delegateName, HttpServlet.class);
delegate.init(new WrapServletConfig(config));
}
@Override
public void destroy()
{
delegate.destroy();
}
@Override
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException
{
delegate.service(req, res);
}
public void setInitParams(Properties initParams)
{
this.initParams = initParams;
}
private class WrapServletConfig implements ServletConfig, ServletContext
{
// we override ServletContext also because it exposes getInitParameterNames()/getInitParemter()
private ServletConfig delegate;
private ServletContext delegateContext;
public WrapServletConfig(ServletConfig config)
{
this.delegate = config;
this.delegateContext = config.getServletContext();
}
@Override
public String getServletName()
{
return delegate.getServletName();
}
@Override
public ServletContext getServletContext()
{
return delegate.getServletContext();
}
@Override
public String getInitParameter(String s)
{
return initParams.getProperty(s);
}
@Override
public Enumeration getInitParameterNames()
{
return initParams.propertyNames();
}
@Override
public Object getAttribute(String s)
{
return delegateContext.getAttribute(s);
}
@Override
public Enumeration getAttributeNames()
{
return delegateContext.getAttributeNames();
}
@Override
public void setAttribute(String s, Object o)
{
delegateContext.setAttribute(s, o);
}
@Override
public void removeAttribute(String s)
{
delegateContext.removeAttribute(s);
}
@Override
public String getServletContextName()
{
return delegateContext.getServletContextName();
}
// the remainer is just straight delegation to ServletContext
@Override
public ServletContext getContext(String s)
{
return delegateContext.getContext(s);
}
@Override
public int getMajorVersion()
{
return delegateContext.getMajorVersion();
}
@Override
public int getMinorVersion()
{
return delegateContext.getMinorVersion();
}
@Override
public String getMimeType(String s)
{
return delegateContext.getMimeType(s);
}
@Override
public Set getResourcePaths(String s)
{
return delegateContext.getResourcePaths(s);
}
@Override
public URL getResource(String s)
throws MalformedURLException
{
return delegateContext.getResource(s);
}
@Override
public InputStream getResourceAsStream(String s)
{
return delegateContext.getResourceAsStream(s);
}
@Override
public RequestDispatcher getRequestDispatcher(String s)
{
return delegateContext.getRequestDispatcher(s);
}
@Override
public RequestDispatcher getNamedDispatcher(String s)
{
return delegateContext.getNamedDispatcher(s);
}
@Override
public Servlet getServlet(String s)
throws ServletException
{
return delegateContext.getServlet(s);
}
@Override
public Enumeration getServlets()
{
return delegateContext.getServlets();
}
@Override
public Enumeration getServletNames()
{
return delegateContext.getServletNames();
}
@Override
public void log(String s)
{
delegateContext.log(s);
}
@Override
public void log(Exception e, String s)
{
delegateContext.log(e, s);
}
@Override
public void log(String s, Throwable throwable)
{
delegateContext.log(s, throwable);
}
@Override
public String getRealPath(String s)
{
return delegateContext.getRealPath(s);
}
@Override
public String getServerInfo()
{
return delegateContext.getServerInfo();
}
}
}