Java ServletConfig 和 ServletContext

2016-01-12

Servlet : 3.1

ServletConfig：

package javax.servlet;

import java.util.Enumeration;

public interface ServletConfig {
    String getServletName();

    ServletContext getServletContext();

    String getInitParameter(String var1);

    Enumeration<String> getInitParameterNames();
}

ServletConfig 持有了 Servlet 的初始化参数，Servelt init 方法被调用时需要 ServletConfig，也可以通过 getServletConfig 直接获取 ServletConfig。

ServeltContext：

package javax.servlet;

import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletRegistration.Dynamic;
import javax.servlet.descriptor.JspConfigDescriptor;

public interface ServletContext {
    String TEMPDIR = "javax.servlet.context.tempdir";
    String ORDERED_LIBS = "javax.servlet.context.orderedLibs";

    String getContextPath();

    ServletContext getContext(String var1);

    int getMajorVersion();

    int getMinorVersion();

    int getEffectiveMajorVersion();

    int getEffectiveMinorVersion();

    String getMimeType(String var1);

    Set<String> getResourcePaths(String var1);

    URL getResource(String var1) throws MalformedURLException;

    InputStream getResourceAsStream(String var1);

    RequestDispatcher getRequestDispatcher(String var1);

    RequestDispatcher getNamedDispatcher(String var1);

    /** @deprecated */
    Servlet getServlet(String var1) throws ServletException;

    /** @deprecated */
    Enumeration<Servlet> getServlets();

    /** @deprecated */
    Enumeration<String> getServletNames();

    void log(String var1);

    /** @deprecated */
    void log(Exception var1, String var2);

    void log(String var1, Throwable var2);

    String getRealPath(String var1);

    String getServerInfo();

    String getInitParameter(String var1);

    Enumeration<String> getInitParameterNames();

    boolean setInitParameter(String var1, String var2);

    Object getAttribute(String var1);

    Enumeration<String> getAttributeNames();

    void setAttribute(String var1, Object var2);

    void removeAttribute(String var1);

    String getServletContextName();

    Dynamic addServlet(String var1, String var2);

    Dynamic addServlet(String var1, Servlet var2);

    Dynamic addServlet(String var1, Class<? extends Servlet> var2);

    <T extends Servlet> T createServlet(Class<T> var1) throws ServletException;

    ServletRegistration getServletRegistration(String var1);

    Map<String, ? extends ServletRegistration> getServletRegistrations();

    javax.servlet.FilterRegistration.Dynamic addFilter(String var1, String var2);

    javax.servlet.FilterRegistration.Dynamic addFilter(String var1, Filter var2);

    javax.servlet.FilterRegistration.Dynamic addFilter(String var1, Class<? extends Filter> var2);

    <T extends Filter> T createFilter(Class<T> var1) throws ServletException;

    FilterRegistration getFilterRegistration(String var1);

    Map<String, ? extends FilterRegistration> getFilterRegistrations();

    SessionCookieConfig getSessionCookieConfig();

    void setSessionTrackingModes(Set<SessionTrackingMode> var1);

    Set<SessionTrackingMode> getDefaultSessionTrackingModes();

    Set<SessionTrackingMode> getEffectiveSessionTrackingModes();

    void addListener(String var1);

    <T extends EventListener> void addListener(T var1);

    void addListener(Class<? extends EventListener> var1);

    <T extends EventListener> T createListener(Class<T> var1) throws ServletException;

    JspConfigDescriptor getJspConfigDescriptor();

    ClassLoader getClassLoader();

    void declareRoles(String... var1);

    String getVirtualServerName();
}

ServletContext 是应用上下文参数，用于应用内不同的 Servlet 用于共享资源信息。

一个应用可以拥有多个 Servlet，每个 Servlet 都拥有自己的 ServeltConfig，但是只能拥有一个 ServletContext