Request、Servlet及其子接口

最近看tomcat源码，这类接口多的有点眩，整理出来看一下。（基于tomcat4）

javax.servlet.ServletRequset接口，和org.apache.catalina.Request接口，有什么联系？

其实就是对Request不同层面上的定义。

一、首先看下javax.servlet.Servlet接口

package javax.servlet;
import java.io.IOException;
public abstract interface Servlet {
    public abstract void init(ServletConfig paramServletConfig)
            throws ServletException;
    public abstract ServletConfig getServletConfig();
    public abstract void service(ServletRequest paramServletRequest,
            ServletResponse paramServletResponse) throws ServletException,
            IOException;
    public abstract String getServletInfo();
    public abstract void destroy();
}

这些方法应该非常熟悉了。

二、javax.servlet.http.HttpServlet抽象类

package javax.servlet.http;

public abstract class HttpServlet extends GenericServlet        implements Serializable {
    ...
}

丰富了servlet接口，对应http协议，添加了doGet, doPut, doPost等方法。

三、javax.servlet.ServletRequest接口

package javax.servlet;

public abstract interface ServletRequest {
    public abstract Object getAttribute(String paramString);

    public abstract Enumeration getAttributeNames();

    public abstract String getCharacterEncoding();

    public abstract void setCharacterEncoding(String paramString)
            throws UnsupportedEncodingException;

    public abstract int getContentLength();

    public abstract String getContentType();

    public abstract ServletInputStream getInputStream() throws IOException;

    public abstract String getParameter(String paramString);

    public abstract Enumeration getParameterNames();

    public abstract String[] getParameterValues(String paramString);

    public abstract Map getParameterMap();

    public abstract String getProtocol();

    public abstract String getScheme();

    public abstract String getServerName();

    public abstract int getServerPort();

    public abstract BufferedReader getReader() throws IOException;

    public abstract String getRemoteAddr();

    public abstract String getRemoteHost();

    public abstract void setAttribute(String paramString, Object paramObject);

    public abstract void removeAttribute(String paramString);

    public abstract Locale getLocale();

    public abstract Enumeration getLocales();

    public abstract boolean isSecure();

    public abstract RequestDispatcher getRequestDispatcher(String paramString);

    /** @deprecated */
    public abstract String getRealPath(String paramString);
}

四、javax.servlet.http.HttpServletRequest

public abstract interface HttpServletRequest extends ServletRequest {...}

添加了http协议部分，比如session，cookie等。

五、org.apache.catalina.Requst（tomcat4，后面的版本有变化）

package org.apache.catalina;

public interface Request {

    public String getAuthorization();

    public void setAuthorization(String authorization);

    public Connector getConnector();

    public void setConnector(Connector connector);

    public Context getContext();

    public void setContext(Context context);

    public String getInfo();

    public ServletRequest getRequest();

    public Response getResponse();

    public void setResponse(Response response);

    public Socket getSocket();

    public void setSocket(Socket socket);

    public InputStream getStream();

    public void setStream(InputStream stream);

    public Wrapper getWrapper();

    public void setWrapper(Wrapper wrapper);

    public ServletInputStream createInputStream() throws IOException;

    public void finishRequest() throws IOException;

    public Object getNote(String name);

    public Iterator getNoteNames();

    public void recycle();

    public void removeNote(String name);

    public void setContentLength(int length);

    public void setContentType(String type);

    public void setNote(String name, Object value);

    public void setProtocol(String protocol);

    public void setRemoteAddr(String remote);

    public void setScheme(String scheme);

    public void setSecure(boolean secure);

    public void setServerName(String name);

    public void setServerPort(int port);
}

六、org.apache.catalina.HttpRequest

public interface HttpRequest extends Request {...}

增加了对http协议头处理部分，比如url，参数，cookies等。

七、org.apache.catalina.connector.HttpRequestBase

虽然已经弃用了，但可以作为一个参考，实现了jdk和catalina定义的Request

public class HttpRequestBase
    extends RequestBase
    implements HttpRequest, HttpServletRequest {...}

小结

tomcat中，对于jdk中的servlet和ServletRequest肯定要实现的。而tomcat作为容器应用，会有很多自身的需求，所以自己定义了一套接口，跟jdk中不同层面。并且提供两套接口的类，让web开发者使用。