有很清楚SERVICE()方法的吗,在下实在搞不懂了!

import java.io.IOException;
import java.io.PrintWriter;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;代码很短,我真的很不理解为什么不能写红色的那句,重写从HttpServlet 继承的service方法不添加SUPER怎么会完成其功能呢?
而且一定要加上SUPER也是个错的?如果要加SUPER怎么加啊?
public class HelloWS extends HttpServlet { @Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
    super.service(req, resp);
PrintWriter out = resp.getWriter();
out.println("<html><head><title></title></head><body></body></html>");
    out.close();
} /*@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
PrintWriter out = resp.getWriter();
out.println("<html><head><title>adfadfad</title></head><body>a星星得过</body></html>");
    out.close();
}*/ private static final long serialVersionUID = 1L;
}

解决方案 »

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这玩意是框架，只要你动用doget()或者dopost(),他会自动的调用service()方法
J2EE API 是这么说的：Receives standard HTTP requests from the public service method and dispatches them to the doXXX methods defined in this class，大概意思就是：当service接到请求时就会转发给doXXX（doGet）方法。而这些方法里都有超类的super调用，所以我们在覆盖的时候重写这个方法了，我是这么理解的。
答:
1)楼主弄错了. super.service(req, resp); 当然可以加,这是从语法角度说的(即:语法上正确的,可以加的).但从HTTP SERVLET的语义处理来说,是错误的.
2)执行过程是:容器自动调用service(...)方法,而service(...)方法内部根据HTTP Request方法的不同,分别再自动调用doGET(....)或者是doPost(....)等.
3)当你不加上super.service(req, resp); 时,容器自动调用你自己定制的service(...)方法,而你自己定制的service(...)方法代码中没有再去调用doGET(..)或doPOST(...),因而:doGET()与doPOST()是没有用到的.
答:我贴上HttpServlet的源代码,这下楼主就更清楚了:(由于只能8000字,我只好贴出核心)package javax.servlet.http;public abstract class HttpServlet extends GenericServlet
    implements Serializable
{
    private static final String METHOD_DELETE = "DELETE";
    private static final String METHOD_HEAD = "HEAD";
    private static final String METHOD_GET = "GET";
    private static final String METHOD_OPTIONS = "OPTIONS";
    private static final String METHOD_POST = "POST";
    private static final String METHOD_PUT = "PUT";
    private static final String METHOD_TRACE = "TRACE";
    private static final String HEADER_IFMODSINCE = "If-Modified-Since";
    private static final String HEADER_LASTMOD = "Last-Modified";
    private static final String LSTRING_FILE
= "javax.servlet.http.LocalStrings";
    private static ResourceBundle lStrings
= ResourceBundle.getBundle("javax.servlet.http.LocalStrings");
    /*synthetic*/ static Class class$javax$servlet$http$HttpServlet;

    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String protocol = req.getProtocol();
String msg = lStrings.getString("http.method_get_not_supported");
if (protocol.endsWith("1.1"))
    resp.sendError(405, msg);
else
    resp.sendError(400, msg);
    }

    protected long getLastModified(HttpServletRequest req) {
return -1L;
    }

    protected void doHead(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
NoBodyResponse response = new NoBodyResponse(resp);
doGet(req, response);
response.setContentLength();
    }

    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String protocol = req.getProtocol();
String msg = lStrings.getString("http.method_post_not_supported");
if (protocol.endsWith("1.1"))
    resp.sendError(405, msg);
else
    resp.sendError(400, msg);
    }

    protected void doPut(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String protocol = req.getProtocol();
String msg = lStrings.getString("http.method_put_not_supported");
if (protocol.endsWith("1.1"))
    resp.sendError(405, msg);
else
    resp.sendError(400, msg);
    }

    protected void doDelete
(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String protocol = req.getProtocol();
String msg = lStrings.getString("http.method_delete_not_supported");
if (protocol.endsWith("1.1"))
    resp.sendError(405, msg);
else
    resp.sendError(400, msg);
    }

    private static Method[] getAllDeclaredMethods(Class c) {
if (c.equals(class$javax$servlet$http$HttpServlet == null
     ? (class$javax$servlet$http$HttpServlet
= class$("javax.servlet.http.HttpServlet"))
     : class$javax$servlet$http$HttpServlet))
    return null;
Method[] parentMethods = getAllDeclaredMethods(c.getSuperclass());
Method[] thisMethods = c.getDeclaredMethods();
if (parentMethods != null && parentMethods.length > 0) {
    Method[] allMethods
= new Method[parentMethods.length + thisMethods.length];
    System.arraycopy(parentMethods, 0, allMethods, 0,
     parentMethods.length);
    System.arraycopy(thisMethods, 0, allMethods, parentMethods.length,
     thisMethods.length);
    thisMethods = allMethods;
}
return thisMethods;
    }

    protected void doOptions
(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
Method[] methods = getAllDeclaredMethods(this.getClass());
boolean ALLOW_GET = false;
boolean ALLOW_HEAD = false;
boolean ALLOW_POST = false;
boolean ALLOW_PUT = false;
boolean ALLOW_DELETE = false;
boolean ALLOW_TRACE = true;
boolean ALLOW_OPTIONS = true;
for (int i = 0; i < methods.length; i++) {
    Method m = methods[i];
    if (m.getName().equals("doGet")) {
ALLOW_GET = true;
ALLOW_HEAD = true;
    }
    if (m.getName().equals("doPost"))
ALLOW_POST = true;
    if (m.getName().equals("doPut"))
ALLOW_PUT = true;
    if (m.getName().equals("doDelete"))
ALLOW_DELETE = true;
}
String allow = null;
if (ALLOW_GET && allow == null)
    allow = "GET";
if (ALLOW_HEAD) {
    if (allow == null)
allow = "HEAD";
    else
allow += ", HEAD";
}
if (ALLOW_POST) {
    if (allow == null)
allow = "POST";
    else
allow += ", POST";
}
if (ALLOW_PUT) {
    if (allow == null)
allow = "PUT";
    else
allow += ", PUT";
}
if (ALLOW_DELETE) {
    if (allow == null)
allow = "DELETE";
    else
allow += ", DELETE";
}
if (ALLOW_TRACE) {
    if (allow == null)
allow = "TRACE";
    else
allow += ", TRACE";
}
if (ALLOW_OPTIONS) {
    if (allow == null)
allow = "OPTIONS";
    else
allow += ", OPTIONS";
}
resp.setHeader("Allow", allow);
    }

    protected void doTrace
(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String CRLF = "\r\n";
String responseString
    = "TRACE " + req.getRequestURI() + " " + req.getProtocol();
Enumeration reqHeaderEnum = req.getHeaderNames();
while (reqHeaderEnum.hasMoreElements()) {
    String headerName = (String) reqHeaderEnum.nextElement();
    responseString += ((String) CRLF + headerName + ": "
       + req.getHeader(headerName));
}
responseString += (String) CRLF;
int responseLength = responseString.length();
resp.setContentType("message/http");
resp.setContentLength(responseLength);
ServletOutputStream out = resp.getOutputStream();
out.print(responseString);
out.close();
    }

//这是核心:根据请求的方法不同,自动地分别调用doXXX(...)方法
    protected void service
(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String method = req.getMethod();
if (method.equals("GET")) {
    long lastModified = getLastModified(req);
    if (lastModified == -1L)
doGet(req, resp);
    else {
long ifModifiedSince = req.getDateHeader("If-Modified-Since");
if (ifModifiedSince < lastModified / 1000L * 1000L) {
    maybeSetLastModified(resp, lastModified);
    doGet(req, resp);
} else
    resp.setStatus(304);
    }
} else if (method.equals("HEAD")) {
    long lastModified = getLastModified(req);
    maybeSetLastModified(resp, lastModified);
    doHead(req, resp);
} else if (method.equals("POST"))
    doPost(req, resp);
else if (method.equals("PUT"))
    doPut(req, resp);
else if (method.equals("DELETE"))
    doDelete(req, resp);
else if (method.equals("OPTIONS"))
    doOptions(req, resp);
else if (method.equals("TRACE"))
    doTrace(req, resp);
else {
    String errMsg = lStrings.getString("http.method_not_implemented");
    Object[] errArgs = new Object[1];
    errArgs[0] = method;
    errMsg = MessageFormat.format(errMsg, errArgs);
    resp.sendError(501, errMsg);
}
    }

    private void maybeSetLastModified(HttpServletResponse resp,
      long lastModified) {
if (!resp.containsHeader("Last-Modified")) {
    if (lastModified >= 0L)
resp.setDateHeader("Last-Modified", lastModified);
}
    }
    //这个是容器真正自动调用的service(...)方法
    public void service(ServletRequest req, ServletResponse res)
throws ServletException, IOException {
HttpServletRequest request;
HttpServletResponse response;
try {
    request = (HttpServletRequest) req;
    response = (HttpServletResponse) res;
} catch (ClassCastException e) {
    throw new ServletException("non-HTTP request or response");
}
service(request, response);  //自动调用HttpServlet版本的service(...)方法
    }

   }
错误的原因是因为，在Httpservlet当中有两个service方法：
protected  void service(HttpServletRequest req, HttpServletResponse resp)

void service(ServletRequest req, ServletResponse res)
jvm不知道该调用那个，所以会出现问题
继承HttpServlet类没有必要重写Service方法，你只需要重写
init，doGet(),doPost(),destroy()
你说的错指的是什么？没有输出你的out.println(" <html> <head> <title> </title> </head> <body> </body> </html>"); 吧
调用完类HttpServlet service（）方法之后就根据请求的方法直接调用你的doGet() doPost()方法了，后边的PrintWriter out = resp.getWriter();
out.println(" <html> <head> <title> </title> </head> <body> </body> </html>");
    out.close(); 没有执行的机会。
7楼讲的很清楚了，一般是重写doGet()和doPost()方法。
一般是重写doGet()和doPost()方法。
我是来学习的  看的很畅快在自己重写的 service() 方法里面再调用他父类的 service()方法我觉得解释不通
java这个破东西多看看源代码就OK了，实在不行，debug一下就OK