Httpservletrequest,httpservletresponse objects in a servlet and differences between service and Doxx methods

One: The HttpServletRequest object is used to obtain the request data.

Core API:                    request line:                         Request.getmethod ();   Request Method                        Request.getrequeturi ()   / request.getrequeturl ()   Request Resource                        Request.getprotocol ()   Request HTTP Protocol version                                        request header:                        Request.getheader ("name")   gets the request value based on the request header                        Request.getheadernames ()    get all request header names                    entity content:                        Request.getinputstream ()   get entity content data

Two: Service and Doxx method differences

httpsevlet type of source code:protected voidService (HttpServletRequest req, HttpServletResponse resp)throwsservletexception, IOException {//get the Request methodString method =Req.getmethod (); if(Method.equals (method_get)) {LongLastModified =getlastmodified (req); if(LastModified = =-1) {                //servlet doesn ' t support if-modified-since, no reason//To go through further expensive logicdoget (req, resp); } Else {                Longifmodifiedsince; Try{ifmodifiedsince=Req.getdateheader (header_ifmodsince); } Catch(illegalargumentexception iae) {//Invalid Date Header-proceed as if none was setIfmodifiedsince =-1; }                if(Ifmodifiedsince < (lastmodified/1000 * 1000)) {                    //If The servlet mod time is later, call Doget ()//Round down to the nearest second for a proper compare//A ifmodifiedsince of-1 would always is lessmaybesetlastmodified (resp, lastmodified);                Doget (req, resp); } Else{resp.setstatus (httpservletresponse.sc_not_modified); }            }        } Else if(Method.equals (Method_head)) {LongLastModified =getlastmodified (req);            Maybesetlastmodified (resp, lastmodified);        Dohead (req, resp); } Else if(Method.equals (method_post)) {DoPost (req, resp); } Else if(Method.equals (method_put)) {DoPut (req, resp); } Else if(Method.equals (Method_delete)) {DoDelete (req, resp); } Else if(Method.equals (method_options)) {dooptions (REQ,RESP); } Else if(Method.equals (method_trace)) {dotrace (REQ,RESP); } Else {            //            //Note that this means NO servlet supports whatever//method is requested, anywhere on the this server. //String errmsg= Lstrings.getstring ("http.method_not_implemented"); Object[] Errargs=NewObject[1]; errargs[0] =method; ErrMsg=Messageformat.format (errmsg, Errargs);        Resp.senderror (httpservletresponse.sc_not_implemented, errmsg); }    }

Three: The request parameter gets passed
Get method: The parameter is placed behind the URI
Post mode: Parameters are placed in the entity content

Get the Get mode parameters:
Request.getquerystring ();
Get post Mode parameters:
Request.getinputstream ();

Four: The problem: But the above two are not common, and the obtained parameters need to be further resolved.
So you can use a uniform and convenient way to get parameters:

The Core API:
Request.getparameter ("parameter name"); Get parameter values based on parameter name (note that you can only get parameters of one value)
Request.getparametervalue ("parameter name"); Gets the parameter value (parameter that can get multiple values) according to the name of the argument

Request.getparameternames (); Get list of all parameter names

Five: Request parameter encoding problem
To modify the post mode parameter encoding:
Request.setcharacterencoding ("Utf-8");
Modify the Get mode parameter encoding:
Manual decoding: String name = new String (Name.getbytes ("iso-8859-1"), "Utf-8");

Six: Response line
#http协议版本
#状态码: The server processes the result of the request (status)
A common state:
200: Request processing complete and perfect return
302: Indicates that the request requires further refinement.
404: The resource that represents the client access is not found.
500: Indicates that the server sent an error to the resource. (Server internal Error)
Seven: Common response headers

Location:http://www.it315.org/index.jsp-Represents the redirected address, which is used with the status code of 302. Server:apache Tomcat---represents the type of server content-encoding:gzip--represents the type of data compression that the server sends to the browser content-LENGTH:80--represents the length of data that the server sends to the browser content-LANGUAGE:ZH-CN--represents the language content supported by the server-type:text/html; charset=gb2312--indicates the data type and content encoding the server sent to the browser last-modified:tue, each Jul 18:23:51 GMT--indicates the last modified time of the server resource refresh:1;url=http://www.it315.org--Indicates timed refreshContent-disposition:attachment; Filename=aaa.zip--means to tell the browser to download the resource (used when downloading the file) Transfer-Encoding:chunkedset-COOKIE:SS=Q0=5LB_NQ; Path=/search--represents the cookie information that the server sends to the browser (for session management) Expires:-1--indicates that the notification browser is not cached cache-control:no-Cachepragma:no-Cacheconnection:close/keep-alive--Indicates the connection status of the server and the browser. Close: Closing connection keep-alive: Saving connection

HttpServletResponse:

HttpServletResponse Object Modification Response information:

Response Line:
Response.setstatus () Setting the status code
Response header:
Response.setheader ("name", "value") Set the response header
Entity content:
Response.getwriter (). writer (); Send character entity content
Response.getoutputstream (). Writer () Send byte entity contents

Httpservletrequest,httpservletresponse objects in a servlet and differences between service and Doxx methods