一．Java Servlet ：
Java program is run on a Web server or application server, which is a database or between applications on the server and HTTP request from the Web browser or other HTTP clients intermediate layer.
The use of Servlet, you can collect user input from a Web form, showing records from a database or other source, you can also create dynamic web pages.
You may receive a request to return a response
Servlet unrelated to the root directory of access paths and packet addresses / representatives when configured with only comment url is project
By accessing the servlet jsp:
(1) Jsp and servlet same package: Direct Access
(2) 1.Jsp the servlet different packages, but in the upper jsp: such as: root directly coupled "servlet package name" / "servlet name"
2.Jsp different packages with a servlet, jsp lower layer: ".." / "servlet package name" / "servlet name"
Reverse similar access.
two. JSP:
JSP stands for Java Server Pages, HTML + CSS + is a dynamic web development technology. It uses the Java code in JSP tag into the HTML page. Tags typically begin with <% in%> end.
JSP is a Java servlet on nature, mainly used for the user interface portion implement Java web applications. Web developers through a combination of HTML code, XHTML code, XML elements and embedded operating JSP and commands to write JSP.
JSP get user input data, access databases and other data sources via a web form, and then dynamically create web pages.
JSP-based Java Servlet API, therefore, JSP has a variety of powerful enterprise-level Java API, including JDBC, JNDI, EJB, JAXP, and so on.
three. Parameters passed in three ways:
1.URL传参： eg. <a href="RegServlet?name=admin&pwd=123">访问regServlet</a>
2. Form parameter passing:
Pass parameters to achieve the form:
Form element name corresponds to the parameter name
Values in the form corresponding to the input parameter value
Request.getParamerter("c")
3. hidden fields to achieve mass participation (of the form elements):
<input type="hidden" name="hide" value="testHide"/>
doGet ---- get treatment type
4.get and post a request for the information package is a difference
1. Security:
DoGet information in the address bar
Information Location:
Get: URL；
Post: request objects;
2. Submit Content Size
Get less content
Post more content
3. encoding issues process
Post: coding setting request object
Get: URL, coding setting request does not work, it is necessary to manually set encoding
// Form form: action = "? Post (or get) mass participation"
Get can not pass
Post can pass
5. solve the Chinese garbled in three ways:
1. Set encoded request and response objects (doPost method is only valid for, because the information in the request is not doGet method)
(1) response.setContentType("text/html;charset=utf-8");
(2) request.setCharacterEncoding("UTF-8");
2. transcoding manually force (for the doGet)
String name=new String(userName.getBytes("ISO-8859-1"),"utf-8");
3. Modify the url encoding tomcat (doGet way for once and for all)
6. Response (concept of flow):
7. redirection request forwarding and
Redirect: The client browser makes a request twice (the second request data request can not be the first time)
response.sendRedirect("response.jsp");
Forwards the request: the address bar does not change, only the client browser sends a request
request.getRequestDispatcher("response.jsp").forward(request, response);
8.request scope (Information Sharing area)
(Request to forward valid)
Request.setAttribute ( "name", "content"): the request information into the shared area (key-value pairs)
Request.getAttribute ( "name"): take the request information from the shared area
the reason:
Redirect: two requests, information sharing area put! = Area information sharing taken
Forwards the request: a request, the discharge area information sharing information sharing area taken ==
9. Session technologies: session, cookie
1.Session: the server side information shared area information sharing across multiple requests.
2. Common use:
Jsp automatically creates a session object;
Servlet does not automatically create session, create session objects by getSession ()
SessionServlet get inside the session:
HttpSession session=request.getSession();
Session.setAttribute(“name”,”my name is Leon.”);
Jsp access session:
<%String name= session.getAttribute(“name”);
Out.print (name); ------------------- because in the jsp, there is no system
%>
3.Session common API:
(1) obtaining session:
HttpSession session = request.getSession (); // get the session object, and if not, created after the return;
Session=request.getSession(true);
// If it is true: getSession () will get the session; / If it is false: get the current session, if there is no return Null
(2) obtain sessionId:
System.out.println(session.getId());
(3) a method of obtaining the session spaced time:
System.out.println (session.getCreationTime ()); // create time of the session
System.out.println (session.getLastAccessedTime ()); // after the last time to get this conversation over how much time
Session.setMaxInactiveInterval (10); // set the session 10S survival time
System.out.println (session.getMaxInactiveInterval ()); // session is survival
(4) Session of the cancellation:
Session.invalidate();
// session set the session time in web.xml
//<session-config>
//<session-timout></session-timeout>
//</session-config>