Three elements of Servlet:
1. Must be inherited from HttpServlet
2. DoGet() or doPost() must be implemented
3. Servlet must be configured in
<servlet>
<servlet-name> </servlet-name>
<servlet-class> </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name> </servlet-name>
<url-pattern> </url-pattern>
</servelt-mapping>
HttpServeltRrequest: Request object
getParameter(): Get the value of the form element
getAttribute(): Get the attribute value in the request range
setAttribute(): Set the attribute value in the reqeust range
setCharacterEncoding(): Set character encoding
HttpSerletResponse: The corresponding object
sendRedirect(): External jump
getWriter(): Get the output stream object
setContentType("text/html; charset=utf-8"): Set the corresponding content format and encoding
Four session tracking methods:
HttpSession session = ();
("name", "zhangsan");
("pwd", "aaa");
String name = (String) ("name");
:
//Create a cookie
Cookie cookie = new Cookie("name", "zhangsan");
//Set the timeout time of the cookie
(24 * 60 * 60 *60);
//Send cookies to the client
(cookie);
//Get the cookie sent by the client
Cookie [] cookies = ();
for(int i=0; i <; i++) {
Cookie temp = cookies[i];
String key = ();
String value = ();
}
3. Hide form field
<input type="hidden" name="name" value="zhangsan" />
("name");
Rewrite
Question marks
LoginServlet?username=zhangsan&pwd=123
String name = ("username");
String pwd =("pwd");
Internal jump:
LoginServlet
("").forward(request, resposne);
External jump:
("");
Internal jump is a request and a response
External jumps are two requests and two responses
ServletContext:Servlet context object
It is a public area that can be shared by all clients
setAttribute(): Put data into the public area
getAttribute(): Get data from the public area
two:
Three: Three standard ranges: request, session, ServletContext
Common points: all setAttribute() and getAttribute()
Difference: Different ranges, request < session < servletContext
Four: Four session tracking methods
Five: Five objects on the server
request, response, servlet, session, servletContext
Jsp:Java Server Page
Page composition: 7 elements
1. Static content:html
2. Directive: page, include, taglib:
<%@ Directive Name Attribute 1="Attribute Value 1" Attribute 2="Attribute Value 2" %>
3. Expression: <%=Expression %>
<% Java Code %>
5. Declaration: <%! %>:Variables and methods
6. Action: <jsp: Action name Attribute="Attribute value"> </jsp: Action name>
7. Comments:
What the client cannot see: <%-- --%>
What the client can see: <!-- -->
Jsp execution process:
1. Translation: Jsp--->Servlet
2. Compilation: Servlet---->.class
3.Execute:.class
The response speed is slow when accessing jsp for the first time, and the response speed is fast when subsequent requests are requested.
script:
Expression: <%= %>
Scriptlet: <% %>
Statement: <%! %>
instruction:
page:language, import, errorPage, isErrorpage
include:file
taglib:uri: Specify the path of the tag library descriptor prefix: Specify the prefix of the tag
Implicit object:
Classification:
1. Input and output objects: request(HttpServletRequest),
response(HttpServletResponse),
out(JspWriter), the out in the servlet is PrintWriter
2. Scope communication object: pageContext, request,
session(HttpSession),
application(ServletContext)
Object: page(this), config
4. Error object: exception
JavaBean:
A standard JavaBean has three conditions
1. Common Classes
2. A common construction method with no parameters
3. Have set() and get() methods
4. Private attributes
Standard actions in Jsp:
: Create an instance of JavaBean
<jsp:useBean class="" scope="page/session/application/request" />
: Assign values to JavaBean properties
<jsp:setProperty name="stu" property="stuName" value="zhangsan" />
<jsp:setProperty name="stu" property="stuName" param="txtName" />
value and param cannot be used at the same time
How to be lazy: <jsp:setProperty name="stu" property="*" />
At this time, it should be noted that the name of the form element must be as well as the attribute value of the JavaBean
Exactly the same
: Obtain the attribute value of JvaBean
<jsp:getProperty name="stu" property="stuName" />
: Internal jump, equivalent to ().forward(request, response);
<jsp:forward page="" />
:Include
<jsp:include page="" flush="true" />
Expression language:
EL: Expression Language
Syntax format: ${expression}
Representation = Operator + Operand
Operator: Compared with Java, there is an extra empty and an assignment operator missing.
${empty ""} : true
${empty null} :true
Operands:
-->Constant: boolean (true/false), integer, floating point, string (can be used '', can also use ""), Null
-->Variables:
1. Refers to attributes (page, request, session, application) placed in four standard ranges
2. Search order within the compilation scope: page-->request--->session--->application
3. How to get variable value: point operator., use []
<%
("name", "lisi");
%>
${}
or
${requestScope["name"]}
-->Implicit Object
: Through it, you can access request, session, servletContext
2. Related to the scope: pageScope, requestScope, sessionScope, applicationScope
3. Related to input: param, paramValues
4. Others: header, cookies, headervalues,
Where EL expressions are applicable:
1. Can be used in static text
2. Use with custom tags
3. Use with JavaBean
<jsp:userBean class="" scope="session" />
<jsp:setProperty name="stu" property="stuName" value="hello" />
${}
Custom tags:
1. Tag handler implementation
--->Implementation: Inherited from BodyTagSupport or TagSupport
DoStartTag(), doEndTag(), doAfterBody() will be rewrite
--->Description:Describe in the tag library descriptor file (.tld)
<taglib>
<tlib-version>1.0 </tlib-version>
<jsp-version>2.0 </jsp-version>
<short-name>simpletag </short-name>
<tag>
<name>showbody </name>
<tag-class> </tag-class>
<body-content>empty/jsp </body-content>
<attribute>
<name>color </name>
</attribute>
</tag>
</taglib>
--->Usage: <%@ taglib uri="WEB-INF/" prefix="my" %>
<my:showbody />
2. Tag file
--->Implementation and Description
Implemented in .tag file
Set the main content: <%@ body-content="empty/scriptless" %>
Set attribute: <%@ attribute name="name" required="true" rtexprvalue="true" %>
There is a main content: <jsp:doBody scope="session" var="theBody" />
<%
String body = (String) ("theBody");
%>
--->Usage
WEB-INF/tags/
<%@ taglib tagdir="/WEB-INF/tags/" prefix="you" %>
<you:sayhello />
Standard Tag Library:
1. Core tag library
-->General:
set: <c:set var="" value="" scope="" />
out: <c:out value="" />
remove: <c:remove var="" scope="" />
--> Conditions:
if: <c:if test="">..... </c:if>
choose: <c:choose>
<c:when test="">... </c:when>
<c:when test="">... </c:when>
<c:when test="">... </c:when>
.....
<c:otherwise>... </otherwise>
</c:choose>
-->Iteration:
forEach: <forEach var="" items="" varStatus="" begin="" end="">
foTokens: <foTodens var="" items="" delim=",;|"> </foTodens>
Java,C#;SQL|C
2.I18N and formatted tag library
-->setLocale: Set the local area
-->bundle: Set resource package
-->setBundle: Set resource package
-->message: Output message
Tag library
-->setDataSource: Set the data source to obtain a connection to the database
-->query:Execute query
-->update:Execute addition, deletion, modification
--> transaction: transaction
-->param:parameters
Tag library
Filter:
life cycle:
1. Example Hua:
2. Initialization: init()
3. Filter: doFilter()
4. Destroy: destroy()
5. Not available
Configuration:
<filter>
<filter-name> </filter-name>
<filter-class> </filter-class>
</filter>
<filter-mapping>
<filter-name> </filter-name>
<url-pattern> </url-pattern>
</filter-mapping>
Several important interfaces:
:init(), doFilter(), destroy()
: doFilter(request, response)
:getFilterName(), getInitParameter(),
Filter chain:--->1--->2--->3--->Servlet request
<----1 <---2 <---3 <---- Response
MvC design mode
:jsp+JavaBean
:jsp+Servlet+JavaBean
jsp---view
servlet---control
javabean---model
MVC:
M--Model:Model:Accessing the background database
V--view:View:Display
C--control:Control:Control program flow
The relationship between ModelII and MVC:
MVC is a design pattern, ModelII is a specific implementation of MVC
1. Must be inherited from HttpServlet
2. DoGet() or doPost() must be implemented
3. Servlet must be configured in
<servlet>
<servlet-name> </servlet-name>
<servlet-class> </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name> </servlet-name>
<url-pattern> </url-pattern>
</servelt-mapping>
HttpServeltRrequest: Request object
getParameter(): Get the value of the form element
getAttribute(): Get the attribute value in the request range
setAttribute(): Set the attribute value in the reqeust range
setCharacterEncoding(): Set character encoding
HttpSerletResponse: The corresponding object
sendRedirect(): External jump
getWriter(): Get the output stream object
setContentType("text/html; charset=utf-8"): Set the corresponding content format and encoding
Four session tracking methods:
HttpSession session = ();
("name", "zhangsan");
("pwd", "aaa");
String name = (String) ("name");
:
//Create a cookie
Cookie cookie = new Cookie("name", "zhangsan");
//Set the timeout time of the cookie
(24 * 60 * 60 *60);
//Send cookies to the client
(cookie);
//Get the cookie sent by the client
Cookie [] cookies = ();
for(int i=0; i <; i++) {
Cookie temp = cookies[i];
String key = ();
String value = ();
}
3. Hide form field
<input type="hidden" name="name" value="zhangsan" />
("name");
Rewrite
Question marks
LoginServlet?username=zhangsan&pwd=123
String name = ("username");
String pwd =("pwd");
Internal jump:
LoginServlet
("").forward(request, resposne);
External jump:
("");
Internal jump is a request and a response
External jumps are two requests and two responses
ServletContext:Servlet context object
It is a public area that can be shared by all clients
setAttribute(): Put data into the public area
getAttribute(): Get data from the public area
two:
Three: Three standard ranges: request, session, ServletContext
Common points: all setAttribute() and getAttribute()
Difference: Different ranges, request < session < servletContext
Four: Four session tracking methods
Five: Five objects on the server
request, response, servlet, session, servletContext
Jsp:Java Server Page
Page composition: 7 elements
1. Static content:html
2. Directive: page, include, taglib:
<%@ Directive Name Attribute 1="Attribute Value 1" Attribute 2="Attribute Value 2" %>
3. Expression: <%=Expression %>
<% Java Code %>
5. Declaration: <%! %>:Variables and methods
6. Action: <jsp: Action name Attribute="Attribute value"> </jsp: Action name>
7. Comments:
What the client cannot see: <%-- --%>
What the client can see: <!-- -->
Jsp execution process:
1. Translation: Jsp--->Servlet
2. Compilation: Servlet---->.class
3.Execute:.class
The response speed is slow when accessing jsp for the first time, and the response speed is fast when subsequent requests are requested.
script:
Expression: <%= %>
Scriptlet: <% %>
Statement: <%! %>
instruction:
page:language, import, errorPage, isErrorpage
include:file
taglib:uri: Specify the path of the tag library descriptor prefix: Specify the prefix of the tag
Implicit object:
Classification:
1. Input and output objects: request(HttpServletRequest),
response(HttpServletResponse),
out(JspWriter), the out in the servlet is PrintWriter
2. Scope communication object: pageContext, request,
session(HttpSession),
application(ServletContext)
Object: page(this), config
4. Error object: exception
JavaBean:
A standard JavaBean has three conditions
1. Common Classes
2. A common construction method with no parameters
3. Have set() and get() methods
4. Private attributes
Standard actions in Jsp:
: Create an instance of JavaBean
<jsp:useBean class="" scope="page/session/application/request" />
: Assign values to JavaBean properties
<jsp:setProperty name="stu" property="stuName" value="zhangsan" />
<jsp:setProperty name="stu" property="stuName" param="txtName" />
value and param cannot be used at the same time
How to be lazy: <jsp:setProperty name="stu" property="*" />
At this time, it should be noted that the name of the form element must be as well as the attribute value of the JavaBean
Exactly the same
: Obtain the attribute value of JvaBean
<jsp:getProperty name="stu" property="stuName" />
: Internal jump, equivalent to ().forward(request, response);
<jsp:forward page="" />
:Include
<jsp:include page="" flush="true" />
Expression language:
EL: Expression Language
Syntax format: ${expression}
Representation = Operator + Operand
Operator: Compared with Java, there is an extra empty and an assignment operator missing.
${empty ""} : true
${empty null} :true
Operands:
-->Constant: boolean (true/false), integer, floating point, string (can be used '', can also use ""), Null
-->Variables:
1. Refers to attributes (page, request, session, application) placed in four standard ranges
2. Search order within the compilation scope: page-->request--->session--->application
3. How to get variable value: point operator., use []
<%
("name", "lisi");
%>
${}
or
${requestScope["name"]}
-->Implicit Object
: Through it, you can access request, session, servletContext
2. Related to the scope: pageScope, requestScope, sessionScope, applicationScope
3. Related to input: param, paramValues
4. Others: header, cookies, headervalues,
Where EL expressions are applicable:
1. Can be used in static text
2. Use with custom tags
3. Use with JavaBean
<jsp:userBean class="" scope="session" />
<jsp:setProperty name="stu" property="stuName" value="hello" />
${}
Custom tags:
1. Tag handler implementation
--->Implementation: Inherited from BodyTagSupport or TagSupport
DoStartTag(), doEndTag(), doAfterBody() will be rewrite
--->Description:Describe in the tag library descriptor file (.tld)
<taglib>
<tlib-version>1.0 </tlib-version>
<jsp-version>2.0 </jsp-version>
<short-name>simpletag </short-name>
<tag>
<name>showbody </name>
<tag-class> </tag-class>
<body-content>empty/jsp </body-content>
<attribute>
<name>color </name>
</attribute>
</tag>
</taglib>
--->Usage: <%@ taglib uri="WEB-INF/" prefix="my" %>
<my:showbody />
2. Tag file
--->Implementation and Description
Implemented in .tag file
Set the main content: <%@ body-content="empty/scriptless" %>
Set attribute: <%@ attribute name="name" required="true" rtexprvalue="true" %>
There is a main content: <jsp:doBody scope="session" var="theBody" />
<%
String body = (String) ("theBody");
%>
--->Usage
WEB-INF/tags/
<%@ taglib tagdir="/WEB-INF/tags/" prefix="you" %>
<you:sayhello />
Standard Tag Library:
1. Core tag library
-->General:
set: <c:set var="" value="" scope="" />
out: <c:out value="" />
remove: <c:remove var="" scope="" />
--> Conditions:
if: <c:if test="">..... </c:if>
choose: <c:choose>
<c:when test="">... </c:when>
<c:when test="">... </c:when>
<c:when test="">... </c:when>
.....
<c:otherwise>... </otherwise>
</c:choose>
-->Iteration:
forEach: <forEach var="" items="" varStatus="" begin="" end="">
foTokens: <foTodens var="" items="" delim=",;|"> </foTodens>
Java,C#;SQL|C
2.I18N and formatted tag library
-->setLocale: Set the local area
-->bundle: Set resource package
-->setBundle: Set resource package
-->message: Output message
Tag library
-->setDataSource: Set the data source to obtain a connection to the database
-->query:Execute query
-->update:Execute addition, deletion, modification
--> transaction: transaction
-->param:parameters
Tag library
Filter:
life cycle:
1. Example Hua:
2. Initialization: init()
3. Filter: doFilter()
4. Destroy: destroy()
5. Not available
Configuration:
<filter>
<filter-name> </filter-name>
<filter-class> </filter-class>
</filter>
<filter-mapping>
<filter-name> </filter-name>
<url-pattern> </url-pattern>
</filter-mapping>
Several important interfaces:
:init(), doFilter(), destroy()
: doFilter(request, response)
:getFilterName(), getInitParameter(),
Filter chain:--->1--->2--->3--->Servlet request
<----1 <---2 <---3 <---- Response
MvC design mode
:jsp+JavaBean
:jsp+Servlet+JavaBean
jsp---view
servlet---control
javabean---model
MVC:
M--Model:Model:Accessing the background database
V--view:View:Display
C--control:Control:Control program flow
The relationship between ModelII and MVC:
MVC is a design pattern, ModelII is a specific implementation of MVC