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Курс по Java, 2016
Servlet, JSP

Servlet API

javax.servlet.Servlet
import javax.servlet.GenericServlet;
public class MyServlet extends GenericServlet {
@Override
public void service(ServletRequest servletRequest,
ServletResponse servletResponse)
throws ServletException, IOException {
// do something
}
}

javax.servlet.ServletRequest
String remoteAddress = servletRequest.getRemoteAddr();
String contentType = servletRequest.getContentType();
InputStream input = servletRequest.getInputStream();
String parameter = servletRequest.getParameter("name");
Object attribute = servletRequest.getAttribute("name");
servletRequest.setAttribute("name", attribute);

javax.servlet.ServletResponse
servletResponse.setContentType("text/html");
servletResponse.setContentLength(256);
OutputStream output = servletResponse.getOutputStream();

javax.servlet.http.HttpServlet
public class MyHttpServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request,
HttpServletResponse response)
// process GET request
}
@Override
protected void doPost(HttpServletRequest request,
// process POST request
}

javax.servlet.http.HttpServletRequest
String remoteAddress = request.getRemoteAddr();
String contentType = request.getContentType();
Reader reader = request.getReader();
String parameter = request.getParameter("name");
Object attribute = request.getAttribute("name");
request.setAttribute("name", attribute);
Cookie[] cookies = request.getCookies();
String proxiedClient = request.getHeader("X-Forwarded-For");
HttpSession session = request.getSession();

javax.servlet.http.HttpSession
HttpSession session = request.getSession();
Object sessionAttribute = session.getAttribute("name");
session.setAttribute("name", sessionAttribute);

javax.servlet.http.HttpServletResponse
response.setContentType("text/html");
response.setContentLength(256);
Writer writer = response.getWriter();
response.addCookie(new Cookie("name", "value"));
response.addHeader("X-My-Header", "value");
response.sendError(500, "Everything failed");
response.sendRedirect("/other-path");

Servlet Container

Apache Tomcat
Самый популярный Servlet/JSP контейнер
https://tomcat.apache.org/

$CATALINA_HOME
├── bin
├── conf
├── lib
├── logs
├── webapps
│ ├── hello
│ │ ├── index.jsp
│ │ ├── META-INF
│ │ └── WEB-INF
│ │ ├── classes
│ │ │ └── it
│ │ │ └── sevenbits
│ │ │ └── example
│ │ │ └── hello
│ │ │ └── HelloWorldServlet.class
│ │ └── web.xml
│ ├── hello.war
│ └── ROOT
└── work

WAR
Web Application aRchive
│ ├── hello.war
│ │ ├── index.jsp
│ │ ├── META-INF
│ │ └── WEB-INF
│ │ ├── classes
│ │ │ └── it
│ │ │ └── sevenbits
│ │ │ └── example
│ │ │ └── hello
│ │ │ └── HelloWorldServlet.class
│ │ └── web.xml

War в Maven
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>it.sevenbits.example</groupId>
<artifactId>hello</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>hello Maven Webapp</name>
<url>http://maven.apache.org</url>
<build>
<finalName>hello</finalName>
</build>
</project>

Webapp в Maven
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
</dependencies>

Webapp в Maven

web.xml
<web-app>
<display-name>Sample Web Application</display-name>
<servlet>
<servlet-name>HelloWorldServlet</servlet-name>
<servlet-class>
it.sevenbits.example.hello.HelloWorldServlet
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServlet</servlet-name>
<url-pattern>/world</url-pattern>
</servlet-mapping>
</web-app>

Сборка веб приложения
mvn package
cp target/hello.war $CATALINA_HOME/webapps

HelloWorldServlet
public class HelloWorldServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request,
response.setContentType("text/plain");
PrintWriter out = response.getWriter();
out.println("Hello, world");
}
}

JSP
Java Server Pages
Servlet наоборот

hello_world.jsp
<!DOCTYPE html>
<html>
<head>
<title>Hello</title>
</head>
<body>
<h1>Hello, world!</h1>
</body>
</html>

Model — View — Controller
MVC

Model
● Атрибуты запроса
● Сессия

View
JSP
<!DOCTYPE html>
<html>
<head>
<title>Hello <%=request.getAttribute("name")%></title>
</head>
<body>
<h1>Hello, <%=request.getAttribute("name")%>!</h1>
</body>
</html>

Controller
Servlet
protected void doPost(HttpServletRequest request,
// model manipulations
String name = request.getParameter("name");
request.setAttribute("name", name);
// forward to view
RequestDispatcher dispatcher =
request.getRequestDispatcher("hello_name.jsp");
dispatcher.forward(request, response);
}

Forward RequestDispatcher.forward(request, response)

Redirect HttpServlerResponse.sendRedirect(“path”)

Домашнее задание
Поставить Tomcat.
Сделать простое веб приложение с отправкой формы.
Посмотреть, в какой java код превращаются JSP страницы.
annie.tarasenko@7bits.it denis.nelubin@7bits.it

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Курс Java-2016. Занятие 11. Servlets, JSP

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