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51 lines
1.7 KiB
Markdown
51 lines
1.7 KiB
Markdown
# Servlet
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A Java servlet is a Java software component that extends the capabilities of a server.
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Although servlets can respond to many types of requests, they most commonly implement web containers for hosting web applications on web servers and thus qualify as a server-side servlet web API.
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## Basic Structure
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```java
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package <package>;
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import java.io.IOException;
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import javax.servlet.ServletException;
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import javax.servlet.annotation.WebServlet;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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@WebServlet("/route")
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public class <className> extends HttpServlet {
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private static final long serialVersionUID = 1L;
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/** handle get request */
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protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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// GET REQUEST: load and display page (forward to JSP)
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// OPTIONAL: add data to request (setAttribute())
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}
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/** handle post request */
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protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
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// POST REQUEST: add stuff to DB, page, ...
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doGet(request, response); // return same page with new content added (default case)
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}
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}
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```
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## Servlet Instructions
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```java
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request.getParameter() // read request parameter
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response.setContentType("text/html"); // to return HTML in the response
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response.getWriter().append(""); //append content to the http response
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request.setAttribute(attributeName, value); // set http attribute of the request
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request.getRequestDispatcher("page.jsp").forward(request, response); // redirect the request to another page
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```
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