Show List
Tutorials > Servlet > Servlet API

Servlet API

The Servlet API is a set of Java classes and interfaces that provides the framework for building web applications in Java using Servlets. The Servlet API defines a standard way for web servers to interact with Servlets, and it provides a set of methods and classes for handling HTTP requests and responses.

Here are some examples of the Servlet API in action:

  • HttpServletRequest: This interface provides methods for retrieving information about an incoming HTTP request, such as the request URL, parameters, and headers. Here's an example of how to retrieve a parameter from a request using the HttpServletRequest interface:
java
Copy code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String username = request.getParameter("username");
    // Do something with the username parameter
}
  • HttpServletResponse: This interface provides methods for sending an HTTP response back to the client, such as setting the response status code, headers, and content. Here's an example of how to send a response with the HttpServletResponse interface:
csharp
Copy code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("<html>");
    out.println("<head><title>Hello World</title></head>");
    out.println("<body>");
    out.println("<h1>Hello World!</h1>");
    out.println("</body>");
    out.println("</html>");
}
  • ServletConfig: This interface provides methods for retrieving configuration information for a Servlet, such as initialization parameters specified in the web.xml file. Here's an example of how to retrieve an initialization parameter using the ServletConfig interface:
java
Copy code
public void init(ServletConfig config) throws ServletException {
    String username = config.getInitParameter("username");
    // Do something with the username initialization parameter
}
  • ServletContext: This interface provides methods for accessing information about the web application, such as application-wide initialization parameters and shared resources. Here's an example of how to retrieve an application-wide initialization parameter using the ServletContext interface:
java
Copy code
public void init(ServletConfig config) throws ServletException {
    ServletContext context = config.getServletContext();
    String appName = context.getInitParameter("appName");
    // Do something with the appName initialization parameter
}
  • ServletOutputStream: This class provides a low-level output stream for writing binary data to the HTTP response. Here's an example of how to write binary data to the response using the ServletOutputStream class:
csharp
Copy code
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    byte[] data = // Binary data to send in the response
    response.setContentType("application/octet-stream");
    response.setContentLength(data.length);
    ServletOutputStream out = response.getOutputStream();
    out.write(data);
    out.flush();
}

These are just a few examples of the many classes and interfaces provided by the Servlet API. The Servlet API is a powerful tool for building web applications in Java, and it provides a standard way for web servers to interact with Servlets.



Next: Servlet Containers

    Leave a Comment

  • captcha text