8.4 Creating an HTTP Response
The servlet container provides several ways to use a rwsf::HttpServletResponse object to return a response to a client. This section discusses the trade-offs involved in each approach.
8.4.1 Using Java-Like Output Functions
Each response object contains an output object that supports a set of overloaded print() and println() functions described in the Servlet Specification. These functions are convenient for programmers accustomed to Java servlet programming. The sample below shows a doGet function that creates a simple HTML response with the Java-like functions:
void myServlet::doGet (rwsf::HttpServletRequest& request,
rwsf::HttpServletResponse& response)
{
response.setContentType("text/html"); // 1
rwsf::ServletOutputStream& out = response.getOutputStream(); // 2
out.println("<html>"); // 3
out.println("<head><title>Simple Response</title></head>");
out.println("<body bgcolor=\"white\">");
out.println("<h1>Simple Response</h1>");
out.println("A simple HTML response.");
out.println("</body></html>");
}
| //1 | Sets the Content-Type of the response to text/html. A client may use the Content-Type to determine the kind of document in the response. Without this line, some clients interpret the response as plain text. |
| //2 | Gets the output stream from the response. |
| //3 | Prints a line of the response to the client. In this version, the servlet prints the string to the client using the Java-like function println(). |
8.4.2 Setting the Response from a String
An rwsf::ServletResponse also provides a setPayload() function. The function sets the body of the response directly, from a single string. This is the most efficient method of setting the content of a response. The doGet function below constructs an string, then uses the setPayload() function to create the response.
void myServlet::doGet (rwsf::HttpServletRequest& request,
rwsf::HttpServletResponse& response)
{
response.setContentType("text/html"); // 1
std::string output("<html>\n"
"<head><title>Simple Response</title></head>\n"
"<body bgcolor=\"white\">\n"
"<h1>Simple Response</h1>\n"
"A simple HTML response.\n"
"</body></html>\n"); // 2
response.setPayload(output); // 3
}
| //1 | Sets the Content-Type of the response to text/html. A client may use the Content-Type to determine the kind of document in the response. Without this line, some clients interpret the response as plain text rather than HTML. |
| //2 | Creates an string containing the response. |
| //3 | Sets the content of the response to output. In this version, the servlet sets the entire response in a single operation. |
The related function appendPayload() appends a string to the current contents of the response.
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