helloworld2.java

来自「精通Java核心技术源代码」· Java 代码 · 共 58 行

JAVA
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// ==================== Program Discription ==========================
// 程序名称:示例14-2: HelloWorld2.java
// 程序目的:编写带有参数的Servlet程序
// ==============================================================
package examples.servlets;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;

public class HelloWorld2 extends HttpServlet 
{
    String defaultGreeting;
    String defaultName;
  
    public void init(ServletConfig config) throws ServletException
    {
        super.init(config);      
       
        if ((defaultGreeting = getInitParameter("greeting")) == null)
            defaultGreeting = "Hello";
        
        if ((defaultName = getInitParameter("person")) == null)
            defaultName = "World";
    }
    
    public void service(HttpServletRequest req, HttpServletResponse res)
        throws IOException
    {
        
        // Check for a request parameter called "name." If the
        // parameter exists (detected when the getParameterValues()
        // method does not return null), use its value for the
        // greeting.

        String name, paramName[];
        if ((paramName = req.getParameterValues("name")) 
            != null) {
            name = paramName[0];
        }
        else {
            name = defaultName;
        }
        
        // Must set the content type first
        res.setContentType("text/html");
        // Now we can obtain a PrintWriter
        PrintWriter out = res.getWriter();
        out.println("<html><head><title>Hello World3.java</title></head>");
        out.println("<body>");
        out.println("<p><img src=images/BEA_Button_Final_web.gif align=right>");
        out.println("<h1>");
        out.println(defaultGreeting + " " + name + "!");
        out.println("</h1></body></html>");
        // Do not close the output stream or print writer. 
    }
}

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