JavaWeb笔记——通过超链接访问servlet
package myservlet;
import java.io.*;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class TriangleServlet
*/
@WebServlet("/TriangleServlet")
public class TriangleServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public TriangleServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see Servlet#init(ServletConfig)
*/
public void init(ServletConfig config) throws ServletException {
// TODO Auto-generated method stub
super.init(config);
}
/**
* @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
*/
protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//1.设置编码格式
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
//2.用printWriter类输出流声明out对象，通过response对象调用getWriter方法获取一个输出流，利用out对象调用println方法输出HTML标记。将背景色设置为绿色
PrintWriter out=response.getWriter();
out.println("<html><body bgcolor=green>");
//3.通过request对象获取JSP页面利用超链接送来的三边的参数，送给字符a,b,c
String a=request.getParameter("sideA");
String b=request.getParameter("sideB");
String c=request.getParameter("sideC");
//4.如果a为空，则service方法结束，否则将字符串a,b,c通过方法转换为double型数据送给变量sideA，sideB，sideC
if(a==null||a.length()==0)
return;
double sideA=0,sideB=0,sideC=0;
try {
sideA=Double.parseDouble(a);
sideB=Double.parseDouble(b);
sideC=Double.parseDouble(c);
}
catch(NumberFormatException exp) {
return;
}
//5.求三角形面积要定义变量area初值为0，半周长p初值也为0.利用海伦公式求三角形面积
double area=0,p=0;
p=(sideA+sideB+sideC)/2;
area=Math.sqrt(p*(p-sideA)*(p-sideB)*(p-sideC));
//6.利用out对象的方法输出三角形面积及HTML标记
out.print("三角形"+a+"，"+b+"，"+c+"的面积是"+area);
out.println("</body></html>");
}
}