package app02a;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* url重写
*/
@WebServlet( name = "Top10Servlet", urlPatterns = "/top10")
public class Top10Servlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private List<String> londonAttractions;
private List<String> parisAttractions;
/**
* Default constructor.
*/
public Top10Servlet() {
// TODO Auto-generated constructor stub
}
/**
* 初始化两个列表存放信息(正常开发存于数据库中)
*/
@Override
public void init() throws ServletException {
londonAttractions = new ArrayList<String>(10);
londonAttractions.add("Buckingham Palace");
londonAttractions.add("London Eye");
londonAttractions.add("British Museum");
londonAttractions.add("National Gallery");
londonAttractions.add("Big Ben");
londonAttractions.add("Tower of London");
londonAttractions.add("Natural History Museum");
londonAttractions.add("Canary Wharf");
londonAttractions.add("2012 Olympic Park");
londonAttractions.add("St Paul's Cathedral");
parisAttractions = new ArrayList<String>(10);
parisAttractions.add("Eiffel Tower");
parisAttractions.add("Notre Dame");
parisAttractions.add("The Louvre");
parisAttractions.add("Champs Elysees");
parisAttractions.add("Arc de Triomphe");
parisAttractions.add("Sainte Chapelle Church");
parisAttractions.add("Les Invalides");
parisAttractions.add("Musee d'Orsay");
parisAttractions.add("Montmarte");
parisAttractions.add("Sacre Couer Basilica");
}
/**
* get请求,判断选择的城市
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String city = request.getParameter("city");
if(city != null && (city.equals("london") || city.equals("paris"))){
// 选择后
showAttractions(request, response, city);
} else{
// 第一次执行
showMainPage(request, response);
}
}
/**
* 显示主页
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
private void showMainPage(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException {
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
writer.print("<html><head>" +
"<title>Top 10 Tourist Attractions</title>" +
"</head><body>" +
"Please select a city:" +
// 重定向体现(使用a标签的href属性)
"<br/><a href='?city=london'>London</a>" +
"<br/><a href='?city=paris'>Paris</a>" +
"</body></html>");
}
/**
* 显示主要信息
* @param request
* @param response
* @param city 选择的城市
* @throws ServletException
* @throws IOException
*/
private void showAttractions(HttpServletRequest request,
HttpServletResponse response, String city)
throws ServletException, IOException {
int page = 1;
String pageParameter = request.getParameter("page");
if (pageParameter != null) {
try {
page = Integer.parseInt(pageParameter);
} catch (NumberFormatException e) {
// do nothing and retain default value for page
}
if (page > 2) {
page = 1;
}
}
List<String> attractions = null;
if (city.equals("london")) {
attractions = londonAttractions;
} else if (city.equals("paris")) {
attractions = parisAttractions;
}
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
writer.println("<html><head>" +
"<title>Top 10 Tourist Attractions</title>" +
"</head><body>");
// 返回主页(href='top10')
writer.println("<a href='top10'>Select City</a> ");
writer.println("<hr/>Page " + page + "<hr/>");
// 总共10条数据,两页,每页显示五条数据(简单的分页实现)
int start = page * 5 - 5;
for (int i = start; i < start + 5; i++) {
writer.println(attractions.get(i) + "<br/>");
}
writer.print("<hr style='color:blue'/>" +
// 重定向体现(使用a标签的href属性)
"<a href='?city=" + city +
"&page=1'>Page 1</a>");
writer.println(" <a href='?city=" + city +
"&page=2'>Page 2</a>");
writer.println("</body></html>");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}