Analysis of Hello2 source code
GreetingServlet.java
package javaeetutorial.hello2; //导入包
//import 导入类和接口
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/greeting") //指定上下文根的相对URL模式
public class GreetingServlet extends HttpServlet { //定义一个GreetingServlet类继承HttpServlet
@Override //覆盖方法
public void doGet(HttpServletRequest request, //定义一个doGet方法 ，有两个参数
HttpServletResponse response)
throws ServletException, IOException { //抛出异常
response.setContentType("text/html"); //获取上下文类型的响应
response.setBufferSize(8192); //设置BufferSize为8192
try (PrintWriter out = response.getWriter()) { //定义一个PrintWriter类型的变量out 写入
out.println("<html lang=\"en\">" //html代码
+ "<head><title>Servlet Hello</title></head>");
// then write the data of the response
out.println("<body bgcolor=\"#ffffff\">"
+ "<img src=\"resources/images/duke.waving.gif\" "
+ "alt=\"Duke waving his hand\">"
+ "<form method=\"get\">"
+ "<h2>Hello, my name is Duke. What's yours?</h2>"
+ "<input title=\"My name is: \" type=\"text\" "
+ "name=\"username\" size=\"25\"/>"
+ "<p></p>"
+ "<input type=\"submit\" value=\"Submit\"/>"
+ "<input type=\"reset\" value=\"Reset\"/>"
+ "</form>");
String username = request.getParameter("username"); //定义string类型变量name 将响应得到的username赋给它
if (username != null && username.length() > 0) { //判断username不存在并且长度大于0
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher("/response"); //将内容跳转到服务器的/response地址上
if (dispatcher != null) {
dispatcher.include(request, response); //包含响应中的资源
}
}
out.println("</body></html>");
}
}
@Override //覆盖，方法重写
public String getServletInfo() { //重写getServletInfo方法 并返回字符串
return "The Hello servlet says hello.";
}
}
ResponseServlet.java
package javaeetutorial.hello2; //引入包
//导入需要使用的类和接口
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/response") //指定上下文的相对URL
public class ResponseServlet extends HttpServlet { //定义一个ResponseServlet类继承HttpServlet
@Override//覆盖
public void doGet(HttpServletRequest request, //定义doGet方法，有两个参数
HttpServletResponse response)
throws ServletException, IOException { //抛出异常
try (PrintWriter out = response.getWriter()) { //定义PrintWrite类型变量out 将getWriter输出的数据赋给它
String username = request.getParameter("username"); //将响应得到的username赋值给String类型的变量username
if (username != null && username.length() > 0) { //如果username不为空并且长度大于0
out.println("<h2>Hello, " + username + "!</h2>");//输出hello+username
}
}
}
@Override//覆盖方法
public String getServletInfo() { //返回字符串
return "The Response servlet says hello.";
}
}
