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.";
} }
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