一. 服务器内部转发
req.getRequestDispatcher("地址").forward(req,resp);
客户端发出请求(地址指向Servlet1),该请求由Servlet1接收,然后Servlet1将请求转发到Servlet2,由Servlet2执行请求,执行完后将响应的数据发送给客户端。
是一次请求-响应的过程,服务器内部经过了多少次转发,客户端是不知道的,地址栏不变。
package ServletStudy;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class Servlet1 extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("Servlet1");
req.getRequestDispatcher("/servlet2").forward(req,resp);
}
}
package ServletStudy;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class Servlet2 extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("Servlet2");
}
}
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>Servlet1</servlet-name>
<servlet-class>ServletStudy.Servlet1</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Servlet1</servlet-name>
<url-pattern>/servlet1</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>Servlet2</servlet-name>
<servlet-class>ServletStudy.Servlet2</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Servlet2</servlet-name>
<url-pattern>/servlet2</url-pattern>
</servlet-mapping>
</web-app>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action = "http://localhost:8080/WebStudy_war_exploded/servlet1" method = "post">
<input type = "submit" value = "提交"/>
</form>
</body>
</html>
二. 客户端重定向
resp.sendRedirect("地址")
客户端发出请求(地址指向Servlet1),该请求由Servlet1接收,然后Servlet1对客户端进行响应,告诉客户端新的地址(即Servlet2的地址)。客户端重新发起请求(地址指向Servlet2),该请求由Servlet2接收,执行完后将响应的数据发送给客户端。
是两次请求-响应的过程,客户端知道url的变化,地址栏会变化。
package ServletStudy;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class Servlet1 extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("Servlet1");
resp.sendRedirect("/WebStudy_war_exploded/servlet2");
}
}
package ServletStudy;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class Servlet2 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("Servlet2");
}
}
本文详细解析了服务器内部转发与客户端重定向的区别。通过具体的Java Servlet实例代码,阐述了一次请求-响应过程中的服务器内部转发机制,以及两次请求-响应过程中的客户端重定向机制。
292

被折叠的 条评论
为什么被折叠?



