Servlet request redirection

Request redirection

• There are two schemes for request redirection, but the second scheme is strongly recommended, and the code is concise.

• Features of request redirection:

  1. Request redirection will make two requests.
  2. Request redirection will not share data in the Request field. Because every time it is requested, it will be encapsulated separately.
  3. Request redirection cannot access resources under WEB-INF, request forwarding can.
  4. Request redirection can access resources outside the project, such as Baidu. The request forwarding cannot be accessed (that is, it cannot be outbound)

Option One:

//设置响应码 302 表示重定向
resp.setStatus(302);
//设置响应头，并设置重定向的地址
resp.setHeader("Location","http://localhost:8080/06-servlet/response2");

E.g:

public class Response1 extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    	System.out.println("曾到此一游，Response1");

		// 设置响应状态码 302 表示重定向，（已搬迁）
    	resp.setStatus(302);
    	// 设置响应头说明新的地址在哪
    	resp.setHeader("Location","http://localhost:8080/06-servlet/response2");*

	}
}


public class Response2 extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    	resp.setContentType("text/html; Charset=UTF-8");
    	resp.getWriter().write("已请求重定向到response2,这是response2处理的业务代码");
	}
}

Configuration in web.xml:

<servlet>
    <servlet-name>Response1</servlet-name>
    <servlet-class>com.servlet.Response1</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>Response1</servlet-name>
    <url-pattern>/response1</url-pattern>
</servlet-mapping>

<servlet>
    <servlet-name>Response2</servlet-name>
    <servlet-class>com.servlet.Response2</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>Response2</servlet-name>
    <url-pattern>/response2</url-pattern>
</servlet-mapping>

Option two (strongly recommended):

//请求重定向
resp.sendRedirect("http://www.baidu.com");

E.g:

public class Response1 extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    System.out.println("曾到此一游，Response1");

    //请求重定向
    resp.sendRedirect("http://www.baidu.com");
	}
}

Configuration in web.xml:

<servlet>
    <servlet-name>Response1</servlet-name>
    <servlet-class>com.servlet.Response1</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>Response1</servlet-name>
    <url-pattern>/response1</url-pattern>
</servlet-mapping>