Interview assault 66: what is the difference between request forwarding and request redirection?

author | Lei brother

source | Java Analysis of the real interview questions （ID：aimianshi666）

Please contact authorization for reprint （ WeChat ID：GG_Stone）

stay Java in , There are two ways to realize jump ： Request forwarding and request redirection , But the two are completely different , So let's play it today . The main difference between request forwarding and request redirection , Contains the following 5 spot ：

1. Different definitions

2. Jump party is different

3. Data sharing is different

4. Final URL Address different

5. The code implementation is different

Next , Let's look at them one by one .

1. Different definitions

Request forwarding （Forward）： Occurs inside the server program , When the server receives a request from a client , Will first request , Forward to the destination address , Then forward the result returned by the target address to the client . And the client has no perception of all this , This is like comparison. , Zhang San （ client ） Look for Li Si （ Server side ） To borrow money , And Li Si has no money , So Li Si went to Wang Wu to borrow money , And lent the money to Zhang San , During the whole process, Zhang San only borrowed money once , The rest of the work was done by Li Si , This is request forwarding . request redirections （Redirect）： Request redirection refers to after the server receives the request from the client , Will return a temporary response header to the client , This temporary response header records , The client needs to send the request again （ Redirect ） Of URL Address , After the client receives the address , The request will be sent to the new address , This is request redirection . It's like Zhang San （ client ） Look for Li Si （ Server side ） To borrow money , Li Si has no money , So Li Si told Zhang San ,“ I have no money , Go to Wang Wu to borrow “, So Zhang San went to Wang Wu's house to borrow money , This is request redirection .

2. The requestor is different

From the above definition of request forwarding and request redirection , We can see that ： Request forwarding is a server-side behavior , The server sends the request instead of the client , And return the result to the client ; And requesting redirection is the behavior of the client , Their interaction process , As shown in the figure below ：

3. Data sharing is different

Request forwarding is implemented on the server , So in the whole execution process , client （ Browser side ） Just send the request once , Therefore, the same one is used in the whole interaction process Request Request object and a Response The response object , So the whole request process , The requested and returned data are shared ; The request redirection client sends two completely different requests , So the data in the two requests are different .

4. Final URL Address different

Request forwarding is the server-side request , And then return the result to the client , So the whole request process URL The address is the same ; The request for redirection is for the server to tell the client ,“ You go to another place to visit ”, So the browser will send the request again , So the client end up showing URL Also the address of the final jump , Instead of the address you just requested , therefore URL The address has changed .

5. The code implementation is different

stay SpringBoot in , The implementation code of request forwarding is as follows ：

@RequestMapping("/fw")
public void forward(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.getRequestDispatcher("/index.html").forward(request, response);
}

The implementation code of request redirection is as follows ：

@RequestMapping("/rt")
public void redirect(HttpServletRequest request, HttpServletResponse response) throws IOException {
    response.sendRedirect("/index.html");
}

summary

Request forwarding and request redirection follow “ The less words , The bigger the matter is ” Principles ,“ Request forwarding ” There are fewer words , It needs to perform jump on behalf of the client ; and “ request redirections ” A lot of words , It does nothing , Just tell the client “ You visit somewhere else ” That's it , This is the key to understand these two concepts . Their differences are mainly reflected in 5 A little bit ： Different definitions 、 The requestor is different 、 Data sharing is different 、 Final URL Address different 、 The code implementation is different .

Reference resources & Acknowledgement

www.jianshu.com/p/81407dff803d

www.cnblogs.com/su-chu-zhi-151/p/11875641.html

It's up to you to judge right and wrong , Disdain is to listen to people , Gain or loss is more important than number .

official account ：Java Analysis of the real interview questions

Interview collection ：https://gitee.com/mydb/interview

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