Let's talk about how to implement SSM for submitting requests in JavaScript

In recent years, the separation of front-end and back-end has become a hot topic in the web field. Javascript, as one of the three core technologies of the front-end, forms a complete enterprise-level development architecture, namely SSM, with Spring MVC and Mybatis on the back-end.

In this architecture, the front end interacts with the back end through http requests, and the corresponding technology for javascript is Ajax. Ajax stands for Asynchronous JavaScript and XML, which is asynchronous Javascript and XML. It supports exchanging data with the server and updating part of the page content without reloading the entire page, thus improving the user experience. This article will introduce the implementation method of submitting request SSM in JavaScript.

1. Front-end code

Let’s first take a look at the front-end javascript implementation code.

1. Create XMLHttpRequest object

In javascript, you need to create an XMLHttpRequest object first, and initiate an asynchronous request through this object.

var xmlhttp;
if (window.XMLHttpRequest) {
  // code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
} else {
  // code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}

2. Send the request and process the response data

Set the request method, request address, asynchronous and other parameters through the open method of the xmlhttp object, and then send the request through the send method. In the request callback function, the response data can be processed by modifying DOM elements, changing styles, etc.

xmlhttp.open("GET","ajax_info.txt",true);
xmlhttp.send();
xmlhttp.onreadystatechange=function()
{
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
  {
    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
  }
}

2. Back-end code

After the front-end processes the request, the back-end needs to respond. In the SSM architecture, the back-end code is implemented using the Spring MVC framework, where the @ResponseBody annotation can mark the return value of a Controller method as json data.

@RequestMapping(value="/getUserName",method=RequestMethod.POST)
@ResponseBody
public String getUserName(@RequestParam("userId")String userId) {
    // 处理业务逻辑，获取用户名称
    String userName = userService.findNameById(userId);
    // 返回json格式的数据
    return "{\"userName\":\"" + userName + "\"}";
}

3. Integration steps

1. Call the backend Controller method in the front-end code

var userId = "123";
$.ajax({
    type : 'POST',
    url : '/ssm-demo/getUserName',
    data: {"userId" : userId},
    dataType : 'json',
    success : function(data) {
        console.log(data.userName);
    }
});

2. Introduce jQuery and Jackson related libraries

In the back-end code, Jackson related libraries need to be introduced to convert json data.

<!-- jQuery库 -->
<dependency>
   <groupid>org.webjars</groupid>
   <artifactid>jquery</artifactid>
   <version>3.3.1</version>
</dependency>
<!-- Jackson库 -->
<dependency>
    <groupid>com.fasterxml.jackson.core</groupid>
    <artifactid>jackson-databind</artifactid>
    <version>2.9.8</version>
</dependency>

3. Configure JavaConfig, scan Controller

In Spring's JavaConfig file, the following configuration is required:

@Configuration
@ComponentScan(basePackages="com.demo.controller")
public class AppConfig {
    // ...
}

4. Configure Spring MVC DispatcherServlet

Configure DispatcherServlet in web.xml and map the Servlet to the specified url. The parameters that need to be configured are:

• contextConfigLocation: Specify the path of Spring's JavaConfig file
• : Specify the mapping url of DispatcherServlet
• DISPATCHER_SERVLET_NAME: Specify the name of DispatcherServlet

<servlet>
   <servlet-name>demo-dispatcher</servlet-name>
   <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
   <init-param>
       <param-name>contextConfigLocation</param-name>
       <param-value>classpath:com/demo/config/AppConfig.java</param-value>
   </init-param>
   <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
   <servlet-name>demo-dispatcher</servlet-name>
   <url-pattern>/</url-pattern>
</servlet-mapping>

By integrating the above steps, you can submit requests through Javascript in the SSM architecture. The advantage of this method is that it can improve the user experience and achieve partial refresh through asynchronous interaction between the front and back ends without reloading the entire page, thereby quickly responding to user operations.

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