How to use parameters in the prehandler method in SpringMVC?

1 year ago
Ava Mitchell
2 minutes

In SpringMVC, preHandler is a method used as an interceptor to preprocess before handling a request. This method can take in three parameters.

  1. HttpServletRequest represents the current HTTP request object, which can be used to obtain information related to the request, such as the request URL and parameters.
  2. HttpServletResponse: Represents the current HTTP response object, allowing to set properties related to the response such as status code and response headers.
  3. Object handler: Refers to the processor handling the current request (i.e. the method in the Controller), from which some information about the processor can be obtained.

In the preHandler method, these parameters can be used to perform operations as needed, for example:

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    // 获取请求的URL
    String url = request.getRequestURL().toString();
    
    // 获取请求的参数
    String param1 = request.getParameter("param1");
    String param2 = request.getParameter("param2");
    
    // 设置响应的字符编码
    response.setCharacterEncoding("UTF-8");
    
    // 设置响应的内容类型
    response.setContentType("application/json");
    
    // 打印处理器的信息
    System.out.println("Handler: " + handler);
    
    // 返回true表示继续执行后续的拦截器和处理器，返回false表示中断请求处理
    return true;
}

It is important to note that the return value of the preHandler method indicates whether to continue executing the following interceptors and handlers. If it returns false, the processing flow of the request will be interrupted and the subsequent interceptors and handlers will not be executed.

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