Determine whether to call AJAX in Java's Struts and use interceptors to optimize it

Strut2 Determine whether it is an AJAX call
1. AJAX and traditional Form form
In fact, both are generally POST requests through HTTP. The difference is that after the browser submits the Form, it expects the server to return a complete HTML page. The AJAX call is issued by the XMLHttpRequest object (different browsers may be different). The browser expects the server to return an HTML fragment. Specifically, there are no requirements for JSON, XML, etc. How to use it after returning to the browser is also determined by the JS script itself.

2. Whether the request is AJAX
So for the server side, how to determine whether an HTTP request is an AJAX call? This requires looking at the HTTP Header.

We can judge by x-request-with in the Header. Although different browsers send AJAX requests to different objects, if jQuery is used to send AJAX requests, the identifier has been added when jQuery implements ajax internally. The jQuery source code looks like this: xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
So, if the front-end page of the project sends AJAX requests through jQuery, this judgment is safe.

The following is the Header information carried by the HTTP request.

Normal Form form submission

===MimeHeaders ===
accept = */*
referer =http://localhost:8080/user2/toQueryPage.action
accept-language = zh-CN
user-agent = Mozilla/4.0 (compatible; MSIE8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C;.NET4.0E)
accept-encoding = gzip, deflate
host = localhost:8080
connection = Keep-Alive
cache-control = no-cache

AJAX call (IE)

===MimeHeaders ===
x-requested-with = XMLHttpRequest
accept-language = zh-cn
referer =http://localhost:8080/user2/toQueryPage.action
accept = application/json, text/javascript,*/*; q=0.01
content-type =application/x-www-form-urlencoded
accept-encoding = gzip, deflate
user-agent = Mozilla/4.0 (compatible; MSIE8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; InfoPath.3; .NET4.0C;.NET4.0E)
host = localhost:8080
content-length = 57
connection = Keep-Alive
cache-control = no-cache

##3. Obtained in Action HTTP request header
In the Action class, obtain the HttpServletRequest object through the ServletRequestAware interface, and then obtain the header information we want through the getHeader method.

public abstract class BaseAction
    <ParamVo extends BaseParamVo, ResultVo extends BaseResultVo>
      extends ActionSupport
        implements ServletRequestAware {
    
  private static final String AJAX_RESULT_NAME = "ajaxResult";
  private static final String XHR_OBJECT_NAME = "XMLHttpRequest";
  private static final String HEADER_REQUEST_WITH = "x-requested-with";
    
  /**
   * Request对象，用来判断请求是否是AJAX调用
   */
  private HttpServletRequest request;
    
  private ParamVo paramVo;
    
  private ResultVo resultVo;
    
  @Override
  public String execute() {
    String resultPage = SUCCESS;
    try {
      resultVo = doExecute(paramVo);
    }
    catch (BaseException e) {
      resultPage = ERROR;
    }
      
    if (XHR_OBJECT_NAME.equals(request.getHeader(HEADER_REQUEST_WITH))) {
      resultPage = AJAX_RESULT_NAME;
    }
      
    return resultPage;
  }
}

Struts2 Performance Tuning Interceptor

When we need to implement some small requirements at work, we might as well conduct a simple survey first and see Does the open source framework we are using already have the functions we need, so we don’t have to reinvent the wheel?
Let’s take performance testing as an example to see how to investigate whether the Struts2 framework has this function.

1. struts-default.xml

Because many of the core functions of Struts2 are implemented based on internal interceptors, we first need to see if it has performance tuning-related interceptions device. This requires checking the default configuration file struts-default.xml in strut2-core-2.3.1.2.jar.

<span style="white-space:pre"> </span><interceptor name="alias" class="com.opensymphony.xwork2.interceptor.AliasInterceptor"/>
      <interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/>
      <interceptor name="chain" class="com.opensymphony.xwork2.interceptor.ChainingInterceptor"/>
      <interceptor name="conversionError" class="org.apache.struts2.interceptor.StrutsConversionErrorInterceptor"/>
      <interceptor name="cookie" class="org.apache.struts2.interceptor.CookieInterceptor"/>
      <interceptor name="clearSession" class="org.apache.struts2.interceptor.ClearSessionInterceptor" />
      <interceptor name="createSession" class="org.apache.struts2.interceptor.CreateSessionInterceptor" />
      <interceptor name="debugging" class="org.apache.struts2.interceptor.debugging.DebuggingInterceptor" />
      <interceptor name="execAndWait" class="org.apache.struts2.interceptor.ExecuteAndWaitInterceptor"/>
      <interceptornameinterceptorname="exception" class="com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor"/>
      <interceptor name="fileUpload" class="org.apache.struts2.interceptor.FileUploadInterceptor"/>
      <interceptor name="i18n" class="com.opensymphony.xwork2.interceptor.I18nInterceptor"/>
      <interceptor name="logger" class="com.opensymphony.xwork2.interceptor.LoggingInterceptor"/>
      <interceptor name="modelDriven" class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/>
      <interceptor name="scopedModelDriven" class="com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/>
      <interceptor name="params" class="com.opensymphony.xwork2.interceptor.ParametersInterceptor"/>
      <interceptor name="actionMappingParams" class="org.apache.struts2.interceptor.ActionMappingParametersInteceptor"/>
      <interceptor name="prepare" class="com.opensymphony.xwork2.interceptor.PrepareInterceptor"/>
      <interceptor name="staticParams" class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor"/>
      <interceptor name="scope" class="org.apache.struts2.interceptor.ScopeInterceptor"/>
      <interceptor name="servletConfig" class="org.apache.struts2.interceptor.ServletConfigInterceptor"/>
      <interceptor name="timer" class="com.opensymphony.xwork2.interceptor.TimerInterceptor"/>
      <interceptor name="token" class="org.apache.struts2.interceptor.TokenInterceptor"/>
      <interceptor name="tokenSession" class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor"/>
      <interceptor name="validation" class="org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor"/>
      <interceptor name="workflow" class="com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor"/>
      <interceptor name="store" class="org.apache.struts2.interceptor.MessageStoreInterceptor" />
      <interceptor name="checkbox" class="org.apache.struts2.interceptor.CheckboxInterceptor" />
      <interceptor name="profiling" class="org.apache.struts2.interceptor.ProfilingActivationInterceptor" />
      <interceptor name="roles" class="org.apache.struts2.interceptor.RolesInterceptor" />
      <interceptor name="annotationWorkflow" class="com.opensymphony.xwork2.interceptor.annotations.AnnotationWorkflowInterceptor" />
      <interceptor name="multiselect" class="org.apache.struts2.interceptor.MultiselectInterceptor" />

Struts2 is like a treasure chest with many built-in interceptors. You can see that profiling is probably the interceptor that meets our needs. Now open the source code. Find out.

2. ProfilingActivationInterceptor

org.apache.struts2.interceptor.ProfilingActivationInterceptor.java

public class ProfilingActivationInterceptor extendsAbstractInterceptor {
   
  private String profilingKey = "profiling";
  private boolean devMode;
    
  @Inject(StrutsConstants.STRUTS_DEVMODE)
  public void setDevMode(String mode) {
    this.devMode = "true".equals(mode);
  }
   
  @Override
  public String intercept(ActionInvocationinvocation) throws Exception {
    if (devMode) {
      Object val =invocation.getInvocationContext().getParameters().get(profilingKey);
      if (val != null) {
        String sval = (val instanceof String ?(String)val : ((String[])val)[0]);
        boolean enable = "yes".equalsIgnoreCase(sval)|| "true".equalsIgnoreCase(sval);
        UtilTimerStack.setActive(enable);
        invocation.getInvocationContext().getParameters().remove(profilingKey);
      }
    }
    return invocation.invoke();
   
  }
   
}

From source code As can be seen in , as long as the HTTP request parameter sent by the browser contains profiling=true or yes, the performance interceptor will open the Timer tool class and print out the execution time of the Action.

3. struts.xml

Because the profiling interceptor is not included in the default defaultStack, we must first append it to our custom interceptor stack.

<package name="ajax-default" extends="velocity-default">
    <result-types>
      <result-type name="json" class="org.apache.struts2.json.JSONResult"/>
    </result-types>
      
    <interceptors>
      <interceptor-stacknameinterceptor-stackname="ajaxInterceptorStack">
      <interceptor-refnameinterceptor-refname="defaultStack" />
      <interceptor-ref name="profiling"/>
      </interceptor-stack>
    </interceptors>
      
    <default-interceptor-refnamedefault-interceptor-refname="ajaxInterceptorStack" />
      
    <global-results>
      <result name="comAjaxResult" type="json">
        <param name="excludeNullProperties">true</param>
        <param name="root">result</param>
        <param name="ignoreHierarchy">false</param>
      </result>
    </global-results>
  </package>

4. userview.js

You can now modify the AJAX call parameters, add profiling parameters, and start performance tuning.

function searchAllUser(){
  jQuery.ajax({
    type:"post",
    url: "searchAllUser.action",
    processData:true,
    dataType:'json',
    data:jQuery("#userQueryForm").serialize() + "&profiling=yes",
    success:function(data) {
    if (data.status == 1) {
       alert("创建成功");
       generateTableFromJson("result", data.resultRows);
    } else {
       alert("创建失败");
    }
    }
  });
}

5. The final effect

The printed result is as follows. In addition to the total execution time, the execution time of the Action method and the rendering time of the Result will be listed separately.

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