Fault Tolerance management for HTTP requests in Android

In the android project, if an HTTP request is used, the timeout management and exception management of the HTTP request must also be added. In this case, a lot of requests are found on Google, however, it is relatively simple to write, and it is okay to make a demo, which is not perfect in the project. I wrote an example myself. You are welcome to correct it.

Note: There are three aspects

How to control the timeout Mechanism

How to handle exceptions

How to handle request errors

           
 Private     Class  Xmlasyncloader  Extends  Xmlresourcerequest {

  Private     Boolean  Miscancle  =    False  ;
  Private  Httpget mget;
  Private  Httpclient mhttp;

  Public  Xmlasyncloader (mxactivity  <?>  Activity, string URL)
  Throws  Malformedurlexception {
  Super  (Activity, URL );
}

@ Override
 Protected     Void  Dotaskinbackground (){
  //  Request data  
    If  (Murl. tolowercase (). startswith (  "  Http ://  "  )){
Mget  =  Inithttpget (murl );
Mhttp =  Inithttp ();
  Try  {
Httpresponse response  =  Mhttp.exe cute (mget );
  If  (Miscancle ){
  Return  ;
}
  If  (Response  ! =     Null  ){
 If  (Response. getstatusline (). getstatuscode ()  ! =  Httpstatus. SC _ OK ){
Onresponseerror (  "  Network Error  "  );
Log. V (tag,  "  The code is:  "  +  Response. getstatusline (). getstatuscode ());
  Return ;
}
Notifyupdateprogress (  70  );
Document Doc  =  Getdocumet (response );
Element Root  =  Doc. getdocumentelement ();
Nodelist applist  =  Root
. Getelementsbytagname (item_element_name );
  Final     Int Len  =  Applist. getlength ();
  If  (Len  <=     0  ){  //  No items  
  Onfoundnoitems ();
  Return  ;
}
  For (  Int  I  =     0  ; I  <  Len; I  ++  ){
Element item  =  (Element) applist. item (I );
  If  (Item. getnodetype ()  = Node. element_node ){
Hahaiteminfo info  =  Createhahaitemino (item );
  If  (Miscancle ){
  Return  ;
}
Onfounditem (info,  80     +     20     *  (I +     1  )  /  Len );
Addurltoqueue (info. usericonurl );
}
};

}
}  Catch  (Connecttimeoutexception e ){
Onresponseerror (  "  Time out  "  );
}  Catch (Clientprotocolexception e ){
  --  Mcurrentpage;
E. printstacktrace ();
}  Catch  (Ioexception e ){
  --  Mcurrentpage;
E. printstacktrace ();
}  Catch  (Xmlpullparserexception e ){
  --  Mcurrentpage;
E. printstacktrace ();
}  Finally {
Notifyloadfinish ();
Notifyloadimages ();
Mhttp. getconnectionmanager (). Shutdown ();
}

}
}


  Private  Httpclient inithttp (){
Httpclient Client  =     New  Defaulthttpclient ();
Client. getparams (). setintparameter (
Httpconnectionparams. so_timeout, time_out_delay );  //  Timeout settings  
 Client. getparams (). setintparameter (
Httpconnectionparams. connection_timeout, time_out_delay );  //  Connection timeout  
    Return  Client;
}

  Private  Httpget inithttpget (string murl ){
Httpget  =     New  Httpget (murl );
Initheader (get );
 Return  Get;
}


@ Override
  Public     Boolean  Trycancel (){
Log. I (tag,  "  Trycanle is working  "  );
Mget. Abort ();
Miscancle  =     True ;
Mhttp. getconnectionmanager (). Shutdown ();
Notifyloadfinish ();
  Return     True  ;
}

} 
 

 
 
This is an asynchronous task class. It sends GET request data, parses server response data, and notifies the UI thread to update the UI.
 
 
In Android, there are many ways to write internet interactions. You can use the packages provided by Apache or the APIS provided by Google. I don't know which one is better, but I am used to using it.
 
 
Apache API.
 
 
1. Set the timeout Mechanism
 
 
Client. getparams (). setintparameter (
Httpconnectionparams. so_timeout, time_out_delay );//Timeout settings
Client. getparams (). setintparameter (
Httpconnectionparams. connection_timeout, time_out_delay );//Connection timeout
 
 
Two timeout methods are set here. The first is request timeout and the second is connection timeout.
 
 
When a request is sent to the server, the request establishes a socket connection with the server, but no socket connection is established for a long time. In this case, the first request times out. This occurs mainly in the request.
 
 
A non-existent server. After timeoutInterruptedioexception.
 
 
Timeout for blocking operations. The argument value is specified in milliseconds.InterruptedioexceptionIs thrown if this timeout expires.
 
The client has established a socket connection with the server, but the server does not process the client's requests and does not have the corresponding server. This is the second connection timeout. Timeout will throw
 
 
Connecttimeoutexception exception. connecttimeoutexception inherits from interruptedioexception, so you only need to capture connecttimeoutexception
You can.
 
 
2. Analyze the request process
 
 
2.1Httpresponse response=Mhttp.exe cute (mget );
 
 
Execute the request method to obtain the server response. (here we have an immature view. response cannot be null and remains to be verified ).
 
 
2.2 GET request response code
 
 If(Response. getstatusline (). getstatuscode ()! =Httpstatus. SC _ OK ){
Onresponseerror ("Network Error");
Log. V (tag,"The code is:"+Response. getstatusline (). getstatuscode ());
Return;
}
 
 
 
 
Even if the server is connected and the data is obtained from the server, the error message returned by the server may be returned. Therefore, special processing is required.
 
2.3 Exception Handling
 
 
For exceptions, you cannot simply catch them. For exampleCode,
 
 
If it succeeds, you do not need to roll back, so you need to handle the exception.
 
 
2.4 Finally keywords
 
 
The link must be closed whether the request is successful or fails.