Rewrite request parameter with Httpservletrequestwrapper

Purpose: Change the value of the request parameter to meet the requirements of the project (e.g., request to filter the request lang! = en)

Method: 1. Rewrite with Httpservletrequestwrapper

1  Public classChangerequestwrapperextendsHttpservletrequestwrapper {2     PrivateMap<string, string[]> Parametermap;//Map Collection of all parameters3 4      PublicChangerequestwrapper (HttpServletRequest request) {5         Super(request);6Parametermap =Request.getparametermap ();7     }8 9     //rewrite the methods in several HttpservletrequestwrapperTen  One     /** A * Get all parameter names -      * -      * @returnreturns all parameter names the      */ - @Override -      PublicEnumeration<string>Getparameternames () { -vector<string> vector =NewVector<string>(Parametermap.keyset ()); +         returnvector.elements (); -     } +  A     /** at * Gets the value of the specified parameter name, if there is a duplicate parameter name, returns the first value that receives a generic variable, such as the text type -      * -      * @paramname Specifies the name of the parameter -      * @returnSpecify the value of the parameter name -      */ - @Override in      Publicstring GetParameter (string name) { -String[] results =parametermap.get (name); to         returnResults[0]; +     } -  the  *     /** $ * Gets an array of all values for the specified parameter name, such as all data for the checkboxPanax Notoginseng * Receive array variables, such as CHECKOBX type -      */ the @Override +      Publicstring[] Getparametervalues (String name) { A         returnparametermap.get (name); the     } +  - @Override $      PublicMap<string, string[]>Getparametermap () { $         returnParametermap; -     } -  the      Public voidSetparametermap (map<string, string[]>Parametermap) { -          This. Parametermap =Parametermap;Wuyi     } the}

      2. Add Filter

1  Public classLangfilterImplementsFilter {2 @Override3      Public voidInit (Filterconfig filterconfig)throwsservletexception {4 5     }6 7 @Override8      Public voidDoFilter (ServletRequest servletrequest, Servletresponse servletresponse, Filterchain filterchain)throwsIOException, servletexception {9 TenChangerequestwrapper Changerequestwrapper =NewChangerequestwrapper ((httpservletrequest) servletrequest); One  Amap<string, string[]> parametermap =NewHashmap<>(Changerequestwrapper.getparametermap ()); -  -String[] strings = Parametermap.get ("lang");
The logical code is given the default parameter value, and if the argument is not Chinese, the exception is returned directly the         if(Strings = =NULL|| Strings.length = = 0) { -strings =NewString[1]; -Strings[0] = "zh"; -Parametermap.put ("Lang", strings); + Changerequestwrapper.setparametermap (parametermap); -}Else{ +String language = Strings[0]; A             if(!language.equals ("zh")) { atmap<string,string> error =NewHashmap<>(); -Error.put ("code", "500"); -  -Servletoutputstream OutputStream =NULL; -                 Try { -OutputStream =Servletresponse.getoutputstream (); in outputstream.write (Jsonutils.obj2byte (Error)); -}finally { to                     if(OutputStream! =NULL) { + Outputstream.flush (); - outputstream.close (); the                     } *                 } $ Panax Notoginseng                 return; -             } the         } +         //use of wrapper after replication A Filterchain.dofilter (Changerequestwrapper, servletresponse); the     } +  - @Override $      Public voiddestroy () { $  -     } -}

3.web.xml Add a filter handle

1  　　 <Filter>2         <Filter-name>Languagefilter</Filter-name>3         <Filter-class>Com.intercepor.LangFilter</Filter-class>4         <Init-param>5             <Param-name>Encoding</Param-name>6             <Param-value>UTF-8</Param-value>7         </Init-param>8         <Init-param>9             <Param-name>Forceencoding</Param-name>Ten             <Param-value>True</Param-value> One         </Init-param> A     </Filter> -  -     <filter-mapping> the         <Filter-name>Languagefilter</Filter-name> -         <Url-pattern>*.do</Url-pattern> -     </filter-mapping>

All. Do requests will validate this parameter

Rewrite request parameter with Httpservletrequestwrapper