MyBatis Interceptor Paging

 PackageCom.test.interceptor;Importjava.sql.Connection;ImportJava.sql.ResultSet;Importjava.sql.SQLException;Importjava.util.List;ImportJava.util.Map;Importjava.util.Properties;ImportOrg.apache.ibatis.executor.Executor;ImportOrg.apache.ibatis.executor.parameter.ParameterHandler;ImportOrg.apache.ibatis.executor.statement.RoutingStatementHandler;ImportOrg.apache.ibatis.executor.statement.StatementHandler;Importorg.apache.ibatis.mapping.BoundSql;Importorg.apache.ibatis.mapping.MappedStatement;Importorg.apache.ibatis.mapping.ParameterMapping;ImportOrg.apache.ibatis.plugin.Interceptor;Importorg.apache.ibatis.plugin.Intercepts;Importorg.apache.ibatis.plugin.Invocation;ImportOrg.apache.ibatis.plugin.Plugin;Importorg.apache.ibatis.plugin.Signature;ImportOrg.apache.ibatis.reflection.MetaObject;ImportOrg.apache.ibatis.reflection.SystemMetaObject;ImportOrg.apache.ibatis.scripting.defaults.DefaultParameterHandler;ImportOrg.apache.ibatis.session.ResultHandler;Importorg.apache.ibatis.session.RowBounds;Importcom.mysql.jdbc.PreparedStatement;Importcom.test.util.Page; @Intercepts ({@Signature (type= Statementhandler.class, method = "Prepare", args = {Connection.class}), @Signature (method= "Query", type = Executor.class, args ={mappedstatement.class, Object.class, Rowbounds.class, Resulthandler.class }) }) Public classStatementhandleinterceptorImplementsInterceptor { Public Static FinalString mysql = "MySQL"; protectedThreadlocal<page> pagethreadlocal =NewThreadlocal<page>();  PublicObject Intercept (invocation invocation)throwsThrowable {if(Invocation.gettarget ()instanceofStatementhandler) {Page<?> page =Pagethreadlocal.get (); if(page==NULL){                returninvocation.proceed (); } Routingstatementhandler Statementhandler=(Routingstatementhandler) invocation. Gettarget (); Statementhandler Delegate=Reflectutil.getfieldvalue (Statementhandler,"Delegate"); Boundsql Boundsql=Delegate.getboundsql (); Connection Connection= (Connection) invocation.getargs () [0]; if(Page.gettotalpage () >-1) {System.out.println ("Total Pages:" +page.gettotalpage ()); }Else{Object obj=Boundsql.getparameterobject (); MetaObject Metastatementhandler=Systemmetaobject.forobject (Statementhandler); Mappedstatement mappedstatement= (mappedstatement) metastatementhandler.getvalue ("Delegate.mappedstatement");            Querytotalrecord (page, obj, mappedstatement, connection); } String SQL=Boundsql.getsql (); String Pagesql=Buildpagesql (Page,sql); System.out.println ("When paging, generate Pagesql:" +pagesql); Reflectutil.setfieldvalue (Object) Boundsql,"SQL", Pagesql); returninvocation.proceed (); }Else{Page<?> page = Findpageobject (Invocation.getargs () [1]); if(page==NULL) {System.out.println ("No page Parameter object, not paged query"); returninvocation.proceed (); }Else{System.out.println ("Page object detected! Using paged query");            } pagethreadlocal.set (page); Try{                returninvocation.proceed (); //can setpage Results                /*Object resultobj = Invocation.proceed ();                if (resultobj instanceof list) {Page.setresults ((List) resultobj); } return resultobj;*/                            }finally{pagethreadlocal.remove (); }        }             }         PrivateString buildpagesql (Page page,string sql) {//calculates the position of the first record, which is recorded in MySQL starting at 0.         intoffset = (Page.getpageno ()-1) *page.getpagesize (); return NewStringBuilder (SQL). Append ("Limit"). Append (offset). Append (","). Append (Page.getpagesize ()). ToString (); }            /*** Determine if paging interception is required *@paramObject *@return     */    PrivatePage<?>Findpageobject (Object object) {if(ObjectinstanceofPage<?>){            return(page<?>) object; }Else if(ObjectinstanceofMap) {             for(Object o: (map<?,? >object). Values ()) {if(OinstanceofPage<?>){                    return(page<?>) O; }            }        }        return NULL; }    /*** Query Total number of records *@paramPage *@paramobj *@paramMappedstatement *@paramConnection *@throwsSQLException*/    Private voidQuerytotalrecord (page<?>page, Object obj, mappedstatement mappedstatement, Connection Connection)throwsSQLException {boundsql boundsql=mappedstatement.getboundsql (page); String SQL=Boundsql.getsql (); String Countsql= This. Buildcountsql (SQL); System.out.println ("When paging, generate Countsql:" +countsql); List<ParameterMapping> parametermappings =boundsql.getparametermappings (); Boundsql Countboundsql=NewBoundsql (Mappedstatement.getconfiguration (), countsql,parametermappings,obj); Parameterhandler Parameterhandler=NewDefaultparameterhandler (mappedstatement, obj, countboundsql); PreparedStatement pstmt=NULL; ResultSet RS=NULL; Try{pstmt=(PreparedStatement) connection.preparestatement (countsql);            Parameterhandler.setparameters (PSTMT); RS=Pstmt.executequery (); if(Rs.next ()) {LongTotalrecord = Rs.getlong (1);            Page.settotalrecord (Totalrecord); }            }finally{            if(rs!=NULL) {rs.close (); }            if(pstmt!=NULL) {pstmt.close (); }        }            }    /*** Construct query total record Count SQL *@paramSQL *@return     */    Privatestring Buildcountsql (String sql) {intindex = Sql.tolowercase (). IndexOf ("from"); return"SELECT COUNT (*)" +sql.substring (index); }     PublicObject Plugin (object target) {returnPlugin.wrap (Target, This); }     Public voidSetProperties (Properties properties) {}}

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MyBatis Interceptor Paging