Annotated learning examples (simulating hibernate,table,column annotations, assembling SQL)

Directly on the code

Package Com.guoxinet.o2o.annotation;import Java.lang.annotation.documented;import Java.lang.annotation.elementtype;import Java.lang.annotation.inherited;import java.lang.annotation.Retention; Import Java.lang.annotation.retentionpolicy;import java.lang.annotation.Target; @Target (Elementtype.field) @ Retention (retentionpolicy.runtime) @Inherited @documentedpublic @interface Column {String value ();}

　　

Package Com.guoxinet.o2o.annotation;import Java.lang.annotation.documented;import Java.lang.annotation.elementtype;import Java.lang.annotation.inherited;import java.lang.annotation.Retention; Import Java.lang.annotation.retentionpolicy;import java.lang.annotation.Target; @Target (Elementtype.type) @ Retention (retentionpolicy.runtime) @Inherited @documentedpublic @interface Table {String value ();}

　　

Package com.guoxinet.o2o.annotation; @Table ("Tb_user") Public classUser {@Column ("user_id")    Private intuserId; @Column ("user_name")    PrivateString UserName; @Column ("Address")    PrivateString address; @Column ("Email")    PrivateString Email;  Public intgetUserId () {returnuserId; }     Public voidSetuserid (intuserId) {         This. UserId =userId; }     PublicString GetUserName () {returnUserName; }     Public voidsetusername (String userName) { This. UserName =UserName; }     PublicString getaddress () {returnaddress; }     Public voidsetaddress (String address) { This. Address =address; }     PublicString Getemail () {returnemail; }     Public voidsetemail (String email) { This. email =email; }}

Package com.guoxinet.o2o.annotation; @Table ("tb_department") Public classDepartMent {@Column ("department_id")    Private intDepartmentID; @Column ("name")    PrivateString name;  Public intGetdepartmentid () {returnDepartmentID; }     Public voidSetdepartmentid (intDepartmentID) {         This. DepartmentID =DepartmentID; }     PublicString GetName () {returnname; }     Public voidsetName (String name) { This. Name =name; }        }

Package com.guoxinet.o2o.annotation;import Java.lang.reflect.field;import Java.lang.reflect.Method; Public classClient { Public Static voidMain (string[] args) {User User=NewUser (); User.setuserid (1); User.setemail ("[email protected],[email protected],[email protected]");                GetSQL (user); DepartMent DM=NewDepartMent (); Dm.setdepartmentid ( -); Dm.setname ("Technical Department");    GetSQL (DM); }         Public StaticString getsql (Object ob) {StringBuilder sb=NewStringBuilder (); //Get class@SuppressWarnings ("Rawtypes") Class C=Ob.getclass (); //get the name of the table@SuppressWarnings ("unchecked") Boolean isexist= C.isannotationpresent (Table.class); if(!isexist) {            return ""; } Table Table= (table) c.getannotation (table).class); String TableName=Table.value (); Sb.append ("SELECT * from"). Append (TableName). Append ("where 1=1"); //Traverse Propertiesfield[] Farray =C.getdeclaredfields ();  for(Field Field:farray) {Boolean fisexist= Field.isannotationpresent (Column.class); if(!fisexist) {                Continue; } Column Column= (column) field.getannotation (column).class); //Column NameString ColumnName =Column.value (); //get the value of the propertyString MethodName ="Get"+field.getname (). SUBSTRING (0,1). toUpperCase () + field.getname (). SUBSTRING (1); Object Fieldvalue=NULL; Try{Method Method=C.getmethod (methodName); Fieldvalue=Method.invoke (OB); if(NULL= = Fieldvalue | | (Fieldvalue instanceof Integer &&0==(Integer) fieldvalue)) {System. out. println (Fieldvalue); Continue; } sb.append (" and"). Append (ColumnName); if(fieldvalue instanceof String) {if((String) fieldvalue). Contains (",") ) {string[] Sarray= (String) fieldvalue. Split (","); Sb.append ("inch"). Append ("(");  for(String s:sarray) {sb.append ("'"). Append (s). Append ("',"); } Sb.deletecharat (Sb.length ()-1); Sb.append (")"); }Else{sb.append (" = "); Sb.append ("'"). Append (Fieldvalue). Append ("'"); }                                    }Else{sb.append (" = "). Append (Fieldvalue); }                            } Catch(Exception e) {//TODO auto-generated Catch blockE.printstacktrace (); }} sb.append (";"); System. out. println (Sb.tostring ()); return NULL; }}

Annotated learning examples (simulating hibernate,table,column annotations, assembling SQL)