hibernate注解，jpa注解根据类生成表

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定义几个注解类

package cn.martin.core.service.anno.e2;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface Constraints {    boolean primaryKey() default false;    boolean  allowNull() default true;    boolean  unique() default false;}

package cn.martin.core.service.anno.e2;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)public @interface DBTable {    public String name() default "";}

package cn.martin.core.service.anno.e2;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface SQLInteger {    String name() default "";    Constraints constraints()  default  @Constraints;}

package cn.martin.core.service.anno.e2;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface SQLString {    int value()  default 0;    String name() default "";    Constraints constraints()  default  @Constraints;}

pojo添加注解

package cn.martin.core.service.anno.e2;@DBTable(name="TB_MEMBER")public class Member {    @SQLString(30)    private String firstname;    @SQLInteger    private int age;    @SQLString(value=30,constraints=@Constraints(primaryKey=true))    String id;    public String getFirstname() {        return firstname;    }    public void setFirstname(String firstname) {        this.firstname = firstname;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public String getId() {        return id;    }    public void setId(String id) {        this.id = id;    }    @Override    public String toString() {        return "Member [id=" + id + "]";    }}

注解处理类

package cn.martin.core.service.anno.e2;import java.lang.annotation.Annotation;import java.lang.reflect.Field;import java.util.ArrayList;import java.util.List;public class TableCreate {    public static void main(String[] args) throws ClassNotFoundException {         String[]  tyleArys = new String [] {"cn.martin.core.service.anno.e2.Member"};         createSql(tyleArys);    }    public static void   createSql(String[] args) throws ClassNotFoundException{        for (String className : args) {            Class<?> cls = Class.forName(className);            DBTable dbTable = cls.getAnnotation(DBTable.class);            if(dbTable == null){                continue;            }            String tableName = dbTable.name();            if(tableName.length() < 1){                tableName = cls.getName().toUpperCase();            }            List<String> columnsDef = new ArrayList<String>();            for (Field  field : cls.getDeclaredFields()) {                String columnName = null;                Annotation[] anns = field.getDeclaredAnnotations();                if(anns.length < 0){                    continue;                }                if(anns[0] instanceof SQLInteger){                    SQLInteger sQLInteger =  (SQLInteger)anns[0];                    if(sQLInteger.name().length() < 1){                        columnName = field.getName().toUpperCase();                    }else{                        columnName = sQLInteger.name();                    }                    columnsDef.add( columnName +" INT  "+ getConstraints(sQLInteger.constraints()));                }                if(anns[0] instanceof SQLString){                    SQLString sQLString = (SQLString)anns[0];                    if(sQLString.name().length() < 1){                        columnName = field.getName().toUpperCase();                    }else {                        columnName = sQLString.name();                    }                    columnsDef.add( columnName + " varchar ("+sQLString.value()+ ")" + getConstraints(sQLString.constraints()));                }            }            StringBuilder sb = new StringBuilder("create  table  "+tableName + " ( ");            for (String column : columnsDef) {                sb.append("\n" + column + " ,");            }            String createTable = sb.substring(0,sb.length()-1)+" );";            System.out.println(createTable);        }    }    public static  String getConstraints(Constraints con){        String constaints = "";        if(!con.allowNull()){            constaints += " not null  ";        }        if(con.primaryKey()){            constaints += " primary key ";        }        if(con.unique()){            constaints += "   unique ";        }        return constaints;    }}

测试结果

create  table  TB_MEMBER ( FIRSTNAME varchar (30) ,AGE INT   ,ID varchar (30) primary key   );

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