package com.bjsxt.test.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(value={ElementType.TYPE})@Retention(RetentionPolicy.RUNTIME)public @interface SxtTable {    String value();}

package com.bjsxt.test.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(value={ElementType.FIELD})@Retention(RetentionPolicy.RUNTIME)public @interface SxtField {    String columnName();    String type();    int length();}

package com.bjsxt.test.annotation;@SxtTable("tb_student")public class SxtStudent {        @SxtField(columnName="id",type="int",length=10)    private int id;    @SxtField(columnName="sname",type="varchar",length=10)    private String studentName;    @SxtField(columnName="age",type="int",length=3)    private int age;            public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getStudentName() {        return studentName;    }    public void setStudentName(String studentName) {        this.studentName = studentName;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }        }

package com.bjsxt.test.annotation;import java.lang.annotation.Annotation;import java.lang.reflect.Field;/** * 使用反射读取注解的信息，模拟处理注解信息的流程 * @author 尚学堂高淇 * */public class Demo03 {        public static void main(String[] args) {        try {            Class clazz = Class.forName("com.bjsxt.test.annotation.SxtStudent");                        //获得类的所有有效注解            Annotation[] annotations=clazz.getAnnotations();            for (Annotation a : annotations) {                System.out.println(a);            }            //获得类的指定的注解            SxtTable st = (SxtTable) clazz.getAnnotation(SxtTable.class);            System.out.println(st.value());                        //获得类的属性的注解            Field f = clazz.getDeclaredField("studentName");            SxtField sxtField = f.getAnnotation(SxtField.class);            System.out.println(sxtField.columnName()+"--"+sxtField.type()+"--"+sxtField.length());                        //根据获得的表名、字段的信息，拼出DDL语句，然后，使用JDBC执行这个SQL，在数据库中生成相关的表                    } catch (Exception e) {            e.printStackTrace();        }            }}

 

程序运行的结果是：

@com.bjsxt.test.annotation.SxtTable(value=tb_student)

tb_student

sname--varchar--10

我们通过注解就可以获得对应的表名、字段的信息，我们就能够拼接处对应的sql语句，使用jdbc执行这个sql语言，在数据库中生成相关的表