一范风顺的笔记

package com.aflfte.test.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * 创建属性与对应字段注解方便解析
 * @author aflft
 *
 */
@Target(value=ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface AflfteField {
String clumnName();
String type();
int length();
}
package com.aflfte.test.annotation;
@Table("tb_student")
public class Student {
@AflfteField(clumnName = "id",type = "int",length = 10)
private int id;
@AflfteField(clumnName = "sname",type = "varchar",length = 10)
private String studentName;
@AflfteField(clumnName = "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.aflfte.test.annotation;

import java.lang.annotation.Annotation;


/**
 * 使用反射读取注解信息，模拟处理注解信息的流程
 * 
 * @author aflft
 *
 */
public class Demo03 {
public static void main(String[] args) {
try {
Class cla=Class.forName("com.aflfte.test.annotation.Student");

//获取类的所有注解
Annotation[] annotation=cla.getAnnotations();
for(Annotation a:annotation) {
System.out.println(a);
}
//获得类指定注解的值
Table table=(Table)cla.getAnnotation(Table.class);
System.out.println(table.value());

//获得类的属性注解
java.lang.reflect.Field[] fs=cla.getDeclaredFields();
/*Field field=f.getAnnotation(Field.class);
System.out.println(field.clumnName()+"-->"+field.type()+"-->"+field.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
StringBuilder sql=new StringBuilder();
sql.append("CREATE TABLE ").append(table.value()).append(" (\r\n");
for(java.lang.reflect.Field f:fs) {
AflfteField fie=f.getAnnotation(AflfteField.class);
sql.append(fie.clumnName()+" "+fie.type()+"("+fie.length()+") NOT NULL,\r\n");
}
sql.append(")");
System.out.println(sql.toString());
} catch (Exception e) {
// TODO 自动生成的 catch 块
e.printStackTrace();
}
}
}