Table，用类表示数据库的表
@Target(value= {ElementType.METHOD,ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Table{
String value();
}
类中的属性，每个属性表示一个字段
@Target(value= ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Fields {
String columnName();
String type();
int length();
}
类：
@Table("tb_student")
public class Student {
@Fields(columnName="id",type="int",length=10)
private int id;
@Fields(columnName="studentName",type="varchar",length=10)
private String studentName;
@Fields(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;
}
}
解析器：
public class Deam {
public static void main(String[] args) throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException, SecurityException, NoSuchFieldException {
try {
Class c=Class.forName("cn.sxt.in.Student");
Annotation[] annotation= c.getAnnotations(); //获得类的所有注解,只是类的，不包括方法等
for(Annotation a:annotation)
{
System.out.println(a);
}
//获得指定类的注解
Table tb=(Table) c.getAnnotation(Table.class);
System.out.println(tb.value());
//获得属性的注解
Field f=c.getDeclaredField("studentName"); //通过内容返回属性
Fields f2=f.getAnnotation(Fields.class); //通过属性返回注解
System.out.println(f2.columnName()+"-->"+f2.type()+"-->"+f2.length());
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
