JAVA使用反射机制和注解实现对信息的处理-----JAVA入门基础教程

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

public class AnnotationTest
{
    public static void main(String[] args) throws Exception
    {
        Class c = Class.forName("Customer");
        c = Customer.class;
        Table table = (Table)c.getDeclaredAnnotation(Table.class);
        System.out.println(table.value());
        Annotation[] annotations = c.getDeclaredAnnotations();
        for(Annotation annotation : annotations)
        {
            System.out.println(annotation.annotationType().getName());
        }
        Field name = c.getDeclaredField("name");
        Column column = name.getDeclaredAnnotation(Column.class);
        System.out.println(column.columnName());
        System.out.println(column.columnType());
    }
}

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;

public class AnnotationTest
{
public static void main(String[] args) throws Exception
{
Class c = Class.forName("Customer");
c = Customer.class;
Table table = (Table)c.getDeclaredAnnotation(Table.class);
System.out.println(table.value());
Annotation[] annotations = c.getDeclaredAnnotations();
for(Annotation annotation : annotations)
{
System.out.println(annotation.annotationType().getName());
}
Field name = c.getDeclaredField("name");
Column column = name.getDeclaredAnnotation(Column.class);
System.out.println(column.columnName());
System.out.println(column.columnType());
}
}

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.FIELD;

@Target({FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Column
{
    String columnName();
    String columnType();
}

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.FIELD;

@Target({FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface Column
{
String columnName();
String columnType();
}

@Table(value = "t_Customer")
public class Customer
{
    @Column(columnName = "Customer_Name",columnType = "varchar(15)")
    private String name;
    @Column(columnName = "age",columnType = "int")
    public int age;
    public Customer()
    {
        System.out.println("Customer");
    }
    public Customer(int age)
    {
        this.age = age;
    }
    private Customer(String name,int age)
    {
        this.age = age;
        this.name = name;
    }

}

@Table(value = "t_Customer")
public class Customer
{
@Column(columnName = "Customer_Name",columnType = "varchar(15)")
private String name;
@Column(columnName = "age",columnType = "int")
public int age;
public Customer()
{
System.out.println("Customer");
}
public Customer(int age)
{
this.age = age;
}
private Customer(String name,int age)
{
this.age = age;
this.name = name;
}

}

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;

@Target({TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Table
{
    String value() default "Stop";
}

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.*;

@Target({TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface Table
{
String value() default "Stop";
}