java反射常用方法未完成

反射操作对象和属性

eg:

class Person{
    private Integer age;
    public String name;
    protected String addr;
    Boolean is18;

}
class Student extends Person{
    private Integer claaNum;
	public String sex;
}

1.获取Class对象

	//获取Class对象的三种方法
    Class<?> clazz = Student.class;
    Class<?> clazz = new Student().getClass();
    Class<?> clazz = Class.forName("com.git.Student");

2.字段的操作

1.获取字段的四种方法源码（jdk1.8）

	/**
	* Returns an array containing {@code Field} objects reflecting all
    * the accessible public fields of the class or interface represented by
    * 返回对象的所有公开成员，包括该类和该类继承的成员
	*/
	@CallerSensitive
    public Field[] getFields() throws SecurityException {
    	//Member.PUBLIC，该类或该接口的所有公共成员的集合，包括继承的成员
        checkMemberAccess(Member.PUBLIC, Reflection.getCallerClass(), true);//这句代码表名了只能返回自身和继承类的共有属性成员
        return copyFields(privateGetPublicFields(null));
    }
	
	 /** 
	 *Returns an array of {@code Field} objects reflecting all the fields
     * declared by the class or interface represented by this
     * {@code Class} object. This includes public, protected, default
     * (package) access, and private fields, but excludes inherited fields.
     * 返回该类自身的所有成员集，包括public，protected，default，private 但是不包括继承的
     * /
	@CallerSensitive
    public Field[] getDeclaredFields() throws SecurityException {
    	//Member.DECLARED,该类或者该接口自己的成员集。不包括继承的成员。
        checkMemberAccess(Member.DECLARED, Reflection.getCallerClass(), true);
        return copyFields(privateGetDeclaredFields(false));
    }
	
	
	/**
	*  Returns a {@code Field} object that reflects the specified public member
     * field of the class or interface represented by this {@code Class}
     * object. The {@code name} parameter is a {@code String} specifying the
     * simple name of the desired field.
	* 返回该对象代表的类或者接口的公共成员的Field对象
	* 参数 字段名
	*/
	 @CallerSensitive
    public Field getField(String name)
        throws NoSuchFieldException, SecurityException {
        checkMemberAccess(Member.PUBLIC, Reflection.getCallerClass(), true);
        Field field = getField0(name);
        if (field == null) {
            throw new NoSuchFieldException(name);
        }
        return field;
    }
  	/* * Returns a {@code Field} object that reflects the specified declared
     * field of the class or interface represented by this {@code Class}
     * object. The {@code name} parameter is a {@code String} that specifies
     * the simple name of the desired field.
     * 返回自定类或者接口的字段（Field）对象
     * 参数 字段名，
     * 
     * /
  @CallerSensitive
    public Field getDeclaredField(String name)
        throws NoSuchFieldException, SecurityException {
        checkMemberAccess(Member.DECLARED, Reflection.getCallerClass(), true);
        Field field = searchFields(privateGetDeclaredFields(false), name);
        if (field == null) {
            throw new NoSuchFieldException(name);
        }
        return field;
    }

测试一：

 public static void main(String[] args) {
        Class<?> clazz = Student.class;
        Field[] fields1 = clazz.getDeclaredFields();//本类的所有属性
        Field[] fields2 = clazz.getFields();//本类或者父类的共有属性
        Arrays.stream(fields1).forEach(System.out::println);
        System.out.println("========================分割线========================");
        Arrays.stream(fields2).forEach(System.out::println);
    }
    //结果
    private java.lang.Integer com.qdz.qdzmart.framework.utils.Student.claaNum
	public java.lang.String com.qdz.qdzmart.framework.utils.Student.sex
	========================分割线========================
	public java.lang.String com.qdz.qdzmart.framework.utils.Student.sex
	public java.lang.String com.qdz.qdzmart.framework.utils.Person.name

测试二：

 		Field field1 = clazz.getField("name");//可以获取
        Field field7 = clazz.getField("sex");//可以获取
        Field field3 = clazz.getField("claaNum");//报错
        Field field4 = clazz.getField("age");//报错
        Field field5 = clazz.getField("addr");//报错
        Field field6 = clazz.getField("is18");//报错

测试三：

  		Field field7 = clazz.getDeclaredField("sex");//可以获取
        Field field3 = clazz.getDeclaredField("claaNum");//可以获取
        Field field1 = clazz.getDeclaredField("name");//报错
        Field field4 = clazz.getDeclaredField("age");//报错
        Field field5 = clazz.getDeclaredField("addr");//报错
        Field field6 = clazz.getDeclaredField("is18");//报错

以上四种方法用于数组等时需要注意下。

2.给成员赋值

这里有点坑