java反射常用方法未完成

反射操作對象和屬性

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.獲取Class對象

	//獲取Class對象的三種方法
    Class<?> clazz = Student.class;
    Class<?> clazz = new Student().getClass();
    Class<?> clazz = Class.forName("com.git.Student");

2.字段的操作

1.獲取字段的四種方法源碼（jdk1.8）

	/**
	* Returns an array containing {@code Field} objects reflecting all
    * the accessible public fields of the class or interface represented by
    * 返回對象的所有公開成員，包括該類和該類繼承的成員
	*/
	@CallerSensitive
    public Field[] getFields() throws SecurityException {
    	//Member.PUBLIC，該類或該接口的所有公共成員的集合，包括繼承的成員
        checkMemberAccess(Member.PUBLIC, Reflection.getCallerClass(), true);//這句代碼表名了只能返回自身和繼承類的共有屬性成員
        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.
     * 返回該類自身的所有成員集，包括public，protected，default，private 但是不包括繼承的
     * /
	@CallerSensitive
    public Field[] getDeclaredFields() throws SecurityException {
    	//Member.DECLARED,該類或者該接口自己的成員集。不包括繼承的成員。
        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.
	* 返回該對象代表的類或者接口的公共成員的Field對象
	* 參數 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.
     * 返回自定類或者接口的字段（Field）對象
     * 參數 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;
    }

測試一：

 public static void main(String[] args) {
        Class<?> clazz = Student.class;
        Field[] fields1 = clazz.getDeclaredFields();//本類的所有屬性
        Field[] fields2 = clazz.getFields();//本類或者父類的共有屬性
        Arrays.stream(fields1).forEach(System.out::println);
        System.out.println("========================分割線========================");
        Arrays.stream(fields2).forEach(System.out::println);
    }
    //結果
    private java.lang.Integer com.qdz.qdzmart.framework.utils.Student.claaNum
	public java.lang.String com.qdz.qdzmart.framework.utils.Student.sex
	========================分割線========================
	public java.lang.String com.qdz.qdzmart.framework.utils.Student.sex
	public java.lang.String com.qdz.qdzmart.framework.utils.Person.name

測試二：

 		Field field1 = clazz.getField("name");//可以獲取
        Field field7 = clazz.getField("sex");//可以獲取
        Field field3 = clazz.getField("claaNum");//報錯
        Field field4 = clazz.getField("age");//報錯
        Field field5 = clazz.getField("addr");//報錯
        Field field6 = clazz.getField("is18");//報錯

測試三：

  		Field field7 = clazz.getDeclaredField("sex");//可以獲取
        Field field3 = clazz.getDeclaredField("claaNum");//可以獲取
        Field field1 = clazz.getDeclaredField("name");//報錯
        Field field4 = clazz.getDeclaredField("age");//報錯
        Field field5 = clazz.getDeclaredField("addr");//報錯
        Field field6 = clazz.getDeclaredField("is18");//報錯

以上四種方法用於數組等時需要注意下。

2.給成員賦值

這裏有點坑