深入理解JAVA核心：揭秘反射机制的奥秘

Person p = new Student();

 //获取Class对象第一种class.forName/

try {
Class clazz1 = Class.forName(“com.aaa.entity.Person”);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

 //获取Class对象第二种.class
Class clazz2 = Person.class;

//获取Class对象第三种getClass（）
/* Person p = new Person();
Class class3 = p.getClass();*/

//获取构造器
Constructor[] cons = s.getClass().getConstructors();
for (Constructor constructor : cons) {
System.out.println(constructor);
}

Method[] methods = clazz2.getMethods();
System.out.println(methods.length);
for (Method method : methods) {
System.out.println(method.getName());
}

/*Method[] methods2 = clazz2.getDeclaredMethods();
		System.out.println(methods2.length);
		for (Method method : methods2) {
			System.out.println(method.getName());
		}*/

Field[] fields = clazz2.getFields();
        System.out.println(fields.length);

Field[] fields = clazz2.getDeclaredFields();
        System.out.println(fields.length);

Student student = new Student();
        Field field = student.getClass().getDeclaredField("name");
        //field.setAccessible(true);
        field.set(student, "张三");
        System.out.println(student.getName());

/**
	 * 通用方法获取对象集合
	 */
	public static List selectObjList(String sql,Object[] params,Class clazz) throws Exception{
		List list = new ArrayList();
		con = getConnection();
		try {
			ps = con.prepareStatement(sql);
			setParams(params);
			rs = ps.executeQuery();
			//列数
			ResultSetMetaData rsm = rs.getMetaData();
			int count = rsm.getColumnCount();//获取列数
			while(rs.next()){
				Object obj = clazz.newInstance();//实例化一个对象
				for(int i=1;i<=count;i++){
					String key = rsm.getColumnName(i);//获取列名
					Object value = rs.getObject(i);//获取对应列的值
					Field field = clazz.getDeclaredField(key);//获取对象的成员变量（字段名）
					field.setAccessible(true);//设置可访问
					if(value!=null){
						field.set(obj, value);
					}
				}
				list.add(obj);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			closeAll();
		}
		return list;
	}