java 数据类型

Literals

^{8bit　  1byte    byte}

^{16bit    2byte　short}

^{32bit　4byte　int}

^{64bit　8byte　long}

 http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.2.1

https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

The values of the integral types are integers in the following ranges:

• For byte, from -128 to 127, inclusive

• For short, from -32768 to 32767, inclusive

• For int, from -2147483648 to 2147483647, inclusive

• For long, from -9223372036854775808 to 9223372036854775807, inclusive

• For char, from '\u0000' to '\uffff' inclusive, that is, from 0 to 65535

0x0000 - 0xffff          0-65535

0x0000 - 0xFFFF       0-65535

 

1个byte可以表示的常见字符：

        try {
            Appender appender = new Appender(new File("D://bytes.txt"));
            for (int i = Byte.MIN_VALUE; i < Byte.MAX_VALUE; i++) {
                appender.follow((char) i + "");
            }
            appender.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

如下（包含空格）：

 !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

使用场景：aes-128 的 key 是 ngrJhBXugRakhDvM 刚好16个字符，也刚好转成长度16的byte数组

-128	ﾀ
-127	ﾁ
-126	ﾂ
-125	ﾃ
-124	ﾄ
-123	ﾅ
-122	ﾆ
-121	ﾇ
-120	ﾈ
-119	ﾉ
-118	ﾊ
-117	ﾋ
-116	ﾌ
-115	ﾍ
-114	ﾎ
-113	ﾏ
-112	ﾐ
-111	ﾑ
-110	ﾒ
-109	ﾓ
-108	ﾔ
-107	ﾕ
-106	ﾖ
-105	ﾗ
-104	ﾘ
-103	ﾙ
-102	ﾚ
-101	ﾛ
-100	ﾜ
-99	ﾝ
-98	ﾞ
-97	ﾟ
-96	ﾠ
-95	ﾡ
-94	ﾢ
-93	ﾣ
-92	ﾤ
-91	ﾥ
-90	ﾦ
-89	ﾧ
-88	ﾨ
-87	ﾩ
-86	ﾪ
-85	ﾫ
-84	ﾬ
-83	ﾭ
-82	ﾮ
-81	ﾯ
-80	ﾰ
-79	ﾱ
-78	ﾲ
-77	ﾳ
-76	ﾴ
-75	ﾵ
-74	ﾶ
-73	ﾷ
-72	ﾸ
-71	ﾹ
-70	ﾺ
-69	ﾻ
-68	ﾼ
-67	ﾽ
-66	ﾾ
-65	﾿
-64	￀
-63	￁
-62	ￂ
-61	ￃ
-60	ￄ
-59	ￅ
-58	ￆ
-57	ￇ
-56	￈
-55	￉
-54	ￊ
-53	ￋ
-52	ￌ
-51	ￍ
-50	ￎ
-49	ￏ
-48	￐
-47	￑
-46	ￒ
-45	ￓ
-44	ￔ
-43	ￕ
-42	ￖ
-41	ￗ
-40	￘
-39	￙
-38	ￚ
-37	ￛ
-36	ￜ
-35	￝
-34	￞
-33	￟
-32	￠
-31	￡
-30	￢
-29	￣
-28	￤
-27	￥
-26	￦
-25	￧
-24	￨
-23	￩
-22	￪
-21	￫
-20	￬
-19	￭
-18	￮
-17	￯
-16	￰
-15	￱
-14	￲
-13	￳
-12	￴
-11	￵
-10	￶
-9	￷
-8	￸
-7	
-6	
-5	
-4	
-3	�
-2	￾
-1	�
0	 
1	

2	
3	
4	
5	
6	
7	
8	
9		
10	

11	
12	
13	
14	
15	
16	
17	
18	
19	
20	
21	
22	
23	
24	
25	
26	
27	
28	
29	
30	
31	
32	 
33	!
34	"
35	#
36	$
37	%
38	&
39	'
40	(
41	)
42	*
43	+
44	,
45	-
46	.
47	/
48	0
49	1
50	2
51	3
52	4
53	5
54	6
55	7
56	8
57	9
58	:
59	;
60	<
61	=
62	>
63	?
64	@
65	A
66	B
67	C
68	D
69	E
70	F
71	G
72	H
73	I
74	J
75	K
76	L
77	M
78	N
79	O
80	P
81	Q
82	R
83	S
84	T
85	U
86	V
87	W
88	X
89	Y
90	Z
91	[
92	\
93	]
94	^
95	_
96	`
97	a
98	b
99	c
100	d
101	e
102	f
103	g
104	h
105	i
106	j
107	k
108	l
109	m
110	n
111	o
112	p
113	q
114	r
115	s
116	t
117	u
118	v
119	w
120	x
121	y
122	z
123	{
124	|
125	}
126	~