【移动应用开发技术】在Java中怎么将 Base64编码与String字符串进行转换

【移动应用开发技术】在Java中怎么将Base64编码与String字符串进行转换

这篇文章给大家介绍在Java中怎么将Base64编码与String字符串进行转换，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。具体方法如下：package

com.duanlian.daimengmusic.utils;

public

final

class

Base64Util

{

private

static

final

int

BASELENGTH

=

128;

private

static

final

int

LOOKUPLENGTH

=

64;

private

static

final

int

TWENTYFOURBITGROUP

=

24;

private

static

final

int

EIGHTBIT

=

8;

private

static

final

int

SIXTEENBIT

=

16;

private

static

final

int

FOURBYTE

=

4;

private

static

final

int

SIGN

=

-128;

private

static

char

PAD

=

'=';

private

static

byte[]

base64Alphabet

=

new

byte[BASELENGTH];

private

static

char[]

lookUpBase64Alphabet

=

new

char[LOOKUPLENGTH];

static

{

for

(int

i

=

0;

i

<

BASELENGTH;

++i)

{

base64Alphabet[i]

=

-1;

}

for

(int

i

=

'Z';

i

>=

'A';

i--)

{

base64Alphabet[i]

=

(byte)

(i

-

'A');

}

for

(int

i

=

'z';

i

>=

'a';

i--)

{

base64Alphabet[i]

=

(byte)

(i

-

'a'

+

26);

}

for

(int

i

=

'9';

i

>=

'0';

i--)

{

base64Alphabet[i]

=

(byte)

(i

-

'0'

+

52);

}

base64Alphabet['+']

=

62;

base64Alphabet['/']

=

63;

for

(int

i

=

0;

i

<=

25;

i++)

{

lookUpBase64Alphabet[i]

=

(char)

('A'

+

i);

}

for

(int

i

=

26,

j

=

0;

i

<=

51;

i++,

j++)

{

lookUpBase64Alphabet[i]

=

(char)

('a'

+

j);

}

for

(int

i

=

52,

j

=

0;

i

<=

61;

i++,

j++)

{

lookUpBase64Alphabet[i]

=

(char)

('0'

+

j);

}

lookUpBase64Alphabet[62]

=

(char)

'+';

lookUpBase64Alphabet[63]

=

(char)

'/';

}

private

static

boolean

isWhiteSpace(char

octect)

{

return

(octect

==

0x20

||

octect

==

0xd

||

octect

==

0xa

||

octect

==

0x9);

}

private

static

boolean

isPad(char

octect)

{

return

(octect

==

PAD);

}

private

static

boolean

isData(char

octect)

{

return

(octect

<

BASELENGTH

&&

base64Alphabet[octect]

!=

-1);

}

/**

把64位byte数组转换成String

*/

public

static

String

encode(byte[]

binaryData)

{

if

(binaryData

==

null)

{

return

null;

}

int

lengthDataBits

=

binaryData.length

*

EIGHTBIT;

if

(lengthDataBits

==

0)

{

return

"";

}

int

fewerThan24bits

=

lengthDataBits

%

TWENTYFOURBITGROUP;

int

numberTriplets

=

lengthDataBits

/

TWENTYFOURBITGROUP;

int

numberQuartet

=

fewerThan24bits

!=

0

?

numberTriplets

+

1

:

numberTriplets;

char

encodedData[]

=

null;

encodedData

=

new

char[numberQuartet

*

4];

byte

k

=

0,

l

=

0,

b1

=

0,

b2

=

0,

b3

=

0;

int

encodedIndex

=

0;

int

dataIndex

=

0;

for

(int

i

=

0;

i

<

numberTriplets;

i++)

{

b1

=

binaryData[dataIndex++];

b2

=

binaryData[dataIndex++];

b3

=

binaryData[dataIndex++];

l

=

(byte)

(b2

&

0x0f);

k

=

(byte)

(b1

&

0x03);

byte

val1

=

((b1

&

SIGN)

==

0)

?

(byte)

(b1

>>

2)

:

(byte)

((b1)

>>

2

^

0xc0);

byte

val2

=

((b2

&

SIGN)

==

0)

?

(byte)

(b2

>>

4)

:

(byte)

((b2)

>>

4

^

0xf0);

byte

val3

=

((b3

&

SIGN)

==

0)

?

(byte)

(b3

>>

6)

:

(byte)

((b3)

>>

6

^

0xfc);

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[val1];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[val2

|

(k

<<

4)];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[(l

<<

2)

|

val3];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[b3

&

0x3f];

}

//

form

integral

number

of

6-bit

groups

if

(fewerThan24bits

==

EIGHTBIT)

{

b1

=

binaryData[dataIndex];

k

=

(byte)

(b1

&

0x03);

byte

val1

=

((b1

&

SIGN)

==

0)

?

(byte)

(b1

>>

2)

:

(byte)

((b1)

>>

2

^

0xc0);

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[val1];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[k

<<

4];

encodedData[encodedIndex++]

=

PAD;

encodedData[encodedIndex++]

=

PAD;

}

else

if

(fewerThan24bits

==

SIXTEENBIT)

{

b1

=

binaryData[dataIndex];

b2

=

binaryData[dataIndex

+

1];

l

=

(byte)

(b2

&

0x0f);

k

=

(byte)

(b1

&

0x03);

byte

val1

=

((b1

&

SIGN)

==

0)

?

(byte)

(b1

>>

2)

:

(byte)

((b1)

>>

2

^

0xc0);

byte

val2

=

((b2

&

SIGN)

==

0)

?

(byte)

(b2

>>

4)

:

(byte)

((b2)

>>

4

^

0xf0);

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[val1];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[val2

|

(k

<<

4)];

encodedData[encodedIndex++]

=

lookUpBase64Alphabet[l

<<

2];

encodedData[encodedIndex++]

=

PAD;

}

return

new

String(encodedData);

}

/**

*

把Base64位编码转换成byte数组

*/

public

static

byte[]

decode(String

encoded)

{

if

(encoded

==

null)

{

return

null;

}

char[]

base64Data

=

encoded.toCharArray();

//

remove

white

spaces

int

len

=

removeWhiteSpace(base64Data);

if

(len

%

FOURBYTE

!=

0)

{

return

null;//

should

be

divisible

by

four

}

int

numberQuadruple

=

(len

/

FOURBYTE);

if

(numberQuadruple

==

0)

{

return

new

byte[0];

}

byte

decodedData[]

=

null;

byte

b1

=

0,

b2

=

0,

b3

=

0,

b4

=

0;

char

d1

=

0,

d2

=

0,

d3

=

0,

d4

=

0;

int

i

=

0;

int

encodedIndex

=

0;

int

dataIndex

=

0;

decodedData

=

new

byte[(numberQuadruple)

*

3];

for

(;

i

<

numberQuadruple

-

1;

i++)

{

if

(!isData((d1

=

base64Data[dataIndex++]))

||

!isData((d2

=

base64Data[dataIndex++]))

||

!isData((d3

=

base64Data[dataIndex++]))

||

!isData((d4

=

base64Data[dataIndex++])))

{

return

null;

}//

if

found

"no

data"

just

return

null

b1

=

base64Alphabet[d1];

b2

=

base64Alphabet[d2];

b3

=

base64Alphabet[d3];

b4

=

base64Alphabet[d4];

decodedData[encodedIndex++]

=

(byte)

(b1

<<

2

|

b2

>>

4);

decodedData[encodedIndex++]

=

(byte)

(((b2

&

0xf)

<<

4)

|

((b3

>>

2)

&

0xf));

decodedData[encodedIndex++]

=

(byte)

(b3

<<

6

|

b4);

}

if

(!isData((d1

=

base64Data[dataIndex++]))

||

!isData((d2

=

base64Data[dataIndex++])))

{

return

null;//

if

found

"no

data"

just

return

null

}

b1

=

base64Alphabet[d1];

b2

=

base64Alphabet[d2];

d3

=

base64Data[dataIndex++];

d4

=

base64Data[dataIndex++];

if

(!isData((d3))

||

!isData((d4)))

{//

Check

if

they

are

PAD

characters

if

(isPad(d3)

&&

isPad(d4))

{

if

((b2

&

0xf)

!=

0)//

last

4

bits

should

be

zero

{

return

null;

}

byte[]

tmp

=

new

byte[i

*

3

+

1];

System.arraycopy(decodedData,

0,

tmp,

0,

i

*

3);

tmp[encodedIndex]

=

(byte)

(b1

<<

2

|

b2

>>

4);

return

tmp;

}

else

if

(!isPad(d3)

&&

isPad(d4))

{

b3

=

base64Alphabet[d3];

if

((b3

&

0x3)

!=

0)//

last

2

bits

should

be

zero

{

return

null;

}

byte[]

tmp

=

new

byte[i

*

3

+

2];

System.arraycopy(decodedData,

0,

tmp,

0,

i

*

3);

tmp[encodedIndex++]

=

(byte)

(b1

<<

2

|

b2

>>

4);

tmp[encodedIndex]

=

(byte)

(((b2

&

0xf)

<<

4)

|

((b3

>>

2)

&

0xf));

return

tmp;

}

else

{

return

null;

}

}

else

{

//

No

PAD

e.g

3cQl

b3

=

base64Alphabet[d3];

b4

=

base64Alphabet[d4];

decodedData[encodedIndex++]

=

(byte)

(b1

<<

2

|

b2

>>

4);

decodedData[encodedIndex++]

=

(byte)

(((b2

&

0xf)

<<

4)

|

((b3

>>

2)

&

0xf));

decodedData[encodedIndex++]

=

(byte)

(b3

<<

6

|

b4);

}

return

decodedData;

}

/**

*

remove

WhiteSpace

from

MIME

containing

encoded

Base64Util

data.

*

*

@param

data

*

the

byte

array

of

base64

data

(with

WS)

*

@return

the

new

length

*/

private

static

int

removeWhiteSpace(char[]

data)

{

if

(data

==

null)

{

return

0;

}

//

count

characters

that's

not

whitespace

int

newSize

=

0;

int

len

=

data.length;

for

(int

i

=

0;

i

<

len;

i++)

{

if

(!isWhiteSpace(data[i]))

{

data[newSize++]

=

data[i];

}

}

return

newSize;

}

}然后是我经过2次封装的类,注释很清楚,拿过去直接用就行package

com.duanlian.daimengmusic.utils;

import

android.graphics.Bitmap;

import

android.graphics.BitmapFactory;

import

android.util.Base64;

import

java.io.ByteArrayOutputStream;

import

java.io.IOException;

/**

*

转换编码

*/

public

class

Base64Object

{

/**

*

把base64的String码转换成正常显示的字符串

*/

public

static

String

base64ToString(String

base64)

{

byte[]

decode

=

Base64Util.decode(base64);

String

s

=

new

String(decode);

return

s;

}

/**

*

把String的转换成base64码

*/

public

static

String

stringToBase64(String

ss)

{

byte[]

bytes

=

ss.getBytes();

String

encode

=

Base64Util.encode(bytes);

return

encode;

}

/**

*

bitmap转为base64

*

@param

bitmap

*

@return

*/

public

static

String

bitmapToBase641(Bitmap

bitmap)

{

String

result

=

null;

ByteArrayOutput