JAVA字节数据与JAVA类型的转换

一、JAVA进制类型转换

十进制转成十六进制：

Integer.toHexString(int i)

十进制转成八进制

Integer.toOctalString(int i)

十进制转成二进制

Integer.toBinaryString(int i)

十六进制转成十进制

Integer.valueOf("FFFF",16).toString()

八进制转成十进制

Integer.valueOf("876",8).toString()

二进制转十进制

Integer.valueOf("0101",2).toString()

有什么方法可以直接将2,8,16进制直接转换为10进制的吗?

java.lang.Integer类

parseInt(String s, int radix)

使用第二个参数指定的基数，将字符串参数解析为有符号的整数。

examples from jdk:

parseInt("0", 10) returns 0

parseInt("473", 10) returns 473

parseInt("-0", 10) returns 0

parseInt("-FF", 16) returns -255

parseInt("1100110", 2) returns 102

parseInt("2147483647", 10) returns 2147483647

parseInt("-2147483648", 10) returns -2147483648

parseInt("2147483648", 10) throws a NumberFormatException

parseInt("99", 8) throws a NumberFormatException

parseInt("Kona", 10) throws a NumberFormatException

parseInt("Kona", 27) returns 411787

进制转换如何写（二，八，十六）不用算法

Integer.toBinaryString

Integer.toOctalString

Integer.toHexString

二、字节数组与JAVA类型转换

//long类型转成byte数组

public static byte[] longToByte(long number) {

long temp = number;

byte[] b = new byte[8];

for (int i = 0; i < b.length; i++) {

b[i] = new Long(temp & 0xff).byteValue();//

将最低位保存在最低位

temp = temp >> 8; // 向右移8位

}

return b;

}

//byte数组转成long

public static long byteToLong(byte[] b) {

long s = 0;

long s0 = b[0] & 0xff;// 最低位

long s1 = b[1] & 0xff;

long s2 = b[2] & 0xff;

long s3 = b[3] & 0xff;

long s4 = b[4] & 0xff;// 最低位

long s5 = b[5] & 0xff;

long s6 = b[6] & 0xff;

long s7 = b[7] & 0xff;

// s0不变

s1 <<= 8;

s2 <<= 16;

s3 <<= 24;

s4 <<= 8 * 4;

s5 <<= 8 * 5;

s6 <<= 8 * 6;

s7 <<= 8 * 7;

s = s0 | s1 | s2 | s3 | s4 | s5 | s6 | s7;

return s;

}

/**

* 注释：int到字节数组的转换！

*

* @param number

* @return

*/

public static byte[] intToByte(int number) {

int temp = number;

byte[] b = new byte[4];

for (int i = 0; i < b.length; i++) {

b[i] = new Integer(temp & 0xff).byteValue();//

将最低位保存在最低位

temp = temp >> 8; // 向右移8位

}

return b;

}

/**

* 注释：字节数组到int的转换！

*

* @param b

* @return

*/

public static int byteToInt(byte[] b) {

int s = 0;

int s0 = b[0] & 0xff;// 最低位

int s1 = b[1] & 0xff;

int s2 = b[2] & 0xff;

int s3 = b[3] & 0xff;

s3 <<= 24;

s2 <<= 16;

s1 <<= 8;

s = s0 | s1 | s2 | s3;

return s;

}

/**

* 注释：short到字节数组的转换！

*

* @param s

* @return

*/

public static byte[] shortToByte(short number) {

int temp = number;

byte[] b = new byte[2];

for (int i = 0; i < b.length; i++) {

b[i] = new Integer(temp & 0xff).byteValue();//

将最低位保存在最低位

temp = temp >> 8; // 向右移8位

}

return b;

}

/**

* 注释：字节数组到short的转换！

*

* @param b

* @return

*/

public static short byteToShort(byte[] b) {

short s = 0;

short s0 = (short) (b[0] & 0xff);// 最低位

short s1 = (short) (b[1] & 0xff);

s1 <<= 8;

s = (short) (s0 | s1);

return s;

}