Java类型转换实例 分类： Java 2015-08-04 16:13 10人阅读 评论(0) 收藏
例：将字符串内容转为浮点数，再还原出原字符串内容
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.DoubleBuffer;
import java.nio.FloatBuffer;
public class test3 {
public static void main(String[] args) {
new test3();
}
/**
* 第一种方法
*/
/**
* 1,整数到字节数组的转换
*
* @param number
* @return
*/
public static byte[] intToByte(int number) {
int temp = number;
byte[] b = new byte[4];
for (int i = b.length - 1; i > -1; i--) {
b[i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位
temp = temp >> 8; // 向右移8位
}
return b;
}
/**
* 2,字节数组到整数的转换
*
* @param b
* @return
*/
public static int byteToInt(byte[] b) {
int s = 0;
for (int i = 0; i < 3; i++) {
if (b[i] >= 0)
s = s + b[i];
else
s = s + 256 + b[i];
s = s * 256;
}
if (b[3] >= 0) // 最后一个之所以不乘，是因为可能会溢出
s = s + b[3];
else
s = s + 256 + b[3];
return s;
}
/**
* 3,字符到字节转换
*
* @param ch
* @return
*/
public static byte[] charToByte(char ch) {
int temp = (int) ch;
byte[] b = new byte[2];
for (int i = b.length - 1; i > -1; i--) {
b[i] = new Integer(temp & 0xff).byteValue(); // 将最高位保存在最低位
temp = temp >> 8; // 向右移8位
}
return b;
}
/**
* 4,字节到字符转换
*
* @param b
* @return
*/
public static char byteToChar(byte[] b) {
int s = 0;
if (b[0] > 0)
s += b[0];
else
s += 256 + b[0];
s *= 256;
if (b[1] > 0)
s += b[1];
else
s += 256 + b[1];
char ch = (char) s;
return ch;
}
/**
* 5,双精度浮点到字节转换
*
* @param d
* @return
*/
public static byte[] doubleToByte(double d) {
byte[] b = new byte[8];
long l = Double.doubleToLongBits(d);
for (int i = 0; i < b.length; i++) {
b[i] = new Long(l).byteValue();
l = l >> 8;
}
return b;
}
/**
* 6,字节到双精度浮点转换
*
* @param b
* @return
*/
public static double byteToDouble(byte[] b) {
long l;
l = b[0];
l &= 0xff;
l |= ((long) b[1] << 8);
l &= 0xffff;
l |= ((long) b[2] << 16);
l &= 0xffffff;
l |= ((long) b[3] << 24);
l &= 0xffffffffl;
l |= ((long) b[4] << 32);
l &= 0xffffffffffl;
l |= ((long) b[5] << 40);
l &= 0xffffffffffffl;
l |= ((long) b[6] << 48);
l |= ((long) b[7] << 56);
return Double.longBitsToDouble(l);
}
/**
* 7，单精度浮点转换为字节
*
* @param f
* @return
*/
public static byte[] float2byte(float f) {
// 把float转换为byte[]
int fbit = Float.floatToIntBits(f);
byte[] b = new byte[4];
for (int i = 0; i < 4; i++) {
b[i] = (byte) (fbit >> (24 - i * 8));
}
// 翻转数组
int len = b.length;
// 建立一个与源数组元素类型相同的数组
byte[] dest = new byte[len];
// 为了防止修改源数组，将源数组拷贝一份副本
System.arraycopy(b, 0, dest, 0, len);
byte temp;
// 将顺位第i个与倒数第i个交换
for (int i = 0; i < len / 2; ++i) {
temp = dest[i];
dest[i] = dest[len - i - 1];
dest[len - i - 1] = temp;
}
return dest;
}
/**
* ,8，字节转换为单精度浮点
*
* @param b
* 字节（至少4个字节）
* @param index
* 开始位置
* @return
*/
public static float byte2float(byte[] b, int index) {
int l;
l = b[index + 0];
l &= 0xff;
l |= ((long) b[index + 1] << 8);
l &= 0xffff;
l |= ((long) b[index + 2] << 16);
l &= 0xffffff;
l |= ((long) b[index + 3] << 24);
return Float.intBitsToFloat(l);
}
/**
* 将Byte转换为String 或者将String转换为Byte
*
* @author Administrator
*
*/
/**
* 默认的字符集编码 UTF-8 一个汉字占三个字节
*/
private static String CHAR_ENCODE = "UTF-8";
/**
* 设置全局的字符编码
*
* @param charEncode
*/
public static void configCharEncode(String charEncode) {
CHAR_ENCODE = charEncode;
}
/**
* @param str
* 源字符串转换成字节数组的字符串
* @return
*/
public static byte[] StringToByte(String str) {
return StringToByte(str, CHAR_ENCODE);
}
/**
*
* @param srcObj
* 源字节数组转换成String的字节数组
* @return
*/
public static String ByteToString(byte[] srcObj) {
return ByteToString(srcObj, CHAR_ENCODE);
}
/**
* UTF-8 一个汉字占三个字节
*
* @param str
* 源字符串 转换成字节数组的字符串
* @return
*/
public static byte[] StringToByte(String str, String charEncode) {
byte[] destObj = null;
try {
if (null == str || str.trim().equals("")) {
destObj = new byte[0];
return destObj;
} else {
destObj = str.getBytes(charEncode);
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return destObj;
}
/**
* @param srcObj
* 源字节数组转换成String的字节数组
* @return
*/
public static String ByteToString(byte[] srcObj, String charEncode) {
String destObj = null;
try {
destObj = new String(srcObj, charEncode);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return destObj.replaceAll("\0", " ");
}
/**
* Convert byte[] to hex string
*
* @param src
* @return
*/
public static String bytesToHexString(byte[] src) {
StringBuilder stringBuilder = new StringBuilder("");
if (src == null || src.length <= 0) {
return null;
}
for (int i = 0; i < src.length; i++) {
int v = src[i] & 0xFF;
String hv = Integer.toHexString(v);
if (hv.length() < 2) {
stringBuilder.append(0);
}
stringBuilder.append(hv);
}
return stringBuilder.toString();
}
/**
* Convert hex string to byte[]
*
* @param hexString
* @return
*/
public static byte[] hexStringToBytes(String hexString) {
if (hexString == null || hexString.equals("")) {
return null;
}
hexString = hexString.toUpperCase();
int length = hexString.length() / 2;
char[] hexChars = hexString.toCharArray();
byte[] d = new byte[length];
for (int i = 0; i < length; i++) {
int pos = i * 2;
d[i] = (byte) (charToBytes(hexChars[pos]) << 4 | charToBytes(hexChars[pos + 1]));
}
return d;
}
/**
* Convert char to byte
*
* @param c
* @return
*/
private static byte charToBytes(char c) {
return (byte) "0123456789ABCDEF".indexOf(c);
}
/**
* 第二种方法
*/
/**
* 1，BYTE转INT
*
* @param b
* @return
*/
protected int byteArrayToInt(byte[] b) {
return (b[0] << 24) + ((b[1] & 0xFF) << 16) + ((b[2] & 0xFF) << 8)
+ (b[3] & 0xFF);
}
/**
* ,2，BYTE转SHORT
*
* @param b
* @return
*/
protected int byteArrayToShort(byte[] b) {
return (b[0] << 8) + (b[1] & 0xFF);
}
/**
* ,3，SHORT转BYTE数据
*
* @param s
* @return
*/
protected byte[] shortToByteArray(short s) {
byte[] shortBuf = new byte[2];
for (int i = 0; i < 2; i++) {
int offset = (shortBuf.length - 1 - i) * 8;
shortBuf[i] = (byte) ((s >>> offset) & 0xff);
}
return shortBuf;
}
/**
* ,4，INT数据转BYTE数据
*
* @param i
* @return
*/
protected byte[] intToByteArray(int i) {
byte[] result = new byte[4];
result[0] = (byte) ((i >> 24) & 0xFF);
result[1] = (byte) ((i >> 16) & 0xFF);
result[2] = (byte) ((i >> 8) & 0xFF);
result[3] = (byte) (i & 0xFF);
return result;
}
/**
* ,5，转换long型为byte数组
*
* @param bb
* @param x
* @param index
*/
public byte[] longToByteArray(long x, int index) {
byte[] bb = new byte[8];
bb[index + 7] = (byte) (x >> 56);
bb[index + 6] = (byte) (x >> 48);
bb[index + 5] = (byte) (x >> 40);
bb[index + 4] = (byte) (x >> 32);
bb[index + 3] = (byte) (x >> 24);
bb[index + 2] = (byte) (x >> 16);
bb[index + 1] = (byte) (x >> 8);
bb[index + 0] = (byte) (x >> 0);
return bb;
}
/**
* ,6，通过byte数组取到long
*
* @param bb
* @param index
* @return
*/
public long byteArrayToLong(byte[] bb, int index) {
return ((((long) bb[index + 7] & 0xff) << 56)
| (((long) bb[index + 6] & 0xff) << 48)
| (((long) bb[index + 5] & 0xff) << 40)
| (((long) bb[index + 4] & 0xff) << 32)
| (((long) bb[index + 3] & 0xff) << 24)
| (((long) bb[index + 2] & 0xff) << 16)
| (((long) bb[index + 1] & 0xff) << 8) | (((long) bb[index + 0] & 0xff) << 0));
}
/**
* ,7，float转换byte
*
* @param bb
* @param x
* @param index
*/
public static byte[] floatTobyteArray(float v) {
ByteBuffer bb = ByteBuffer.allocate(4);
byte[] ret = new byte[4];
FloatBuffer fb = bb.asFloatBuffer();
fb.put(v);
bb.get(ret);
return ret;
}
/**
* ,8，通过byte数组取得float
*
* @param bb
* @param index
* @return
*/
public static float byteArrayToFloat(byte[] v) {
ByteBuffer bb = ByteBuffer.wrap(v);
FloatBuffer fb = bb.asFloatBuffer();
return fb.get();
}
/**
* ,9，double转换byte
*
* @param bb
* @param x
* @param index
*/
public byte[] doubleToByteArray(double x) {
ByteBuffer bb = ByteBuffer.allocate(8);
byte[] ret = new byte[8];
DoubleBuffer fb = bb.asDoubleBuffer();
fb.put(x);
bb.get(ret);
return ret;
}
/**
* ,10，通过byte数组取得float
*
* @param bb
* @param index
* @return
*/
public double byteArrayToDouble(byte[] b) {
ByteBuffer bb = ByteBuffer.wrap(b);
DoubleBuffer fb = bb.asDoubleBuffer();
return fb.get();
}
public test3() {
//例：将字符串内容转为浮点数，再还原出原字符串内容
String Content = "Contiune";
System.out.println("例：将字符串内容转为浮点数，再还原出原字符串内容");
// 1，字符串转为浮点
// （1）先将字符串转为数组
System.out.println("1，字符串转为浮点:（1）先将字符串转为数组Content="
+ StringToByte(Content));
// （2）再将数组转化为浮点
System.out.println("1，字符串转为浮点:（1）再将数组转化为浮点Content="
+ byteToDouble(StringToByte(Content)));
// 2，浮点转成字符串
// （1）先将浮点转为字节数组
System.out.println("2，浮点转成字符串:（1）先将浮点转为字节数组Content="
+ doubleToByte(byteToDouble(StringToByte(Content))));
// （2）再将字节数组转为字符串
System.out
.println("2，浮点转成字符串:（2）再将字节数组转为字符串Content="
+ ByteToString(doubleToByte(byteToDouble(StringToByte(Content)))));
}
}
例：将字符串内容转为浮点数，再还原出原字符串内容
1，字符串转为浮点:（1）先将字符串转为数组Content=[B@659e0bfd
1，字符串转为浮点:（1）再将数组转化为浮点Content=3.949643824749462E180
2，浮点转成字符串:（1）先将浮点转为字节数组Content=[B@2a139a55
2，浮点转成字符串:（2）再将字节数组转为字符串Content=Contiune，即还原出原字符串内容。
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