Java 基础 byte[]与各种数据类型互相转换的简单示例

java 基础 byte[]与各种数据类型互相转换的简单示例

这里对byte[]类型对long,int,double,float，short,cahr，object,string类型相互转换的实例，

在socket开发过程中，通常需要将一些具体的值（这些值可能是各种java类型）转化为byte[]类型，为此我总结了如下这个示例，贴出来，以便经常翻看：

public class testcase { 
   
  /** 
   * short到字节数组的转换. 
   */ 
  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; 
  } 
 
  /** 
   * 字节数组到short的转换. 
   */ 
  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; 
  } 
   
   
  /** 
   * int到字节数组的转换. 
   */ 
  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; 
  } 
 
  /** 
   * 字节数组到int的转换. 
   */ 
  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; 
  } 
   
   
  /** 
   * 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; 
  } 
 
  /** 
   * 字节数组到long的转换. 
   */ 
  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; 
  } 
   
  /** 
   * double到字节数组的转换. 
   */ 
  public static byte[] doubletobyte(double num) {  
    byte[] b = new byte[8];  
    long l = double.doubletolongbits(num);  
    for (int i = 0; i < 8; i++) {  
      b[i] = new long(l).bytevalue();  
      l = l >> 8;  
    } 
    return b; 
  } 
   
  /** 
   * 字节数组到double的转换. 
   */ 
  public static double getdouble(byte[] b) {  
    long m;  
    m = b[0];  
    m &= 0xff;  
    m |= ((long) b[1] << 8);  
    m &= 0xffff;  
    m |= ((long) b[2] << 16);  
    m &= 0xffffff;  
    m |= ((long) b[3] << 24);  
    m &= 0xffffffffl;  
    m |= ((long) b[4] << 32);  
    m &= 0xffffffffffl;  
    m |= ((long) b[5] << 40);  
    m &= 0xffffffffffffl;  
    m |= ((long) b[6] << 48);  
    m &= 0xffffffffffffffl;  
    m |= ((long) b[7] << 56);  
    return double.longbitstodouble(m);  
  } 
   
   
  /** 
   * float到字节数组的转换. 
   */ 
  public static void floattobyte(float x) { 
    //先用 float.floattointbits(f)转换成int 
  } 
   
  /** 
   * 字节数组到float的转换. 
   */ 
  public static float getfloat(byte[] b) {  
    // 4 bytes  
    int accum = 0;  
    for ( int shiftby = 0; shiftby < 4; shiftby++ ) {  
        accum |= (b[shiftby] & 0xff) << shiftby * 8;  
    }  
    return float.intbitstofloat(accum);  
  }  
 
   /** 
   * char到字节数组的转换. 
   */ 
   public static byte[] chartobyte(char c){ 
    byte[] b = new byte[2]; 
    b[0] = (byte) ((c & 0xff00) >> 8); 
    b[1] = (byte) (c & 0xff); 
    return b; 
   } 
    
   /** 
   * 字节数组到char的转换. 
   */ 
   public static char bytetochar(byte[] b){ 
    char c = (char) (((b[0] & 0xff) << 8) | (b[1] & 0xff)); 
    return c; 
   } 
   
  /** 
   * string到字节数组的转换. 
   */ 
  public static byte[] stringtobyte(string str) throws unsupportedencodingexception{ 
    return str.getbytes("gbk"); 
  } 
   
  /** 
   * 字节数组到string的转换. 
   */ 
  public static string bytestostring(byte[] str) { 
    string keyword = null; 
    try { 
      keyword = new string(str,"gbk"); 
    } catch (unsupportedencodingexception e) { 
      e.printstacktrace(); 
    } 
    return keyword; 
  } 
   
   
  /** 
   * object到字节数组的转换 
   */ 
  @test 
  public void testobject2bytearray() throws ioexception, 
      classnotfoundexception { 
    // object obj = ""; 
    integer[] obj = { 1, 3, 4 }; 
 
    // // object to bytearray 
    bytearrayoutputstream bo = new bytearrayoutputstream(); 
    objectoutputstream oo = new objectoutputstream(bo); 
    oo.writeobject(obj); 
    byte[] bytes = bo.tobytearray(); 
    bo.close(); 
    oo.close(); 
    system.out.println(arrays.tostring(bytes)); 
 
    integer[] intarr = (integer[]) testbytearray2object(bytes); 
    system.out.println(arrays.aslist(intarr)); 
 
 
    byte[] b2 = inttobyte(123); 
    system.out.println(arrays.tostring(b2)); 
 
    int a = bytetoint(b2); 
    system.out.println(a); 
 
  } 
 
  /** 
   * 字节数组到object的转换. 
   */ 
  private object testbytearray2object(byte[] bytes) throws ioexception, 
      classnotfoundexception { 
    // byte[] bytes = null; 
    object obj; 
    // bytearray to object 
    bytearrayinputstream bi = new bytearrayinputstream(bytes); 
    objectinputstream oi = new objectinputstream(bi); 
    obj = oi.readobject(); 
    bi.close(); 
    oi.close(); 
    system.out.println(obj); 
    return obj; 
  } 
 
} 

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