java中各种数据类型占用字节数

1字节(Byte)=8bit

java的基本类型

类型 所占字节
byte 1
short 2
int 4
long 8
float 4
double 8
char 2

String中字母和汉字所占字符是不一样的,并且与编码有关

英文字母:A

字节数 编码
1 GB2312
1 GBK
1 GB18030
1 ISO-8859-1
1 UTF-8
4 UTF-16
2 UTF-16BE
2 UTF-16-LE

中文汉字:我

字节数 编码
1 GB2312
2 GBK
2 GB18030
1 ISO-8859-1
3 UTF-8
4 UTF-16
2 UTF-16BE
2 UTF-16-LE

附录:计算String字节数的代码

package com.dingrui.stringbytelength;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException; import org.dozer.loader.api.FieldDefinition; public class StringByteLength { /*
* GB2312 GBK GB18030 ISO-8859-1 UTF-8 UTF-16 UTF-16BE UTF-16LE
*/
public static void main(String[] args) throws IOException { String s1 = "a";
String s2 = "龘"; System.out.println(s1 + " GB2312 " + s1.getBytes("GB2312").length);
System.out.println(s1 + " GBK " + s1.getBytes("GBK").length);
System.out.println(s1 + " GB18030 " + s1.getBytes("GB18030").length);
System.out.println(s1 + " ISO-8859-1 " + s1.getBytes("ISO-8859-1").length);
System.out.println(s1 + " UTF-8 " + s1.getBytes("UTF-8").length);
System.out.println(s1 + " UTF-16 " + s1.getBytes("UTF-16").length);
System.out.println(s1 + " UTF-16BE " + s1.getBytes("UTF-16BE").length);
System.out.println(s1 + " UTF-16LE " + s1.getBytes("UTF-16LE").length);
System.out.println("---------------");
System.out.println(s2 + " GB2312 " + s2.getBytes("GB2312").length);
System.out.println(s2 + " GBK " + s2.getBytes("GBK").length);
System.out.println(s2 + " GB18030 " + s2.getBytes("GB18030").length);
System.out.println(s2 + " ISO-8859-1 " + s2.getBytes("ISO-8859-1").length);
System.out.println(s2 + " UTF-8 " + s2.getBytes("UTF-8").length);
System.out.println(s2 + " UTF-16 " + s2.getBytes("UTF-16").length);
System.out.println(s2 + " UTF-16BE " + s2.getBytes("UTF-16BE").length);
System.out.println(s2 + " UTF-16LE " + s2.getBytes("UTF-16LE").length); } /**
* 将转码后的文字写入文件,通过编辑器打开测试,确认写入的是相应编码
*
* @param bytes
* @throws IOException
*/
public void writeFile(byte[] bytes) throws IOException {
String path = StringByteLength.class.getResource("/").getPath();
System.out.println(path);
String file_path = path + "charsetFile"; File file = new File(file_path);
if (!file.exists()) {
file.createNewFile();
} FileOutputStream out = new FileOutputStream(file);
out.write(bytes);
out.close();
}
}

  

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