Java基础知识复习（七）-- 中文编码问题

版权声明：无意呢。 https://blog.csdn.net/qq_41900081/article/details/85399192

一、练习-数字对应的中文

找出 E5 B1 8C 这3个十六进制对应UTF-8编码的汉字

参考代码1

		// 找出 E5 B1 8C 这3个十六进制对应UTF-8编码的汉字
		byte[] bs = new byte[3];
		bs[0] = (byte) 0xE5;
		bs[1] = (byte) 0xB1;
		bs[2] = (byte) 0x8C;

		String str = new String(bs, "UTF-8");
		System.out.println("E5B18C 对应的字符是：" + str);

参考代码2

		String s = "E5B18C";
		int total = s.length() / 2;
		byte[] buffer = new byte[total];
		for (int i = 0; i < total; i++) {

			int start = i * 2;
			//先将字符转换为16进制数字，再强制转换为字节
			buffer[i] = (byte) Integer.parseInt(s.substring(start, start + 2), 16);
		}

		String result = new String(buffer, "UTF-8");
		System.out.println("E5B18C 对应的字符是：" + result);

运作结果

二、练习-移除BOM

如果用记事本根据UTF-8编码保存汉字就会在最前面生成一段标示符，这个标示符用于表示该文件是使用UTF-8编码的，找出这段标示符对应的十六进制，并且开发一个方法，自动去除这段标示符

在移除BOM之前，我们首先要知道UTF-8的BOM对应的编码是多少，测试代码如下

package test;

import java.io.File;
import java.io.FileInputStream;

public class Test1 {
	public static void main(String[] args) {
		File f = new File("D:/Test/test1.txt");
		try(FileInputStream fis = new FileInputStream(f)) {
			byte[] bytes = new byte[(int) f.length()];
			fis.read(bytes);
			System.out.println("文件text1.txt中的内容："+new String(bytes,"UTF-8"));
			System.out.print("对应的16进制表示：");
			for(byte b : bytes) {
				int a = b & 0x0000ff;
				String hexString = Integer.toHexString(a).toUpperCase();
				System.out.print(hexString+" ");
			}
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}
}

测试结果

从测试结果以及上一个练习题可以知道，UTF-8的BOM对应的编码为：EF BB BF,且为前三个，到这里就可以开始解决我们的问题了

参考代码1

package review4;

import java.io.File;
import java.io.FileInputStream;
import java.util.Arrays;

public class RemoveBOM {
	public static void main(String[] args) {
		File f = new File("D:/Test/test1.txt");
		try(FileInputStream fis = new FileInputStream(f)) {
			byte[] read = new byte[(int) f.length()];		
			fis.read(read);
			System.out.print("文件中读出来的数据是:");
					
			System.out.println(new String(read,"UTF-8"));
			
			removeBom(f);
			
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		
	}
	
	public static void removeBom(File f) {
		try(FileInputStream fis = new FileInputStream(f)) {
			byte[] read = new byte[(int) f.length()];
			byte[] result = new byte[(int) f.length()-3];
			fis.read(read);
			System.out.print("除去BOM后的结果:");
			for(int i = 3; i < read.length; i++) {
				int a = read[i] & 0x000000ff;
				result[i-3] = (byte) a;
			}			
			System.out.println(new String(result,"UTF-8"));
			
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}
	
	
}

参考代码2

package review4;

import java.io.File;
import java.io.FileInputStream;
import java.util.Arrays;

public class RemoveBOM {
	public static void main(String[] args) {
		File f = new File("D:/Test/test1.txt");
		try(FileInputStream fis = new FileInputStream(f)) {
			byte[] read = new byte[(int) f.length()];		
			fis.read(read);
			System.out.print("文件中读出来的数据是:");				
			System.out.println(new String(read,"UTF-8"));		
			byte[] result = removeBom(read);		
			System.out.println("除去BOM后的结果:"+new String(result,"UTF-8"));
				
		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
		
	}
	
	public static byte[] removeBom(byte[] read) {
		return Arrays.copyOfRange(read, 3,read.length);
	}
}

运行结果