unicode.java

编码解码的实验

import java.io.BufferedReader; 
import java.io.File; 
import java.io.FileReader; 
import java.io.FileWriter; 

/*
 * 目的： 
 *     测试不同字符编码解码方式对多字节编码（中文）处理
 *     的影响 输入： 
 *     可以从命令行输入测试字符串 输出： 
 *     测试1 按照不同解码方式处理字符串，
 *     并按不同编码方式写入文件 
 *     测试2 按照不同解码方式从文件中将字符串读出 
 */   

class HelloUnicode {  
    public static void main(String[] args) { 
        String hello = "Hello world 世界你好"; 

        //read from command line input 
        if (args.length > 0) { 
            hello = args[0]; 
        } 

        try { 
            /* 
             * 试验1: 从测试字符串按系统缺省编码方式解码，并写入文件 
             */ 
            System.out.println(">>>>testing1: write hello world to files<<<<"); 
            System.out.println("[test 1-1]: with system default encoding=" 
                + System.getProperty("file.encoding") + "\nstring=" + hello 
                + "\tlength=" + hello.length()); 
            printCharArray(hello); 
            writeFile("hello.orig.html", hello); 

            //把字符串按GB2312解码 
            hello = new String(hello.getBytes(), "GB2312"); 
            System.out.println( 
                "[test 1-2]: getBytes with platform default encoding and decoding as gb2312:\nstring=" 
                + hello + "\tlength=" + hello.length()); 
            writeFile("hello.gb2312.html", hello); 
            printCharArray(hello); 

            //把字符串按UTF8解码成字节流，并打印相应的字节 
            hello = new String(hello.getBytes("UTF8")); 
            System.out.println("[test 1-3]: convert string to UTF8\nstring=" 
                + hello + "\tlength=" + hello.length()); 
            writeFile("hello.utf8.html", hello); 
            printCharArray(hello); 

            /* 
             * 试验2: 从试验1的输出文件中读取，并按照不同方式解码 
             */ 
            System.out.println( 
                ">>>>testing2: reading and decoding from files<<<<"); 

            //first file: encoding with system default 
            hello = readFile("hello.orig.html"); 
            System.out.println( 
                "[test 2-1]: read hello.orig.html: decoding with system default encoding\nstring=" 
                + hello + "\tlength=" + hello.length()); 
            printCharArray(hello); 

            //second file: decoding from GBK 
            hello = readFile("hello.gb2312.html"); 
          //  hello = new String(hello.getBytes(), "GB2312"); 
            System.out.println( 
                "[test 2-2]: read hello.gb2312.html: decoding as GB2312\nstring=" 
                + hello + "\tlength=" + hello.length()); 
            printCharArray(hello); 

            //third file: decoding from UTF8 
            hello = readFile("hello.utf8.html"); 
            hello = new String(hello.getBytes(), "UTF8"); 
            System.out.println( 
                "[test 2-3]: read hello.utf8.html: decoding as UTF8\nstring=" 
                + hello + "\tlength=" + hello.length()); 
            printCharArray(hello); 
        } catch (Exception e) { 
            System.out.println(e.toString()); 
        } 
    } 

    /*
     * print char array 
     * @param inStr input string 
     */ 
    public static void printCharArray(String inStr) { 
        char[] myBuffer = inStr.toCharArray(); 

        //list each Charactor in byte value, short value, and UnicodeBlock Mapping 
        for (int i = 0; i < inStr.length(); i++) { 
            byte b = (byte) myBuffer[i]; 
            short s = (short) myBuffer[i]; 
            String hexB = Integer.toHexString(b).toUpperCase(); 
            String hexS = Integer.toHexString(s).toUpperCase(); 
            StringBuffer sb = new StringBuffer(); 

            //print char 
            sb.append("char["); 
            sb.append(i); 
            sb.append("]='"); 
            sb.append(myBuffer[i]); 
            sb.append("'\t"); 

            //byte value 
            sb.append("byte="); 
            sb.append(b); 
            sb.append(" \\u"); 
            sb.append(hexB); 
            sb.append('\t'); 

            //short value 
            sb.append("short="); 
            sb.append(s); 
            sb.append(" \\u"); 
            sb.append(hexS); 
            sb.append('\t'); 

            //Unicode Block 
            sb.append(Character.UnicodeBlock.of(myBuffer[i])); 

            System.out.println(sb.toString()); 
        } 

        System.out.println(); 
    } 

    /*
     * write content to output file 
     * @param fileName output file name 
     * @param content  file content to write 
     */ 
    private static void writeFile(String fileName, String content) { 
        try { 
            File tmpFile = new File(fileName); 

            if (tmpFile.exists()) { 
                tmpFile.delete(); 
            } 

            FileWriter fw = new FileWriter(fileName, true); 
            fw.write(content); 
            fw.close(); 
        } catch (Exception e) { 
            System.out.println(e.toString()); 
        } 
    } 

    /* 
     * read content from input file 
     * @param fileName input file name 
     * @return String file content 
     */ 
    private static String readFile(String fileName) { 
        try { 
            BufferedReader fr = new BufferedReader(new FileReader(fileName)); 
            StringBuffer out = new StringBuffer(); 
            String thisLine = new String(); 

            while (thisLine != null) { 
                thisLine = fr.readLine(); 

                if (thisLine != null) { 
                    out.append(thisLine); 
                } 
            } 

            fr.close(); 

            return out.toString(); 
        } catch (Exception e) { 
            System.out.print(e.toString()); 
            return null; 
        } 
    } 
}