java字符转码的三种方法总结及实例

//用于解码的构造器: 
String(byte[] bytes, int offset, int length, String charsetName)  
String(byte[] bytes, String charsetName)  
 
用于编码的方法: 
byte[] getBytes(String charsetName) //使用指定字符集进行编码 
 byte[] getBytes() //使用系统默认字符集进行编码 

public void convertionString() throws UnsupportedEncodingException{ 
    String s = "清山"; 
    byte[] b = s.getBytes("gbk");//编码 
    String sa = new String(b, "gbk");//解码:用什么字符集编码就用什么字符集解码 
    System.out.println(sa); 
     
    b = sa.getBytes("utf-8");//编码 
    sa = new String(b, "utf-8");//解码 
    System.err.println(sa); 
  } 

package com.qingshan.io; 
 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.io.OutputStream; 
import java.io.OutputStreamWriter; 
import java.io.UnsupportedEncodingException; 
 
/** 
 * 
 
 * 使用java.io桥转换:对文件进行转码 
 * 
 
 * 
 
 * 2012 Qingshan Group 版权所有 
 * 
 
 * @author thetopofqingshan 
 * @version 1.0.0 
 * @since  JDK 1.5 
 * @date  2012-4-28 
 */ 
public class CharsetConvertion { 
  private FileInputStream fis;// 文件输入流:读取文件中内容 
  private InputStream is; 
  private InputStreamReader isr; 
  private OutputStream os; 
  private OutputStreamWriter osw;//写入 
  private char[] ch = new char[1024]; 
  public void convertionFile() throws IOException{ 
    is = new FileInputStream("C:/项目进度跟踪.txt");//文件读取 
    isr = new InputStreamReader(is, "gbk");//解码 
    os = new FileOutputStream("C:/项目进度跟踪_utf-8.txt");//文件输出 
    osw = new OutputStreamWriter(os, "utf-8");//开始编码 
    char[] c = new char[1024];//缓冲 
    int length = 0; 
    while(true){ 
      length = isr.read(c); 
      if(length == -1){ 
        break; 
      } 
      System.out.println(new String(c, 0, length)); 
      osw.write(c, 0, length); 
      osw.flush(); 
    } 
     
  } 
   
  public void convertionString() throws UnsupportedEncodingException{ 
    String s = "清山集团"; 
    byte[] b = s.getBytes("gbk");//编码 
    String sa = new String(b, "gbk");//解码:用什么字符集编码就用什么字符集解码 
    System.out.println(sa); 
     
    b = sa.getBytes("utf-8");//编码 
    sa = new String(b, "utf-8");//解码 
    System.err.println(sa); 
  } 
   
   
 
  /** 
   * 
 
   * 关闭所有流 
   * 
 
   * 
   */ 
  public void close(){ 
    if(isr != null){ 
      try { 
        isr.close(); 
      } catch (IOException e) { 
        e.printStackTrace(); 
      } 
    } 
    if(is != null){ 
      try { 
        is.close(); 
      } catch (IOException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
    } 
     
    if(osw != null){ 
      try { 
        osw.close(); 
      } catch (IOException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
    } 
     
    if(os != null){ 
      try { 
        os.close(); 
      } catch (IOException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
    } 
  } 
   
  /** 
   * 
 
   * 用io读取文件内容 
   * 
 
   * 
   * @throws IOException 
   *       读取过程中发生错误 
   * 
   */ 
   
  /** 
   * 
 
   * 
   * 
 
   * @param path 
   * @param charset 
   * @throws IOException 
   * 
   */ 
  public void read(String path, String charset) throws IOException { 
    fis = new FileInputStream(path); 
    isr = new InputStreamReader(fis, charset); 
    while (fis.available() > 0) { 
      int length = isr.read(ch);  
      System.out.println(new String(ch)); 
    } 
  } 
 
   
  public static void main(String[] args) { 
    try { 
      CharsetConvertion cc = new CharsetConvertion(); 
      cc.convertionFile(); 
      cc.convertionString(); 
      cc.close(); 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  } 
} 

package com.qingshan.nio; 
 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.nio.ByteBuffer; 
import java.nio.CharBuffer; 
import java.nio.channels.FileChannel; 
import java.nio.charset.Charset; 
import java.nio.charset.CharsetDecoder; 
import java.nio.charset.CharsetEncoder; 
 
/** 
 * 
 
 * 使用nio中的Charset转换字符:整个流程是文件读取-->byte-->解码(正确)-->编码--->byte-->写入文件 
 * 
 
 * 
 
 *  
 * 2012 Qingshan Group 版权所有 
 * 
 
 *  
 * 
 * @author thetopofqingshan 
 * @version 1.0.0 
 * @since JDK 1.5 
 * @date 2012-4-27 
 */ 
public class CharsetConvertion { 
  private FileInputStream fis;// 文件输入流:读取文件中内容 
  private FileChannel in;// 文件通道:双向,流从中而过 
  private FileChannel out;// 文件通道:双向,流从中而过 
  private FileOutputStream fos;// 文件输出流:向文件中写入内容 
  private ByteBuffer b = ByteBuffer.allocate(1024 * 3);// 设置缓存区的大小 
  private Charset inSet;// 解码字符集 
  private Charset outSet;// 编码字符集 
  private CharsetDecoder de;// 解码器 
  private CharsetEncoder en;// 编码器 
  private CharBuffer convertion;// 中间的字符数据 
  private ByteBuffer temp = ByteBuffer.allocate(1024 * 3);// 设置缓存区的大小:临时 
  private byte[] by = new byte[1024]; 
  private InputStreamReader isr; 
  private char[] ch = new char[1024]; 
 
  /** 
   * 
 
   * 
   * 
 
   * 
   * @param src 
   * @param dest 
   * @throws IOException 
   * 
   */ 
  public void convertionFile_nio(String src, String dest) throws IOException { 
    fis = new FileInputStream(src); 
    in = fis.getChannel(); 
    fos = new FileOutputStream(dest); 
    out = fos.getChannel(); 
    inSet = Charset.forName("gbk"); 
    outSet = Charset.forName("utf-8"); 
    de = inSet.newDecoder(); 
    en = outSet.newEncoder(); 
    while (fis.available() > 0) { 
      b.clear();// 清除标记 
      in.read(b); // 将文件内容读入到缓冲区内:将标记位置从0-b.capacity(), 
            // 读取完毕标记在0-b.capacity()之间 
      b.flip();// 调节标记,下次读取从该位置读起 
      convertion = de.decode(b);// 开始编码 
 
      temp.clear();// 清除标记 
      temp = en.encode(convertion); 
      b.flip(); // 将标记移到缓冲区的开始,并保存其中所有的数据:将标记移到开始0 
      out.write(temp); // 将缓冲区内的内容写入文件中:从标记处开始取出数据 
    } 
  } 
 
  /** 
   * 
 
   * 测试转码是否成功, 指定字符集读取文件 
   * 
 
   * 
   * @param src 
   *      被复制文件全路径 
   * @param charset 解码字符集 
   * 
   * @throws IOException 读取过程中的发生的异常 
   * 
   */ 
  public void read(String path, String charset) throws IOException { 
    fis = new FileInputStream(path); 
    isr = new InputStreamReader(fis, charset); 
    while (fis.available() > 0) { 
      int length = isr.read(ch); 
      System.out.println(new String(ch)); 
    } 
  } 
 
  /** 
   * 
 
   * 关闭所有流或通道 
   * 
 
   * 
   */ 
  public void close() { 
    try { 
      if (in != null) { 
        in.close(); 
      } 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
 
    try { 
      if (out != null) { 
        out.close(); 
      } 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
 
    try { 
      if (fis != null) { 
        fis.close(); 
      } 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
 
    try { 
      if (fos != null) { 
        fos.close(); 
      } 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } 
  } 
 
  public static void main(String[] args) { 
    CharsetConvertion n = new CharsetConvertion(); 
    try { 
       n.convertionFile_nio("C:/项目进度跟踪.txt", "C:/nio_write.txt"); 
//     n.read("C:/nio_write.txt", "utf-8");// 正确 
      // n.read("C:/nio_write.txt", "gbk");//乱码 
    } catch (IOException e) { 
      e.printStackTrace(); 
    } finally { 
      n.close(); 
    } 
  } 
 
}