java字符转码的三种方法总结及实例

java字符转码:三种方法

转码成功的前提:解码后无乱码

转码流程:文件(gbk)-->解码-->编码--->文件(utf-8) 

注:如有问题请留言 

下面具体的实例

 方法一:Java.lang.String

//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);
}

方法二:java.io.InputStreamReader/OutputStreamWriter:桥转换 

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;
/**
* <pre>
* 使用java.io桥转换:对文件进行转码
* </pre>
* <hr Color="green" ></hr>
* 2012 Qingshan Group 版权所有
* <hr Color="green" ></hr>
* @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);
}
/**
* <pre>
* 关闭所有流
* </pre>
*
*/
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();
}
}
}
/**
* <pre>
* 用io读取文件内容
* </pre>
*
* @throws IOException
*       读取过程中发生错误
*
*/
/**
* <pre>
*
* </pre>
* @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();
}
}
}

方法三:java.nio.Charset

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;
/**
* <pre>
* 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
* </pre>
* <hr Color="green" >
* </hr>
* 2012 Qingshan Group 版权所有
* <hr Color="green" >
* </hr>
*
* @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];
/**
* <pre>
*
* </pre>
*
* @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
}
}
/**
* <pre>
* 测试转码是否成功, 指定字符集读取文件
* </pre>
*
* @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));
}
}
/**
* <pre>
* 关闭所有流或通道
* </pre>
*
*/
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();
}
}
}

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