<BIO>以字节的方式（写入，读取）文本，以字符的方式（写入，读取）文本和<NIO>的写入，读取

[code=plain]package v2ch01.textFile;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.util.Scanner;

import org.junit.Test;

public class FileTest {

/**
* 以字符的方式写入文本
* @throws FileNotFoundException
* @throws UnsupportedEncodingException
*/
@Test
public  void writeWenBen() throws FileNotFoundException, UnsupportedEncodingException {

PrintWriter out = new PrintWriter(new File("e://test.txt"),"utf-8");
out.write("abcde");
//		out.flush();
out.close();

}

/**
* 以字符的方式读取文本
* @throws FileNotFoundException
*/
@Test
public void readWenBen() throws FileNotFoundException{

Scanner scanner = new Scanner(new FileInputStream(new File("e://test.txt")), "utf-8");
while(scanner.hasNext())
System.out.println(scanner.nextLine());

}

/**
* 以字节的方式写入文本
* @throws FileNotFoundException
*/
@Test
public void writeByte() throws FileNotFoundException{

OutputStream outputStream = new FileOutputStream(new File("e://test.txt"));
String str = "I LOVE YOU EVE ";
char[] ch = str.toCharArray();
//		char[] ch = {'a','b','c','d'};
for (char c : ch) {
try {
outputStream.write(c);
} catch (IOException e) {
e.printStackTrace();
}
}
try {
outputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* 以字节的方式读取文本
*/
@Test
public void readByte(){

try {
InputStream inputStream = new BufferedInputStream(new FileInputStream("e://test.txt"));
int i=0;
StringBuilder builder = new StringBuilder();
while((i=inputStream.read())!=-1){

builder.append((char)i);
}
System.out.println(builder.toString());
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
}

}
}

java NIO从一个文件写到另一个文件

/**
*通道之间的数据传输
* transferFrom()方法将数据源从通道传输到FileChannel中
* @throws IOException
*/
@Test
public void transferFrom() throws IOException{

RandomAccessFile fromFile = new RandomAccessFile("e://1.txt", "rw");
FileChannel fromChannel = fromFile.getChannel();

RandomAccessFile toFile = new RandomAccessFile("e://2.txt", "rw");
FileChannel toChannel = toFile.getChannel();

long position = 0;
long count = fromChannel.size();

toChannel.transferFrom(fromChannel, position, count);
}

/**
* transferTo()方法将数据从FileChannel传输到其他的channel中
* @throws IOException
*/
@Test
public void transferTo() throws IOException{

RandomAccessFile fromFile = new RandomAccessFile("e://1.txt", "rw");
FileChannel fromChannel = fromFile.getChannel();

RandomAccessFile toFile = new RandomAccessFile("e://2.txt", "rw");
FileChannel toChannel = toFile.getChannel();

long position=0;
long count = fromChannel.size();

fromChannel.transferTo(position, count, toChannel);
}

Java NIO读取文件（可能中文输出乱码）

/**
* FileChannel无法设置为非阻塞模式，总是运行在阻塞模式下
* @throws IOException
*/
@Test
public void testReadFromChannel() throws IOException{

Charset charset = Charset.forName("utf-8");

RandomAccessFile file = new RandomAccessFile(new File("e://2.txt"), "rw");
FileChannel channel = file.getChannel();

ByteBuffer buf = ByteBuffer.allocate(40000);
int byteRead = channel.read(buf);

StringBuilder sb = new StringBuilder();

while(byteRead!=-1){

buf.flip();
while(buf.hasRemaining()){
sb.append((char)buf.get());
}
buf.clear();
byteRead = channel.read(buf);
}

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

}

Java NIO写数据到文件

/**
* 向FileChannel中写数据
* @throws IOException
*/
@Test
public void testWriteToChannel() throws IOException{

@SuppressWarnings("resource")
RandomAccessFile file = new RandomAccessFile("e://2.txt", "rw");
FileChannel channel = file.getChannel();
String newData = "New String to write to 我是阿凡达 ..... "+System.currentTimeMillis();
ByteBuffer buf = ByteBuffer.allocate(1024);
buf.clear();

buf.put(newData.getBytes());
buf.flip();

while(buf.hasRemaining()){
channel.write(buf);
}

channel.close();
}