Java——NIO

1.缓冲区Buffer

 

import java.nio.IntBuffer;

//主类
//Function        : 	IntBuffer_demo
public class IntBuffer_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		IntBuffer buf = IntBuffer.allocate(10);			//开辟10个大小的缓冲区
		System.out.print("1.写入数据之前的position、limit和capacity");
		System.out.println("position="+buf.position()+"、limit="+buf.limit()+"、capacity="+buf.capacity());
		int temp[] = {3,5,7};					//定义整型数组
		buf.put(3);									//向缓冲区写入数据
		buf.put(temp);							//向缓冲区中写入一组数据
		System.out.print("2.写入数据之后的position、limit和capacity");
		System.out.println("position="+buf.position()+"、limit="+buf.limit()+"、capacity="+buf.capacity());
		buf.flip();						//重设缓冲区，改变指针
		System.out.print("3.准备输出数据时的position、limit和capacity");
		System.out.println("position="+buf.position()+"、limit="+buf.limit()+"、capacity="+buf.capacity());
		while(buf.hasRemaining()){
			int x = buf.get();
			System.out.print(x+"、");
		}
	}

}

 

 

创建子缓冲区

import java.nio.IntBuffer;

//主类
//Function        : 	IntBuffer_demo
public class IntBuffer_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		
		IntBuffer buf = IntBuffer.allocate(10);			//开辟10个大小的缓冲区
		IntBuffer sub = null;											//定义缓冲区对象
		for(int i=0;i<10;i++){
			buf.put(2*i+1);
		}
		buf.position(2);
		buf.limit(6);
		sub = buf.slice();				//开辟子缓冲区
		for(int i=0;i<sub.capacity();i++){
			int temp = sub.get(i);
			sub.put(temp-1);
		}
		buf.flip();			//重设缓冲区
		buf.limit(buf.capacity());	//设置limit
		System.out.println("主缓冲区中的内容：");
		while(buf.hasRemaining()){
			int x = buf.get();					//取出当前内容
			System.out.print(x+"、");
		}
	}

}

 

 

import java.nio.IntBuffer;

//主类
//Function        : 	IntBuffer_demo
public class IntBuffer_demo {

	public static void main(String[] args) {
		// TODO 自动生成的方法存根
		
		IntBuffer buf = IntBuffer.allocate(10);			//开辟10个大小的缓冲区
		IntBuffer read = null;											//定义缓冲区对象
		for(int i=0;i<10;i++){
			buf.put(2*i+1);
		}
		read = buf.asReadOnlyBuffer();			//创建只读缓冲区
		buf.flip();			//重设缓冲区
		System.out.println("主缓冲区中的内容：");
		while(buf.hasRemaining()){
			int x = buf.get();					//取出当前内容
			System.out.print(x+"、");
		}
		System.out.println();
		read.put(30);			//错误，不可写
	}

}

 

2.通道Channel

import java.io.File;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

//主类
//Function        : 	FileChannel_demo
public class FileChannel_demo {

	public static void main(String[] args) throws Exception{
		// TODO 自动生成的方法存根
		String info[] = {"123","456","789"};
		File f = new File("/home/common/software/coding/HelloWord/HelloWord/out.txt");//路径
		FileOutputStream output = null;
		output = new FileOutputStream(f);	
		FileChannel fout = null;							//声明输出的通道
		fout = output.getChannel();						//得到输出的文件通道
		ByteBuffer buf = ByteBuffer.allocate(1024);		//开辟缓冲
		for(int i=0;i<info.length;i++){
			buf.put(info[i].getBytes());
		}
		buf.flip();				//重设缓冲区，准备输出
		fout.write(buf);	//输出
		fout.close();
		output.close();
		
	}

}

 读写文件

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

//主类
//Function        : 	FileChannel_demo
public class FileChannel_demo {

	public static void main(String[] args) throws Exception{
		// TODO 自动生成的方法存根
		
		File f1 = new File("/home/common/software/coding/HelloWord/HelloWord/out.txt");//路径
		File f2 = new File("/home/common/software/coding/HelloWord/HelloWord/outnote.txt");//路径
		FileInputStream input = null;
		FileOutputStream output = null;
		input = new FileInputStream(f1);
		output = new FileOutputStream(f2);	
		FileChannel fin = null;							//声明输入的通道
		FileChannel fout = null;						//声明输出的通道
		fin = input.getChannel();						//得到输入的文件通道
		fout = output.getChannel();						//得到输出的文件通道
		ByteBuffer buf = ByteBuffer.allocate(1024);		//开辟缓冲
		int temp = 0;											//声明变量接收内容
		while((temp=fin.read(buf)) != -1){
			buf.flip();
			fout.write(buf);
			buf.clear();
		}
		fin.close();
		fout.close();
		input.close();
		output.close();
		
	}

}

 

 

3.Selector