基于Java NIO 实现文件基础功能：写入、读取和拷贝功能（基础代码）

偏执的太偏执、 2023-10-17 22:09 29阅读 0赞

package com.springcloud.nio;
    
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.nio.ByteBuffer;
    import java.nio.CharBuffer;
    import java.nio.channels.FileChannel;
    import java.nio.charset.Charset;
    import java.nio.charset.CharsetDecoder;
    
    public class NIOFileUtil {
    	
    	private String file;
    	
    	public String getFile() {
    		return file;
    	}
    
    	public void setFile(String file) {
    		this.file = file;
    	}
    
    	public NIOFileUtil(String file) throws IOException {
    		super();
    		this.file = file;
    	}
    	
    	public void read(int allocate) throws IOException{
    		//RandomAccessFile access = new RandomAccessFile(this.file, "r");
    		FileInputStream inputStream = new FileInputStream(this.file);
    		FileChannel channel = inputStream.getChannel();
    		ByteBuffer byteBuffer = ByteBuffer.allocate(allocate);
    		// 解决汉字乱码问题
    		CharBuffer charBuffer = CharBuffer.allocate(allocate);
    		Charset charset = Charset.forName("GBK");
            CharsetDecoder decoder = charset.newDecoder();
            
    		int length = channel.read(byteBuffer);
    		while(length != -1){
    			byteBuffer.flip();			
                decoder.decode(byteBuffer, charBuffer, true);
                charBuffer.flip();
                System.out.println(charBuffer.toString());
                // 清空缓存
                byteBuffer.clear();
                charBuffer.clear();
                // 再次读取文本内容
                length = channel.read(byteBuffer);
                
    		}
    		channel.close();
    		if(inputStream != null){
    			inputStream.close();
    		}		
    	}
    	
    	public void write(String context, int allocate, String chartName) throws IOException{
    		// FileOutputStream outputStream = new FileOutputStream(this.file); //文件内容覆盖模式 --不推荐
    		FileOutputStream outputStream = new FileOutputStream(this.file, true); //文件内容追加模式--推荐
    		FileChannel channel = outputStream.getChannel();
    		ByteBuffer byteBuffer = ByteBuffer.allocate(allocate);
    		byteBuffer.put(context.getBytes(chartName));
    		byteBuffer.flip();//读取模式转换为写入模式
    		channel.write(byteBuffer);
    		channel.close();
    		if(outputStream != null){
    			outputStream.close();
    		}
    	}
    	
    	public void cpoy(String source, String target, int allocate) throws IOException{
    		ByteBuffer byteBuffer = ByteBuffer.allocate(allocate);
    		
    		FileInputStream inputStream = new FileInputStream(source);
    		FileChannel inChannel = inputStream.getChannel();
    		
    		FileOutputStream outputStream = new FileOutputStream(target);
    		FileChannel outChannel = outputStream.getChannel();
    		
    		int length = inChannel.read(byteBuffer);
    		while(length != -1){
    			byteBuffer.flip();//读取模式转换写入模式
    			outChannel.write(byteBuffer);
    			byteBuffer.clear(); //清空缓存，等待下次写入
    			// 再次读取文本内容
                length = inChannel.read(byteBuffer);
    		}
    		outputStream.close();
    		outChannel.close();
    		inputStream.close();
    		inChannel.close();
    	}
    
    	public static void main(String[] args) throws IOException {
    		// TODO Auto-generated method stub
    		NIOFileUtil util = new NIOFileUtil("D://内容.txt");
    		//util.read(20);
    //		String context ="我爱我的祖国123456";
    //		util.write(context, 40, "GBK");
    		
    		util.cpoy("D://内容.txt", "D://赋值内容.txt", 1024);
    	}
    
    }