学步园

方法一

public class Copy {

	public static void main(String[] args) throws IOException {
		//建立输入输出
		FileReader fr = new FileReader("test.txt");
		
		FileWriter fw = new FileWriter("copy.txt");
		
		//输入输出操作
		int ch = 0;
		while((ch=fr.read())!=-1){
			fw.write(ch);
		}
		
		//关闭流
		fr.close();
		fw.close();
		
	}

}

方法二

public class Copy2 {

	private static final int BUFFER_SIZE = 1024;

	public static void main(String[] args){
		
		FileReader fr = null;
		FileWriter fw = null;
		
		int len = 0;
		
		//创建临时容器
		char[] buf = new char[BUFFER_SIZE];
		
		try {
			fr = new FileReader("test.txt");
			fw = new FileWriter("copy2.txt");
			
			while(((len = fr.read(buf))!=-1)){
				fw.write(buf, 0, len);
			}
		} catch (Exception e) {
//			System.out.println("读写失败");
			throw new RuntimeException("读写失败");
		}finally{
			
			
			try {
				if(fr!=null)
					fr.close();
			} catch (IOException e1) {
				e1.printStackTrace();
			}
			try {
				if(fw!=null)
					fw.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		
	}

}

注意导入io必要的包