java_25 FileReader类和FileWriter类

1.FileWriter

　　1.1FileWriter 用于写入字符流。要写入原始字节流，请考虑使用 FileOutputStream。

public class Demo {
	public static void main(String[] args) throws IOException{
		FileWriter fileWriter = new FileWriter("d:\\aaa.txt");
		//添加字符
		fileWriter.write(100);
		fileWriter.write(101);
		//添加字符数组
		char[] c = {'a','b','c','d'};
		fileWriter.write(c);
		fileWriter.write(c,1,2);
		//添加字符串
		fileWriter.write("hello world");
		fileWriter.flush();
		fileWriter.close();
	}
}

2.FileReader

　　1.1用来读取字符文件的便捷类。FileReader 用于读取字符流。要读取原始字节流，请考虑使用 FileInputStream。

　　//flush  和close区别
       // flush用来刷新缓冲区的  只有字符流才需要刷新

　　字节读取

public class Demo {
	public static void main(String[] args) throws IOException{
		FileReader fileReader = new FileReader("d:\\aaa.txt");
		int len = 0;
		while((len=fileReader.read())!=-1) {
			System.out.print((char)len);
		}
		fileReader.close();
	}
}

　　字符数组读取

public class Demo {
	public static void main(String[] args) throws IOException{
		FileReader fileReader = new FileReader("d:\\aaa.txt");
		char[] b = new char[1024];
		int len = 0;
		while((len = fileReader.read(b))!=-1) {
			System.out.println(new String(b,0,len));
		}
		fileReader.close();
	}
}

3.传输数据

　　

public class Demo {
	public static void main(String[] args){
		FileReader fileReader = null;
		FileWriter fileWriter = null;
		try {
			fileReader = new FileReader("d:\\aaa.txt");
			fileWriter = new FileWriter("d:\\bbb/txt");
			char[] ch = new char[1024];
			int len = 0;
			while((len=fileReader.read(ch))!=-1) {
				fileWriter.write(ch,0,len);
				fileWriter.flush();
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			if(fileWriter!=null) {
				try {
					fileWriter.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(fileReader!=null) {
				try {
					fileReader.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
		}
	}
}