day10(IO流汇总)

字节流（Reader,Writer）

　　　　输入流 FileReader

public class Demo {

	public static void main(String[] args) throws IOException {

		FileReader fr=new FileReader("b.txt");

		int len;

		while((len=fr.read())!=-1){

			System.out.print((char)len);

		}

		fr.close();

	}

}

　　　　输出流 FileWriter

public class Demo {

	public static void main(String[] args) throws IOException {

		FileReader fr=new FileReader("b.txt");

		//创建输出流对象

		FileWriter fw=new FileWriter("a.txt");

		char[] ch=new char[1024];

		int len;

		while((len=fr.read(ch))!=-1){//读数据

			//写出数据

			fw.write(ch,0,len);

		}

		//关闭流

		fr.close();

		fw.close();

	}

　　　高效流 BufferedReader BufferedWriter

public class Demo {

	public static void main(String[] args) throws IOException {

		//fileReaderDemo();

		FileReader fr=new FileReader("b.txt");
　　　　　　　　　　//创建高效输入字符流对象

		BufferedReader br=new BufferedReader(fr);

		//创建输出流对象

		FileWriter fw=new FileWriter("a.txt");

		BufferedWriter bw=new BufferedWriter(fw);

		char[] ch=new char[1024];

		String len;

		while((len=br.readLine())!=null){//读数据

			//写出数据

			bw.write(len);

			bw.newLine();

			bw.flush();

		}

		//关闭流

		br.close();

		bw.close();

	}

}

字符流 (InputStream,OutputStream)

　　　　输入流 FileInputStream

public class Demo {

	public static void main(String[] args) throws IOException {

		FileInputStream fis=new FileInputStream("a.txt");

			int len;

			while ((len=fis.read())!=-1) {

				System.out.print((char)len);

			}

			fis.close();

	}

}

　　　　输出流 FileOutputStream

public class Demo {

	public static void main(String[] args) throws IOException {

		//fileReaderDemo();

		//method01();

		FileInputStream fis=new FileInputStream("b.txt");

		FileOutputStream ios=new FileOutputStream("a.txt");

			int len;

			while ((len=fis.read())!=-1) {

				ios.write(len);

			}

			fis.close();

			ios.close();

	}

}

　　　　高效流

public class Demo {

	public static void main(String[] args) throws IOException {

		//fileReaderDemo();

		//method01();

		FileInputStream fis=new FileInputStream("b.txt");

		BufferedInputStream bis=new BufferedInputStream(fis);

		FileOutputStream ios=new FileOutputStream("a.txt");

		BufferedOutputStream bos=new BufferedOutputStream(ios);

			byte[] b=new byte[1024];

			int len;

			while ((len=bis.read(b))!=-1) {

				bos.write(b,0,len);

				bos.flush();

			}

			fis.close();

			ios.close();

	}

}

转换流

　　　　输入流 InputStreamReader

　　　　输出流 outputStreamWriter

public class Demo {

	public static void main(String[] args) throws IOException {

		//fileReaderDemo();

		//method01();

		FileInputStream fis=new FileInputStream("b.txt");

		InputStreamReader isr=new InputStreamReader(fis);//转化为字符流  转换输入流

		BufferedReader br=new BufferedReader(isr);//包装为高效流

		FileOutputStream ios=new FileOutputStream("a.txt");//转化为字符流  转换输出流

		OutputStreamWriter osw=new OutputStreamWriter(ios);//包装为高效流

		BufferedWriter bw=new BufferedWriter(osw);

			String len;

			while ((len=br.readLine())!=null) {

				bw.write(len);

				bw.newLine();

				bw.flush();

			}

			bw.close();

			br.close();

	}

标准流

　　　　输入流

public class Demo {

	public static void main(String[] args) throws IOException {

		//标准输入流

		InputStream in = System.in;

		InputStreamReader fis=new InputStreamReader(in);

		int len;

		while ((len=fis.read())!=-1) {

			System.out.print((char)len);

		}

		fis.close();

	}

}

　　　　输出流

public class Demo {

	public static void main(String[] args) throws IOException {

		PrintStream out = System.out;

		InputStreamReader fis=new InputStreamReader(new FileInputStream("a.txt"));

		OutputStreamWriter osw=new OutputStreamWriter(out);

		int len;

		while((len=fis.read())!=-1){

			osw.write(len);//输出到控制台

		}

		fis.close();

		osw.close();

	}

}

输出流 (不能写出)

　　　　输入流 PrintWriter(父类为Writer)

		PrintWriter pw=new PrintWriter("c.txt");

		pw.println("hello");

		pw.println("world");//将内容写入c.txt文件中   自带刷新功能

		pw.close();

对象流（序列化）

　　　　输出流（将对象写入到文件中，这个对象必须序列化才能写入到文件中否则会报错）

　　　　输入流（）

public class ObjectTest {

	public static void main(String[] args) throws IOException, Exception {

		ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(

				"d.txt"));

		ArrayList<Student> array = new ArrayList<Student>();

		Student s1 = new Student("赵云", 15);

		Student s2 = new Student("张飞", 15);

		array.add(s1);

		array.add(s2);

		oos.writeObject(array);//序列化过程

		oos.close();

		ObjectInputStream ois = new ObjectInputStream(new FileInputStream(//反序列化

				"d.txt"));

		ArrayList<Student> arrays = (ArrayList<Student>) ois.readObject();

		for (Student student : arrays) {

			System.out.println(student);

		}

	}

}

public class Student implements Serializable {

	/**

	 *

	 */

	private static final long serialVersionUID = -3919560601713535195L;
       // serialVersionUID 用来标识类的唯一性  它是根据类的内容计算出来的  如果写入和读出的类的id不一致 则会报错

	String name;

	int age;

	String sex;

	public Student(String name,int age){

		this.name=name;

		this.age=age;

	}

	@Override

	public String toString() {

		return "Student [name=" + name + ", age=" + age + "]";

	}

}

错误异常

 java.io.InvalidClassException

local class incompatible: 类不相容

stream classdesc serialVersionUID = -3919560601713535195, local class serialVersionUID = 5350889806824666248

解决方案：

给类进行唯一标识

让类自动生成  UID

巴特西

day10(IO流汇总)

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