Java基础之IO操作（二）

深藏阁楼爱情的钟 2022-04-22 11:42 128阅读 0赞

# Java基础之IO操作（二） #

## 一、BufferedInputStream ##

public static void main(String[] args) {
    File src = new File("abc.txt");
    //2、选择流
    InputStream  is =null;
    try {
    	is =new BufferedInputStream(new FileInputStream(src));
    	//3、操作 (分段读取)
    	byte[] flush = new byte[1024]; //缓冲容器
    	int len = -1; //接收长度
    	while((len=is.read(flush))!=-1) {
    		//字节数组-->字符串 (解码)
    		String str = new String(flush,0,len);
    		System.out.println(str);
    	}		
    		
    } catch (FileNotFoundException e) {
    	e.printStackTrace();
    } catch (IOException e) {
    	e.printStackTrace();
    }finally {
    	//4、释放资源
    	try {
    		if(null!=is) {
    			is.close();
    		}
    	} catch (IOException e) {
    		e.printStackTrace();
    	}			
    }
    }

## 二、BufferedOutputStream ##

public static void main(String[] args) {
    //1、创建源
    File dest = new File("dest.txt");
    //2、选择流
    OutputStream os =null;
    try {
    	os =new BufferedOutputStream( new FileOutputStream(dest));
    	//3、操作(写出)
    	String msg ="IO is so easy\r\n";
    	byte[] datas =msg.getBytes(); // 字符串-->字节数组(编码)
    	os.write(datas,0,datas.length);
    	os.flush();
    }catch(FileNotFoundException e) {		
    	e.printStackTrace();
    }catch (IOException e) {
    	e.printStackTrace();
    }finally{
    	//4、释放资源
    	try {
    		if (null != os) {
    			os.close();
    		} 
    	} catch (Exception e) {
    	}
    }
    }

## 三、BufferedReader ##

public static void main(String[] args) {
    //1、创建源
    File src = new File("abc.txt");
    //2、选择流
    BufferedReader  reader =null;
    try {
    	reader =new BufferedReader(new FileReader(src));
    	//3、操作 (分段读取)
    	String line =null;
    	while((line=reader.readLine())!=null) {
    		//字符数组-->字符串
    		System.out.println(line);
    	}		
    		
    } catch (FileNotFoundException e) {
    	e.printStackTrace();
    } catch (IOException e) {
    	e.printStackTrace();
    }finally {
    	//4、释放资源
    	try {
    		if(null!=reader) {
    			reader.close();
    		}
    	} catch (IOException e) {
    		e.printStackTrace();
    	}
    }
    }

## 四、BufferedWriter ##

public static void main(String[] args) {
    //1、创建源
    File dest = new File("dest.txt");
    //2、选择流
    BufferedWriter writer =null;
    try {
    	writer = new BufferedWriter(new FileWriter(dest));
    	//3、操作(写出)			
    	writer.append("IO is so easy");
    	writer.newLine();
    	writer.append("尚学堂欢迎你");
    	writer.flush();
    }catch(FileNotFoundException e) {		
    	e.printStackTrace();
    }catch (IOException e) {
    	e.printStackTrace();
    }finally{
    	//4、释放资源
    	try {
    		if (null != writer) {
    			writer.close();
    		} 
    	} catch (Exception e) {
    	}
    }
    }

## 五、转换流 ##

public static void main(String[] args) {
    //操作System.in 和System.out，可以指定编码格式进行转化
    try(BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    	BufferedWriter writer =new BufferedWriter(new OutputStreamWriter(System.out));){
    	//循环获取键盘的输入(exit退出)，输出此内容
    	String msg ="";
    	while(!msg.equals("exit")) {
    		msg = reader.readLine(); //循环读取
    		writer.write(msg); //循环写出
    		writer.newLine();
    		writer.flush(); //强制刷新
    	}
    	}catch(IOException e) {
    		System.out.println("操作异常");
    	}	
    }

## 六、数据操作流 ##

public static void main(String[] args) throws IOException {
    	//写出
    	ByteArrayOutputStream baos =new ByteArrayOutputStream();
    	DataOutputStream dos =new DataOutputStream(new BufferedOutputStream(baos));
    	//操作数据类型 +数据
    	dos.writeUTF("编码辛酸泪");
    	dos.writeInt(18);
    	dos.writeBoolean(false);
    	dos.writeChar('a');
    	dos.flush();
    	byte[] datas =baos.toByteArray();
    	System.out.println(datas.length);
    	//读取
    	DataInputStream dis =new DataInputStream(new BufferedInputStream(new ByteArrayInputStream(datas)));
    	//顺序与写出一致
    	String msg = dis.readUTF(); 
    	int age = dis.readInt();
    	boolean flag = dis.readBoolean();
    	char ch = dis.readChar();
    	System.out.println(flag);
    }

## 七、对象操作流 ##

public class ObjectTest {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
    //写出 -->序列化
    	ByteArrayOutputStream baos =new ByteArrayOutputStream();
    	ObjectOutputStream oos =new ObjectOutputStream(new BufferedOutputStream(baos));
    	//操作数据类型 +数据
    	oos.writeUTF("编码辛酸泪");
    	oos.writeInt(18);
    	oos.writeBoolean(false);
    	oos.writeChar('a');
    	//对象
    	oos.writeObject("谁解其中味");
    	oos.writeObject(new Date());
    	Employee emp =new Employee("马云",400);
    	oos.writeObject(emp);
    	oos.flush();
    	byte[] datas =baos.toByteArray();
    	System.out.println(datas.length);
    	//读取 -->反序列化
    	ObjectInputStream ois =new ObjectInputStream(new BufferedInputStream(new ByteArrayInputStream(datas)));
    	//顺序与写出一致
    	String msg = ois.readUTF(); 
    	int age = ois.readInt();
    	boolean flag = ois.readBoolean();
    	char ch = ois.readChar();
    	System.out.println(flag);
    	//对象的数据还原  
    	Object str = ois.readObject();
    	Object date = ois.readObject();
    	Object employee = ois.readObject();
    		
    	if(str instanceof String) {
    		String strObj = (String) str;
    		System.out.println(strObj);
    	}
    	if(date instanceof Date) {
    		Date dateObj = (Date) date;
    		System.out.println(dateObj);
    	}
    	if(employee instanceof Employee) {
    		Employee empObj = (Employee) employee;
    		System.out.println(empObj.getName()+"-->"+empObj.getSalary());
    	}
    		
    }
    
    }
    //javabean 封装数据
    class Employee implements java.io.Serializable{
    	private transient String name; //该数据不需要序列化
    	private double salary;
    	public Employee() {
    	}
    	public Employee(String name, double salary) {
    		this.name = name;
    		this.salary = salary;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public double getSalary() {
    		return salary;
    	}
    	public void setSalary(double salary) {
    		this.salary = salary;
    	}
    	
    }