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IO流.md
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IO流.md
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# IO流体系结构
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251223143732944.png" alt="image-20251223143723814" style="zoom: 50%;" />
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# 字节流：
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## FileOutPutStream 字节输出流
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### 构造方法和成员方法和注意事项：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251223145353953.png" alt="image-20251223145352942" style="zoom:67%;" />
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### 成员方法
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### IO流的异常处理方式
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示例：
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```JAVA
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public static void main(String[] args) throws IOException {
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//记住输出流一定要关闭，使用try catch保证不管如何都会执行关闭
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//创建字节输出流对象是，可以传两个参数第一个是字符串或者是file对象，第二个是打开或关闭复写的开关
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//try小括号里的对象必须实现了AutoCloseAble接口
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try (FileOutputStream fos = new FileOutputStream("D:\\A.txt",true);){
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fos.write(97);
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fos.write(97);
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fos.write("八奈见杏菜".getBytes());
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}catch (IOException e){
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e.printStackTrace();
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}
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}
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```
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## FileInPutStream字节输入流：
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### 构造和成员方法：
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## 案例：copy数据：
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```Java
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/**
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拷贝文件
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*/
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public static void main(String[] args) throws IOException {
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//创建输入流对象读取要复制的数据
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FileInputStream fis = new FileInputStream("C:\\Users\\asus\\Pictures\\老八.jpg");
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byte[] bys= new byte[1024];//定义一个空字节数组用来装数据
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//创建输出流对象粘贴读取的数据
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FileOutputStream fos= new FileOutputStream("D:\\老八.jpg");
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int len;
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while ((len = fis.read(bys)) != -1){
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fos.write(bys,0, len);
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}
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//记得关闭流
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fis.close();
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fos.close();
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}
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```
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## 字节缓冲流：（未听）
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# 小知识点：字符编码：
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## 编码和解码：
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## 总结：（可记）
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251223171936927.png" alt="image-20251223171919671" style="zoom:50%;" />
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# FileWriter字符输出流
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## **成员方法**：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251223173014161.png" alt="image-20251223173006416" style="zoom: 50%;" />
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# 字符缓冲流：
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## 构造方法：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224164934256.png" alt="image-20251224164929596" style="zoom: 50%;" />
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## 特有成员方法：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224165014103.png" alt="image-20251224165012852" style="zoom:50%;" />
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## 重点：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224164902592.png" alt="image-20251224164854046" style="zoom:50%;" />
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## 案例：
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三组对象写入文件后读取文件并封装成对象打印
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```Java
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public static void main(String[] args) throws IOException {
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Student stu1 = new Student("杏菜",15);
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Student stu2 = new Student("梦子",16);
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Student stu3 = new Student("佳树",17);
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BufferedWriter bw = new BufferedWriter(new FileWriter("D:\\测试.txt"));
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bw.write(stu1.getName()+"-"+stu1.getAge());
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bw.newLine();
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bw.write(stu2.getName()+"-"+stu2.getAge());
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bw.newLine();
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bw.write(stu3.getName()+"-"+stu3.getAge());
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bw.newLine();
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//写入程序三组数据
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bw.close();
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//读取三组数据
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BufferedReader br = new BufferedReader(new FileReader("D:\\测试.txt"));
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String line;
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while ((line = br.readLine()) != null){
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String[] split = line.split("-");
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Student stu = new Student(split[0],Integer.parseInt(split[1]));
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System.out.println(stu);
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}
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}
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```
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# 转换流：
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## 作用：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224171828583.png" alt="image-20251224171827438" style="zoom:50%;" />
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## 总结：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224171551986.png" alt="image-20251224171550851" style="zoom:50%;" />
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# 序列化流：
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## 构造方法：
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## 序列化流的操作：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224173737299.png" alt="image-20251224173735968" style="zoom: 50%;" />
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## 注意事项：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224173938954.png" alt="image-20251224173937811" style="zoom:50%;" />
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**transient 瞬态关键字类中某些成员变量不想被序列化操作即可加上此关键字**
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## 注意：要是序列化多次对象，有两种方式
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**try catch捕获异常，来结束循环**
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```Java
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public static void main(String[] args) throws IOException, ClassNotFoundException {
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ObjectInputStream ois = new ObjectInputStream(new FileInputStream("D:\\a.txt"));
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while (true){
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try {
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Object o = ois.readObject();
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System.out.println(o);
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} catch (EOFException O) {
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break;
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}
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}
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ois.close();
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}
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private static void write() throws IOException {
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Student stu1 = new Student("杏菜",15);
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Student stu2 = new Student("佳树",16);
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Student stu3 = new Student("梦子",17);
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ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("D:\\a.txt"));
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oos.writeObject(stu1);
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oos.writeObject(stu2);
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oos.writeObject(stu3);
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oos.close();
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}
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```
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**只序列化一次，将对象装入一个集合中，读取和写入只进行一次**
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```java
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public static void main(String[] args) throws IOException, ClassNotFoundException {
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//运用集合，使其只读取（序列化和反序列化一次）
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ObjectInputStream ois = new ObjectInputStream(new FileInputStream("D:\\a.txt"));
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ArrayList<Student> list = (ArrayList<Student>) ois.readObject();
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for (Student student : list) {
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System.out.println(student);
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}
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ois.close();
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}
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private static void write() throws IOException {
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Student stu1 = new Student("杏菜", 15);
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Student stu2 = new Student("佳树", 16);
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Student stu3 = new Student("梦子", 17);
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//创建一个集合将对象装入集合并序列化操作一次写入文件
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ArrayList<Student> list = new ArrayList<>();
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Collections.addAll(list, stu1, stu2, stu3);
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ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("D:\\a.txt", true));
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oos.writeObject(list);
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oos.close();
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}
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```
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# 打印流：
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## 基本使用：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251224184742093.png" alt="image-20251224184740951" style="zoom: 67%;" />
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251226154205072.png" alt="image-20251226154156446" style="zoom:50%;" />
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## 字符打印流：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251226154313700.png" alt="image-20251226154307707" style="zoom:50%;" />
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# properties
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## 和io有关的方法：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251226162808390.png" alt="image-20251226162807035" style="zoom: 67%;" />
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**本质是一个map集合**
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## 总结：
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<img src="https://gitee.com/icecat2233/picture/raw/master/20251226162640827.png" alt="image-20251226162638992" style="zoom: 50%;" />
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