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1.字符IO流的输入/输出

首先，IO流根据多方面划分。

1. 根据方向划分
   输入流/输出流
2. 根据处理单元划分
   字节流/字符流
3. 根据功能划分
   节点流/处理流
   
   尝试一下使用字符输入流在读写文件：

package IOStream;import java.io.*;public class Test {public static void main(String[] args) throws IOException {//对文件进行操作，将文件封装为对象File f = new File("d:\\test.txt");//输入字符流,io流FileReader fr = new FileReader(f);//每次只读取一个字符,若读取到文件末尾，则不再进行输出int n1 = fr.read();while(n1!=-1){System.out.println(n1);n1 = fr.read();}//        System.out.println(n1);fr.close();String str = "IOStream Output Test";FileWriter fw = new FileWriter(f);fw.write(str);fw.close();}
}

原本txt文件中有自己的内容，但写入流写入的内容会把原来的文件内容直接覆盖掉。

2.书城项目IO版

之前有个很简单的项目，书城，是用集合来存储书籍信息的，这边改进一下，使用文件来存储信息了

首先，要想实现将对象内容序列化输出到文件中，需要先让Book对象实现Serializable功能

package bookstorw;import java.io.Serializable;public class Book implements Serializable {//书籍编号private int bno;//书籍名称private String bname;//书籍作者private String bwriter;public int getBno() {return bno;}public void setBno(int bno) {this.bno = bno;}public String getBwriter() {return bwriter;}public void setBwriter(String bwriter) {this.bwriter = bwriter;}public String getBname() {return bname;}public void setBname(String bname) {this.bname = bname;}public Book() {}public Book(int bno, String bname, String bwriter) {this.bno = bno;this.bname = bname;this.bwriter = bwriter;}public static void main(String[] args) {}
}

然后改进一下写入读取功能，现在是用流将集合写入文件或者从文件中读取出来

package bookstorw;import com.sun.corba.se.impl.io.OutputStreamHook;import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;public class Test {public static void main(String[] args) throws IOException, ClassNotFoundException {while(true) {System.out.println("欢迎来到书城：");System.out.println("1.展示书籍：");System.out.println("2.上新书籍：");System.out.println("3.下架书籍：");System.out.println("4.退出应用：");//借助Scanner类,扫描键盘输入Scanner sc = new Scanner(System.in);System.out.println("请输入整数序号。");//获取键盘输入的整数值int choice = sc.nextInt();if (choice == 1) {System.out.println("1>>>>>展示书籍");//从文件中读取File f = new File("d:\\test.txt");if(f.exists() == true){FileInputStream fi = new FileInputStream(f);ObjectInputStream fooin = new ObjectInputStream(fi);//在这边读出来的是个对象，所以要做强制类型转换ArrayList list = (ArrayList)(fooin.readObject());for(int i = 0;i <= list.size() - 1; i++){//获取到i之后，将他强制转换为book类型的对象Book b = (Book)(list.get(i));System.out.println(b.getBno()+"----"+b.getBname()+"-----"+b.getBwriter());}}else{System.out.println("书籍不存在，请先上新");}}if (choice == 2) {System.out.println("2>>>>>上新书籍");//从键盘录入书籍信息System.out.println("请输入书籍编号：");int bNo = sc.nextInt();System.out.println("请输入书籍名字：");String bName = sc.next();System.out.println("请输入书籍作者：");String bWriter = sc.next();//创建一个书籍对象Book b = new Book();b.setBno(bNo);b.setBname(bName);b.setBwriter(bWriter);File f = new File("d:\\test.txt");FileInputStream fi = new FileInputStream(f);ObjectInputStream fooin = new ObjectInputStream(fi);ArrayList list = (ArrayList)(fooin.readObject());//创建一个集合，存放书籍对象
//                ArrayList list = new ArrayList();list.add(b);File f2 = new File("d:\\test.txt");FileOutputStream fos = new FileOutputStream(f2);ObjectOutputStream oos = new ObjectOutputStream(fos);oos.writeObject(list);oos.close();fos.close();}if (choice == 3) {System.out.println("3>>>>>下架书籍");System.out.println("录入需要下架的书籍的编号：");int deleteBook = sc.nextInt();//                for(int i = 0;i <= list.size() - 1; i++){
//                    //获取到i之后，将他强制转换为book类型的对象
//                    Book b = (Book)(list.get(i));
//                    if(b.getBno() == deleteBook){
//                        list.remove(b);
//                        System.out.println("书籍下架成功。");
//                        break;
//                    }
//                }}if (choice == 4) {System.out.println("4>>>>>退出应用");break;}}}}

后面再优化就是写入读出数据库