```java
public class Student {
// 姓名
private String name;
// 语文成绩
private int chinese;
// 数学成绩
private int math;
// 英语成绩
private int english;
public Student() {
super();
}
public Student(String name, int chinese, int math, int english) {
super();
this.name = name;
this.chinese = chinese;
this.math = math;
this.english = english;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getChinese() {
return chinese;
}
public void setChinese(int chinese) {
this.chinese = chinese;
}
public int getMath() {
return math;
}
public void setMath(int math) {
this.math = math;
}
public int getEnglish() {
return english;
}
public void setEnglish(int english) {
this.english = english;
}
public int getSum() {
return this.chinese + this.math + this.english;
}
}
```
- 测试类
```java
public class TreeSetToFileDemo {
public static void main(String[] args) throws IOException {
//创建TreeSet集合，通过比较器排序进行排序
TreeSet<Student> ts = new TreeSet<Student>(new Comparator<Student>() {
@Override
public int compare(Student s1, Student s2) {
//成绩总分从高到低
int num = s2.getSum() - s1.getSum();
//次要条件
int num2 = num == 0 ? s1.getChinese() - s2.getChinese() : num;
int num3 = num2 == 0 ? s1.getMath() - s2.getMath() : num2;
int num4 = num3 == 0 ? s1.getName().compareTo(s2.getName()) : num3;
return num4;
}
});
//键盘录入学生数据
for (int i = 0; i < 5; i++) {
Scanner sc = new Scanner(System.in);
System.out.println("请录入第" + (i + 1) + "个学生信息：");
System.out.println("姓名：");
String name = sc.nextLine();
System.out.println("语文成绩：");
int chinese = sc.nextInt();
System.out.println("数学成绩：");
int math = sc.nextInt();
System.out.println("英语成绩：");
int english = sc.nextInt();
//创建学生对象，把键盘录入的数据对应赋值给学生对象的成员变量
Student s = new Student();
s.setName(name);
s.setChinese(chinese);
s.setMath(math);
s.setEnglish(english);
//把学生对象添加到TreeSet集合
ts.add(s);
}
//创建字符缓冲输出流对象
BufferedWriter bw = new BufferedWriter(new FileWriter("myCharStream\\ts.txt"));
//遍历集合，得到每一个学生对象
for (Student s : ts) {
//把学生对象的数据拼接成指定格式的字符串
//格式：姓名,语文成绩,数学成绩,英语成绩
StringBuilder sb = new StringBuilder();
sb.append(s.getName()).append(",").append(s.getChinese()).append(",").append(s.getMath()).append(",").append(s.getEnglish()).append(",").append(s.getSum());
```java
public class CopyFolderDemo {
public static void main(String[] args) throws IOException {
//创建数据源目录File对象，路径是E:\\itcast
File srcFolder = new File("E:\\itcast");
private static void copyFile(File srcFile, File destFile) throws IOException {
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(srcFile));
BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(destFile));
byte[] bys = new byte[1024];
int len;
while ((len=bis.read(bys))!=-1) {
bos.write(bys,0,len);
}
bos.close();
bis.close();
}
}
```
### 1.3复制多级文件夹【应用】
#### 1.3.1案例需求
- 把“E:\\itcast”这个文件夹复制到 F盘目录下
#### 1.3.2分析步骤
1. 创建数据源File对象，路径是E:\\itcast
2. 创建目的地File对象，路径是F:\\
3. 写方法实现文件夹的复制，参数为数据源File对象和目的地File对象
4. 判断数据源File是否是文件
是文件：直接复制，用字节流
不是文件：
在目的地下创建该目录
遍历获取该目录下的所有文件的File数组，得到每一个File对象
回到3继续(递归)
#### 1.3.3代码实现
```java
public class CopyFoldersDemo {
public static void main(String[] args) throws IOException {
//创建数据源File对象，路径是E:\\itcast
File srcFile = new File("E:\\itcast");
//创建目的地File对象，路径是F:\\
File destFile = new File("F:\\");
//抛出处理
private static void method1() throws IOException {
FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
fw.close();
fr.close();
}
}
```
#### 1.4.2JDK7版本改进
```java
public class CopyFileDemo {
public static void main(String[] args) {
}
//JDK7的改进方案
private static void method3() {
try(FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");){
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
```
#### 1.4.3JDK9版本改进
```java
public class CopyFileDemo {
public static void main(String[] args) {
}
//JDK9的改进方案
private static void method4() throws IOException {
FileReader fr = new FileReader("fr.txt");
FileWriter fw = new FileWriter("fw.txt");
try(fr;fw){
char[] chs = new char[1024];
int len;
while ((len = fr.read()) != -1) {
fw.write(chs, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
```
## 2.IO特殊操作流
### 2.1标准输入流【应用】
- System类中有两个静态的成员变量
- public static final InputStream in：标准输入流。通常该流对应于键盘输入或由主机环境或用户指定的另一个输入源
- public static final PrintStream out：标准输出流。通常该流对应于显示输出或由主机环境或用户指定的另一个输出目标
- 自己实现键盘录入数据
```java
public class SystemInDemo {
public static void main(String[] args) throws IOException {
//public static final InputStream in：标准输入流
// InputStream is = System.in;
// int by;
// while ((by=is.read())!=-1) {
// System.out.print((char)by);
// }
//如何把字节流转换为字符流？用转换流
// InputStreamReader isr = new InputStreamReader(is);
// //使用字符流能不能够实现一次读取一行数据呢？可以
// //但是，一次读取一行数据的方法是字符缓冲输入流的特有方法
// BufferedReader br = new BufferedReader(isr);
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入一个字符串：");
String line = br.readLine();
System.out.println("你输入的字符串是：" + line);
System.out.println("请输入一个整数：");
int i = Integer.parseInt(br.readLine());
System.out.println("你输入的整数是：" + i);
//自己实现键盘录入数据太麻烦了，所以Java就提供了一个类供我们使用
Scanner sc = new Scanner(System.in);
}
}
```
### 2.2标准输出流【应用】
- System类中有两个静态的成员变量
- public static final InputStream in：标准输入流。通常该流对应于键盘输入或由主机环境或用户指定的另一个输入源
- public static final PrintStream out：标准输出流。通常该流对应于显示输出或由主机环境或用户指定的另一个输出目标
public static void setOut(PrintStream out)：重新分配“标准”输出流
- 示例代码
```java
public class PrintStreamDemo {
public static void main(String[] args) throws IOException {
//PrintStream(String fileName)：使用指定的文件名创建新的打印流
PrintStream ps = new PrintStream("myOtherStream\\ps.txt");
```java
public class Student implements Serializable {
private static final long serialVersionUID = 42L;
private String name;
// private int age;
private transient int age;
public Student() {
}
public Student(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
// @Override
// public String toString() {
// return "Student{" +
// "name='" + name + '\'' +
// ", age=" + age +
// '}';
// }
}
```
- 测试类
```java
public class ObjectStreamDemo {
public static void main(String[] args) throws IOException, ClassNotFoundException {
// write();
read();
}
```java
public class PropertiesDemo01 {
public static void main(String[] args) {
//创建集合对象
// Properties<String,String> prop = new Properties<String,String>(); //错误
Properties prop = new Properties();
```java
public class PropertiesTest {
public static void main(String[] args) throws IOException {
//从文件中读取数据到Properties集合，用load()方法实现
Properties prop = new Properties();
FileReader fr = new FileReader("myOtherStream\\game.txt");
prop.load(fr);
fr.close();
//通过Properties集合获取到玩游戏的次数
String count = prop.getProperty("count");
int number = Integer.parseInt(count);