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