Java的IO其他流(及Properties) Li.044

序列流

• SequenceInputStream 关闭时会关闭所有流

public class Demo1_Stream {
    public static void main(String[] args) throws IOException {
        FileInputStream fr1 = new FileInputStream("read1.md");
        FileInputStream fr2 = new FileInputStream("read2.md");
        SequenceInputStream sis = new SequenceInputStream(fr1,fr2);
        FileOutputStream fos = new FileOutputStream("read3.md");
        int b ;
        while ( ( b = sis.read()) != -1){
            fos.write(b);
        }
        sis.close();
        fos.close();
    }
    public static void demo1() throws IOException {
        FileInputStream fr1 = new FileInputStream("read1.md");
        FileOutputStream fos = new FileOutputStream("read3.md");
        int b;
        while ((b = fr1.read()) != -1) {
            fos.write(b);
        }
        fr1.close();
        FileInputStream fr2 = new FileInputStream("read2.md");
        while ((b = fr2.read()) != -1) {
            fos.write(b);
        }
        fr2.close();
        fos.close();
    }
}

IO 流整合多个

public class Demo1_Stream {
    public static void main(String[] args) throws IOException {
        Vector<FileInputStream> v = new Vector<>();
        FileInputStream fr1 = new FileInputStream("read1.md");
        FileInputStream fr2 = new FileInputStream("read2.md");
        v.add(fr1);
        v.add(fr2);
        Enumeration<FileInputStream> en = v.elements();
        SequenceInputStream sis = new SequenceInputStream(en);
        FileOutputStream fos = new FileOutputStream("read3.md");
        int b ;
        while ( (b = sis.read()) != -1){
            fos.write(b);
        }
        sis.close();
        fos.close();
    }
}

ByteArrayOutputStream 获取数据

• ByteArrayOutputStream 的 toString 可直接转为默认或指定的字符

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class Deom2_ByteArrayOutputStream {
    public static void main(String[] args) throws IOException {
        FileInputStream fi = new FileInputStream("read1.md");
        ByteArrayOutputStream baos  = new ByteArrayOutputStream();
        int b ;
        while ( (b = fi.read()) != -1){
            baos.write(b);
        }
        fi.close();
        System.out.println(baos.toString());
        System.out.println(baos.toString("utf-8"));
    }

    private static void Demo1() throws IOException {
        FileInputStream fi = new FileInputStream("read1.md");
        byte[] arr = new byte[3];
        int len;
        while ( ( len = fi.read(arr)) != -1){
            System.out.println(new String(arr,0,len));
        }
        fi.close();
    }
}

内存输出

import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.IOException;

public class Demo3_Test {
    public static void main(String[] args) throws IOException {
        FileInputStream fis = new FileInputStream("read1.md");
        byte[] arr = new byte[5];
        int len;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();

        while ( (len = fis.read(arr)) != -1){
            bos.write(arr,0,len);
        }
        fis.close();
        System.out.println(bos.toString());
        bos.close();
    }
}

随机读和存 RandomAccessFile

import java.io.IOException;
import java.io.RandomAccessFile;

public class Demo4_RandomAccessFile {
    public static void main(String[] args) throws IOException {
//        Demo1();
        Demo2();
    }
    public static void Demo2() throws IOException{
        RandomAccessFile raf = new RandomAccessFile("random.txt","rw");
        int b;
        while ( (b = raf.read()) != -1){
            System.out.println(b);
        }
        raf.close();
    }

    private static void Demo1() throws IOException {
        RandomAccessFile raf = new RandomAccessFile("random.txt","rw");
        raf.write(97);
        raf.seek(10);
        raf.write(98);
        raf.close();
    }
}

对象操作流 ObjecOutputStream

• 输出对象流, 序列化

import com.lizicai.bean.Person;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;

public class Demo5_ObjectOutputStream {
    public static void main(String[] args) throws IOException {
        Person p1 = new Person("小明", 23);
        Person p2 = new Person("小红", 23);

        ObjectOutputStream oos = new ObjectOutputStream( new FileOutputStream("person.txt"));
        oos.writeObject(p1);
        oos.writeObject(p2);
        oos.close();
    }
}

• 读取对象流

import com.lizicai.bean.Person;

import java.io.*;

public class Deom6_ObjectInputStream {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        ObjectInputStream oos = new ObjectInputStream(new FileInputStream("person.txt"));
        Person p1 = (Person) oos.readObject();
        System.out.println(p1.getName()+p1.getAge());
        Person p2 = (Person) oos.readObject();
        System.out.println(p2.getName()+p2.getAge());
    }
}

对象操作优化

• 对象放入集合中, 集合输出到流

import com.lizicai.bean.Person;

import java.io.*;
import java.util.ArrayList;

public class Demo7_OptimeObjectStream {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("hashSetPerson.txt"));
        ArrayList<Person> arrayList = new ArrayList<>();
        arrayList.add(new Person("小明",25));
        arrayList.add(new Person("小红",23));
        arrayList.add(new Person("小王",26));
        oos.writeObject(arrayList);
        oos.close();

        ObjectInputStream ois = new ObjectInputStream(new FileInputStream("hashSetPerson.txt"));
        ArrayList<Person> personArrayList = ( ArrayList<Person> ) ois.readObject();
        for(Person p : personArrayList){
            System.out.println(p.getName() + p.getAge());
        }
    }
}

IO 流增加 id 号

• 更改Person属性时更改serialVersionUID 可以准备知道原来Persion和现在Persion属性区别

import java.io.Serializable;

public class Person implements Serializable {

    private static final long serialVersionUID= 1L;

    private String name;
    private int age;

    public Person(){}
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getAge() {
        return age;
    }
}

IO 基本数据流, DataInputStream DataOutputStream

import java.io.*;

public class Demo8_DataInputStream {
    public static void main(String[] args) throws IOException {
        Demo1();
        DataOutputStream dos = new DataOutputStream(new FileOutputStream("outData.txt"));
        dos.writeInt(997);
        dos.writeInt(998);
        dos.writeInt(999);
        dos.close();
        DataInputStream dis = new DataInputStream(new FileInputStream("outData.txt"));
        int x = dis.readInt();
        int y = dis.readInt();
        int z = dis.readInt();
        System.out.println(x);
        System.out.println(y);
        System.out.println(z);
        dis.close();


    }

    private static void Demo1() throws IOException {
        FileOutputStream fos = new FileOutputStream("output.txt");
        fos.write(997);
        fos.close();
    }
    private static void Demo2() throws IOException {
        FileInputStream fis = new FileInputStream("output.txt");
        int b = fis.read();
        fis.close();
    }
}

打印流的概述和特点

• PrintStream 和 PrintWriter 分别是打印的字节流和字符流
• 只操作数据目的
• 自动刷出作用不大

import java.io.*;

public class Demo9_PrintStream {
    public static void main(String[] args) throws IOException {
//        Demo2();
        PrintWriter pw = new PrintWriter(new FileOutputStream("printWriter.txt"), true);
        pw.println(97);
    }

    private static void Demo2() throws FileNotFoundException {
        PrintWriter pw = new PrintWriter("printWriter.txt");
        pw.println(97);
        pw.write(97);
        pw.flush();
        pw.close();
    }

    private static void demo1() {
        PrintStream p = System.out;
        p.println("Hello World!");
        p.write(97);
        p.close();
    }
}

标准输入输出流概述和输出语句

• 标准输入只有1个, 未关联到文件, 不用关闭, 关闭后无法打开了
• 标准输出流未关联文件, 也不用关闭

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;

public class Demo10_SystemInOut {
    public static void main(String[] args) throws IOException {
//        demo1();
        System.setIn(new FileInputStream("systemin.txt"));
        System.setOut(new PrintStream("systemout.txt"));
        InputStream is = System.in;
        PrintStream ps = System.out;
        int b;
        while ( ( b = is.read()) != -1){
            ps.write(b);
        }
        is.close();
        ps.close();

    }

    private static void demo1() throws IOException {
        InputStream is = System.in;
        int x = is.read();
        System.out.println(x);
        is.close();

        InputStream is2 = System.in;
        int y = is2.read();
        System.out.println(y);
    }
}

• 练习, 复制文件, 增加使用数组, 增加复制速度

import java.io.*;

public class Demo11_SystemInOutTest {
    public static void main(String[] args) throws IOException {
        System.setIn(new FileInputStream("systemin.txt"));
        System.setOut(new PrintStream("systemout.txt"));
        InputStream is = System.in;
        PrintStream ps = System.out;
        byte [] arr = new byte[1024];
        int len;
        while ( ( len = is.read(arr)) != -1){
            ps.write(arr,0,len);
        }
        is.close();
        ps.close();
    }
}

2种键盘录入方式

import java.util.Scanner;

public class Demo12_SystemIn {
    public static void main(String[] args) throws IOException {
//        demo1();
        Scanner sc = new Scanner(System.in);
        String s = null;
        if(sc.hasNext()){
            s = sc.nextLine();
        }
        System.out.println(s);
    }

    private static void demo1() throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String line = br.readLine();
        System.out.println(line);
    }
}

Properties的概述和作为Map集合的使用

• Object setProperty(String key, String value) 添加键值对
• Enumeration propertyNames() 获取 key值枚举
• String getProperty(String key) 根据key 值获取 value

import java.util.Enumeration;
import java.util.Properties;

public class Demo13_Properties {
    public static void main(String[] args) {
//        demo1();
        Properties pp = new Properties();
        pp.setProperty("name", "小明");
        pp.setProperty("tel", "12310001000");
        System.out.println(pp);
        Enumeration <String> en = (Enumeration<String>) pp.propertyNames();
        while ( en.hasMoreElements()){
            String key = en.nextElement();
            System.out.println(key+pp.getProperty(key));
        }

    }

    private static void demo1() {
        Properties p = new Properties();
        p.put("intA", 12);
        System.out.println(p);
    }
}

Properties 读和存

• void load(InputStream inStream) throws IOException 读取文件
• void store(OutputStream out, String comments) throws IOException 写到文件, comments 加入注释

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;

public class Demo13_Properties {
    public static void main(String[] args) throws IOException {
        Properties pp = new Properties();
        System.out.println(pp);
        pp.load(new FileInputStream("config.properties"));
        System.out.println(pp);
        pp.setProperty("qq","123");
        System.out.println(pp);
        pp.store(new FileOutputStream("config.properties"), "utf-8");
    }
}