2.使用方式java
FileInputStream fis1 = new FileInputStream("a.txt"); //建立输入流对象,关联a.txt FileInputStream fis2 = new FileInputStream("b.txt"); //建立输入流对象,关联b.txt SequenceInputStream sis = new SequenceInputStream(fis1, fis2); //将两个流整合成一个流 FileOutputStream fos = new FileOutputStream("c.txt"); //建立输出流对象,关联c.txt int b; while((b = sis.read()) != -1) { //用整合后的读 fos.write(b); //写到指定文件上 } sis.close(); fos.close();
FileInputStream fis1 = new FileInputStream("a.txt"); //建立输入流对象,关联a.txt FileInputStream fis2 = new FileInputStream("b.txt"); //建立输入流对象,关联b.txt FileInputStream fis3 = new FileInputStream("c.txt"); //建立输入流对象,关联c.txt Vector<InputStream> v = new Vector<>(); //建立vector集合对象 v.add(fis1); //将流对象添加 v.add(fis2); v.add(fis3); Enumeration<InputStream> en = v.elements(); //获取枚举引用 SequenceInputStream sis = new SequenceInputStream(en); //传递给SequenceInputStream构造 FileOutputStream fos = new FileOutputStream("d.txt"); int b; while((b = sis.read()) != -1) { fos.write(b); } sis.close(); fos.close();
package com.heima.otherio; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.SequenceInputStream; import java.util.Enumeration; import java.util.Vector; public class Demo01_SequenceInputStream { /** * @param args * 整合两个输入流 * SequenceInputStream(InputStream s1, InputStream s2) * 整合多个输入流 * SequenceInputStream(Enumeration<? extends InputStream> e) * @throws IOException */ public static void main(String[] args) throws IOException { //demo1(); //demo2(); FileInputStream fis1 = new FileInputStream("a.txt"); FileInputStream fis2 = new FileInputStream("b.txt"); FileInputStream fis3 = new FileInputStream("c.txt"); Vector<FileInputStream> v = new Vector<>(); //建立集合对象 v.add(fis1); //将流对象存储进来 v.add(fis2); v.add(fis3); Enumeration<FileInputStream> en = v.elements(); SequenceInputStream sis = new SequenceInputStream(en); //将枚举中的输入流整合成一个 FileOutputStream fos = new FileOutputStream("d.txt"); int b; while((b = sis.read()) != -1) { fos.write(b); } sis.close(); fos.close(); } public static void demo2() throws FileNotFoundException, IOException { FileInputStream fis1 = new FileInputStream("a.txt"); FileInputStream fis2 = new FileInputStream("b.txt"); SequenceInputStream sis = new SequenceInputStream(fis1, fis2); FileOutputStream fos = new FileOutputStream("c.txt"); int b; while((b = sis.read()) != -1) { fos.write(b); } sis.close(); //sis在关闭的时候,会将构造方法中传入的流对象也都关闭 fos.close(); } public static void demo1() throws FileNotFoundException, IOException { FileInputStream fis1 = new FileInputStream("a.txt"); //建立字节输入流关联a.txt FileOutputStream fos = new FileOutputStream("c.txt"); //建立字节输出流关联c.txt int b1; while((b1 = fis1.read()) != -1) { //不断的在a.txt上读取字节 fos.write(b1); //将读到的字节写到c.txt上 } fis1.close(); //关闭字节输入流 FileInputStream fis2 = new FileInputStream("b.txt"); int b2; while((b2 = fis2.read()) != -1) { fos.write(b2); } fis2.close(); fos.close(); } }
2.使用方式面试
FileInputStream fis = new FileInputStream("a.txt"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); int b; while((b = fis.read()) != -1) { baos.write(b); } //byte[] newArr = baos.toByteArray(); //将内存缓冲区中全部的字节存储在newArr中 //System.out.println(new String(newArr)); System.out.println(baos); fis.close();
package com.heima.otherio; import java.io.ByteArrayOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class Demo02_ByteArrayOutputStream { /** * @param args * ByteArrayOutputStream * 内存输出流 * * FileInputStream读取中文的时候出现了乱码 * * 解决方案 * 1,字符流读取 * 2,ByteArrayOutputStream * @throws IOException */ public static void main(String[] args) throws IOException { //demo1(); FileInputStream fis = new FileInputStream("e.txt"); ByteArrayOutputStream baos = new ByteArrayOutputStream(); //在内存中建立了能够增加的内存数组 int b; while((b = fis.read()) != -1) { baos.write(b); //将读取到的数据逐个写到内存中 } //byte[] arr = baos.toByteArray(); //将缓冲区的数据所有获取出来,并赋值给arr数组 //System.out.println(new String(arr)); System.out.println(baos.toString()); //将缓冲区的内容转换为了字符串,在输出语句中能够省略调用toString方法 fis.close(); } public static void demo1() throws FileNotFoundException, IOException { FileInputStream fis = new FileInputStream("e.txt"); byte[] arr = new byte[3]; int len; while((len = fis.read(arr)) != -1) { System.out.println(new String(arr,0,len)); } fis.close(); } }
FileInputStream fis = new FileInputStream("a.txt"); //建立字节输入流,关联a.txt ByteArrayOutputStream baos = new ByteArrayOutputStream(); //建立内存输出流 byte[] arr = new byte[5]; //建立字节数组,大小为5 int len; while((len = fis.read(arr)) != -1) { //将文件上的数据读到字节数组中 baos.write(arr, 0, len); //将字节数组的数据写到内存缓冲区中 } System.out.println(baos); //将内存缓冲区的内容转换为字符串打印 fis.close();
A:随机访问流概述数组
B:read(),write(),seek()dom
package com.heima.otherio; import java.io.FileNotFoundException; import java.io.IOException; import java.io.RandomAccessFile; public class Demo08_RandomAccessFile { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { RandomAccessFile raf = new RandomAccessFile("g.txt", "rw"); //raf.write(97); //int x = raf.read(); //System.out.println(x); raf.seek(0); //在指定位置设置指针 raf.write(98); raf.close(); } }
2.使用方式优化
写出: new ObjectOutputStream(OutputStream), writeObject()spa
public class Demo3_ObjectOutputStream { /** * @param args * @throws IOException * 将对象写出,序列化 */ public static void main(String[] args) throws IOException { Person p1 = new Person("张三", 23); Person p2 = new Person("李四", 24); // FileOutputStream fos = new FileOutputStream("e.txt"); // fos.write(p1); // FileWriter fw = new FileWriter("e.txt"); // fw.write(p1); //不管是字节输出流,仍是字符输出流都不能直接写出对象 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("e.txt"));//建立对象输出流 oos.writeObject(p1); oos.writeObject(p2); oos.close(); } }
package com.heima.otherio; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectOutputStream; import java.util.ArrayList; import com.heima.bean.Person; public class Demo03_ObjectOutputStream { /** * @param args * 序列化:将对象写到文件上 * @throws IOException */ public static void main(String[] args) throws IOException { //demo1(); Person p1 = new Person("张三", 23); Person p2 = new Person("李四", 24); Person p3 = new Person("王五", 25); Person p4 = new Person("赵六", 26); ArrayList<Person> list = new ArrayList<>(); list.add(p1); list.add(p2); list.add(p3); list.add(p4); ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("e.txt")); oos.writeObject(list); //把整个集合对象一次写出 oos.close(); } public static void demo1() throws IOException, FileNotFoundException { Person p1 = new Person("张三", 23); Person p2 = new Person("李四", 24); ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("e.txt")); oos.writeObject(p1); oos.writeObject(p2); oos.close(); } }
读取: new ObjectInputStream(InputStream), readObject()指针
public class Demo3_ObjectInputStream { /** * @param args * @throws IOException * @throws ClassNotFoundException * @throws FileNotFoundException * 读取对象,反序列化 */ public static void main(String[] args) throws IOException, ClassNotFoundException { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e.txt")); Person p1 = (Person) ois.readObject(); Person p2 = (Person) ois.readObject(); System.out.println(p1); System.out.println(p2); ois.close(); } }
package com.heima.otherio; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.ObjectInputStream; import java.util.ArrayList; import com.heima.bean.Person; public class Demo04_ObjectInputStream { /** * @param args * @throws IOException * @throws FileNotFoundException * @throws ClassNotFoundException * ObjectInputStream * 对象输入流,反序列化 */ public static void main(String[] args) throws FileNotFoundException, IOException, ClassNotFoundException { //demo1(); ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e.txt")); ArrayList<Person> list = (ArrayList<Person>) ois.readObject(); //将集合对象一次读取 for (Person person : list) { System.out.println(person); } ois.close(); } public static void demo1() throws IOException, FileNotFoundException, ClassNotFoundException { ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e.txt")); Person p1 = (Person) ois.readObject(); Person p2 = (Person) ois.readObject(); //Person p3 = (Person) ois.readObject(); //当文件读取到了末尾时出现EOFException System.out.println(p1); System.out.println(p2); ois.close(); } }
* 将对象存储在集合中写出code
Person p1 = new Person("张三", 23); Person p2 = new Person("李四", 24); Person p3 = new Person("马哥", 18); Person p4 = new Person("辉哥", 20); ArrayList<Person> list = new ArrayList<>(); list.add(p1); list.add(p2); list.add(p3); list.add(p4); ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("f.txt")); oos.writeObject(list); //写出集合对象 oos.close();
读取到的是一个集合对象对象
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("f.txt")); ArrayList<Person> list = (ArrayList<Person>)ois.readObject(); //泛型在运行期会被擦除,索引运行期至关于没有泛型 //想去掉黄色能够加注解 @SuppressWarnings("unchecked") for (Person person : list) { System.out.println(person); } ois.close();
2.使用方式索引
DataOutputStream(OutputStream), writeInt(), writeLong()
DataOutputStream dos = new DataOutputStream(new FileOutputStream("b.txt")); dos.writeInt(997); dos.writeInt(998); dos.writeInt(999); dos.close();
DataInputStream(InputStream), readInt(), readLong()
DataInputStream dis = new DataInputStream(new FileInputStream("b.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();
package com.heima.otherio; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; public class Demo09_Data { /** * @param args * @throws IOException * 00000000 00000000 00000011 11100101 int类型997 * 11100101 * 00000000 00000000 00000000 11100101 */ public static void main(String[] args) throws IOException { //demo1(); //demo2(); //demo3(); DataInputStream dis = new DataInputStream(new FileInputStream("h.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(); } public static void demo3() throws FileNotFoundException, IOException { DataOutputStream dos = new DataOutputStream(new FileOutputStream("h.txt")); dos.writeInt(997); dos.writeInt(998); dos.writeInt(999); dos.close(); } public static void demo2() throws FileNotFoundException, IOException { FileInputStream fis = new FileInputStream("h.txt"); int x = fis.read(); int y = fis.read(); int z = fis.read(); System.out.println(x); System.out.println(y); System.out.println(z); fis.close(); } public static void demo1() throws FileNotFoundException, IOException { FileOutputStream fos = new FileOutputStream("h.txt"); fos.write(997); fos.write(998); fos.write(999); fos.close(); } }
1.什么是打印流
System.out就是一个PrintStream, 其默认向控制台输出信息
PrintStream ps = System.out; ps.println(97); //其实底层用的是Integer.toString(x),将x转换为数字字符串打印 ps.println("xxx"); ps.println(new Person("张三", 23)); Person p = null; ps.println(p); //若是是null,就返回null,若是不是null,就调用对象的toString()
2.使用方式
打印流只操做数据目的
PrintWriter pw = new PrintWriter(new FileOutputStream("g.txt"), true); pw.write(97); pw.print("你们好"); pw.println("你好"); //自动刷出,只针对的是println方法 pw.close();
package com.heima.otherio; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.PrintStream; import java.io.PrintWriter; import com.heima.bean.Person; public class Demo05_PrintStream { /** * @param args * @throws IOException * PrintStream和PrintWriter分别是打印的字节流和字符流 * 只操做数据目的的 */ public static void main(String[] args) throws IOException { //demo1(); PrintWriter pw = new PrintWriter(new FileOutputStream("f.txt"),true); //pw.println(97); //自动刷出功能只针对的是println方法 //pw.write(97); pw.print(97); pw.println(97); pw.close(); } public static void demo1() { System.out.println("aaa"); PrintStream ps = System.out; //获取标注输出流 ps.println(97); //底层经过Integer.toString()将97转换成字符串并打印 ps.write(97); //查找码表,找到对应的a并打印 Person p1 = new Person("张三", 23); ps.println(p1); //默认调用p1的toString方法 Person p2 = null; //打印引用数据类型,若是是null,就打印null,若是不是null就打印对象的toString方法 ps.println(p2); ps.close(); } }
2.修改标准输入输出流(了解)
System.setIn(new FileInputStream("a.txt")); //修改标准输入流 System.setOut(new PrintStream("b.txt")); //修改标准输出流 InputStream in = System.in; //获取标准输入流 PrintStream ps = System.out; //获取标准输出流 int b; while((b = in.read()) != -1) { //从a.txt上读取数据 ps.write(b); //将数据写到b.txt上 } in.close(); ps.close();
package com.heima.otherio; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.PrintStream; public class Demo06_SystemInOut { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { //demo1(); System.setIn(new FileInputStream("a.txt")); //改变标准输入流 System.setOut(new PrintStream("b.txt")); //改变标注输出流 InputStream is = System.in; //获取标准的键盘输入流,默认指向键盘,改变后指向文件 PrintStream ps = System.out; //获取标准输出流,默认指向的是控制台,改变后就指向文件 int b; while((b = is.read()) != -1) { ps.write(b); } //System.out.println(); //也是一个输出流,不用关,由于没有和硬盘上的文件产生关联的管道 is.close(); ps.close(); } public 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); } }
package com.heima.otherio; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Scanner; public class Demo07_SystemIn { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { /*BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); //InputStreamReader转换流 String line = br.readLine(); System.out.println(line); br.close();*/ Scanner sc = new Scanner(System.in); String line = sc.nextLine(); System.out.println(line); sc.close(); } }
System.setIn(new FileInputStream("IO图片.png")); //改变标准输入流 System.setOut(new PrintStream("copy.png")); //改变标准输出流 InputStream is = System.in; //获取标准输入流 PrintStream ps = System.out; //获取标准输出流 int len; byte[] arr = new byte[1024 * 8]; while((len = is.read(arr)) != -1) { ps.write(arr, 0, len); } is.close(); ps.close();
package com.heima.test; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.PrintStream; public class Test2 { /** * @param args * @throws IOException */ public static void main(String[] args) throws IOException { System.setIn(new FileInputStream("双元.jpg")); //改变标准输入流 System.setOut(new PrintStream("copy.jpg")); //改变标准输出流 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(); } }
package com.heima.otherio; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.Enumeration; import java.util.Properties; public class Demo10_Properties { /** * @param args * Properties是Hashtable的子类 * @throws IOException * @throws FileNotFoundException */ public static void main(String[] args) throws FileNotFoundException, IOException { //demo1(); //demo2(); Properties prop = new Properties(); prop.load(new FileInputStream("config.properties")); //将文件上的键值对读取到集合中 prop.setProperty("tel", "18912345678"); prop.store(new FileOutputStream("config.properties"), null);//第二个参数是对列表参数的描述,能够给值,也能够给null System.out.println(prop); } public static void demo2() { Properties prop = new Properties(); prop.setProperty("name", "张三"); prop.setProperty("tel", "18912345678"); //System.out.println(prop); Enumeration<String> en = (Enumeration<String>) prop.propertyNames(); while(en.hasMoreElements()) { String key = en.nextElement(); //获取Properties中的每个键 String value = prop.getProperty(key); //根据键获取值 System.out.println(key + "="+ value); } } public static void demo1() { Properties prop = new Properties(); prop.put("abc", 123); System.out.println(prop); } }
package com.heima.test; import java.io.ByteArrayOutputStream; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; public class Test1 { /** * @param args * 定义一个文件输入流,调用read(byte[] b)方法,将a.txt文件中的内容打印出来(byte数组大小限制为5) * * 分析: * 1,reda(byte[] b)是字节输入流的方法,建立FileInputStream,关联a.txt * 2,建立内存输出流,将读到的数据写到内存输出流中 * 3,建立字节数组,长度为5 * 4,将内存输出流的数据所有转换为字符串打印 * 5,关闭输入流 * @throws IOException */ public static void main(String[] args) throws IOException { //1,reda(byte[] b)是字节输入流的方法,建立FileInputStream,关联a.txt FileInputStream fis = new FileInputStream("a.txt"); //2,建立内存输出流,将读到的数据写到内存输出流中 ByteArrayOutputStream baos = new ByteArrayOutputStream(); //3,建立字节数组,长度为5 byte[] arr = new byte[5]; int len; while((len = fis.read(arr)) != -1) { baos.write(arr, 0, len); //System.out.println(new String(arr,0,len)); } //4,将内存输出流的数据所有转换为字符串打印 System.out.println(baos); //即便没有调用,底层也会默认帮咱们调用toString()方法 //5,关闭输入流 fis.close(); } }