PrintStream
特点
- 提供了打印方法
print()可以对多种数据类型值进行打印，并保持数据的表现形式，但是不保证数据的大小（即输入与输出的东西看起来一模一样） - 他不抛IOException
SequenceInputStream
特点
序列流
将多个流进行合并
例
将1.txt、2.txt、3.txt中的数据合并到4.txt中
public class SequenceInputStreamDemo {
public static void main(String[] args) throws IOException {
ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
al.add(new FileInputStream("D:\\1.txt"));
al.add(new FileInputStream("D:\\2.txt"));
al.add(new FileInputStream("D:\\3.txt"));
Enumeration<FileInputStream> en = Collections.enumeration(al);
SequenceInputStream sis = new SequenceInputStream(en);
FileOutputStream fos = new FileOutputStream("D:\\4.txt");
byte[] b = new byte[1024];
int len = 0;
while((len=sis.read(b)) != -1) {
fos.write(b,0,len);
}
sis.close();
fos.close();
}
}
文件切割器
public class SplitFile {
private static final int SIZE = 1024*1024;
public static void main(String[] args) throws IOException {
//File file = new File("D:\\IOtest\\1.png");
File file = new File("E:\\Pictures\\身份证正面.jpg");
splitFile(file);
}
private static void splitFile(File file) throws IOException {
//用读取流关联源文件
FileInputStream fis = new FileInputStream(file);
//自定义1M的缓冲区
byte[] buf = new byte[SIZE];
//创建目的
FileOutputStream fos = null;
int len = 0;
int count = 1;
File dir = new File("D:\\IOtest\\part");
if(!dir.exists()) {
dir.mkdirs();
}
while((len = fis.read(buf)) != -1) {
fos = new FileOutputStream(new File(dir,count++ + ".part"));
fos.write(buf,0,len);
}
//保存切割文件的配置信息
Properties prop = new Properties();
prop.setProperty("partCount", count+"");
prop.setProperty("fileName", file.getName());
prop.store(new FileOutputStream(new File(dir,"my.properties")), "save file info");
fis.close();
fos.close();
}
}
合并文件
public class MergeFile {
public static void main(String[] args) throws IOException {
File dir = new File("D:\\IOtest\\part");
mergeFile(dir);
}
private static void mergeFile(File dir) throws IOException {
//得到配置信息
Properties prop = getConfig(dir);
String partCount = (String) prop.get("partCount");
int count = Integer.parseInt(partCount);
//配置文件校验
validateConfig(count,dir);
ArrayList<FileInputStream> al = new ArrayList<FileInputStream>();
for (int i = 1; i < count; i++) {
al.add(new FileInputStream(new File(dir,i+".part")));
}
Enumeration<FileInputStream> en = Collections.enumeration(al);
SequenceInputStream sis = new SequenceInputStream(en);
FileOutputStream fos = new FileOutputStream(new File(dir,prop.getProperty("fileName")));
byte[] buf = new byte[1024];
int len = 0;
while((len = sis.read(buf)) != -1) {
fos.write(buf, 0, len);
}
sis.close();
fos.close();
}
private static void validateConfig(int count, File dir) {
String[] list = dir.list(new FilenameFilter() {
public boolean accept(File arg0, String arg1) {
boolean endsWith = arg1.endsWith(".part");
return endsWith;
}
});
if (count - 1 != list.length) {
throw new RuntimeException("碎片文件个数不对");
}
}
private static Properties getConfig(File dir) throws IOException {
Properties prop = new Properties();
File file = new File(dir,"my.properties");
if(!file.exists())
throw new RuntimeException("配置文件不存在");
prop.load(new FileInputStream(file));
return prop;
}
}
Object(input|Output)Stream
一个操作对象的流
代码
public class ObjectOutputStreamDemo {
public static void main(String[] args) throws IOException, ClassNotFoundException {
//writeObj();
readerObj();
}
private static void readerObj() throws IOException, ClassNotFoundException {
ObjectInputStream ois = new ObjectInputStream(new FileInputStream("D:\\IOtest\\obj.object"));
Person p = (Person) ois.readObject();
System.out.println(p.getName()+":"+p.getAge());
}
private static void writeObj() throws IOException {
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("D:\\IOtest\\obj.object"));
oos.writeObject(new Person("小强",18));
oos.close();
}
}
对象序列化
Serializable:
- 用于给被序列化的类加入ID号
- 用于判断类和对象是否是同一个版本
public class Person implements Serializable{
private static final long serialVersionUID = 1L;
private String name;
private int age;
public Person(String name, int age) {
super();
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;
}
}
RandomAccessFile
特点
- 该对象既能读，也能写
- 该对象内部维护了一个byte数组，并通过指针可以操作数组中的元素
- 可以通过getFilePointer方法获取指针的位置，和通过seek方法设置指针的位置
- 其实该对象就是讲字节输入流和输出流进行了封装
- 该对象的源和目的只能是文件。
代码
public class RandomAccessFileDemo {
public static void main(String[] args) throws IOException {
/*
* 特点：
* 1.该对象既能读，也能写
* 2.该对象内部维护了一个byte数组，并通过指针可以操作数组中的元素
* 3.可以通过getFilePointer方法获取指针的位置，和通过seek方法设置指针的位置
* 4.其实该对象就是讲字节输入流和输出流进行了封装
* 5.该对象的源和目的只能是文件。
*/
writerFile();
readerFile();
}
private static void readerFile() throws IOException {
RandomAccessFile raf = new RandomAccessFile("D:\\IOtest\\random.txt", "r");
//通过seek设置指针的位置
raf.seek(0*8);//随机的读取。只要指定指针的位置即可
byte[] buf = new byte[4];
raf.read(buf);
String name = new String(buf);
int age = raf.readInt();
System.out.println("name="+name);
System.out.println("age="+age);
System.out.println("pos:"+raf.getFilePointer());
raf.close();
}
//使用RandomAccessFile对象写入一些人员信息，比如姓名和年龄
private static void writerFile() throws IOException {
RandomAccessFile raf = new RandomAccessFile("D:\\IOtest\\random.txt", "rw");
raf.write("张三".getBytes());
raf.writeInt(97);
raf.write("李四".getBytes());
raf.writeInt(32);
raf.close();
}
}
管道流
输入输出可以直接进行连接，通过结合多线程使用。
public class PipedStreamDemo {
public static void main(String[] args) throws IOException {
PipedInputStream in = new PipedInputStream();
PipedOutputStream out = new PipedOutputStream();
in.connect(out);
new Thread(new Input(in)).start();
new Thread(new Output(out)).start();
}
}
class Input implements Runnable{
PipedInputStream in;
Input(PipedInputStream in){
this.in = in;
}
@Override
public void run() {
try {
byte[] buf = new byte[1024];
int len = in.read(buf);
String s = new String(buf,0,len);
System.out.println(s);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
class Output implements Runnable{
PipedOutputStream out;
Output(PipedOutputStream out){
this.out = out;
}
@Override
public void run() {
try {
Thread.sleep(5000);
out.write("管道来了！".getBytes());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
DataStream
操作基本数据类型用该流
public class DataStreamDemo {
public static void main(String[] args) throws IOException {
writeDate();
readDate();
}
@SuppressWarnings("resource")
private static void readDate() throws IOException {
DataInputStream dis = new DataInputStream(new FileInputStream("D:\\IOtest\\data.txt"));
String s = dis.readUTF();
System.out.println(s);
dis.close();
}
@SuppressWarnings("resource")
private static void writeDate() throws IOException {
DataOutputStream dos = new DataOutputStream(new FileOutputStream("D:\\IOtest\\data.txt"));
dos.writeUTF("你好");
dos.close();
}
}