File类 IO流 第五讲091205B

1）file.listFiles()返回f目录下的文件数组
2）File.listRoots()返回本地磁盘驱动器的数组

TestFile.java
File类

import java.io.File;
import java.text.SimpleDateFormat;

public class TestFile {
	public static void main(String[] args) {
		File f=new File("e:\\1.txt");
		System.out.println(f.exists());
		System.out.println(f.canExecute());
		System.out.println(f.getName());
		System.out.println(f.getFreeSpace()/1024.0/1024/1024);
		System.out.println(f.listFiles());//（1） 
		SimpleDateFormat smp=new SimpleDateFormat("yy-MM-dd");
		System.out.println(smp.format(f.lastModified()));
	
		System.out.println(File.listRoots()[3]); //（2）
		}
}

输出：
true
true
1.txt
10.352336883544922
null
09-12-06
F:\

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MyDir.java
制作自己的DIR .对file类的属性方法进行练习。

import java.io.File;
import java.text.DecimalFormat;
import java.text.SimpleDateFormat;

public class MyDir {

	public static void main(String[] args) {
		File f = new File("e:\\");
		File fs[] = f.listFiles();
		for (File file : fs) {
			Show(file);
		}
	}

	static void Show(File f) {
		SimpleDateFormat smp = new SimpleDateFormat("yy-MM-dd");
		DecimalFormat df = new DecimalFormat("#.0000000MB");
		String time = smp.format(f.lastModified());
		String isdir = f.isDirectory() ? "<DIR>" : "";
		String size = df.format(f.length() / 1024.0 / 1024);
		String name = f.getName();
		System.out.println(String.format("%1$-10s%2$-8s%3$-15s%4$-20s", time , isdir, size, name));
	}
}

输出：
09-12-06          .0001984MB     1.log              
09-12-06          .0000095MB     1.txt              
09-12-06          .0009766MB     3.txt              
09-12-06          .0000000MB     4.txt              
09-12-06          .0000267MB     5.txt              
09-12-06          .0000725MB     data.txt           
09-02-17  <DIR>   .0000000MB     game               
08-10-06  <DIR>   .0000000MB     GHOST              
09-12-06          .0000000MB     log.txt            
09-11-15  <DIR>   .0000000MB     movie              
09-02-25  <DIR>   .0000000MB     music              
09-12-06  <DIR>   .0000000MB     myjava             
09-12-06          .0000343MB     MyLog4j.properties 
09-12-06          .0000715MB     p.txt              
09-12-06          .0000124MB     pro.txt            
09-04-22          .0004606MB     pwk.rar            
08-10-06  <DIR>   .0000000MB     RECYCLER           
09-11-29  <DIR>   .0000000MB     soft_JAVA          
70-01-01  <DIR>   .0000000MB     System Volume Information
09-02-24          .0131836MB     Thumbs.db             
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IOStreamTest.JAVA
对“E:\\1.TXT”的文件进行读写操作。fileinputstream.read();fileoutputstream.write()

import java.io.*;

public class IOStreamTest {
	public static void main(String[] args) {	
		//输出流
		try {
			OutputStream ops = new FileOutputStream("e:\\1.txt");
			ops.write('B');
			ops.write('M');
			ops.write('W'); 
			
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		//输入流
		try {
			InputStream ipts = new FileInputStream("e:\\1.txt");
			int i = 0;
			while (true) {
				i = ipts.read();
				if (i == -1)
					break;
				System.out.print((char) i);
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

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1) 把bis读入的信息写入数组b[]
2) 把b[]数组里面的信息写入bos
3）BufferedInput（Output）Stream为处理流，在节点流外头套了一个套子。 StreamCopy.java
文件按位拷贝

import java.io.*;

public class StreamCopy {

	public static void main(String[] args) {
		try {
			InputStream is = new FileInputStream("e:\\1.txt");
			InputStream bis = new BufferedInputStream(is); //（3）

			OutputStream os = new FileOutputStream("e:\\3.txt");
			OutputStream bos = new BufferedOutputStream(os);

			byte b[] = new byte[1024];
			while ((bis.read(b)) != -1) {//（1）
				bos.write(b);//（2）
			}
			bos.close();

		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}

	}
}

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TestFileReader.java。。。。。。。。。。。。。。。。。。。
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1)类要被读取写入，该类需要实现序列接口
2）PersonOut.java将定义的人物“new Person(9527, "唐伯虎")”，记录到“e:\\data.txt”文件中。PersonIn.java从文件中读出object类。
（transient使用此关键字标记属性，使该属性不被记录。Person 若实现Externalizable接口可以定义读取写入规则。）

Object流
Person.java

import java.io.Serializable;
public class Person implements Serializable {//（1）
	private static final long serialVersionUID = 2894597671409392626L;
	int id;
	String name;
	@Override
	public String toString() {
		return this.id+"|"+this.name;
	}
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Person(int id, String name) {
		super();
		this.id = id;
		this.name = name;
	}
}

PersonOut.java

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

public class PersonOut {
	public static void main(String[] args) {
		Person p = new Person(9527, "唐伯虎");		 
		try {
			OutputStream os = new FileOutputStream("e:\\data.txt");
			ObjectOutputStream oos = new ObjectOutputStream(os);
			oos.writeObject(p);		 
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

PersonIn.java

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;

public class PersonIn {
	public static void main(String[] args) {
		try {
			InputStream is=new FileInputStream("e:\\data.txt");
			ObjectInputStream ois= new ObjectInputStream(is);
			System.out.println(ois.readObject());			 	
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}		
	}
}

输出：
9527|唐伯虎
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Properties类是一类特殊的map集合框架
1）加载读取文件内的属性的方法。Properties.load(),properties.store()

PropertiesLoadTest.java

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

public class PropertiesLoadTest {
	public static void main(String[] args) {
		Properties pr = new Properties();
		try {
			pr.load(new FileInputStream("e:\\pro.txt"));//（1）
			/*pro.txt
			 * b=2（换行）a=1（换行） c=3
			 */
			Set<?> s = pr.keySet();
			for (Object object : s) {
				System.out.println(object + "=" + pr.get(object));
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

输出：
b=2
a=1
c=33
PropertiesSendTest.java

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

public class PropertiesSendTest {
	public static void main(String[] args) {
		Properties pro= new Properties();
		pro.put("122", "alue");
		pro.put("120", "aluew");
		pro.put("432", "aluewe");
		try {
			pro.store(new FileOutputStream("e:\\p.txt"), "MyComments");//（1）
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

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Log4jDemo.java。。。。。。。。。。。。。。。。。。。
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