java之IO整理（中）

Posted 2020-09-23 Ipeter

一：打印流
/*System.out.println()重定向输出*/
	/*public static void main(String[] args) {
		System.out.println("MM");//直接输出到控制台
		File file=new File("d:"+File.separator+"mm.txt");
		try {
			System.setOut(new PrintStream(new FileOutputStream(file)));
		} catch (FileNotFoundException e) {			
			e.printStackTrace();
		}
		System.out.println("这些内容在文件中才能看到哦！");
	}*/
	
	/*System.err重定向 这个例子也提示我们可以使用这种方法保存错误信息*/
	/*public static void main(String[] args) {
		File file=new File("d:"+File.separator+"mm.txt");
		System.out.println("这些在控制台输出！");
		try {
			System.setErr(new PrintStream(new FileOutputStream(file)));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
		System.out.println("这些内容在文件中才能看到哦！");
	}*/
	
	/*BufferedReader的小例子
	注意： BufferedReader只能接受字符流的缓冲区，因为每一个中文需要占据两个字节，所以需要将System.in这个字节输入流变为字符输入流，采用：
	BufferedReader buf = new BufferedReader(
	new InputStreamReader(System.in));*/
	public static void main(String[] args) {
		BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(System.in));
		String str=null;
		System.out.println("请输入内容：");
		try {
			str=bufferedReader.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		System.out.println("你输入的内容是："+str);
	}

　　二：合并流：

package com.js.ai.modules.pointwall.testxfz;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.SequenceInputStream;
/*将两个文本文件合并为另外一个文本文件*/
public class SequenceInputStreamDemo {
public static void main(String[] args) throws IOException {
	File file1=new File("d:"+File.separator+"hello1.txt");
	File file2=new File("d:"+File.separator+"hello2.txt");
	File file3=new File("d:"+File.separator+"hello.txt");
	InputStream inputStream1=new FileInputStream(file1);
	InputStream inputStream2=new FileInputStream(file2);
	OutputStream outputStream=new FileOutputStream(file3);
	//合并流
	SequenceInputStream sequenceInputStream=new SequenceInputStream(inputStream1, inputStream2);
	int temp=0;
	while((temp=sequenceInputStream.read())!=(-1)){
		outputStream.write(temp);
	}
	inputStream1.close();
	inputStream2.close();
	outputStream.close();
	sequenceInputStream.close();
}
}

　　三：文件压缩：

/*压缩单个文件*/
public class ZipOutputStreamDemo1 {
public static void main(String[] args) throws IOException {
	File file=new File("d:"+File.separator+"hello.txt");
	File zipFile=new File("d:"+File.separator+"hello.zip");
	InputStream inputStream=new FileInputStream(file);
	ZipOutputStream zipOutputStream=new ZipOutputStream(new FileOutputStream(zipFile));
	zipOutputStream.putNextEntry(new ZipEntry(file.getName()));
	zipOutputStream.setComment("Hello");//设置注释
	int temp=0;
	while((temp=inputStream.read())!=(-1)){
		zipOutputStream.write(temp);
	}
	inputStream.close();
	zipOutputStream.close();
}
}

　　

/*压缩多个文件*/
public class ZipOutputStreamDemo1 {
public static void main(String[] args) throws IOException {
	File file=new File("d:"+File.separator+"temp");// 要被压缩的文件夹
	File zipFile=new File("d:"+File.separator+"zipFile.zip");
	InputStream inputStream=null;
	ZipOutputStream zipOutputStream=new ZipOutputStream(new FileOutputStream(zipFile));
	zipOutputStream.setComment("Hello");//设置注释
	if(file.isDirectory()){
		File[] files =file.listFiles();
		for(int i=0;i<files.length;i++){
			inputStream=new FileInputStream(files[i]);
			zipOutputStream.putNextEntry(new ZipEntry(file.getName()+File.separator+files[i].getName()));
			int temp=0;
			while((temp=inputStream.read())!=(-1)){
				zipOutputStream.write(temp);
			}
			inputStream.close();
		}
	}	
	zipOutputStream.close();
}
}

　　四：文件解压

/*解压单个文件*/
public class ZipOutputStreamDemo1 {
public static void main(String[] args) throws IOException {
	File file=new File("d:"+File.separator+"hello.zip");
	File outFile=new File("d:"+File.separator+"outZipFile.txt");
	ZipFile zipFile=new ZipFile(file);
	ZipEntry entry=zipFile.getEntry("hello.txt");	
	InputStream inputStream=zipFile.getInputStream(entry);
	OutputStream OutputStream=new FileOutputStream(outFile);	
			int temp=0;
			while((temp=inputStream.read())!=(-1)){
				OutputStream.write(temp);
			}
			inputStream.close();			
	OutputStream.close();
}
}

　　

/*解压一个压缩文件中包含多个文件的情况*/
public class ZipOutputStreamDemo1 {
public static void main(String[] args) throws IOException {
	File file=new File("d:"+File.separator+"zipFile.zip");
	File outFile=null;
	ZipFile zipFile=new ZipFile(file);
	ZipInputStream zipInputStream=new ZipInputStream(new FileInputStream(file));
	ZipEntry entry=null;
	InputStream inputStream=null;
	OutputStream OutputStream=null;	
	while((entry=zipInputStream.getNextEntry())!=null){
		System.out.println("解压文件："+entry.getName());
		outFile=new File("d:"+File.separator+entry.getName());
		if(!outFile.getParentFile().exists()){
			outFile.getParentFile().mkdirs();
		}
		if(!outFile.exists()){
			outFile.createNewFile();
		}
		inputStream=zipFile.getInputStream(entry);
		OutputStream=new FileOutputStream(outFile);
		int temp=0;
		while((temp=inputStream.read())!=(-1)){
			OutputStream.write(temp);
		}
		inputStream.close();			
		OutputStream.close();
	}			
}
}

　　五、回退流

public class PushBackInputStreamDemo {
public static void main(String[] args) throws Exception {
	String str="hello,rollenholt";
	PushbackInputStream push=null;
	ByteArrayInputStream bat=null;
	bat=new ByteArrayInputStream(str.getBytes());
	push=new PushbackInputStream(bat);
	int temp=0;
	while((temp=push.read())!=(-1)){
		if(temp==‘,‘){
			push.unread(temp);
			temp=push.read();
			System.out.print("(回退："+(char)temp+")");
		}else {
			System.out.print((char)temp);
		}
	}
}
}