Java IO总结之缓冲读入文件

package com.io;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.LinkedList;

/**
 * 缓冲读入文件
 * @author Administrator
 *
 */
public class BufferedInputFile {

    public static String read(String filename) throws IOException{
            //reading input by lines:
        BufferedReader in = new BufferedReader(new FileReader(filename));
        String s;
        StringBuilder sb= new StringBuilder();
        
        while((s=in.readLine())!=null){
            sb.append(s+"\n");
        }
        in.close();
        return sb.toString();
    }
    
    //test1,打开一个文本文件,每次读取一行内容,将每行作为一个string读入,并将该string对象存入linklist中,逆序打印linklist
    public static void printLinkList(String fileName) throws IOException{
        BufferedReader in = new BufferedReader(new FileReader("C:/Users/Administrator/Desktop/exec.txt"));
        String string;
        LinkedList<String> list = new LinkedList<String>();
        while((string=in.readLine())!=null){
            list.add(string);
        }
        /*for(int i=list.size();i>=0;i--){
            System.out.println(list.get(i));
        }*/
        java.util.ListIterator<String> item = list.listIterator(list.size());
        
        while(item.hasPrevious()){
            System.out.println(item.previous());
        }
        
        while(item.hasNext()){
            System.out.println(item.next());
        }
        
        /**
         * 结果:
         *  4-->4-->4:4:4:ghdgml11
            3-->3-->3:3:3:flypiger
            2-->2-->2:2:2:ghdgml11
            1-->1-->1:1:1:flypiger
         */
        
    }
    
    public static void main(String[] args) throws IOException {
        //System.out.println(read("C:/Users/Administrator/Desktop/exec.txt"));
        printLinkList("C:/Users/Administrator/Desktop/exec.txt");
    }
}

不要问为什么,代码诠释一切

package com.io;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringReader;
/**
 * 基本的io
 * @author Administrator
 *
 */
public class BasicFileOutput {

    public static String file = "C:/Users/Administrator/Desktop/exec.txt";
    public static String file1 = "C:/Users/Administrator/Desktop/exe.txt";
    public static void main(String[] args) throws IOException {
        //使用BufferedReader缓冲读入流,使用StringReader包装一个BufferedInputFile.read方法读取的字符串文件流
        System.out.println(BufferedInputFile.read(file));
        BufferedReader in = new BufferedReader(new StringReader(BufferedInputFile.read(file)));
        //FileWriter可以写数据的对象,用BufferedWriter缓冲流包装提升性能,再用PrintWriter包装提升格式
        PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(file1)));
        int lineCount = 1;
        String string;
        while((string=in.readLine())!=null){
            out.println(lineCount++ +": "+string);
        }
        out.flush();
        out.close();
        in.close();
        System.out.println(BufferedInputFile.read(file1));
    }
}

package com.io;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

/**
 * 读取二进制文件
 * @author Administrator
 *
 */
public class BinaryFile {

    public static byte[] read(File file) throws IOException{
        BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(file));
        byte[] data = new byte[inputStream.available()];
        
        inputStream.read(data);
        inputStream.close();
        
        return data;
        
    }
    public static byte[] read(String file) throws IOException{
        return read(new File(file).getAbsoluteFile());
    }
}

package com.io;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
/**
 * 格式化的内存输出
 * @author Administrator
 *
 */
public class FormattedMemoryInput {

    public static void main(String[] args) throws IOException {
        DataInputStream in= new DataInputStream(new ByteArrayInputStream(BufferedInputFile.read("C:/Users/Administrator/Desktop/exec.txt").getBytes()));
        //available用来查询还有多少可供存取的字符
        while(in.available()!=0){
            System.out.println(in.readByte());
        }
    }
}

package com.io;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
 * 用GZIP进行压缩,有空总结常用流的包装
 * @author Administrator
 *
 */
public class GZIPcompress {
    /**压缩/解压缩 常用流,可根据实例替换
     * ZipOutputStream 
     * ZipInputStream
     * GZipOutputStream 
     * GZipInputStream
     * @param args
     * @throws IOException
     */
    
    public static void main(String[] args) throws IOException {
        if(args.length==0){
            System.out.println(
            "Usage: \nGZIPcompress file\n"+
            "\tUsers GZIP compression to compress "+
            "the file to test.gz"
            );
        BufferedReader in = new BufferedReader(new FileReader("C:/Users/Administrator/Desktop/exec.txt"));
                                                                                                                                    //后缀名可以是.gz .gzip.zip
        BufferedOutputStream out= new BufferedOutputStream(new GZIPOutputStream(new FileOutputStream("C:/Users/Administrator/Desktop/test.gz")));
        System.out.println("Writing file*********************************");
        
        int c;
        while((c=in.read())!=-1){
            out.write(c);
        }
        out.close();
        in.close();
        System.out.println("reading file*********************************");
        
        BufferedReader in2 = new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream("C:/Users/Administrator/Desktop/test.gz"))));
        String string;
        while((string=in2.readLine())!=null){
            System.out.println(string);
        }
        }
    }
}

package com.io;

import java.io.IOException;
import java.io.StringReader;

/**
 * 从内存中读取,没什么好说的
 * @author Administrator
 *
 */
public class MemoryInput {

    public static void main(String[] args) throws IOException {
        StringReader in = new StringReader(BufferedInputFile.read("C:/Users/Administrator/Desktop/exec.txt"));
        //SringReader读取的int类型的,所以要转换成char打印
        int c;
        while((c=in.read())!=-1){
            System.out.println((char)c);
        }
    }
}