java读写文件

大大源码 • 2023年4月13日 pm9:02 • 未分类

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.util.*;

public class ReadFromFile {
    /**
     * 以字节为单位读取文件，常用于读二进制文件，如图片、声音、影像等文件。
     */
private static DataInputStream dis=null;
private static DataOutputStream dos=null;
private static List<MrBean> list=new ArrayList<MrBean>();

    public static void readFileByBytes(String fileName) {
        File file = new File(fileName);
        InputStream in = null;
        int i=0;
        /*try {
            System.out.println("以字节为单位读取文件内容，一次读一个字节：");
            // 一次读一个字节
            in = new FileInputStream(file);
            int tempbyte;
            while ((tempbyte = in.read()) != -1) {
                System.out.println(tempbyte);
            }
            in.close();
        } catch (IOException e) {
            e.printStackTrace();
            return;
        }*/
        try {
            System.out.println("以字节为单位读取文件内容，一次读多个字节：");
            // 一次读多个字节
            byte[] tempbytes = new byte[20];
            int byteread = 0;
            in = new FileInputStream(fileName);
            ReadFromFile.showAvailableBytes(in);

            // 读入多个字节到字节数组中，byteread为一次读入的字节数
            while ((byteread = in.read(tempbytes)) != -1) {
            //System.out.println(Integer.parseInt(new String(tempbytes, 0, 4)));
            System.out.write(tempbytes, 0, 4);
            System.out.write(tempbytes, 4, 2);
            System.out.write(tempbytes, 6, 2);
            System.out.write(tempbytes, 8, 2);
            System.out.write(tempbytes, 10, 2);
            System.out.write(tempbytes, 12, 1);
            System.out.write(tempbytes, 13, 1);
            System.out.write(tempbytes, 14, 1);
            System.out.write(tempbytes, 15, 1);
            System.out.write(tempbytes, 16, 4);
                //System.out.println(tempbytes.toString());
            System.out.write(tempbytes, 0, byteread);
            System.out.print("\n");
                //System.out.println(new String(tempbytes, 0, byteread));
            i++;
            if(i==10)
              break;
            }
        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 以字符为单位读取文件，常用于读文本，数字等类型的文件
     */
    public static void readFileByChars(String fileName) {
        File file = new File(fileName);
        Reader reader = null;
       /* try {
            System.out.println("以字符为单位读取文件内容，一次读一个字节：");
            // 一次读一个字符
            reader = new InputStreamReader(new FileInputStream(file));
            int tempchar;
            while ((tempchar = reader.read()) != -1) {
                // 对于windows下，\r\n这两个字符在一起时，表示一个换行。
                // 但如果这两个字符分开显示时，会换两次行。
                // 因此，屏蔽掉\r，或者屏蔽\n。否则，将会多出很多空行。
                if (((char) tempchar) != '\r') {
                    System.out.print((char) tempchar);
                }
            }
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }*/
        try {
            System.out.println("以字符为单位读取文件内容，一次读多个字节：");
            // 一次读多个字符
            char[] tempchars = new char[20];
            int charread = 0;
            reader = new InputStreamReader(new FileInputStream(fileName));
            // 读入多个字符到字符数组中，charread为一次读取字符数
            while ((charread = reader.read(tempchars)) != -1) {
                // 同样屏蔽掉\r不显示
                if ((charread == tempchars.length)
                        && (tempchars[tempchars.length - 1] != '\r')) {
                    System.out.print(tempchars);
                } else {
                    for (int i = 0; i < charread; i++) {
                        if (tempchars[i] == '\r') {
                            continue;
                        } else {
                            System.out.print(tempchars[i]);
                        }
                    }
                }
            }

        } catch (Exception e1) {
            e1.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 以行为单位读取文件，常用于读面向行的格式化文件
     */
    public static void readFileByLines(String fileName) {
        File file = new File(fileName);
        BufferedReader reader = null;
        try {
            System.out.println("以行为单位读取文件内容，一次读一整行：");
            reader = new BufferedReader(new FileReader(file));
            String tempString = null;
            int line = 1;
            // 一次读入一行，直到读入null为文件结束
            while ((tempString = reader.readLine()) != null) {
                // 显示行号
                System.out.println("line " + line + ": " + tempString);
                line++;
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                }
            }
        }
    }

    /**
     * 显示输入流中还剩的字节数
     */
    private static void showAvailableBytes(InputStream in) {
        try {
            System.out.println("当前字节输入流中的字节数为:" + in.available());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void readMethod2(String fileName)
    {
        try
        {
            FileInputStream stream=new FileInputStream(fileName);
            int c;
            while((c=stream.read())!=-1)
            {
                System.out.println(c);
            }
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    /**读取二进制文件**/
    public static void readBinaryStream(String fileName){
    //System.out.println("123");
    //int i=0;
    //File file = new File(fileName);
        try{
        dis=new DataInputStream(new FileInputStream(new File(fileName)));
        //System.out.println(dis.available());
            if(dis!=null){
                while(dis.available()>0){
                //System.out.println("456");
                    //System.out.println(dis.available());
                MrBean mrBean=new MrBean();
                    //System.out.print(dis.readInt()+" ");
                    mrBean.setTIME_STAMP(dis.readInt());
                    //System.out.print((int)dis.readChar()+" ");
                    mrBean.setTRX_ID((int)dis.readChar());
                    //System.out.print((int)dis.readChar()+" ");
                    mrBean.setLAC((int)dis.readChar());
                    //System.out.print((int)dis.readChar()+" ");
                    mrBean.setCI((int)dis.readChar());
                    //System.out.print((int)dis.readChar()+" ");
                    mrBean.setTEI((int)dis.readChar());
                    //System.out.print(dis.readByte()+" ");
                    mrBean.setVALUE_1(dis.readByte());
                    //System.out.print(dis.readByte()+" ");
                    mrBean.setVALUE_2(dis.readByte());
                    //System.out.print(dis.readByte()+" ");
                    mrBean.setVALUE_3(dis.readByte());
                    //System.out.print(dis.readByte()+" ");
                    mrBean.setVALUE_4(dis.readByte());
                    //System.out.print(dis.readInt()+" ");
                    mrBean.setCOUNTS(dis.readInt());
                    //System.out.println(dis.read(m_datapadding));
                    list.add(mrBean);
                    //System.out.println("");
                   /* i++;
                    if(i==100)
                    break;*/
                }
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    /**写入二进制文件**/
    public static void writeBinaryStream(String fileName,List<MrBean> list){
        try{
        dos=new DataOutputStream(new FileOutputStream(new File(fileName)));
            if(dos!=null){
                for(int i=0;i<list.size();i++){
                    dos.writeInt(list.get(i).getTIME_STAMP());
                    dos.writeChar(list.get(i).getTRX_ID());
                    dos.writeChar(list.get(i).getLAC());
                    dos.writeChar(list.get(i).getCI());
                    dos.writeChar(list.get(i).getTEI());
                    dos.writeByte(list.get(i).getVALUE_1());
                    dos.writeByte(list.get(i).getVALUE_2());
                    dos.writeByte(list.get(i).getVALUE_3());
                    dos.writeByte(list.get(i).getVALUE_4());
                    dos.writeInt(list.get(i).getCOUNTS());
                    //dos.write(m_datapadding);
                }
                dos.flush();
                dos.close();
            }
        }catch(Exception e){
            e.printStackTrace();
        }
    }


    public static void main(String[] args) {
        String fileName = "E:/RLU_RLD.dat";
        String outFileName = "E:/RLU_RLD_SORTED.DAT.dat";
        //ReadFromFile.readMethod2(fileName);
        //ReadFromFile.readFileByBytes(fileName);
        //ReadFromFile.readFileByChars(fileName);
        //ReadFromFile.readFileByLines(fileName);
        //ReadFromFile.readFileByRandomAccess(fileName);
        ReadFromFile.readBinaryStream(fileName);
        QuickSort.quickSortByList(list, 0, list.size()-1);
        for(int i=0;i<list.size();i++)
        {
        System.out.println(list.get(i).getTIME_STAMP()+" "+list.get(i).getTRX_ID()+" "+list.get(i).getLAC()+" "+list.get(i).getCI()+" "+list.get(i).getTEI()+" "+list.get(i).getVALUE_1()+" "+list.get(i).getVALUE_2()+" "+list.get(i).getVALUE_3()+" "+list.get(i).getVALUE_4()+" "+list.get(i).getCOUNTS());
        }
        ReadFromFile.writeBinaryStream(outFileName, list);
    }
}

原文链接：https://blog.csdn.net/merry3602/article/details/7045512

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