Java File类功能扩展

在Java中，File类无法提供：删除文件指定行，获得文件指定行，复制文件的某一行到指定文件，文件倒序，以及匹配文件中的关键信息等操作。而这些操作往往又是我们工作中需要用到的，今天写出来供大家分享。

package util;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.util.ArrayList;public class DoWithFile {    /**     * @param inPutFilePath     * @param OutputFilePath     * @param startLine     * @param endLine     * @describe 复制文件中的指定行数到指定的文件中     * @return     */    public static boolean copyFileByLineRang(String inPutFilePath, String OutputFilePath, int startLine, int endLine){        if(inPutFilePath == null || inPutFilePath.trim().equals("") || OutputFilePath == null || OutputFilePath.trim().equals("") || startLine < 0 || endLine < 0 || startLine > endLine){            return false;        }        String stringTemp = null;        try {            ArrayList<String> arrayList = new ArrayList<String>();            File inPutFile = new File(inPutFilePath);            File outPutFile = new File(OutputFilePath);            if(!inPutFile.exists()){                return false;            }            if(!outPutFile.exists()){                outPutFile.getParentFile().mkdirs();            }            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(inPutFile),"UTF-8"));            while((stringTemp = bufferedReader.readLine()) != null){                arrayList.add(stringTemp);            }            bufferedReader.close();            if(arrayList.size() > 0){                //不想覆盖原有的信息，那么就加一个true，表示后续追加//              PrintWriter printWriter = new PrintWriter(new FileOutputStream(outPutFile,true));                PrintWriter printWriter = new PrintWriter(new FileOutputStream(outPutFile));                endLine = Math.min(arrayList.size(), endLine + 1);                if(startLine > endLine){                    return false;                }                for(int linCount = startLine; linCount < endLine; linCount++){                    printWriter.println(arrayList.get(linCount));                    printWriter.flush();                }                printWriter.close();            }        } catch (FileNotFoundException e) {            e.printStackTrace();            return false;        } catch (IOException e) {            e.printStackTrace();            return false;        }        return true;    }    /**     * @param inPutFilePath     * @param OutputFilePath     * @param startLine     * @param endLine     * @describe 根据关键字来获取到对应的信息，并且输出到指定文件     * @return     */    public static boolean outPutFileByContains(String inPutFilePath, String OutputFilePath, String containStrtemp){        if(inPutFilePath == null || inPutFilePath.trim().equals("") || OutputFilePath == null || OutputFilePath.trim().equals("") || containStrtemp == null || containStrtemp.equals("")){            return false;        }        String stringTemp = null;        try {            ArrayList<String> arrayList = new ArrayList<String>();            File inPutFile = new File(inPutFilePath);            File outPutFile = new File(OutputFilePath);            if(!inPutFile.exists()){                return false;            }            if(!outPutFile.exists()){                outPutFile.getParentFile().mkdirs();            }            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(inPutFile),"UTF-8"));            while((stringTemp = bufferedReader.readLine()) != null){                arrayList.add(stringTemp);            }            bufferedReader.close();            if(arrayList.size() > 0){                boolean ifFind = false;                PrintWriter printWriter = new PrintWriter(new FileOutputStream(outPutFile));                for(int linCount = 0; linCount < arrayList.size(); linCount++){                    stringTemp = arrayList.get(linCount);                    if(stringTemp.contains(containStrtemp)){                        ifFind = true;                        System.out.println("Line: " + (linCount<10?"0"+linCount:linCount)  + "       contant is:  \"" + stringTemp + "\"");                        printWriter.println(arrayList.get(linCount));                        printWriter.flush();                    }                }                printWriter.close();                if(!ifFind){                    System.out.println("没有找到相应的信息");                }            }        } catch (FileNotFoundException e) {            e.printStackTrace();            return false;        } catch (IOException e) {            e.printStackTrace();            return false;        }        return true;    }    /**     * @param filePath     * @param index     * @describe 获取文件中指定行的内容     * @return     */    public static String getOneLine(String filePath, int index){        if(filePath == null || filePath.trim().equals("") || index < 0){            return null;        }        String stringTemp = null;        try {            ArrayList<String> arrayList = new ArrayList<String>();            File file = new File(filePath);            if(!file.exists()){                return null;            }            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file),"UTF-8"));            while((stringTemp = bufferedReader.readLine()) != null){                arrayList.add(stringTemp);            }            bufferedReader.close();            if(arrayList.size() > index){                return arrayList.get(index);            }        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return null;    }    /**     * @param filePath     * @param index     * @describe 删除文件中指定行的内容     * @return     */    public static String deleteOneLineByLinecount(String filePath, int index){        if(filePath == null || filePath.trim().equals("")){            return null;        }        String stringTemp = null;        try {            ArrayList<String> arrayList = new ArrayList<String>();            File file = new File(filePath);            if(!file.exists()){                return null;            }            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file),"UTF-8"));            while((stringTemp = bufferedReader.readLine()) != null){                arrayList.add(stringTemp);            }            bufferedReader.close();            PrintWriter printWriter = new PrintWriter(file);            if(arrayList.size() > index){                stringTemp = arrayList.get(index);                arrayList.remove(index);            }            if(arrayList.size() > 0){                for(String str : arrayList){                    printWriter.println(str);                    printWriter.flush();                }            }            printWriter.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return stringTemp;    }    /**     * @param filePath     * @describe 倒序文件     * @return     */    public static boolean reverseFile(String filePath){        if(filePath == null || filePath.trim().equals("")){            return false;        }        String stringTemp = null;        try {            ArrayList<String> arrayList = new ArrayList<String>();            File file = new File(filePath);            if(!file.exists()){                return false;            }            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file),"UTF-8"));            while((stringTemp = bufferedReader.readLine()) != null){                arrayList.add(stringTemp);            }            bufferedReader.close();            PrintWriter printWriter = new PrintWriter(file);            if(arrayList.size() > 0){                for(int i = arrayList.size()-1; i >= 0; i--){                    printWriter.println(arrayList.get(i));                    printWriter.flush();                }            }            printWriter.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return true;    }    /**     * @param fileinput     * @param fileoutput     * @throws IOException     * @describe 以字节流的形式将一个文件复制到指定的地方，这种方式比较适合于那些应用程序的复制以及用网络socket形式传输文件     *           因为安装程序需要一个字节都准确无误的传送过去，因而需要使用字节流，同时注意缓冲数组的字节数读取长度，     *           原则：写进去多少字节，就读取多少字节。     */    public static void copyFile(File fileinput, File fileoutput) throws IOException{        fileinput = new File("D:/LiufuKin/AccountNum.txt");        fileoutput = new File("D:/LiufuKin/test/AccountNum.txt");        if(!fileinput.exists()){            System.out.println("你所选择的文件不存在");            return ;        }        //写信息如缓存去数组        if(!fileoutput.exists()){            fileoutput.getParentFile().mkdirs();        }        FileInputStream fileInputStream = new FileInputStream(fileinput);        byte[] bt = new byte[1024000];        FileOutputStream fileOutputStream = new FileOutputStream(fileoutput);        int lengthTemp = 0;        while((lengthTemp = fileInputStream.read(bt)) >0){            fileOutputStream.write(bt,0,lengthTemp); //这一步很重要，写入缓冲区多少，就拿出来多少，否则会使得文件和原来的不一样。            fileOutputStream.flush();        }        fileInputStream.close();        fileOutputStream.close();    }    /**     * @param file     * @throws IOException     * @describe 以字符流的形式，一行一行的读取文件，这种方式适用于对文件进行分析，匹配的场景     */    public static void readFile(File file) throws IOException{        if(!file.exists()){            System.out.println("你选择的文件不存在");            return;        }        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));        String str = null;        while ((str = bufferedReader.readLine()) != null) {            System.out.println(str);        }    }    /**     * @param file     * @param length     * @describe 显示文件夹之下所有的文件名     */    public static void showAllFile(File file,int length){        String string = "----------------------------------------";        ArrayList<File> arrayList = new ArrayList<File>();        if(!file.exists()){            System.out.println("文件不存在");            return ;        }        if(file.isDirectory()){            if(length==0){                System.out.println("文件夹：" + file.getName());            }else{                System.out.println(string.substring(0,length) + file.getParentFile().getName() + "~~子文件夹：" + file.getName());            }            File[] files = file.listFiles();            if(files ==null || files.length ==0){                return;            }            for(File subFile : files){                if(subFile.isDirectory()){                    arrayList.add(subFile);                }else{                    System.out.println(string.substring(0,length+4) + subFile.getName());                }            }            System.out.println();            if(arrayList.size() >0){                for (File subFile:arrayList) {                    System.out.println();                    showAllFile(subFile,length+4);                }            }        }else{            System.out.println(string.substring(0,length)+file.getName());        }    }}

注意：如果不想覆盖原有的文件内容，则需要在创建输出流的时候，在outputFileStream 中指定为“true”。比如：
//不想覆盖原有的信息，那么就加一个true，表示后续追加
PrintWriter printWriter = new PrintWriter(new FileOutputStream(outPutFile,true));