java常见文件操作

　　收集整理的java常见文件操作，方便平时使用：

//1.创建文件夹   
//import java.io.*;   
File myFolderPath = new File(str1);   
try {   
    if (!myFolderPath.exists()) {   
       myFolderPath.mkdir();   
    }   
}   
catch (Exception e) {   
    System.out.println("新建目录操作出错");   
    e.printStackTrace();   
}    
  

//2.创建文件   
//import java.io.*;   
File myFilePath = new File(str1);   
try {   
    if (!myFilePath.exists()) {   
        myFilePath.createNewFile();   
    }   
    FileWriter resultFile = new FileWriter(myFilePath);   
    PrintWriter myFile = new PrintWriter(resultFile);   
    myFile.println(str2);   
    resultFile.close();   
}   
catch (Exception e) {   
    System.out.println("新建文件操作出错");   
    e.printStackTrace();   
}    
  

//3.删除文件   
//import java.io.*;   
File myDelFile = new File(str1);   
try {   
    myDelFile.delete();   
}   
catch (Exception e) {   
    System.out.println("删除文件操作出错");   
    e.printStackTrace();   
}    
  

//4.删除文件夹   
//import java.io.*;   
File delFolderPath = new File(str1);   
try {   
    delFolderPath.delete(); //删除空文件夹   
}   
catch (Exception e) {   
    System.out.println("删除文件夹操作出错");   
    e.printStackTrace();   
}    
  

//5.删除一个文件下夹所有的文件夹   
//import java.io.*;   
File delfile=new File(str1);   
File[] files=delfile.listFiles();   
for(int i=0;i<files.length;i++){   
    if(files[i].isDirectory()){   
        files[i].delete();   
    }   
}     
   

//6.清空文件夹   
//import java.io.*;   
File delfilefolder=new File(str1);   
try {   
    if (!delfilefolder.exists()) {   
        delfilefolder.delete();   
    }   
    delfilefolder.mkdir();   
}   
catch (Exception e) {   
    System.out.println("清空目录操作出错");   
    e.printStackTrace();   
}    
  

//7.读取文件   
//import java.io.*;   
// 逐行读取数据   
FileReader fr = new FileReader(str1);   
BufferedReader br = new BufferedReader(fr);   
String str2 = br.readLine();   
while (str2 != null) {   
    str3   
    str2 = br.readLine();   
}   
br.close();   
fr.close();    
  

//8.写入文件   
//import java.io.*;   
// 将数据写入文件   
try {   
    FileWriter fw = new FileWriter(str1);   
    fw.write(str2);   
    fw.flush();   
    fw.close();    
} catch (IOException e) {   
    e.printStackTrace();   
}   
  

//9.写入随机文件   
//import java.io.*;   
try {   
    RandomAcessFile logFile=new RandomAcessFile(str1,"rw");   
    long lg=logFile.length();   
    logFile.seek(str2);   
    logFile.writeByte(str3);   
}catch(IOException ioe){   
    System.out.println("无法写入文件："+ioe.getMessage());   
}    
  

//10.读取文件属性   
//import java.io.*;   
// 文件属性的取得   
File f = new File(str1);   
if (af.exists()) {   
    System.out.println(f.getName() + "的属性如下： 文件长度为：" + f.length());   
    System.out.println(f.isFile() ? "是文件" : "不是文件");   
    System.out.println(f.isDirectory() ? "是目录" : "不是目录");   
    System.out.println(f.canRead() ? "可读取" : "不");   
    System.out.println(f.canWrite() ? "是隐藏文件" : "");   
    System.out.println("文件夹的最后修改日期为：" + new Date(f.lastModified()));   
    } else {   
    System.out.println(f.getName() + "的属性如下：");   
    System.out.println(f.isFile() ? "是文件" : "不是文件");   
    System.out.println(f.isDirectory() ? "是目录" : "不是目录");   
    System.out.println(f.canRead() ? "可读取" : "不");   
    System.out.println(f.canWrite() ? "是隐藏文件" : "");   
    System.out.println("文件的最后修改日期为：" + new Date(f.lastModified()));   
}   
if(f.canRead()){   
    str2   
}   
if(f.canWrite()){   
    str3   
}   
  

//11.写入属性   
//import java.io.*;   
File filereadonly=new File(str1);   
try {   
    boolean b=filereadonly.setReadOnly();   
}   
catch (Exception e) {   
    System.out.println("拒绝写访问："+e.printStackTrace());   
}    
  

//12.枚举一个文件夹中的所有文件   
//import java.io.*;   
//import java.util.*;   
LinkedList folderList = new LinkedList();   
folderList.add(str1);   
while (folderList.size() > 0) {   
    File file = new File(folderList.peek());   
    folderList.removeLast();   
    File[] files = file.listFiles();   
    ArrayList fileList = new ArrayList();   
    for (int i = 0; i < files.length; i++) {   
        if (files[i].isDirectory()) {   
            folderList.add(files[i].getPath());   
        } else {   
            fileList.add(files[i]);   
        }   
    }   
    for (File f : fileList) {   
        str2=f.getAbsoluteFile();   
        str3   
    }   
}   
  

//13.复制文件夹    
//import java.io.*;   
//import java.util.*;   
LinkedList folderList = new LinkedList();   
folderList.add(str1);   
LinkedList folderList2 = new LinkedList();   
folderList2.add(str2+ str1.substring(str1.lastIndexOf("\")));   
while (folderList.size() > 0) {   
    (new File(folderList2.peek())).mkdirs(); // 如果文件夹不存在 则建立新文件夹   
    File folders = new File(folderList.peek());   
    String[] file = folders.list();   
    File temp = null;   
    try {   
        for (int i = 0; i < file.length; i++) {   
            if (folderList.peek().endsWith(File.separator)) {   
                temp = new File(folderList.peek() + File.separator   
                + file[i]);   
            } else {   
                temp = new File(folderList.peek() + File.separator + file[i]);   
            }   
            if (temp.isFile()) {   
                FileInputStream input = new FileInputStream(temp);   
                FileOutputStream output = new FileOutputStream(   
                folderList2.peek() + File.separator + (temp.getName()).toString());   
                byte[] b = new byte[5120];   
                int len;   
                while ((len = input.read(b)) != -1) {   
                    output.write(b, 0, len);   
                }   
                output.flush();   
                output.close();   
                input.close();   
            }   
            if (temp.isDirectory()) {// 如果是子文件夹   
                for (File f : temp.listFiles()) {   
                    if (f.isDirectory()) {   
                        folderList.add(f.getPath());   
                        folderList2.add(folderList2.peek()   
                        + File.separator + f.getName());   
                    }   
                }   
            }   
        }   
    } catch (Exception e) {   
    //System.out.println("复制整个文件夹内容操作出错");   
        e.printStackTrace();   
    }   
    folderList.removeFirst();   
    folderList2.removeFirst();   
}   
  

//14.复制一个文件夹下所有的文件夹到另一个文件夹下   
//import java.io.*;   
//import java.util.*;   
File copyfolders=new File(str1);   
File[] copyfoldersList=copyfolders.listFiles();   
for(int k=0;k<copyfoldersList.length;k++){   
    if(copyfoldersList[k].isDirectory()){   
        ArrayListfolderList=new ArrayList();   
        folderList.add(copyfoldersList[k].getPath());   
        ArrayListfolderList2=new ArrayList();   
        folderList2.add(str2+"/"+copyfoldersList[k].getName());   
        for(int j=0;j<folderList.length;j++){   
             (new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹   
             File folders=new File(folderList.get(j));   
             String[] file=folders.list();   
             File temp=null;   
             try {   
                 for (int i = 0; i < file.length; i++) {   
                     if(folderList.get(j).endsWith(File.separator)){   
                         temp=new File(folderList.get(j)+"/"+file[i]);   
                     } else {   
                         temp=new File(folderList.get(j)+"/"+File.separator+file[i]);   
                     }   
                     FileInputStream input = new FileInputStream(temp);   
                     if(temp.isFile()){   
                         FileInputStream input = new FileInputStream(temp);   
                         FileOutputStream output = new FileOutputStream(folderList2.get(j) + "/" + (temp.getName()).toString());   
                         byte[] b = new byte[5120];   
                         int len;   
                         while ( (len = input.read(b)) != -1) {   
                             output.write(b, 0, len);   
                         }   
                         output.flush();   
                         output.close();   
                         input.close();   
                     }   
                     if(temp.isDirectory()){//如果是子文件夹   
                         folderList.add(folderList.get(j)+"/"+file[i]);   
                         folderList2.add(folderList2.get(j)+"/"+file[i]);   
                     }   
                 }   
             }   
             catch (Exception e) {   
                 System.out.println("复制整个文件夹内容操作出错");   
                 e.printStackTrace();   
             }   
        }   
    }   
}   
  

//15.移动文件夹   
//import java.io.*;   
//import java.util.*;   
LinkedList folderList = new LinkedList();   
folderList.add(str1);   
LinkedList folderList2 = new LinkedList();   
folderList2.add(str2 + str1.substring(str1.lastIndexOf("\")));   
while (folderList.size() > 0) {   
    (new File(folderList2.peek())).mkdirs(); // 如果文件夹不存在 则建立新文件夹   
    File folders = new File(folderList.peek());   
    String[] file = folders.list();   
    File temp = null;   
    try {   
        for (int i = 0; i < file.length; i++) {   
            if (folderList.peek().endsWith(File.separator)) {   
                temp = new File(folderList.peek() + File.separator + file[i]);   
            } else {   
                temp = new File(folderList.peek() + File.separator + file[i]);   
            }   
            if (temp.isFile()) {   
                FileInputStream input = new FileInputStream(temp);   
                FileOutputStream output = new FileOutputStream(   
                folderList2.peek() + File.separator + (temp.getName()).toString());   
                byte[] b = new byte[5120];   
                int len;   
                while ((len = input.read(b)) != -1) {   
                    output.write(b, 0, len);   
                }   
                output.flush();   
                output.close();   
                input.close();   
                if (!temp.delete())   
                System.out.println("删除单个文件操作出错!");   
            }   
            if (temp.isDirectory()) {// 如果是子文件夹   
                for (File f : temp.listFiles()) {   
                    if (f.isDirectory()) {   
                        folderList.add(f.getPath());   
                        folderList2.add(folderList2.peek() + File.separator + f.getName());   
                    }   
                }   
            }   
        }   
    } catch (Exception e) {   
        // System.out.println("复制整个文件夹内容操作出错");   
        e.printStackTrace();   
    }   
    folderList.removeFirst();   
    folderList2.removeFirst();   
}   
File f = new File(str1);   
if (!f.delete()) {   
    for (File file : f.listFiles()) {   
        if (file.list().length == 0) {   
            System.out.println(file.getPath());   
            file.delete();   
        }   
    }   
}   

//16.移动一个文件夹下所有的文件夹到另一个目录下   
//import java.io.*;   
//import java.util.*;   
File movefolders=new File(str1);   
File[] movefoldersList=movefolders.listFiles();   
for(int k=0;k<movefoldersList.length;k++){   
    if(movefoldersList[k].isDirectory()){   
        ArrayListfolderList=new ArrayList();   
        folderList.add(movefoldersList[k].getPath());   
        ArrayListfolderList2=new ArrayList();   
        folderList2.add(str2+"/"+movefoldersList[k].getName());   
        for(int j=0;j<folderList.length;j++){   
             (new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹   
             File folders=new File(folderList.get(j));   
             String[] file=folders.list();   
             File temp=null;   
             try {   
                 for (int i = 0; i < file.length; i++) {   
                     if(folderList.get(j).endsWith(File.separator)){   
                         temp=new File(folderList.get(j)+"/"+file[i]);   
                     }   
                     else{   
                         temp=new File(folderList.get(j)+"/"+File.separator+file[i]);   
                     }   
                     FileInputStream input = new FileInputStream(temp);   
                     if(temp.isFile()){   
                         FileInputStream input = new FileInputStream(temp);   
                         FileOutputStream output = new FileOutputStream(folderList2.get(j) + "/" + (temp.getName()).toString());   
                         byte[] b = new byte[5120];   
                         int len;   
                         while ( (len = input.read(b)) != -1) {   
                             output.write(b, 0, len);   
                         }   
                         output.flush();   
                         output.close();   
                         input.close();   
                         temp.delete();   
                     }   
                     if(temp.isDirectory()){//如果是子文件夹   
                         folderList.add(folderList.get(j)+"/"+file[i]);   
                         folderList2.add(folderList2.get(j)+"/"+file[i]);   
                     }   
                 }   
             }   
             catch (Exception e) {   
                 System.out.println("复制整个文件夹内容操作出错");   
                 e.printStackTrace();   
             }   
        }   
        movefoldersList[k].delete();   
    }   
}   
  

//17.以一个文件夹的框架在另一个目录创建文件夹和空文件   
//import java.io.*;   
//import java.util.*;   
boolean b=false;//不创建空文件   
ArrayListfolderList=new ArrayList();   
folderList.add(str1);   
ArrayListfolderList2=new ArrayList();   
folderList2.add(str2);   
for(int j=0;j<folderList.length;j++){   
    (new File(folderList2.get(j))).mkdirs(); //如果文件夹不存在 则建立新文件夹   
    File folders=new File(folderList.get(j));   
    String[] file=folders.list();   
    File temp=null;   
    try {   
        for (int i = 0; i < file.length; i++) {   
            if(folderList.get(j).endsWith(File.separator)){   
                temp=new File(folderList.get(j)+"/"+file[i]);   
            }   
            else{   
                temp=new File(folderList.get(j)+"/"+File.separator+file[i]);   
            }   
            FileInputStream input = new FileInputStream(temp);   
            if(temp.isFile()){   
                if (b) temp.createNewFile();   
            }   
            if(temp.isDirectory()){//如果是子文件夹   
                folderList.add(folderList.get(j)+"/"+file[i]);   
                folderList2.add(folderList2.get(j)+"/"+file[i]);   
            }   
        }   
    }   
    catch (Exception e) {   
        System.out.println("复制整个文件夹内容操作出错");   
        e.printStackTrace();   
    }   
}   
  

//18.复制文件   
//import java.io.*;   
 int bytesum = 0;   
 int byteread = 0;   
 File oldfile = new File(str1);   
 try {   
 if (oldfile.exists()) { //文件存在时   
 FileInputStream inStream = new FileInputStream(oldfile); //读入原文件   
 FileOutputStream fs = new FileOutputStream(new File(str2,oldfile.getName()));   
 byte[] buffer = new byte[5120];   
 int length;   
 while ( (byteread = inStream.read(buffer)) != -1) {   
 bytesum += byteread; //字节数 文件大小   
 System.out.println(bytesum);   
 fs.write(buffer, 0, byteread);   
 }   
 inStream.close();   
 }   
 }   
 catch (Exception e) {   
 System.out.println("复制单个文件操作出错");   
 e.printStackTrace();   
 }    
  

//19.复制一个文件夹下所有的文件到另一个目录   
//import java.io.*;   
File copyfiles=new File(str1);   
File[] files=copyfiles.listFiles();   
for(int i=0;i<files.length;i++){   
    if(!files[i].isDirectory()){   
        int bytesum = 0;   
        int byteread = 0;   
        try {   
            InputStream inStream = new FileInputStream(files[i]); //读入原文件   
            FileOutputStream fs = new FileOutputStream(new File(str2,files[i].getName());   
            byte[] buffer = new byte[5120];   
            int length;   
            while ( (byteread = inStream.read(buffer)) != -1) {   
                bytesum += byteread; //字节数 文件大小   
                System.out.println(bytesum);   
                fs.write(buffer, 0, byteread);   
            }   
            inStream.close();   
        } catch (Exception e) {   
            System.out.println("复制单个文件操作出错");   
            e.printStackTrace();   
        }   
    }   
}    
 

 
//20.提取扩展名   
　　String str2=str1.substring(str1.lastIndexOf(".")+1);