11.4

package qimoxiangmu;

import javax.swing.*;

import java.io.*;

public class ChooseFile
{
    public static void main(String[] args)
    {
    
      JFileChooser fileChooser = new JFileChooser();

      fileChooser.setFileSelectionMode(
         JFileChooser.FILES_ONLY );
         //显示打开文件对话框
      int result = fileChooser.showOpenDialog( null );
 
      // user clicked Cancel button on dialog
      if ( result == JFileChooser.CANCEL_OPTION )
         return;

      File fileName = fileChooser.getSelectedFile();
      
      System.out.println("您选择了：" + fileName.getName());
    }
}

运行结果如下：

 

您选择了：9. 山花绽放.lnk

package qimoxiangmu;

import java.io.IOException;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;


public class FileFinder extends SimpleFileVisitor<Path> {



    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
            throws IOException {
        Path name=file.getFileName();
        System.out.println("Examining "+name);
        if(matcher.matches(name)){
            foundPaths.add(file);
        }
        return FileVisitResult.CONTINUE;
    }

    private PathMatcher matcher;
    
    public ArrayList<Path> foundPaths=new ArrayList<>();
    
    public FileFinder(String pattern){
        matcher=FileSystems.getDefault().getPathMatcher("glob:"+pattern);    
    }
    
    public static void main(String[] args) {
        Path fileDir=Paths.get("D:\\test");
        FileFinder finder=new FileFinder("*.java");
        try {
            Files.walkFileTree(fileDir, finder);
            ArrayList<Path> foundFiles=finder.foundPaths;
            if(foundFiles.size()>0){
                for (Path path : foundFiles) {
                System.out.println(path.toRealPath(LinkOption.NOFOLLOW_LINKS));
                }
            }
            else {
                System.out.println("No files were found!");
            }
            
        } catch (IOException e) {
        
            e.printStackTrace();
        }

    }

}

运行结果如下：

No files were found!

package qimoxiangmu;
import java.io.IOException;
import java.nio.charset.Charset;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;
import java.util.Arrays;
import java.util.List;

public class FilesTest {
    public static void main(String[] args) {
        // copy file
        Path source = Paths.get("D:/Temp/line1.bmp");
        Path target = Paths.get("D:/Temp/backup.bmp");
        try {
            Files.copy(source, target, StandardCopyOption.REPLACE_EXISTING);
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        Path source2 = Paths.get("D:/Temp/backup.bmp");
        Path target2 = Paths.get("D:/123data/backup2.bmp");
        try {
            Files.move(source2, target2, StandardCopyOption.REPLACE_EXISTING);
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        
        // write and read to a text file
        Path textFile = Paths.get("D:/Temp/speech.txt");
        Charset charset = Charset.forName("US-ASCII");
        String line1 = "Easy read and write";
        String line2 = "with java.nio.file.Files";
        List<String> lines = Arrays.asList(line1, line2);
        try {
            Files.write(textFile, lines, charset);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        List<String> linesRead = null;
        try {
            // read back
            linesRead = Files.readAllLines(textFile, charset);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        
        if (linesRead != null) {
            for (String line : linesRead) {
                System.out.println(line);
            }
            
        }
    }
    
}

运行结果如下：

Easy read and write
with java.nio.file.Files

 

package qimoxiangmu;
import java.io.*;
import java.util.ArrayList;

public class FileTest {

    public static void main(String[] args) throws IOException {
        
         File file = new File("c:\\windows");
         if(file.isFile()) { // 是否为文件
             System.out.println(" 文件"); 
             System.out.print(
                   file.canRead() ? "可读" : "不可读"); 
             System.out.print(
                   file.canWrite() ? "可写" : "不可写"); 
             System.out.println(
                   file.length() + "字节"); 
         } 
         else { 
             // 列出所有的文件及目录
             File[] files = file.listFiles(); 
             ArrayList<File> fileList = 
                                 new ArrayList<File>(); 
             for(int i = 0; i < files.length; i++) { 
                 // 先列出目录 
                 if(files[i].isDirectory()) { //是否为目录
                     // 取得路径名
                     System.out.println("[" + 
                             files[i].getPath() + "]"); 
                 }
                 else {
                     // 文件先存入fileList，待会再列出??
                     fileList.add(files[i]); 
                 }
             } 

             // 列出文件 
             for(File f: fileList) {
                 System.out.println(f.toString());
             }
             System.out.println(); 
         } 
        
        
        //以当前路径来创建一个File对象
        file = new File(".");
        //直接获取文件名，输出一点
        System.out.println(file.getName());
        //获取相对路径的父路径可能出错，下面代码输出null
        System.out.println(file.getParent());
        //获取绝对路径
        System.out.println(file.getAbsoluteFile());
        //获取上一级路径
        System.out.println(file.getAbsoluteFile().getParent());
        //在当前路径下创建一个临时文件
        File tmpFile = File.createTempFile("aaa", ".txt", file);
        //指定当JVM退出时删除该文件
        tmpFile.deleteOnExit();
        //以系统当前时间作为新文件名来创建新文件
        File newFile = new File(System.currentTimeMillis() + "");
        System.out.println("newFile对象是否存在：" + newFile.exists());
        //以指定newFile对象来创建一个文件
        newFile.createNewFile();
        //以newFile对象来创建一个目录，因为newFile已经存在，
        //所以下面方法返回false，即无法创建该目录
        newFile.mkdir();
        //使用list方法来列出当前路径下的所有文件和路径
        String[] fileList = file.list();
        System.out.println("======当前路径下所有文件和路径如下=====");
        for (String fileName : fileList) {
            System.out.println(fileName);
        }

        //listRoots静态方法列出所有的磁盘根路径。
        File[] roots = File.listRoots();
        System.out.println("======系统所有根路径如下=====");
        for (File root : roots) {
            System.out.println(root);
        }
    }
}

运行结果如下：

[c:\windows\addins]
[c:\windows\appcompat]
[c:\windows\apppatch]
[c:\windows\AppReadiness]
[c:\windows\assembly]
[c:\windows\bcastdvr]
[c:\windows\Boot]
[c:\windows\Branding]
[c:\windows\CbsTemp]
[c:\windows\Containers]
[c:\windows\Cursors]
[c:\windows\debug]
[c:\windows\Defender]
[c:\windows\diagnostics]
[c:\windows\DiagTrack]
[c:\windows\DigitalLocker]
[c:\windows\Downloaded Program Files]
[c:\windows\ELAMBKUP]
[c:\windows\en-US]
[c:\windows\Favicon_ICON]
[c:\windows\Fonts]
[c:\windows\GameBarPresenceWriter]
[c:\windows\Globalization]
[c:\windows\Help]
[c:\windows\IdentityCRL]
[c:\windows\IME]
[c:\windows\ImmersiveControlPanel]
[c:\windows\INF]
[c:\windows\InputMethod]
[c:\windows\Installer]
[c:\windows\java]
[c:\windows\L2Schemas]
[c:\windows\LanguageOverlayCache]
[c:\windows\Lenovo]
[c:\windows\LiveKernelReports]
[c:\windows\Logs]
[c:\windows\Media]
[c:\windows\Microsoft.NET]
[c:\windows\Migration]
[c:\windows\minidump]
[c:\windows\ModemLogs]
[c:\windows\Netease]
[c:\windows\OCR]
[c:\windows\Offline Web Pages]
[c:\windows\panther]
[c:\windows\PCHEALTH]
[c:\windows\Performance]
[c:\windows\PLA]
[c:\windows\PolicyDefinitions]
[c:\windows\Prefetch]
[c:\windows\PrintDialog]
[c:\windows\Provisioning]
[c:\windows\Registration]
[c:\windows\rescache]
[c:\windows\Resources]
[c:\windows\SchCache]
[c:\windows\schemas]
[c:\windows\security]
[c:\windows\ServiceProfiles]
[c:\windows\ServiceState]
[c:\windows\servicing]
[c:\windows\Setup]
[c:\windows\ShellComponents]
[c:\windows\ShellExperiences]
[c:\windows\SKB]
[c:\windows\SoftwareDistribution]
[c:\windows\Speech]
[c:\windows\Speech_OneCore]
[c:\windows\symbols]
[c:\windows\System]
[c:\windows\System32]
[c:\windows\SystemApps]
[c:\windows\SystemResources]
[c:\windows\SysWOW64]
[c:\windows\TAPI]
[c:\windows\Tasks]
[c:\windows\Temp]
[c:\windows\TextInput]
[c:\windows\tracing]
[c:\windows\twain_32]
[c:\windows\Vss]
[c:\windows\WaaS]
[c:\windows\Web]
[c:\windows\WinSxS]
[c:\windows\zh-CN]
c:\windows\acct.txt
c:\windows\area.txt
c:\windows\authsel.txt
c:\windows\AvsOpt.txt
c:\windows\a_domain.txt
c:\windows\bfsvc.exe
c:\windows\bootstat.dat
c:\windows\CNI.TAG
c:\windows\core.ver
c:\windows\CoreCountrySpecific.xml
c:\windows\csup.txt
c:\windows\diagerr.xml
c:\windows\diagwrn.xml
c:\windows\DirectX.log
c:\windows\eap.txt
c:\windows\eapkeep.txt
c:\windows\edu_look.bmp
c:\windows\explorer.exe
c:\windows\guest.txt
c:\windows\HelpPane.exe
c:\windows\hh.exe
c:\windows\info.txt
c:\windows\language.txt
c:\windows\machineinfo.sav
c:\windows\MFGSTAT.zip
c:\windows\mib.bin
c:\windows\msginfosize.txt
c:\windows\notepad.exe
c:\windows\NvContainerRecovery.bat
c:\windows\NvTelemetryContainerRecovery.bat
c:\windows\ODBC.INI
c:\windows\PFRO.log
c:\windows\PLDDATA.XML
c:\windows\ProductInfo.ini
c:\windows\regedit.exe
c:\windows\setupact.log
c:\windows\setuperr.log
c:\windows\splwow64.exe
c:\windows\system.ini
c:\windows\twain_32.dll
c:\windows\vbaddin.ini
c:\windows\win.ini
c:\windows\WindowsShell.Manifest
c:\windows\WindowsUpdate.log
c:\windows\winhlp32.exe
c:\windows\WMSysPr9.prx
c:\windows\write.exe

.
null
D:\JAVA\新建文件夹\qimoxiangmu\.
D:\JAVA\新建文件夹\qimoxiangmu
newFile对象是否存在：false
======当前路径下所有文件和路径如下=====
.classpath
.project
.settings
1608220060270
aaa5574514488376449911.txt
bin
src
======系统所有根路径如下=====
C:\
D:\
F:\

package qimoxiangmu;
import java.io.IOException;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;


public class FileVisitorDemo extends SimpleFileVisitor<Path> {

    
    @Override
    public FileVisitResult postVisitDirectory(Path dir, IOException exc)
            throws IOException {
        System.out.println("Just visited "+dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
            throws IOException {
        System.out.println("Aoout to visit "+dir);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
            throws IOException {
        if(attrs.isRegularFile()){
            System.out.println("Regular File:");
        }
        System.out.println(file);
        return FileVisitResult.CONTINUE;
    }

    @Override
    public FileVisitResult visitFileFailed(Path file, IOException exc)
            throws IOException {
        System.err.println(exc.getMessage());
        return FileVisitResult.CONTINUE;
    }

    public static void main(String[] args) {
        Path fileDirPath=Paths.get("D:\\test");
        FileVisitorDemo visitor=new FileVisitorDemo();
        try {
            Files.walkFileTree(fileDirPath, visitor);
        } catch (IOException e) {
            
            e.printStackTrace();
        }
        
        
        
    }

}

运行结果如下：

D:\test

package qimoxiangmu;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.util.HashMap;
import java.util.Map;


public class FileWatcherDemo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        //创建一个WatchService对象，此对象将用于管理特定文件夹的变动信息队列。
        try(WatchService service=FileSystems.getDefault().newWatchService()) {
            //此集合可保存多个文件夹的监控信息，当前只使用了一个
            Map<WatchKey, Path> keyMap=new HashMap<>();
            Path path=Paths.get("D:\\test");
            //设置WatchService对象管理的内部队列，将保存指定的文件夹的创建、删除和修改事件信息
            //返回的WatchKey对象可用于从事件队列中获取事件对象
            WatchKey key=path.register(service, StandardWatchEventKinds.ENTRY_CREATE,
                    StandardWatchEventKinds.ENTRY_DELETE,StandardWatchEventKinds.ENTRY_MODIFY);
            keyMap.put(key, path);
            
            do {
                //开始监控，阻塞等待，当感兴趣的事件发生时，take()方法返回。
                key=service.take();
                Path eventDir=keyMap.get(key);
                //从事件队列中提取所有的事件
                for (WatchEvent<?> event : key.pollEvents()) {
                    //是什么类型的事件？
                    WatchEvent.Kind<?> kind=event.kind();
                    //是哪个对象发生了变动？
                    Path eventPath=(Path)event.context();
                    System.out.println(eventDir+":"+kind+":"+eventPath);
                }
            } while (key.reset()); //reset方法重置此对象，让其可以重新接收信息
            
        } catch (Exception e) {
            
        }

    }

}

package qimoxiangmu;
import java.io.IOException;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

public class PathTest {
    public static void main(String[] args) {
        FileSystem fileSystem=FileSystems.getDefault();
        Path examplePath=fileSystem.getPath("c:/windows");
        System.out.println(examplePath.toString());
        Path path = Paths.get("D:/Temp/pathTest.txt");
        System.out.println("path name count:" + path.getNameCount());
        System.out.println(path.getName(0));
        System.out.println(path.getName(1));
        
        System.out.println("filename: " + path.getFileName());
        System.out.println("parent: " + path.getParent());
        Path parent = path.getParent();
        System.out.println("parent: " + parent.getParent().getParent());
        
        
        try {
            Files.deleteIfExists(path);
            Files.createFile(path);
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        
        Path newDir = Paths.get("D:/Temp/newDir");
        try {
            if (Files.notExists(path)) {
                Files.createDirectory(newDir);
                
            }
            System.out.println("isDirectory: " + Files.isDirectory(newDir));
            System.out.println("size  : " + Files.size(newDir));
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        System.out.println("DONE");
        
    }
    
}

运行结果如下：

c:\windows
path name count:2
Temp
pathTest.txt
filename: pathTest.txt
parent: D:\Temp
parent: null
isDirectory: true
size  : 0
DONE