java基础——文件操作

刺骨的言语ヽ痛彻心扉 2023-06-27 14:58 1阅读 0赞

package file;
    
    import java.io.File;
    import java.io.IOException;
    import java.util.Date;
    
    public class TestFile { 
        static long minSize = Integer.MAX_VALUE;
        static long maxSize = 0;
        static File minFile = null;
        static File maxFile = null;
    
        public static void main(String[] args) throws IOException { 
            File f = new File("d:/test");
            listFiles(f);
            System.out.println("max: "+maxFile.getAbsolutePath()+" :length: "+maxFile.length());
            System.out.println("min: "+minFile.getAbsolutePath()+" :length: "+minFile.length());
    
        }
        //遍历文件夹，查询最大、最小文件
        private static void listFiles(File file){ 
            if(file.isFile()){ 
                if(file.length()>maxSize){ 
                    maxSize = file.length();
                    maxFile = file;
                }
                if(file.length()!=0&&file.length()<minSize){ 
                    minSize = file.length();
                    minFile = file;
                }
                return;
            }
            if(file.isDirectory()){ 
                File[] fs = file.listFiles();
                if(null!=fs){ 
                    for(File f:fs){ 
                        listFiles(f);
                    }
                }
            }
        }
    }

二、文件多线程查找

package multiplethread;
    
    import java.io.File;
    
    public class TestThread { 
        public static void main(String[] args){ 
            File folder = new File("d:/test");
            search(folder,"Magic");
        }
    
        public static void search(File file, String search){ 
            if(file.isFile()){ 
                if(file.getName().toLowerCase().endsWith(".txt")){ 
                    new SearchFileThread(file,search).start();
                }
            }
            if(file.isDirectory()){ 
                File[] fs = file.listFiles();
                for(File f:fs){ 
                    search(f,search);
                }
            }
        }
    }

package multiplethread;
    
    import java.io.File;
    import java.io.FileReader;
    import java.io.IOException;
    
    //继承Thread类
    public class SearchFileThread extends Thread{ 
        private File file;
        private String search;
        public SearchFileThread(File file,String search){ 
            this.file = file;
            this.search = search;
        }
        public void run(){ 
            String fileContent = readFileContent(file);
            if(fileContent.contains(search)){ 
                System.out.printf("找到了目标字符串%s,在文件%s%n",search,file);
            }
        }
        public String readFileContent(File file){ 
            try(FileReader fr = new FileReader(file)){ 
                char[] all =  new char[(int)file.length()];
                fr.read(all);
                return new String(all);
            }catch(IOException e){ 
                e.printStackTrace();
                return null;
            }
        }
    }