day19

src/main/java/com/sf/day19/Test01.java

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+package com.sf.day19;
+
+import org.junit.Test;
+
+import java.io.*;
+import java.util.Arrays;
+import java.util.Date;
+
+public class Test01 {
+    @Test
+    public void t1(){
+        /**
+         * file类
+         * win   \\    linux  /
+         */
+        String pathname = "D:\\a.txt";
+        File file = new File(pathname);
+        System.out.println(file);
+
+        //构造器的第二种方式    通过父路径和子路径字符串
+        String parent = "D:\\aaa";
+        String child = "bbb.txt";
+        File file1 = new File(parent, child);
+        System.out.println(file1);
+
+        /**
+         * file构造器的第三种方式   通过父级File对象和子路径字符串
+         */
+        File file2 = new File("D:\\aaa");
+        String child2 = "bbb.txt";
+        File file3 = new File(file2, child2);
+        System.out.println(file3);
+    }
+
+    /**
+     * file类下的方法演示
+     */
+    @Test
+    public void t2(){
+        File file = new File("D:\\ruanjian\\aDrive\\locales\\af.pak");
+        //获取当前文件的名称
+        System.out.println(file.getName());
+        //获取文件的相对路径
+        System.out.println(file.getPath());
+        //获取文件的绝对路径
+        System.out.println(file.getAbsolutePath());
+        //获取文件的父路径
+        System.out.println(file.getParent());
+    }
+
+    @Test
+    public void t3(){
+        File file = new File("D:\\Program Files\\IntelliJ IDEA 2019.3.3\\VIP33\\a.txt");
+        System.out.println(System.getProperty("user.dir"));
+        System.out.println(file.getName());
+        System.out.println(file.getParent());
+        System.out.println(file.getPath());
+        System.out.println(file.getAbsolutePath());
+        System.out.println(file.getAbsoluteFile().getParent());
+    }
+
+    /**
+     * file类的常用方法
+     */
+    @Test
+    public void t4(){
+        File file = new File("D:\\a.txt");
+        System.out.println(file.getPath());
+        System.out.println(file.getAbsolutePath());
+        System.out.println(file.getParent());
+        System.out.println(file.getName());
+        System.out.println(file.length());
+        long time = file.lastModified();
+        System.out.println(file.lastModified());
+        Date date = new Date(time);
+        System.out.println(date);
+
+    }
+
+    @Test
+    public void t5(){
+        File file = new File("D:\\");
+        //列出当前目录下的所有文件和目录
+       String[] strs = file.list();
+        System.out.println(Arrays.toString(strs));
+        for (String str : strs) {
+            System.out.println(str);
+        }
+        //返回当前路径下的文件和目录   因为file对象  + 目录+文件
+        File[] files = file.listFiles();
+        for (File file1 : files) {
+            System.out.println(file1);
+        }
+    }
+
+    /**
+     * file类的重新命名  renameTo
+     */
+    @Test
+    public void t6(){
+        File file = new File("D:\\a.txt");
+        File file1 = new File("D:\\b.txt");
+        boolean b = file.renameTo(file1);
+        System.out.println(b);
+        boolean b1 = file1.renameTo(file);
+        System.out.println(b1);
+    }
+
+
+    @Test
+    public void t7(){
+        File file = new File("F:\\a.txt");
+        boolean exists = file.exists();   //判断当前文件是否存在
+        System.out.println(exists);
+        boolean directory = file.isDirectory();  //判断当前是否为文件目录
+        System.out.println(directory);
+        System.out.println(file.isFile());  //判断当前是否为文件
+        System.out.println(file.isHidden());  //判断当前是否隐藏
+        System.out.println(file.canRead());//可读
+        System.out.println(file.canWrite());//可写
+
+    }
+
+    /**
+     * 创建文件
+     * @throws IOException
+     */
+    @Test
+    public void t8() throws IOException {
+        File file = new File("aaa.txt");
+        System.out.println(file.exists());
+        System.out.println(file.createNewFile());
+        System.out.println(file.exists());
+    }
+
+    /**
+     * 创建目录
+     * @throws IOException
+     */
+    @Test
+    public void t9() throws IOException {
+//        File f2= new File("newDir");
+//        System.out.println("newDir是否存在:"+f2.exists());
+//        System.out.println("newDir是否创建:"+f2.mkdir());
+//        System.out.println("newDir是否存在:"+f2.exists());
+        // 创建多级目录
+        File f5= new File("aaa.txt");
+//        System.out.println("newDira\\newDirb创建：" + f5.mkdirs());
+        boolean delete = f5.delete();
+        System.out.println(delete);
+    }
+
+    @Test
+    public void t10() throws IOException {
+        File file = new File("D:\\file");
+        boolean mkdirs = file.mkdirs();
+        if(mkdirs){
+            File file1 = new File("D:\\file\\h.java");
+            boolean newFile = file1.createNewFile();
+            if(newFile){
+                System.out.println("创建成功");
+                boolean delete = file1.delete();
+                if(delete){
+                    System.out.println("删除成功");
+                    file.delete();
+                }
+            }
+        }
+
+    }
+
+    @Test
+    public void t11(){
+//        //方式一
+//        File file = new File("D:\\demo");
+//        for (String s : file.list()) {
+//            if(s.endsWith(".md")){
+//                System.out.println(s);
+//            }
+//        }
+
+//        //方式二
+//        File file = new File("D:\\demo");
+//        for (File listFile : file.listFiles()) {
+//            if(listFile.getName().endsWith(".md")){
+//                System.out.println(listFile.getName());
+//            }
+//        }
+
+        //方式三
+        /*
+         * File类提供了两个文件过滤器方法
+         * public String[] list(FilenameFilter filter)
+         * public File[] listFiles(FileFilter filter)
+         */
+//        File file = new File("D:\\demo");
+//        File[] files = file.listFiles(new FilenameFilter() {
+//            @Override
+//            public boolean accept(File dir, String name) {
+//                return name.endsWith(".md");
+//            }
+//        });
+//        for (File file1 : files) {
+//            System.out.println(file1.getName());
+//        }
+
+        File file = new File("D:\\demo");
+        File[] files = file.listFiles(new FileFilter() {
+            @Override
+            public boolean accept(File pathname) {
+                return pathname.getName().endsWith(".md");
+            }
+        });
+        for (File file1 : files) {
+            System.out.println(file1.getName());
+        }
+    }
+
+    /**
+     * 练习3：遍历指定目录所有文件名称，包括子文件目录中的文件。
+     *
+     *   拓展1：并计算指定目录占用空间的大小
+     *
+     *   拓展2：删除指定文件目录及其下的所有文件
+     */
+    @Test
+    public void t12(){
+        File file = new File("D:\\aaa");
+         deleteDirectory(file);
+//        printSubFile(file);
+//        long directorySize = getDirectorySize(file);
+//        System.out.println(directorySize);
+    }
+
+    /**
+     * 递归方法   遍历子文件夹
+     * @param file
+     */
+    public static void printSubFile(File file){
+        File[] files = file.listFiles();
+        for (File file1 : files) {
+            if(file1.isDirectory()){
+                System.out.println(file1.getName());//目录
+                printSubFile(file1);
+
+            }else {  //文件
+                System.out.println(file1.getName());
+            }
+        }
+    }
+
+
+    public static long getDirectorySize(File file){
+        long lengthCount = 0;
+        if(file.isFile()){
+            lengthCount = file.length();
+        }else {
+            File[] files = file.listFiles();
+            for (File file1 : files) {
+                lengthCount += getDirectorySize(file1);
+            }
+        }
+        return lengthCount;
+    }
+
+    /**
+     *   // 拓展2：删除指定的目录
+     */
+    public static void deleteDirectory(File file){
+        if(file.isDirectory()){
+            File[] files = file.listFiles();
+            for (File file1 : files) {
+                deleteDirectory(file1);
+            }
+        }
+        file.delete();//删掉        //从里向外删除
+    }
+
+    /**
+     * 读取hello.txt文件中的字符数据，并显示在控制台上
+     */
+    @Test
+    public void t13() throws IOException {
+        File file = new File("D:\\a.txt");
+        FileReader fr = new FileReader(file);
+        int data;
+        while ((data = fr.read()) !=-1){
+            System.out.println(data);
+            System.out.println((char)data);
+        }
+        fr.close();  //关闭资源
+    }
+
+
+    /*
+        //实现方式3：调用read(char[] cbuf),每次从文件中读取多个字符
+     */
+    @Test
+    public void t14() throws IOException {
+        File file = new File("D:\\a.txt");
+        FileReader fileReader = new FileReader(file);
+        char[] chars = new char[5];
+//        fileReader.read(chars);
+        int data ;
+        while ((data = fileReader.read(chars)) != -1){
+            System.out.println(Arrays.toString(chars));
+        }
+        fileReader.close();
+    }
+}

src/main/java/com/sf/reflectiontest/Student.java

@@ -0,0 +1,38 @@
+package com.sf.reflectiontest;
+
+public class Student {
+    private Integer id;
+    private String name;
+
+    public Student() {
+    }
+
+    public Student(Integer id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return "Student{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                '}';
+    }
+}

src/main/java/com/sf/reflectiontest/Test01.java

@@ -0,0 +1,45 @@
+package com.sf.reflectiontest;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ * 反射的练习
+ */
+public class Test01 {
+
+    @Test
+    public void t1() throws ClassNotFoundException, InstantiationException, IllegalAccessException, NoSuchMethodException {
+//        Student student = new Student();
+//        Class<? extends Student> aClass = student.getClass();
+//        Class<?> aClass1 = Class.forName("java.lang.String");
+//        Class c1 = String.class;
+//        String obj = new String();
+//        Class c2 = obj.getClass();
+//        Class c3 = Class.forName("java.lang.String");
+//        Class c4 = ClassLoader.getSystemClassLoader().loadClass("java.lang.String");
+//        System.out.println("c1 = " + c1);
+//        System.out.println("c2 = " + c2);
+//        System.out.println("c3 = " + c3);
+//        System.out.println("c4 = " + c4);
+//
+//        System.out.println(c1 == c2);
+//        System.out.println(c1 == c3);
+//        System.out.println(c1 == c4);
+        String str = "com.sf.reflectiontest.Student";
+        Class<?> clazz = Class.forName(str);
+        Object o = clazz.newInstance();
+        System.out.println((Student)o);
+        String name = clazz.getName();
+        System.out.println(name);
+        System.out.println(clazz.getSuperclass());
+        System.out.println(Arrays.toString(clazz.getInterfaces()));
+        ClassLoader classLoader = clazz.getClassLoader();
+        System.out.println(classLoader);
+        System.out.println(Arrays.toString(clazz.getConstructors()));
+        System.out.println(Arrays.toString(clazz.getDeclaredMethods()));
+        System.out.println(Arrays.toString(clazz.getMethods()));
+        System.out.println(clazz.getMethod("setId",Integer.class));
+    }
+}