java日常笔记2016-12-26

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1：

/** * 1:获取绝对路径  * 2：File和String的等价  * 3：File(parent,children)  * 4:存在删除，不存在创建 *  * @author Administrator * */public class FileDemo1 {public static void main(String[] args) throws IOException {// 3:File f = new File("e://hehe");File ff = new File(f, "haha");// 4:/*if (!f.isDirectory()) {f.mkdir();ff.createNewFile();} else {if (!ff.exists()) {ff.createNewFile();} else {System.out.println("成功");}}*///1:File a1 = ff.getAbsoluteFile();String a2 = ff.getAbsolutePath();System.out.println(a1);//2:System.out.println(a2);boolean isexists = ff.exists();if(!isexists){ff.createNewFile();}else{ff.delete();}}

2： System.out.println(f.getParent());//String
System.out.println(f.getParentFile());//File

System.out.println(f.isFile());
System.out.println(f.isDirectory());

3：

/** * 查找文件夹下的所有文件 * @author Administrator * */public class For_Demo {public static void main(String[] args) {File d = new File("E:\\ADSafe");File[] ff = d.listFiles();for (int i = 0; i < ff.length; i++) {if(ff[i].isDirectory()){System.out.println("文件夹："+ff[i]);File[] fff = ff[i].listFiles();for (File file : fff) {System.out.println("文件名："+file.getName());}}else{System.out.println(ff[i]);}}}

4：索引查找

public class Index_find {public static void main(String[] args) {File f = new File("E:\\ADSafe");File[] ff = f.listFiles(new FileFilter() {@Overridepublic boolean accept(File fff) {// TODO Auto-generated method stubreturn fff.isFile()&&fff.getName().endsWith("exe");}});for (File file : ff) {System.out.println(file);}}}

5：读文件

public class IOStreanDemo_2 {public static void main(String[] args) {File f = new File("e://aa.txt");InputStream is = null;if(f.exists()){try {is = new FileInputStream(f);int value = -1;byte[] tong = new byte[512];while((value=is.read(tong)) !=-1){String string = new String(tong, 0, value,"GBK");System.out.println(string);}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally {if(is!=null){try {is.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}

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