File类示例
public class FileUsageTest { private static void usage() { System.err.println("Usage: FileUsageTest path1 ... \n" + "Creates each path\n" + "Usage: FileUsageTest -d path1 ...\n" + "Deletes each path\n" + "Usage: FileUsageTest -r path1 path2\n" + "Renames from path1 to path2"); System.exit(1); } /** * 获取文件元数据信息 * * @param f */ private static void fileData(File f) { System.out.println("Absolute Path: " + f.getAbsolutePath() + "\n Readable: " + f.canRead() + "\n Writable: " + f.canWrite() + "\n Name: " + f.getName() + "\n Parent Dir: " + f.getParent() + "\n Size: " + f.length() + "\n Last Modified: " + f.lastModified()); if (f.isFile()) { System.out.println(f + " is a file"); } else if (f.isDirectory()) { System.out.println(f + " is a directory"); } } /** * 通过传入参数控制功能 * * @param args */ public static void main(String[] args) { // 参数不符合要求 if (args.length < 1) { usage(); } else if (args[0].equals("-r")) { // 重命名文件 if (args.length != 3) usage(); File old = new File(args[1]); File rname = new File(args[2]); if (old.renameTo(rname)) { System.out.println("Rename file " + old + " to " + rname + " successfully"); } else { System.out.println("Rename file " + old + " to " + rname + " fail"); } fileData(old); fileData(rname); } else if (args[0].equals("-d")) { // 依次删除文件 for (int i = 1; i < args.length; i++) { File f = new File(args[i]); if (f.delete()) { System.out.println(f + " exists"); System.out.println("Delete " + f + " successfully"); } else { System.out.println("Delete " + f + " fail"); } fileData(f); } } else { // 创建文件 for (String arg : args) { File f = new File(arg); try { if (f.createNewFile()) { System.out.println("Created " + f + " successfully"); } else { System.out.println("Created " + f + " fail"); } } catch (IOException e) { e.printStackTrace(); } fileData(f); } } } }
运行 java e:\\test\\testFile1 e:\\test\\testFile2
Created e:\test\testFile1 successfully
Absolute Path: e:\test\testFile1
Readable: true
Writable: true
Name: testFile1
Parent Dir: e:\test
Size: 0
Last Modified: 1378630413535
e:\test\testFile1 is a file
Created e:\test\testFile2 successfully
Absolute Path: e:\test\testFile2
Readable: true
Writable: true
Name: testFile2
Parent Dir: e:\test
Size: 0
Last Modified: 1378630413536
e:\test\testFile2 is a file
运行 java -r e:\\test\\testFile1 e:\\test\\testFile3
Rename file e:\test\testFile1 to e:\test\testFile3 successfully
Absolute Path: e:\test\testFile1
Readable: false
Writable: false
Name: testFile1
Parent Dir: e:\test
Size: 0
Last Modified: 0
Absolute Path: e:\test\testFile3
Readable: true
Writable: true
Name: testFile3
Parent Dir: e:\test
Size: 0
Last Modified: 1378630413535
e:\test\testFile3 is a file
运行 -d e:\\test\\testFile1 e:\\test\\testFile2
Delete e:\test\testFile1 fail
Absolute Path: e:\test\testFile1
Readable: false
Writable: false
Name: testFile1
Parent Dir: e:\test
Size: 0
Last Modified: 0
e:\test\testFile2 exists
Delete e:\test\testFile2 successfully
Absolute Path: e:\test\testFile2
Readable: false
Writable: false
Name: testFile2
Parent Dir: e:\test
Size: 0
Last Modified: 0
FilenameFilter示例
/** * 用于File.list()方法回调的文件名过滤器 * 返回list()中自定义正则表达式匹配的文件名 * * @author zhenwei.liu created on 2013 13-8-20 上午11:08 * @version $Id$ */ public class RegxFilenameFilter implements FilenameFilter { private Pattern pattern; public RegxFilenameFilter(String regx) { this.pattern = Pattern.compile(regx); } @Override public boolean accept(File dir, String name) { return pattern.matcher(name).matches(); } public static void main(String[] args) { File path = new File("D:\\"); // 此处可以考虑使用匿名类解决问题 String[] list = path.list(new RegxFilenameFilter("\\w+")); Arrays.sort(list, String.CASE_INSENSITIVE_ORDER); for (String file : list) { System.out.println(file); } } }
AliWangWang
CollabNet
data
Datagenerator
Evolus
Fiddler2
home
javalib
KuGou
mavenrepo
my_config_files...
执行系统命令
public class OSExecute { public static void command(String command) { boolean err = false; try { // 执行命令 Process process = new ProcessBuilder(command.split(" ")).start(); String s; // 获取标准输出 BufferedReader stdOut = new BufferedReader(new InputStreamReader(process.getInputStream(), "GBK")); while ((s = stdOut.readLine()) != null) System.out.println(s); // 获取标准错误输出 BufferedReader errOut = new BufferedReader(new InputStreamReader(process.getErrorStream(), "GBK")); while ((s = errOut.readLine()) != null) { System.out.println(s); err = true; } } catch (Exception e) { if (!command.startsWith("CMD /C")) command("CMD /C " + command); else throw new RuntimeException(e); } if (err) throw new OSExecuteException("Errors executing " + command); } public static void main(String[] args) { command("dir c:\\"); } }
驱动器 C 中的卷没有标签。
卷的序列号是 C47F-784Dc:\ 的目录
2012/11/08 16:13 <DIR> Dell
2013/08/28 18:02 <DIR> IdeaProjects
2013/08/09 02:24 <DIR> Intel
2009/07/14 11:20 <DIR> PerfLogs
2013/09/03 16:19 <DIR> Program Files
2013/09/01 18:28 <DIR> Program Files (x86)
2013/07/24 23:50 <DIR> Ruby200-x64
2013/08/28 17:12 <DIR> svn_repository
2013/09/01 19:26 <DIR> Users
2013/09/04 22:22 <DIR> Windows
0 个文件 0 字节
10 个目录 77,945,860,096 可用字节
BufferedReader示例
public class BufferedReaderTest { public static String read(String filename) throws IOException { // 装饰器的使用 BufferedReader br = new BufferedReader(new FileReader(filename)); String s; StringBuilder sb = new StringBuilder(); try { while ((s = br.readLine()) != null) { sb.append(s); sb.append("\n"); } } finally { br.close(); } return sb.toString(); } public static void main(String[] args) throws IOException { System.out.println(read(Data.IN_FILE_PATH)); } }
StringReader示例
public class StringReaderTest { public static void main(String[] args) throws IOException { StringReader in = new StringReader(BufferedReaderTest.read(Data.IN_FILE_PATH)); int c; try { while ((c = in.read()) != -1) { // 可以直接读取中文 System.out.print((char) c); } } finally { in.close(); } } }
DataInputStream示例
/** * DataInputStream主要用于读取格式化的int,long,byte等基本类型,并且这是平台无关的 * * @author zhenwei.liu created on 2013 13-8-22 下午9:57 * @version $Id$ */ public class DataInputStreamTest { public static void main(String[] args) throws IOException { DataInputStream in = new DataInputStream(new ByteArrayInputStream(BufferedReaderTest.read(Data.IN_FILE_PATH) .getBytes())); try { while (in.available() != 0) { // 单字节读,中文会乱码 System.out.print((char) in.readByte()); } } finally { in.close(); } } }
PrintWriter示例
public class PrintWriterTest { public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new FileReader(Data.IN_FILE_PATH)); // PrintWriter的便捷构造方法 // 等同于 new PrintWriter(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName)))) PrintWriter out = new PrintWriter(Data.OUT_FILE_PATH); // PrintWriter out = new PrintWriter(new BufferedWriter(new FileWriter(Data.OUT_FILE_PATH))); String s; int lineCount = 0; try { while ((s = in.readLine()) != null) { out.println(++lineCount + " : " + s); } } finally { out.close(); in.close(); } System.out.println(BufferedReaderTest.read(Data.OUT_FILE_PATH)); } }
System.in示例
/** * System.in测试,回显输入的每一行 * * @author zhenwei.liu created on 2013 13-8-24 下午1:12 * @version $Id$ */ public class SystemInTest { public static void main(String[] args) throws IOException { BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String s; try { while ((s = in.readLine()) != null && !s.equals("")) System.out.println(s); } finally { in.close(); } } }
System.out示例
public class SystemOutTest { public static void main(String[] args) { PrintWriter printWriter = new PrintWriter(System.out, true); printWriter.println("I'm System.out"); } }
