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");
}
}