{% code %} package _8javaio;
import java.io.; import java.nio.charset.StandardCharsets; import java.nio.file.; import java.util.Arrays; import java.util.zip.GZIPInputStream; import java.util.zip.ZipEntry; import java.util.zip.ZipInputStream; import java.util.zip.ZipOutputStream;
public class Main { public static byte[] getFileDataAsBytes(File f) { byte[] data = new byte[(int)f.length()]; try(InputStream is =new FileInputStream(f)) { int n; while((n=is.read(data))!=-1) { System.out.println("read"+n+"bytes"); }
}catch(IOException e)
{
e.printStackTrace();
}
return data;
}
static void printFiles(File[] files) {
System.out.println("==========");
if (files != null) {
for (File f : files) {
System.out.println(f);
}
}
System.out.println("==========");
}
public static void main(String[] args) throws Exception{
//File对象
File f = new File("..");
System.out.println(f.getPath()); //构造方法传入路径
System.out.println(f.getAbsolutePath()); //返回绝对路径
System.out.println(f.getCanonicalPath());//返回规范绝对路径
System.out.println(File.separator); //返回当前平台系统路径分隔符
// File f1 = new File("C:\Windows"); // File f2 = new File("C:\Windows\notepad.exe"); // File f3 = new File("C:\Windows\nothing"); // System.out.println(f1.isFile()); //false 文件 // System.out.println(f1.isDirectory()); //true 目录 // System.out.println(f2.isFile()); //true // System.out.println(f2.isDirectory()); //false // System.out.println(f3.isFile()); //false // System.out.println(f3.isDirectory()); //false
//文件权限和大小
// System.out.println(f2.canRead()); //是否可读 // System.out.println(f2.canWrite()); //是否可写 // System.out.println(f2.canExecute());//是否可执行 // System.out.println(f2.length()); //文件字节大小
//创建删除文件
File file = new File("test/test.txt"); //与src同一级
if (file.createNewFile()) {
// 文件创建成功:
System.out.println("create success");
System.out.println(file.getAbsolutePath());
// TODO:
if (file.delete()) {
// 删除文件成功:
System.out.println("delete success");
}
}
//创建临时文件
// File f4 = File.createTempFile("tmp-", ".txt"); // 提供临时文件的前缀和后缀 // f4.deleteOnExit(); // JVM退出时自动删除 // System.out.println(f4.isFile()); // System.out.println(f4.getAbsolutePath());
//遍历文件和目录
// File f5 = new File("C:Windows"); // // File[] fs1 = f5.listFiles(); // 列出所有文件和子目录 // printFiles(fs1); // File[] fs2 = f5.listFiles(new FilenameFilter() { // 仅列出.exe文件 // public boolean accept(File dir, String name) { // return name.endsWith(".exe"); // 返回true表示接受该文件 // } // }); // printFiles(fs2);
//创建和删除目录
new File("hello").mkdir();
new File("hello/le").mkdirs();
new File("hello/le").delete();
new File("hello").delete();
//Path
Path p1 = Paths.get(".", "project", "study"); // 构造一个Path对象
System.out.println(p1);
Path p2 = p1.toAbsolutePath(); // 转换为绝对路径
System.out.println(p2);
Path p3 = p2.normalize(); // 转换为规范路径
System.out.println(p3);
File f6 = p3.toFile(); // 转换为File对象
System.out.println(f6);
for (Path p : Paths.get("..").toAbsolutePath()) { // 可以直接遍历Path
System.out.println(" " + p);
}
/**InputStream*/
//字节读文件
// 创建一个FileInputStream对象:
File file2 = new File("test/readme.txt");
file2.createNewFile();
try (InputStream input = new FileInputStream("test/readme.txt")) {
int n;
while ((n = input.read()) != -1) {
System.out.println(n);
}
} // 编译器在此自动为我们写入finally并调用close()
//缓冲读文件
try (InputStream input = new FileInputStream("test/readme.txt")) {
// 定义1000个字节大小的缓冲区:
byte[] buffer = new byte[1000];
int n;
while ((n = input.read(buffer)) != -1) { // 读取到缓冲区
System.out.println("read " + n + " bytes.");
}
}
//模拟InputStream
String s;
byte[] data = { 72, 101, 108, 108, 111, 33 };
try (InputStream input = new ByteArrayInputStream(data)) {
int n;
StringBuilder sb = new StringBuilder();
while ((n = input.read()) != -1) {
sb.append((char) n);
System.out.println((char)n);
}
s = sb.toString();
}
System.out.println(s);
/**OutputStream*/
//一次写入一个字节
OutputStream output = new FileOutputStream("test/readme.txt");
output.write(72); // H
output.write(101); // e
output.write(108); // l
output.write(108); // l
output.write(111); // o
output.close();
//一次写入若干字节
try (OutputStream output1 = new FileOutputStream("test/readme.txt")) {
output1.write("Hello！".getBytes("UTF-8")); // Hello
} // 编译器在此自动为我们写入finally并调用close()
//模拟OutputStream
byte[] data3;
try (ByteArrayOutputStream output3 = new ByteArrayOutputStream()) {
output3.write("Hello ".getBytes("UTF-8"));
output3.write("world!".getBytes("UTF-8"));
data3 = output3.toByteArray();
}
System.out.println(new String(data3, "UTF-8"));
//Filter模式
InputStream file7 = new FileInputStream("test/test.gz");
InputStream buffered = new BufferedInputStream(file7);
InputStream gzip = new GZIPInputStream(buffered);
System.out.println(gzip);
file7.close();
/**操作Zip*/
//读取zip
try (ZipInputStream zip = new ZipInputStream(new FileInputStream("test/test.zip"))) {
ZipEntry entry = null;
while ((entry = zip.getNextEntry()) != null) {
String name = entry.getName();
System.out.println("name："+name);
if (!entry.isDirectory()) {
int n;
while ((n = zip.read()) != -1) {
System.out.println(n);
}
}
}
}
//写入zip
try (ZipOutputStream zip = new ZipOutputStream(new FileOutputStream("test/log.zip"))) {
File ff = new File("log");
File[] files = ff.listFiles();
for (File file1 : files) {
zip.putNextEntry(new ZipEntry(file1.getName()));
zip.write(getFileDataAsBytes(file1));
zip.closeEntry();
}
}
/**序列化*/
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
try (ObjectOutputStream output1 = new ObjectOutputStream(buffer)) {
// 写入int:
output1.writeInt(12345);
// 写入String:
output1.writeUTF("Hello");
// 写入Object:
output1.writeObject(Double.valueOf(123.456));
}
System.out.println(Arrays.toString(buffer.toByteArray()));
/**反序列化*/
ByteArrayInputStream input1 = new ByteArrayInputStream(buffer.toByteArray());
try (ObjectInputStream input2 = new ObjectInputStream(input1)) {
int n1 = input2.readInt();
String s1 = input2.readUTF();
Double d1 = (Double) input2.readObject();
System.out.println(n1+s1+d1);
}
/**Reader 字符流*/
//FileReader
try (Reader reader = new FileReader("test/test.txt")) {
char[] buffer1 = new char[1000];
int n;
while ((n = reader.read(buffer1)) != -1) {
System.out.println("read " + n + " chars.");
}
}
//CharArrayReader 模拟Reader
try (Reader reader = new CharArrayReader("Hello".toCharArray())) {
System.out.println(reader);
}
//StringReader
try (Reader reader = new StringReader("Hello")) {
System.out.println(reader);
}
//InputStreamReader
try (Reader reader = new InputStreamReader(new FileInputStream("test/test.txt"), "UTF-8")) {
// TODO:
System.out.println(reader);
}
/**Wirter 字符流*/
//FileWriter
try (Writer writer = new FileWriter("test/test.txt")) {
writer.write('H'); // 写入单个字符
writer.write("Hello".toCharArray()); // 写入char[]
writer.write("Hello"); // 写入String
writer.write("你好");
}
//CharArrayWriter
try (CharArrayWriter writer = new CharArrayWriter()) {
writer.write(65);
writer.write(66);
writer.write(67);
char[] data4 = writer.toCharArray(); // { 'A', 'B', 'C' }
System.out.println(data4);
}
//StringWriter
//OutputStreamWriter
try (Writer writer = new OutputStreamWriter(new FileOutputStream("test/test.txt"), "UTF-8")) {
// TODO:
System.out.println(writer);
}
/**PrintStream和PrintWriter*/
System.out.print(12345); // 输出12345
System.out.print(new Object()); // 输出类似java.lang.Object@3c7a835a
System.out.println("Hello"); // 输出Hello并换行
StringWriter buffer4 = new StringWriter();
try (PrintWriter pw = new PrintWriter(buffer4)) {
pw.println("Hello");
pw.println(12345);
pw.println(true);
}
System.out.println(buffer4.toString());
}
} {% endcode %}