Java操作文件的常用方法

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1.包含： 解压文件、读取文件内容、删除文件、删除文件夹、将图片转换成二进制与还原。

2.FileUtils.java: 

import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Enumeration;

import javax.imageio.ImageIO;

import org.apache.tools.zip.ZipEntry;
import org.apache.tools.zip.ZipFile;
import org.junit.Test;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class FileUtils {

	private static BASE64Encoder encoder = new sun.misc.BASE64Encoder();
	private static BASE64Decoder decoder = new sun.misc.BASE64Decoder();

	public FileUtils() {
	}

	/**
	 * @param sourcefiles
	 *            源文件(服务器上的zip包存放地址)
	 * @param decompreDirectory
	 *            解压缩后文件存放的目录
	 * @throws IOException
	 *             IO异常
	 */
	public static void unzip(String sourcefiles, String decompreDirectory) throws IOException {
		ZipFile readfile = null;
		try {
			readfile = new ZipFile(sourcefiles);
			Enumeration<?> takeentrie = readfile.getEntries();
			ZipEntry zipEntry = null;
			File credirectory = new File(decompreDirectory);
			credirectory.mkdirs();
			while (takeentrie.hasMoreElements()) {
				zipEntry = (ZipEntry) takeentrie.nextElement();
				String entryName = zipEntry.getName();
				InputStream in = null;
				FileOutputStream out = null;
				try {
					if (zipEntry.isDirectory()) {
						String name = zipEntry.getName();
						name = name.substring(0, name.length() - 1);
						File createDirectory = new File(decompreDirectory + File.separator + name);
						createDirectory.mkdirs();
					} else {
						int index = entryName.lastIndexOf("\\");
						if (index != -1) {
							File createDirectory = new File(
									decompreDirectory + File.separator + entryName.substring(0, index));
							createDirectory.mkdirs();
						}
						index = entryName.lastIndexOf("/");
						if (index != -1) {
							File createDirectory = new File(
									decompreDirectory + File.separator + entryName.substring(0, index));
							createDirectory.mkdirs();
						}
						File unpackfile = new File(decompreDirectory + File.separator + zipEntry.getName());
						in = readfile.getInputStream(zipEntry);
						out = new FileOutputStream(unpackfile);
						int c;
						byte[] by = new byte[1024];
						while ((c = in.read(by)) != -1) {
							out.write(by, 0, c);
						}
						out.flush();
					}
				} catch (IOException ex) {
					ex.printStackTrace();
					throw new IOException("解压失败：" + ex.toString());
				} finally {
					if (in != null) {
						try {
							in.close();
						} catch (IOException ex) {

						}
					}
					if (out != null) {
						try {
							out.close();
						} catch (IOException ex) {
							ex.printStackTrace();
						}
					}
					in = null;
					out = null;
				}

			}
		} catch (IOException ex) {
			ex.printStackTrace();
			throw new IOException("解压失败：" + ex.toString());
		} finally {
			if (readfile != null) {
				try {
					readfile.close();
				} catch (IOException ex) {
					ex.printStackTrace();
					throw new IOException("解压失败：" + ex.toString());
				}
			}
		}
	}

	/**
	 * @param filePath
	 * @param encode
	 * @return 读取文件内容
	 * @throws Exception
	 */
	public static String readFile(String filePath) {
		return readFile(filePath, "utf-8");
	}

	/**
	 * @param filePath
	 * @param encode
	 * @param limit
	 * @return 读取文件内容
	 * @throws Exception
	 */
	public static String readFile(String filePath, String encode) {
		String result = "";
		File file = new File(filePath);
		FileInputStream inputStream = null;
		InputStreamReader inputReader = null;
		try {
			inputStream = new FileInputStream(file);
			inputReader = new InputStreamReader(inputStream, encode);
			BufferedReader br = new BufferedReader(inputReader);
			String str = "";
			while ((str = br.readLine()) != null) {
				result += str + "\n"; // TODO \n
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				inputReader.close();
				inputStream.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return result;
	}

	/**
	 * @param filePath
	 * @return 删除文件
	 */
	public static boolean delFile(String filePath) {
		boolean flag = false;
		File file = new File(filePath);
		if (file.isFile() && file.exists()) {
			flag = file.delete();
		}
		return flag;
	}

	/**
	 * @param dir
	 * @return 删除文件夹
	 */
	public static boolean deleteDir(File dir) {
		if (dir.isDirectory()) {
			String[] children = dir.list();
			// 递归删除目录中的子目录下
			for (int i = 0; i < children.length; i++) {
				boolean success = deleteDir(new File(dir, children[i]));
				if (!success) {
					return false;
				}
			}
		}
		// 目录此时为空，可以删除
		return dir.delete();
	}

	/**
	 * 将图片转换成二进制
	 * @return
	 */
	public static String getImageBinary(File file) {
		String fileName = file.getName();
		// System.out.println(fileName + " " + fileName.substring(fileName.indexOf(".")+1, fileName.length()));
		
		BufferedImage bi;
		try {
			bi = ImageIO.read(file);
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			ImageIO.write(bi, fileName.substring(fileName.indexOf(".")+1, fileName.length()), baos); // 经测试转换的图片是格式这里就什么格式，否则会失真
			byte[] bytes = baos.toByteArray();

			return encoder.encodeBuffer(bytes).trim();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
	}

	/**
	 * @param base64String
	 * @param savePath
	 * @param type
	 * 将二进制转换为图片
	 */
	public static void base64StringToImage(String base64String, String savePath) {
		try {
			byte[] bytes1 = decoder.decodeBuffer(base64String);

			ByteArrayInputStream bais = new ByteArrayInputStream(bytes1);
			BufferedImage bi1 = ImageIO.read(bais);
			File w2 = new File(savePath);// File w2 = new File("e://QQ.jpg") 可以是jpg,png,gif格式
			// TODO jpg
			ImageIO.write(bi1, savePath.substring(savePath.indexOf(".")+1, savePath.length()), w2);// 不管输出什么格式图片，此处不需改动  
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	// 解压 zip
	public static void main(String[] args) {
		try {
			unzip("D:/workplace/Producer/files/20190116.zip",
					"D:/workplace/Producer/files/abc");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	// 读取内容
	@Test
	public void test01() {
		System.out.println(
				readFile("D:/workplace/Producer/files/20190116/1547449028337.txt"));
	}

	// 删除文件夹
	@Test
	public void test02() throws IOException {
		unzip("D:/workplace/Producer/files/20190116.zip",
				"D:/workplace/Producer/files/");
		deleteDir(new File("D:/workplace/Producer/files/20190116"));
	}

	// 文件属性
	@Test
	public void test03() throws IOException {
		File file = new File("D:/workplace/Producer/files/20190116.zip");
		System.out.println(file.getAbsolutePath());
		System.out.println(file.getCanonicalPath());
		System.out.println(file.getPath());
		System.out.println(file.getTotalSpace());
		System.out.println(file.getFreeSpace());
		System.out.println(file.getUsableSpace());

		System.out.println(file.getParent());
	}
	
	// 图片处理
	@Test
	public void test04() {
		String photo = getImageBinary(new File("D:/workplace/Producer/files/714b348d35e1e1ec3d5c769c8bbdb727__1.jpg"));	
		System.out.println(photo);
		
		base64StringToImage(photo, "D:/workplace/Producer/files/20190114/a.jpg");
	}
	
	@Test
	public void test05() {
		String str = "abc\ndef\nghi";
		String str_[] = str.split("\n");
		System.out.println( str_.length + " " + str_[0] + "," + str_[1] + "," + str_[2] );
	}
	
}