- java压缩文件
- ZipOutputStream、ZipFile、ZipInputStream
- CRC32 算法
- Java安全管理器SecurityManager
- 文件下载
- no main manifest attribute, in xxxx.jar 项目部署报错
java压缩文件
package dhy.com.utils;
import dhy.com.exception.CustomException;
import dhy.com.exception.CustomExceptionType;
import java.io.*;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
public class FileUtils
{
//默认的缓冲区大小
private static final int BUFFER_SIZE = 2 * 1024;
//默认的生成的压缩包名字
private static final String DEFAULT_ZIP_NAME="dhy.zip";
//默认是否保留原来的目录结构
private static final Boolean SAVE_ORIGINAL_STRUCTURE=true;
public static void toZip(String srcDir) throws FileNotFoundException
{
File file = new File(srcDir);
if(!file.exists())
{
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR,"下载的资源不存在");
}
FileOutputStream fileOutputStream = new FileOutputStream(file.getParent()+File.separator+DEFAULT_ZIP_NAME);
toZip(srcDir,fileOutputStream,SAVE_ORIGINAL_STRUCTURE);
}
public static void toZip(String srcDir,String zipFileName) throws FileNotFoundException
{
File file = new File(srcDir);
if(!file.exists())
{
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR,"下载的资源不存在");
}
FileOutputStream fileOutputStream = new FileOutputStream(file.getParent()+File.separator+DEFAULT_ZIP_NAME);
toZip(srcDir,fileOutputStream,SAVE_ORIGINAL_STRUCTURE);
}
public static void toZip(String srcDir, boolean KeepDirStructure) throws FileNotFoundException {
File file = new File(srcDir);
if(!file.exists())
{
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR,"下载的资源不存在");
}
FileOutputStream fileOutputStream = new FileOutputStream(file.getParent()+File.separator+DEFAULT_ZIP_NAME);
toZip(srcDir,fileOutputStream,KeepDirStructure);
}
public static void toZip(String srcDir,String zipFileName ,boolean KeepDirStructure) throws FileNotFoundException {
File file = new File(srcDir);
if(!file.exists())
{
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR,"下载的资源不存在");
}
FileOutputStream fileOutputStream = new FileOutputStream(file.getParent()+File.separator+DEFAULT_ZIP_NAME);
toZip(srcDir,fileOutputStream,KeepDirStructure);
}
private static void toZip(String srcDir, OutputStream out, boolean KeepDirStructure)
throws RuntimeException{
long start = System.currentTimeMillis();
ZipOutputStream zos = null ;
try {
zos = new ZipOutputStream(out);
File sourceFile = new File(srcDir);
//源文件,输出流,压缩文件的路径,是否保持目录结构
compress(sourceFile,zos,sourceFile.getName(),KeepDirStructure);
long end = System.currentTimeMillis();
System.out.println("压缩完成，耗时：" + (end - start) +" ms");
} catch (Exception e) {
throw new RuntimeException("zip error from ZipUtils",e);
}finally{
if(zos != null){
try {
zos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static void toZip(List srcFiles , OutputStream out)throws RuntimeException {
long start = System.currentTimeMillis();
ZipOutputStream zos = null ;
try {
zos = new ZipOutputStream(out);
for (File srcFile : srcFiles) {
byte[] buf = new byte[BUFFER_SIZE];
zos.putNextEntry(new ZipEntry(srcFile.getName()));
int len;
FileInputStream in = new FileInputStream(srcFile);
while ((len = in.read(buf)) != -1){
zos.write(buf, 0, len);
}
zos.closeEntry();
in.close();
}
long end = System.currentTimeMillis();
System.out.println("压缩完成，耗时：" + (end - start) +" ms");
} catch (Exception e) {
throw new RuntimeException("zip error from ZipUtils",e);
}finally{
if(zos != null){
try {
zos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
private static void compress(File sourceFile, ZipOutputStream zos, String name,
boolean KeepDirStructure) throws Exception{
byte[] buf = new byte[BUFFER_SIZE];
if(sourceFile.isFile()){
// 向zip输出流中添加一个zip实体，构造器中name为zip实体的文件的名字
zos.putNextEntry(new ZipEntry(name));
// copy文件到zip输出流中
int len;
FileInputStream in = new FileInputStream(sourceFile);
while ((len = in.read(buf)) != -1){
zos.write(buf, 0, len);
}
// Complete the entry
zos.closeEntry();
in.close();
} else {
File[] listFiles = sourceFile.listFiles();
if(listFiles == null || listFiles.length == 0){
// 需要保留原来的文件结构时,需要对空文件夹进行处理
if(KeepDirStructure){
// 空文件夹的处理
zos.putNextEntry(new ZipEntry(name + "/"));
// 没有文件，不需要文件的copy
zos.closeEntry();
}
}else {
for (File file : listFiles) {
// 判断是否需要保留原来的文件结构
if (KeepDirStructure) {
// 注意：file.getName()前面需要带上父文件夹的名字加一斜杠,
// 不然最后压缩包中就不能保留原来的文件结构,即：所有文件都跑到压缩包根目录下了
compress(file, zos, name + "/" + file.getName(),KeepDirStructure);
} else {
compress(file, zos, file.getName(),KeepDirStructure);
}
}
}
}
}
}
使用ZipEntry压缩与解压缩
java实现文件打包压缩处理
java文件压缩工具类，打包zip
工具类2：用java进行多文件压缩为一个ZIP包
Java实现将文件或者文件夹压缩成zip
ZipOutputStream、ZipFile、ZipInputStream
Java IO操作——掌握压缩流的使用（ZipOutputStream、ZipFile、ZipInputStream）[java.util包中]
ZipOutputStream使用
CRC32 算法
在远距离数据通信中，为确保高效而无差错地传送数据，必须对数据进行校验即差错控制。循环冗余校验CRC(Cyclic Redundancy Check/Code)是对一个传送数据块进行校验，是一种高效的差错控制方法。
CRC32 算法
Java安全管理器SecurityManager
Java安全管理器SecurityManager
文件下载
SpringBoot实现文件下载
Spring Boot实现文件上传与下载
//下载爬取到的图片
public void downLoad() {
ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.currentRequestAttributes();
HttpSession session = requestAttributes.getRequest().getSession();
//用户是否开启了爬虫线程----主要判断session,如果为空，抛出异常
if(session==null)
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR,"请先爬取再下载资源");
String sessionID =session.getId();
//判断当前用户的爬虫线程是否关闭
List userClawerList = getUserClawerList();
//当前用户开启了一个爬虫线程，还未关闭，不能继续开启爬虫线程
if (userClawerList != null && userClawerList.size() == 1) {
throw new CustomException(CustomExceptionType.USER_INPUT_ERROR, "请先关闭已经开启的爬虫线程");
}
//TODO:将下载的图片,的文件夹进行打包
String zipPath="";
try {
zipPath = FileUtils.toZip(clawerProperties.getFilePathPrefix() + sessionID + "/");
} catch (FileNotFoundException e) {
e.printStackTrace();
}
HttpServletResponse response = requestAttributes.getResponse();
File file = new File(zipPath);
if (file == null||!file.exists())
throw new CustomException(CustomExceptionType.SYSTEM_ERROR, "下载的文件不存在");
response.setContentType("application/octet-stream");
response.setHeader("content-type", "application/octet-stream");
try {
response.addHeader("Content-Disposition", "attachment;fileName="+ URLEncoder.encode(file.getName(), "UTF-8"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
byte[] buffer = new byte[1024];
OutputStream os=null;
try (FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis))
{
os = response.getOutputStream();
int i = -1;
while ((i = bis.read(buffer)) != -1) {
os.write(buffer, 0, i);
}
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
//删除文件压缩包
FileUtils.delFile(zipPath);
}
}
no main manifest attribute, in xxxx.jar 项目部署报错
no main manifest attribute, in xxxx.jar 项目部署报错
找不到main方法，需要我们在pom.xml指定
org.springframework.boot spring-boot-maven-plugin package repackage true com.qiruipeng.eureka.EurekaApplication
