异步任务

同步，在网站上发送邮件时，后台会去发送邮件，这个过程中前台会造成响应不动，直到邮件发送完毕，响应才会成功。

@EnableAsync开启异步注解功能

package com.tasks;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;

@SpringBootApplication
@EnableAsync //开启异步注解功能
public class TasksApplication {

    public static void main(String[] args) {
        SpringApplication.run(TasksApplication.class, args);
    }
   
}

@Async告诉Spring这是一个异步方法

package com.tasks.asyn;

import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

@Service
public class AsyncService {

    @Async //告诉Spring这是一个异步方法
    public void sleep(){
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("发送邮件完成...");
    }
}

使用异步后，网页瞬间响应，后台代码依旧执行

定时任务

项目开发中经常需要执行一些定时任务，比如需要在每天凌晨的时候，分析一次前一天的日志信息，Spring为我们提供了异步执行任务调度的方式，提供了TaskExecutor 、TaskScheduler 两个接口。

TaskExecutor 任务调度
TaskScheduler任务执行者

两个注解：

@EnableScheduling 开启定时任务的注解
@Scheduled 什么时候执行

Cron表达式，在Linux定时任务常用

格式：秒分钟小时日月周年
在线Cron表达式生成器

https://www.beejson.com/tool/cron.html

https://cron.qqe2.com/

image-20200823223351004.png

package com.tasks;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableAsync //开启异步注解功能
@EnableScheduling //开启定时任务注解功能
public class TasksApplication {

    public static void main(String[] args) {
        SpringApplication.run(TasksApplication.class, args);
    }

}

package com.tasks.scheduled;

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;

@Service
public class ScheduledService {
    //每秒执行一次
    @Scheduled(cron = "* * * * * ?")
    public void hello(){
        mysqlUtil.backup();
        System.out.println("备份数据库");
    }
}

邮件发送

邮件发送，在我们的日常开发中，也非常的多，Springboot也帮我们做了支持

邮件发送需要引入spring-boot-start-mail
SpringBoot 自动配置MailSenderAutoConfiguration
定义MailProperties内容，配置在application.yml中
自动装配JavaMailSender
测试邮件发送

spring:
  mail:
    username: strtz3@163.com
    password: 密钥
    host: smtp.163.com

以下的配置可以解决一些异常

spring.mail.protocol=smtp
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.ssl.enable=true
spring.mail.test-connection=true

JavaMailUtils工具类

package com.tasks.utils;

import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSenderImpl;
import org.springframework.mail.javamail.MimeMessageHelper;

import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import java.io.File;

public class JavaMailUtils {
    //默认编码
    public static final String DEFAULT_ENCODING = "UTF-8";
    
    /**
     * 简单邮件发送
     *
     * @param javaMailSender
     * @param subject
     * @param content
     * @param target
     * @param form
     */
    public static void sendSimpleMessage(JavaMailSenderImpl javaMailSender, String subject, String content, String target, String form) {
        SimpleMailMessage simpleMailMessage = new SimpleMailMessage();
        //邮件内容
        simpleMailMessage.setSubject(subject);
        simpleMailMessage.setText(content);
        //发送和接收方
        simpleMailMessage.setTo(target);
        simpleMailMessage.setFrom(form);
        javaMailSender.send(simpleMailMessage);
    }

    /**
     * 复杂邮件发送
     *
     * @param javaMailSender
     * @param subject        主体
     * @param body           内容
     * @param isHtml         是否html
     * @param target         发送方
     * @param form           发件方
     * @param attachment     附件
     * @throws MessagingException
     */
    public static void sendMimeMessage(JavaMailSenderImpl javaMailSender, String subject, String body, Boolean isHtml, String target, String form, File attachment
    ) throws MessagingException {
        MimeMessage mimeMessage = javaMailSender.createMimeMessage();
        //创建一个helper来处理复杂邮件封装,true开启文件上传功能
        MimeMessageHelper messageHelper = new MimeMessageHelper(mimeMessage, true);
        //邮件内容
        messageHelper.setSubject(subject);
        messageHelper.setText(body, isHtml);
        messageHelper.addAttachment(attachment.getName(), attachment);
        //发送和接收方
        messageHelper.setFrom(form);
        messageHelper.setTo(target);
        javaMailSender.send(mimeMessage);
    }
}

测试

package com.tasks;

import com.tasks.utils.JavaMailUtils;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSenderImpl;

import javax.mail.MessagingException;
import java.io.File;

@SpringBootTest

class TasksApplicationTests {
    @Autowired
    private JavaMailSenderImpl javaMailSender;

    @Test
    void contextLoads() throws MessagingException {
        JavaMailUtils.sendMimeMessage(javaMailSender,"工具类发送复杂","<a href=''>go</a>",true,"strtz3@163.com","strtz3@163.com",new File("C:/Users/str/Desktop/mp.jpg"));
    }

}

https://blog.csdn.net/qq_41741884/article/details/99079716 其他内容可以参考该文章

备份与恢复数据库

mysqldump -h127.0.0.1 -uroot -p123456 test > d:/test.sql 备份数据
mysql -h127.0.0.1 -uroot -p123456 test< d:/test.sql 恢复数据

在cmd调用命令行，其实是调用 mysql安装路径下面的bin目录下面的msqldump.exe和mysql.exe来完成相应的工作

//linux
String[] command = { "/bin/sh", "-c", command };
//window
String[] command = { "cmd", "/c", command};
//java调用外部软件exe执行命令的api；
Process ps = Runtime.getRuntime().exec(command );

package com.tasks.utils;

import java.io.*;
import java.text.SimpleDateFormat;
import java.util.Date;


/**
 * 数据库备份和还原
 */
public class mysqlUtil {

    /**
     * 备份数据库db
     * mysqldump -hlocalhost -uroot -proot test > d:/db.sql
     *
     * @param root
     * @param pwd
     * @param dbName
     * @param backPath
     * @param backName
     */
    public static void dbBackUp(String root, String pwd, String dbName, String backPath, String backName) throws Exception {
        String pathSql = backPath + backName;
        File fileSql = new File(pathSql);
        //创建备份sql文件
        if (!fileSql.exists()) {
            fileSql.createNewFile();
        }
        //mysqldump -hlocalhost -uroot -p123456 db > /home/back.sql
        StringBuffer sb = new StringBuffer();
        sb.append("mysqldump");
        sb.append(" -hlocalhost");
        sb.append(" -u" + root);
        sb.append(" -p" + pwd);
        sb.append(" " + dbName + " >");
        sb.append(pathSql);
        System.out.println("cmd命令为：" + sb.toString());
        Runtime runtime = Runtime.getRuntime();
        System.out.println("开始备份：" + dbName);
        Process process = runtime.exec("cmd /c" + sb.toString());
        System.out.println("备份成功!");
    }

    /**
     * 恢复数据库
     *
     * @param root
     * @param pwd
     * @param dbName
     * @param filePath mysql -hlocalhost -uroot -proot db < /home/back.sql
     */
    public static void dbRestore(String root, String pwd, String dbName, String filePath) {
        StringBuilder sb = new StringBuilder();
        sb.append("mysql");
        sb.append(" -hlocalhost");
        sb.append(" -u" + root);
        sb.append(" -p" + pwd);
        sb.append(" " + dbName + " <");
        sb.append(filePath);
        System.out.println("cmd命令为：" + sb.toString());
        Runtime runtime = Runtime.getRuntime();
        System.out.println("开始还原数据");
        try {
            Process process = runtime.exec("cmd /c" + sb.toString());
            InputStream is = process.getInputStream();
            BufferedReader bf = new BufferedReader(new InputStreamReader(is, "utf8"));
            String line = null;
            while ((line = bf.readLine()) != null) {
                System.out.println(line);
            }
            is.close();
            bf.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("还原成功！");
    }


    public static void main(String[] args) throws Exception {
        String backName = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss").format(new Date()) + ".sql";
        mysqlUtil.dbBackUp("root", "root", "myblog", "E:/", backName);
        //dbRestore("root", "root", "myblog", "name.sql");
    }
}

Springboot 任务

Springboot 任务

异步任务

定时任务

邮件发送

备份与恢复数据库