How to use Java to create a JAR package that can be referenced by the project?

jar package?

jar package: A compressed package of java bytecode files that implements specific functions.
Essentially is a compiled java project, packaged into jar files
log4j.jar, mysql-connection-8.01.jar, etc.

Create the jar package yourself and let others use it:

• 1. Create a new java project

• 2. Create a class that implements specific functions

• 3. Generate the project into a jar package

• 4. Publish the jar package for others to use

1. Create project and verify

1.1 Create project

Create Project project named dateUtil

or:

Project dateUtil is created:

1.2 Create packages and classes

1.3 Corresponding code

package com.aaa.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
/**日期转换工具类
 * @author: XYT
 * @create-date: 2022/7/26 15:12
 */
public class DateConvertUtil {
    /**   注释方法：/**+回车键 形参会被自动提取出来并加粗描黑。这就是为什么引用系统方法的时候，会有很多的说明
     * 将字符串转为日期，默认格式为yyyy-MM-dd
     * @param strDate 字符串日期
     * @return 返回转换的日期
     */
    public static Date getDate(String strDate){ //一个参数；对下方方法的一种封装;这种方式叫“语法糖”；
        return getDate(strDate,"yyyy-MM-dd"); //格式是默认的 getDate
    }
    /**
     * 将字符串转为日期类型
     * @param strDate 字符串日期
     * @param format 转换格式
     * @return 返回转换的日期，转换失败返回null
     */
    public static Date getDate(String strDate, String format){ //两个参数
        SimpleDateFormat sdf=new SimpleDateFormat(format); //格式需要自己指定（设置）

//        try {  //自动生成try-catch
//            return sdf.parse(strDate);
//        } catch (ParseException e) {
//            throw new RuntimeException(e);
//        }
//    }
        try {  //课堂代码try-catch
            return sdf.parse(strDate);  //注意：parse
        } catch (ParseException e) {
            e.printStackTrace(); //这里不一样
        }
        return null;
    }
    /**
     * 将日期转为字符串，固定格式为yyyy-MM-dd
     * @param date 日期
     * @return 返回转换的字符串
     */
    public static String getDate(Date date){
        return getDate(date,"yyyy-MM-dd"); //格式是默认的 getDate
    }
    /**
     * 将日期转为字符串
     * date 日期
     * format 格式字符串
     * 返回转换后的字符串
     */
    public static String getDate(Date date,String format){ //两个参数
        SimpleDateFormat sdf=new SimpleDateFormat(format); //格式需要自己指定（设置）
        return sdf.format(date);   //注意：format
    }
}

package com.aaa.util;
/**
 * @author: XYT
 * @create-date: 2022/7/26 16:02
 */
public class StringUtils {
    /**
     * 判断字符串是否为空
     * @param str
     * @return
     */
    public static boolean isNullOrEmpty(String str){
        return str==null || str.isEmpty();  //注意 ==
    }
}

Verification code part:

package com.aaa.test;
import com.aaa.util.DateConvertUtil;
import java.util.Date;
/**
 * @author: XYT
 * @create-date: 2022/7/26 16:08
 */
public class Test { //测试
    public static void main(String[] args) {
        //日期转为字符串
        System.out.println(DateConvertUtil.getDate(new Date()));
        //日期转为固定格式的字符串
        System.out.println(DateConvertUtil.getDate(new Date(),"yyyy-MM-dd HH:mm:ss"));
    }
}

Test result:

2. Packaging and reference package

Select Project Structure in File.

Introducing the toolbar and specific functions of Project Structure:

#2.1 Make jar package

#Copy the generated jar package to the desktop, and then open it with the decompression tool:

##2.2 Import the generated jar package

##2.3 Verify the correctness of the jar package import/application

The above is the detailed content of How to use Java to create a JAR package that can be referenced by the project?. For more information, please follow other related articles on the PHP Chinese website!