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后端技術(shù)

一、構(gòu)建后端SpringBoot項(xiàng)目

1、使用Spring Initializr構(gòu)建項(xiàng)目

2、創(chuàng)建spring項(xiàng)目時(shí)勾選以下依賴

• Developer Tools: SpringBoot DevTools、Lombok
• Web: SpringWeb
• SQL: SpringData JPA、MySQL Driver

二、使用Spring Data JPA構(gòu)建數(shù)據(jù)訪問層

1、使用ide連接MySQL數(shù)據(jù)庫

2、使用Persistence插件生成實(shí)體對(duì)象

（1）創(chuàng)建包‘edu.friday.model’,作為實(shí)體對(duì)象的生成位置
（2）使用Persistence插件生成數(shù)據(jù)表對(duì)應(yīng)的實(shí)體對(duì)象（生成持久層）

3、引入Lombok插件簡(jiǎn)化實(shí)體類代碼

生成的實(shí)體類中有大量的getxxx和setxxx的代碼片段，導(dǎo)致實(shí)體類比較冗長(zhǎng)，可以使用Lombok注解來消除Java類中的大量冗長(zhǎng)代碼。
1、改寫SysUser實(shí)體類，再SysUser類上面增加下面三個(gè)Lombok注解：

• @Data:用于給類增加get、set、equals、hashCode和toString方法；
• @NoArgsConstructor:用于給類增加無參構(gòu)造器；
• @AllArgsConstructor:用于給類增加包含所有參數(shù)的構(gòu)造器。
  2、將Entity注解放到字段上面，然后刪除掉多余的getXXX、setXXX、equals和hashCode方法，另外不建議使用原始類型，將userId的long原始類型改為L(zhǎng)ong封裝類型，因?yàn)镾pring Data JPA默認(rèn)long的值為0，0在業(yè)務(wù)中是一個(gè)有意義的數(shù)值，而Long默認(rèn)值為NULL;

4、編寫UserRepository接口操作SysUser實(shí)體類

1、在‘edu.friday.repository’包里創(chuàng)建SysUserRepository接口，繼承JpaRepository<SysUser,Long>即可實(shí)現(xiàn)對(duì)SysUser對(duì)象的操作

5、配置數(shù)據(jù)源連接池

1、在pom.xml文件中添加alibaba druid數(shù)據(jù)連接池的依賴

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
        </dependency>

2、resources目錄下新建yml文件，做基礎(chǔ)配置

3、編寫測(cè)試類

class FridayApplicationTests {
    @Autowired
    SysUserRepository sysUserRepository;
    @Test
    void contextLoads() {
    }
    @Test
    void testLog(){
        System.out.println(666);
    }
    /**
     * 查找所有用戶列表
     * */
    @Test
    void testFindUsers(){
        System.out.println(sysUserRepository.findAll());
    }
}

4、運(yùn)行結(jié)果，成功獲取到數(shù)據(jù)

6、編寫通用BaseModel類

業(yè)務(wù)系統(tǒng)的大部分表都有create_time、create_by、update_time、update_by這四個(gè)公共字段，用來記錄數(shù)據(jù)的創(chuàng)建和更新時(shí)間信息等，為了簡(jiǎn)化代碼，編寫B(tài)aseModel作為Entity基類來管理公共字段。

package edu.friday.common.base;
import com.fasterxml.jackson.annotation.JsonFormat;
import jakarta.persistence.Column;
import jakarta.persistence.MappedSuperclass;
import jakarta.persistence.PrePersist;
import jakarta.persistence.PreUpdate;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.io.Serializable;
import java.util.Date;
/**
 * Entity基類
 */
@MappedSuperclass
@Data
@NoArgsConstructor
@AllArgsConstructor
public class BaseModel implements Serializable {
    private static final long serialVersionUID = 1L;
    /**
     * 創(chuàng)建者
     */
    private String createBy;
    /**
     * 創(chuàng)建時(shí)間
     */
    @Column(updatable = false)
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date createTime;
    /**
     * 更新者
     */
    private String updateBy;
    /**
     * 更新時(shí)間
     */
    @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
    private Date updateTime;
    @PrePersist
    protected void onCreate() {
        createTime = new Date();
    }
    @PreUpdate
    protected void onUpdate() {
        updateTime = new Date();
    }
}

SysUser改寫為如下所示

package edu.friday.model;
import edu.friday.common.base.BaseModel;
import jakarta.persistence.*;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.sql.Timestamp;
import java.util.Objects;
@Entity
@Table(name = "sys_user", schema = "friday", catalog = "")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class SysUser extends BaseModel {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    @Column(name = "user_id")
    private Long userId;
    @Basic
    @Column(name = "user_name")
    private String userName;
    @Basic
    @Column(name = "nick_name")
    private String nickName;
    @Basic
    @Column(name = "user_type")
    private String userType;
    @Basic
    @Column(name = "email")
    private String email;
    @Basic
    @Column(name = "phonenumber")
    private String phonenumber;
    @Basic
    @Column(name = "sex")
    private String sex;
    @Basic
    @Column(name = "avatar")
    private String avatar;
    @Basic
    @Column(name = "password")
    private String password;
    @Basic
    @Column(name = "status")
    private String status;
    @Basic
    @Column(name = "del_flag")
    private String delFlag;
    @Basic
    @Column(name = "login_ip")
    private String loginIp;
    @Basic
    @Column(name = "login_date")
    private Timestamp loginDate;
/**    @Basic
    @Column(name = "create_by")
    private String createBy;
    @Basic
    @Column(name = "create_time")
    private Timestamp createTime;
    @Basic
    @Column(name = "update_by")
    private String updateBy;
    @Basic
    @Column(name = "update_time")
    private Timestamp updateTime;*/
    @Basic
    @Column(name = "remark")
    private String remark;
}

7、工具類與封裝HTTP結(jié)果