IDEA连接DB2数据库自动生成Entity实体类(SpringBoot + Spring JPA + Lombok + DB2)

一。简介

本篇博客主要介绍如何使用IDEA连接数据库，并且自动生成与table对应的实体类，省时省力。
项目环境：SpringBoot + Spring JPA + Lombok + DB2

二。操作流程

1.连接DB2数据库，打开IDEA，找到最右侧的Database，创建一个新的DB2的连接：

2.注意这里要选Type4和IBM Db2：

3.db信息填完之后再点击Schemas，选择你需要连接的数据库：

4.这个时候你就能在IDEA中看到数据库的详细信息了，如果加载慢，尝试多手动点击刷新按钮即可：

5.选中任意table点击鼠标右键，Scripted Extensions --> GoTo Scripts Directory，找到Generate POJOs.groovy文件，这个是IDEA生成Entity的初始脚本模板：


6.往往IDEA生成的初始模板不能满足我们的需求，所以我们可以复制Generate POJOs.groovy并重命名为Generate POJOs-new.groovy，下面是我自己写的groovy脚本：

import com.intellij.database.model.DasTable
import com.intellij.database.util.Case
import com.intellij.database.util.DasUtil

/*
 * Available context bindings:
 *   SELECTION   Iterable
 *   PROJECT     project
 *   FILES       files helper
 */
//1.这里更改成你想要的包名
packageName = "package com.example.demo;"
//2.这里是DB2的类型typeMapping，自行变换成自己需要的
typeMapping = [
        (~/(?i)int/)                      : "Integer",
        (~/(?i)float|double|decimal|real/): "BigDecimal",
        (~/(?i)datetime|timestamp/)       : "LocalDateTime",
        (~/(?i)date/)                     : "LocalDate",
        (~/(?i)time/)                     : "LocalTime",
        (~/(?i)/)                         : "String"
]

FILES.chooseDirectoryAndSave("Choose directory", "Choose where to store generated files") { dir ->
    SELECTION.filter { it instanceof DasTable }.each { generate(it, dir) }
}

def generate(table, dir) {
    def className = javaName(table.getName(), true)
    def fields = calcFields(table)
    new File(dir, className + ".java").withPrintWriter { out -> generate(out, className, fields, table) }
}

def generate(out, className, fields, table) {
    //3.增加你需要导入的包或者添加的注解
    out.println "package $packageName"
    out.println ""
    out.println "import lombok.AllArgsConstructor;"
    out.println "import lombok.Data;"
    out.println "import lombok.NoArgsConstructor;"
    out.println "import lombok.experimental.SuperBuilder;"
    out.println "import javax.persistence.*;"
    out.println "import java.io.Serializable;"
    out.println "import java.math.BigDecimal;"
    out.println "import java.time.LocalDate;"
    out.println "import java.time.LocalDateTime;"
    out.println ""
    out.println "@Data"
    out.println "@SuperBuilder"
    out.println "@NoArgsConstructor"
    out.println "@AllArgsConstructor"
    out.println "@Entity"
    out.println "@Table(name = \"${table.getName()}\", schema = \"FOS\")"
    out.println "public class $className implements Serializable{"
    out.println ""
    fields.each() {
        if (it.annos != "") out.println "  ${it.annos}"
        //4.增加@Column注解
        out.println "  @Column(name= = \"${it.filed}\")"
        out.println "  private ${it.type} ${it.name};"
        out.println ""
    }
    out.println ""
    //5.因为使用Lombok插件，注释Getter和Setter方法
//    fields.each() {
//        out.println ""
//        out.println "  public ${it.type} get${it.name.capitalize()}() {"
//        out.println "    return ${it.name};"
//        out.println "  }"
//        out.println ""
//        out.println "  public void set${it.name.capitalize()}(${it.type} ${it.name}) {"
//        out.println "    this.${it.name} = ${it.name};"
//        out.println "  }"
//        out.println ""
//    }
    out.println "}"
}

def calcFields(table) {
    DasUtil.getColumns(table).reduce([]) { fields, col ->
        def spec = Case.LOWER.apply(col.getDataType().getSpecification())
        def typeStr = typeMapping.find { p, t -> p.matcher(spec).find() }.value
        fields += [[
                           name : javaName(col.getName(), false),
                           type : typeStr,
                           //6.增加filed属性，给@Column获取table中的属性名
                           filed: col.getName(),
                           annos: ""]]
    }
}

def javaName(str, capitalize) {
    def s = com.intellij.psi.codeStyle.NameUtil.splitNameIntoWords(str)
            .collect { Case.LOWER.apply(it).capitalize() }
            .join("")
            .replaceAll(/[^\p{javaJavaIdentifierPart}[_]]/, "_")
    capitalize || s.length() == 1? s : Case.LOWER.apply(s[0]) + s[1..-1]
}

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三。生成Entity示例

注意，生成的Entity不能自动识别到table中的主键，所以需要手动修改并添加@Id注解