Generating JPA Entity Classes in IntelliJ IDEA Using Groovy Scripts

This article explains how to generate JPA‑annotated entity classes directly from a database schema using IntelliJ IDEA.

First it shows how to configure a database connection in the Ultimate edition of IDEA, including driver download and connection parameters.

Then it describes the two built‑in generation methods: (1) generating simple POJOs without annotations via the “Generate POJOs.groovy” script, and (2) generating JPA‑annotated entities using the Persistence tool after adding the JPA module.

Finally it provides a step‑by‑step guide to create a custom Groovy script that produces fully annotated entity classes, covering script placement, package handling, field mapping, annotation insertion, and optional enhancements such as hashCode/equals generation. The complete script source is included.

Running the script from the Database tool window creates Java files with @Entity, @Table, @Id, @Column annotations and standard getters, setters, toString and serialVersionUID.

import com.intellij.database.model.DasTable
import com.intellij.database.model.ObjectKind
import com.intellij.database.util.Case
import com.intellij.database.util.DasUtil
import java.text.SimpleDateFormat

/*
 * Available context bindings:
 *   SELECTION   Iterable<DasObject>
 *   PROJECT     project
 *   FILES       files helper
 */
packageName = ""
typeMapping = [
        (~/(?i)tinyint|smallint|mediumint/)      : "Integer",
        (~/(?i)int/)                               : "Long",
        (~/(?i)bool|bit/)                          : "Boolean",
        (~/(?i)float|double|decimal|real/)        : "Double",
        (~/(?i)datetime|timestamp|date|time/)    : "Date",
        (~/(?i)blob|binary|bfile|clob|raw|image/): "InputStream",
        (~/(?i)/)                                   : "String"
]

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

def generate(table, dir) {
    def className = javaName(table.getName(), true)
    def fields = calcFields(table)
    packageName = getPackageName(dir)
    PrintWriter printWriter = new PrintWriter(new OutputStreamWriter(new FileOutputStream(new File(dir, className + ".java")), "UTF-8"))
    printWriter.withPrintWriter { out -> generate(out, className, fields, table) }
}

def getPackageName(dir) {
    return dir.toString().replaceAll("\\\\", ".").replaceAll("/", ".").replaceAll("^.*src(\\.main\\.java\\.)?", "") + ";"
}

def generate(out, className, fields, table) {
    out.println "package $packageName"
    out.println ""
    out.println "import javax.persistence.Column;"
    out.println "import javax.persistence.Entity;"
    out.println "import javax.persistence.Table;"
    out.println "import javax.persistence.Id;"
    out.println "import javax.persistence.GeneratedValue;"
    out.println "import java.io.Serializable;"
    if (fields.any { it.type == "Date" }) out.println "import java.util.Date;"
    if (fields.any { it.type == "InputStream" }) out.println "import java.io.InputStream;"
    out.println ""
    out.println "/**
 * @Description
 * @Author  idea
 * @Date " + new SimpleDateFormat("yyyy-MM-dd").format(new Date()) + "
 */"
    out.println ""
    out.println "@Entity"
    out.println "@Table(name=\"" + table.getName() + "\", schema=\"\")"
    out.println "public class $className implements Serializable {"
    out.println ""
    out.println genSerialID()
    fields.each { 
        out.println ""
        if (isNotEmpty(it.commoent)) {
            out.println "\t/**"
            out.println "\t * ${it.commoent.toString()}"
            out.println "\t */"
        }
        if (it.annos.contains("[@Id]")) out.println "\t@Id"
        if (it.annos != "") out.println "\t${it.annos.replace("[@Id]", "")}"
        out.println "\tprivate ${it.type} ${it.name};"
    }
    fields.each { 
        out.println ""
        out.println "\tpublic ${it.type} get${it.name.capitalize()}() {"
        out.println "\t    return this.${it.name};"
        out.println "\t}"
        out.println ""
        out.println "\tpublic void set${it.name.capitalize()}(${it.type} ${it.name}) {"
        out.println "\t    this.${it.name} = ${it.name};"
        out.println "\t}"
    }
    out.println ""
    out.println "\t@Override"
    out.println "\tpublic String toString() {"
    out.println "\t    return \"TpApiConfig{\" +"
    fields.each { out.println "\t        \"${it.name}='\" + ${it.name} + '\'' + \"\" +" }
    out.println "\t        '}';"
    out.println "\t}"
    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
        def comm = [
            colName : col.getName(),
            name    : javaName(col.getName(), false),
            type    : typeStr,
            commoent: col.getComment(),
            annos   : "\t@Column(name = \"" + col.getName() + "\")"
        ]
        if ("id".equals(Case.LOWER.apply(col.getName()))) comm.annos += ["@Id"]
        fields += [comm]
    }
}

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

def isNotEmpty(content) { return content != null && content.toString().trim().length() > 0 }

static String genSerialID() {
    return "\tprivate static final long serialVersionUID = " + Math.abs(new Random().nextLong()) + "L;"
}