add post

_posts/2024-09-24-custom-idea-mybatis-code-generator.md

@@ -0,0 +1,301 @@
+---
+layout: post
+title: 后端｜在 IDEA 里自动生成 MyBatis 模板代码
+categories: [Java]
+description: 除了使用 MyBatis Generator，还可以在 IDEA 里自定义代码生成器，实现自动生成 MyBatis 模板代码。
+keywords: 后端, Java, MyBatis, IDEA, 代码生成器
+mermaid: false
+sequence: false
+flow: false
+mathjax: false
+mindmap: false
+mindmap2: false
+---
+
+## 背景
+
+基于 MyBatis 开发的项目，新增数据库表以后，总是需要编写对应的 Entity、Mapper 和 Service 等等 Class 的代码，这些都是重复的工作，我们可以想一些办法来自动生成这些代码。
+
+## 方案
+
+一种可选的方案是使用 MyBatis Generator，官方支持，常见需求一般也都能满足。但是它的配置文件比较繁琐，如果有一些项目相关的个性化需求，不一定很好处理。
+
+这里介绍另外一种我觉得更为简便灵活的方法。
+
+近几年版本的 IDEA 里已经自带了 Database Tools and SQL 插件，可以连接数据库进行常用的操作，并且，它还自带了数据库表对应 POJO 类的代码生成器：在 Database 面板里配置好数据源以后，右键表名，依次选择 Scripted Extensions、Generate POJOs.groovy，选择生成路径后，即可生成对应的 Entity 类。
+
+![](/images/posts/java/generate-pojos.png)
+
+既然能够生成 Entity，那么我们可以基于它进行修改，让它一次性生成我们需要的 Entity、Mapper 和 Service。
+
+## 需求
+
+基于项目情况，我们对生成的代码有如下要求：
+
+1. Entity 需要继承指定基类，数据库表的公共字段放在基类里；
+2. Mapper、Service 和 ServiceImpl 分别需要实现指定的类继承关系；
+3. Entity、Mapper 和 Service 需要自动放在对应的子包下。
+
+以 t_promotion_channel 表为例，指定该表和对应的代码目录之后，生成的目录结构如下：
+
+```
+.
+├── entity
+│   └── PromotionChannel.java
+├── mapper
+│   └── PromotionChannelMapper.java
+└── service
+    ├── PromotionChannelService.java
+    └── impl
+        └── PromotionChannelServiceImpl.java
+```
+
+需要生成的代码如下：
+
+*entity/PromotionChannel.java*
+
+```java
+package com.test.data.promotion.entity;
+
+import com.test.common.base.BaseEntity;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+import javax.persistence.Table;
+
+/**
+ * @author mazhuang
+ */
+@EqualsAndHashCode(callSuper = true)
+@Data
+@Table(name = "t_promotion_channel")
+public class PromotionChannel extends BaseEntity {
+
+    private static final long serialVersionUID = 5495175453870776988L;
+    /**
+     * 用户ID
+    */
+    private Long fkUserId;
+
+    /**
+     * 渠道名称
+    */
+    private String channelName;
+
+}
+```
+
+*mapper/PromotionChannelMapper.java*
+
+```java
+package com.test.data.promotion.mapper;
+
+import com.test.common.base.BaseMapper;
+import com.test.data.promotion.entity.PromotionChannel;
+
+/**
+ * @author mazhuang
+ */
+public interface PromotionChannelMapper extends BaseMapper<PromotionChannel> {
+
+}
+```
+
+*service/PromotionChannelService.java*
+
+```java
+package com.test.data.promotion.service;
+
+import com.test.common.base.BaseService;
+import com.test.data.promotion.entity.PromotionChannel;
+
+/**
+ * @author mazhuang
+ */
+public interface PromotionChannelService extends BaseService<PromotionChannel> {
+
+}
+```
+
+*service/impl/PromotionChannelServiceImpl.java*
+
+```java
+package com.test.data.promotion.service.impl;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+import com.test.common.base.BaseServiceImpl;
+import com.test.data.promotion.entity.PromotionChannel;
+import com.test.data.promotion.mapper.PromotionChannelMapper;
+import com.test.data.promotion.service.PromotionChannelService;
+
+/**
+ * @author mazhuang
+ */
+@Slf4j
+@Service
+public class PromotionChannelServiceImpl extends BaseServiceImpl<PromotionChannelMapper, PromotionChannel> implements PromotionChannelService {
+
+}
+```
+
+## 实现
+
+右键一个数据库表，依次选择 Scripted Extensions、Go to Scripts Directory，进入生成的脚本目录，找到 Generate POJOs.groovy，复制一份，重命名为 Generate MyBatis Code.groovy，然后修改内容如下：
+
+```groovy
+import com.intellij.database.model.DasTable
+import com.intellij.database.util.Case
+import com.intellij.database.util.DasUtil
+
+/*
+ * Available context bindings:
+ *   SELECTION   Iterable<DasObject>
+ *   PROJECT     project
+ *   FILES       files helper
+ */
+
+typeMapping = [
+        (~/(?i)int/)                      : "Long",
+        (~/(?i)float|double|decimal|real/): "BigDecimal",
+        (~/(?i)datetime|timestamp/)       : "java.util.Date",
+        (~/(?i)date/)                     : "java.sql.Date",
+        (~/(?i)time/)                     : "java.sql.Time",
+        (~/(?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().replaceFirst('t_', ''), true)
+    def fields = calcFields(table)
+
+    dirPath = dir.getAbsolutePath()
+    packageName = calcPackageName(dirPath)
+
+    // Generate POJO
+    new File(dirPath + File.separator + "entity", className + ".java").withPrintWriter("utf-8") { out -> generateEntity(out, table.getName(), className, fields, packageName) }
+
+    // Generate Mapper
+    new File(dirPath + File.separator + "mapper", className + "Mapper.java").withPrintWriter("utf-8") { out -> generateMapper(out, className, packageName) }
+
+    // Generate Service
+    new File(dirPath + File.separator + "service", className + "Service.java").withPrintWriter("utf-8") { out -> generateService(out, className, packageName) }
+
+    // Generate ServiceImpl
+    new File(dirPath + File.separator + "service" + File.separator + "impl", className + "ServiceImpl.java").withPrintWriter("utf-8") { out -> generateServiceImpl(out, className, packageName) }
+}
+
+static def generateEntity(out, tableName, className, fields, packageName) {
+    out.println "package $packageName" + ".entity;"
+    out.println ""
+    out.println "import com.test.common.base.BaseEntity;"
+    out.println "import lombok.Data;"
+    out.println "import lombok.EqualsAndHashCode;"
+    out.println "import javax.persistence.Table;"
+    out.println ""
+    out.println "/**\n * @author mazhuang\n */"
+    out.println "@EqualsAndHashCode(callSuper = true)"
+    out.println "@Data"
+    out.println "@Table(name = \"$tableName\")"
+    out.println "public class $className extends BaseEntity {"
+    out.println ""
+
+    def baseEntityFields = ['pkid', 'addedBy', 'addedTime', 'lastModifiedBy', 'lastModifiedTime', 'valid']
+    fields.each() {
+        if (baseEntityFields.contains(it.name)) {
+            return
+        }
+        if (it.annos != "") out.println "  ${it.annos}"
+        if (it.comment != null) out.println "    /**\n     * ${it.comment}\n    */"
+        out.println "    private ${it.type} ${it.name};\n"
+    }
+
+    out.println "}"
+}
+
+static def generateMapper(out, className, packageName) {
+    out.println "package $packageName" + ".mapper;"
+    out.println ""
+
+    out.println "import com.test.common.base.BaseMapper;"
+    out.println "import $packageName" + ".entity.$className;"
+    out.println ""
+
+    out.println "/**\n * @author mazhuang\n */"
+    out.println "public interface $className" + "Mapper extends BaseMapper<$className> {"
+    out.println ""
+    out.println "}"
+}
+
+static def generateService(out, className, packageName) {
+    out.println "package $packageName" + ".service;"
+    out.println ""
+
+    out.println "import com.test.common.base.BaseService;"
+    out.println "import $packageName" + ".entity.$className;"
+    out.println ""
+
+    out.println "/**\n * @author mazhuang\n */"
+    out.println "public interface $className" + "Service extends BaseService<$className> {"
+    out.println ""
+    out.println "}"
+}
+
+static def generateServiceImpl(out, className, packageName) {
+    out.println "package $packageName" + ".service.impl;"
+    out.println ""
+
+    out.println "import lombok.extern.slf4j.Slf4j;"
+    out.println "import org.springframework.stereotype.Service;"
+    out.println "import com.test.common.base.BaseServiceImpl;"
+    out.println "import $packageName" + ".entity.$className;"
+    out.println "import $packageName" + ".mapper.$className" + "Mapper;"
+    out.println "import $packageName" + ".service.$className" + "Service;"
+    out.println ""
+
+    out.println "/**\n * @author mazhuang\n */"
+    out.println "@Slf4j"
+    out.println "@Service"
+    out.println "public class $className" + "ServiceImpl extends BaseServiceImpl<$className" + "Mapper, $className> implements $className" + "Service {"
+    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,
+                               comment: col.getComment(), // 注释
+                               default: col.getDefault(), // 默认值
+                               annos  : ""]]
+
+    }
+}
+
+static def calcPackageName(dirPath) {
+    def startPos = dirPath.indexOf('com')
+    return dirPath.substring(startPos).replaceAll(File.separator, ".")
+}
+
+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]
+}
+```
+
+大功告成，现在右键一个数据库表，依次选择 Scripted Extensions、Generate MyBatis Code.groovy，在弹出的目录选择框里选择想要放置代码的目录，即可生成期望的模板代码了。
+
+后续如果有一些个性化的代码生成需求，可以根据实际情况修改、新增脚本来完成。
+
+## 其它
+
+本文代码生成器脚本已上传至 GitHub，仓库地址：<https://github.com/mzlogin/code-generator>，以后如果有更新，或者新的代码生成脚本，也会放在这个仓库里。