MyBatis Generator代码生成配置

官方文档学习：http://www.mybatis.org/generator/configreference/xmlconfig.html

1、generatorConfig.xml 配置参考如下（都是通用配置，稍微修改即可使用）：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
  PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
  "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
	<context id="test" targetRuntime="MyBatis3">
		<property name="javaFileEncoding" value="UTF-8" />
		<!-- <plugin type="org.mybatis.generator.plugins.EqualsHashCodePlugin"></plugin> -->
		<!-- <plugin type="org.mybatis.generator.plugins.ToStringPlugin"></plugin> -->
		<plugin type="org.mybatis.generator.plugins.SerializablePlugin"></plugin>

		<commentGenerator>
			<property name="suppressDate" value="true" />
			<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
			<property name="suppressAllComments" value="false" />
		</commentGenerator>

		<!--数据库链接URL，用户名、密码 -->
		<jdbcConnection driverClass="com.mysql.jdbc.Driver"
			connectionURL="jdbc:mysql://localhost:3306/mybatisdb" userId="root"
			password="123456">
		</jdbcConnection>

		<javaTypeResolver>
			<!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 
				和 NUMERIC 类型解析为java.math.BigDecimal -->
			<property name="forceBigDecimals" value="false" />
		</javaTypeResolver>

		<!-- 生成模型的包名和位置 -->
		<javaModelGenerator targetPackage="com.cjh.pojo"
			targetProject="src/main/java">
			<!-- 是否对model添加 构造函数 -->
			<property name="constructorBased" value="true" />
			<!-- 是否允许子包，即targetPackage.schemaName.tableName -->
			<property name="enableSubPackages" value="true" />
			<!-- 是否对类CHAR类型的列的数据进行trim操作 -->
			<property name="trimStrings" value="true" />
		</javaModelGenerator>

		<!-- 生成映射文件的包名和位置 -->
		<sqlMapGenerator targetPackage="com.cjh.mapping"
			targetProject="src/main/java">
			<!-- 是否允许子包，即targetPackage.schemaName.tableName -->
			<property name="enableSubPackages" value="true" />
		</sqlMapGenerator>

		<!-- 生成DAO的包名和位置 -->
		<javaClientGenerator type="XMLMAPPER"
			targetPackage="com.cjh.dao" implementationPackage="com.cjh.dao.impl"
			targetProject="src/main/java">
			<!-- 是否允许子包，即targetPackage.schemaName.tableName -->
			<property name="enableSubPackages" value="true" />
		</javaClientGenerator>

		<!-- 要生成哪些表 -->
		<table tableName="student" domainObjectName="Student"
			enableCountByExample="false" enableUpdateByExample="false"
			enableDeleteByExample="false" enableSelectByExample="false"
			selectByExampleQueryId="false" />

	</context>
</generatorConfiguration>

2、运行，生成代码

（1）如果通过maven方式生成代码，需要在pom配置添加mybatis-generator-maven-plugin插件，参考如下：

<build>
		<plugins>
			<!-- 统一源代码编译输出的JDK版本 -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>2.3.2</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
					<encoding>UTF-8</encoding>
				</configuration>
			</plugin>
			<!-- 打包时跳过单元测试 -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-surefire-plugin</artifactId>
				<version>2.19.1</version>
				<configuration>
					<skipTests>true</skipTests>
				</configuration>
			</plugin>

			<plugin>
				<groupId>org.mybatis.generator</groupId>
				<artifactId>mybatis-generator-maven-plugin</artifactId>
				<version>1.3.2</version>
				<dependencies>
					<!-- mysql-connector-java 依赖 -->
					<dependency>
						<groupId>mysql</groupId>
						<artifactId>mysql-connector-java</artifactId>
						<version>5.1.47</version>
					</dependency>
					<!-- mybatis-generator-core -->
					<dependency>
						<groupId>org.mybatis.generator</groupId>
						<artifactId>mybatis-generator-core</artifactId>
						<version>1.3.2</version>
					</dependency>

				</dependencies>
				<configuration>
					<!--generatorConfig.xml配置文件的路径 -->
					<configurationFile>${basedir}/src/main/resources/generatorConfig.xml</configurationFile>
					<overwrite>true</overwrite>
				</configuration>
			</plugin>
			<!--mybatis-generator:generate -->
		</plugins>
	</build>

（2）如果通过java代码方式来生成，如下：

  a.还需添加依赖，如下：

<dependencies>
		<!-- mybatis-generator-core -->
		<dependency>
			<groupId>org.mybatis.generator</groupId>
			<artifactId>mybatis-generator-core</artifactId>
			<version>1.3.2</version>
		</dependency>
		<!-- mysql-connector-java 依赖 -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.47</version>
		</dependency>
	</dependencies>

  b.运行代码：

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import org.mybatis.generator.api.MyBatisGenerator;
import org.mybatis.generator.config.Configuration;
import org.mybatis.generator.config.xml.ConfigurationParser;
import org.mybatis.generator.internal.DefaultShellCallback;

public class Test {
	public static void main(String[] args) {
	    try {
	        List<String> warnings = new ArrayList<String>();
	        boolean overwrite = true;
	        
	        InputStream resourceAsStream = Test.class.getResourceAsStream("generatorConfig.xml");
	        ConfigurationParser cp = new ConfigurationParser(warnings);
	       
	        Configuration config = cp.parseConfiguration(resourceAsStream);
	        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
	        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
	        myBatisGenerator.generate(null);
	        
	    } catch (Exception e) {
	        e.printStackTrace();
	    }
	}
}

3、自定义生成代码注释

如何实现？

继承org.mybatis.generator.internal.DefaultCommentGenerator类（默认）或实现org.mybatis.generator.api.CommentGenerator接口。重写里面的方法即可。建议参考org.mybatis.generator.internal.DefaultCommentGenerator类，进一步做修改即可，以免出错。

参考（根据需要自己仿DefaultCommentGenerator重写）：

package com.cjh.mybatis.generator;

import static org.mybatis.generator.internal.util.StringUtility.isTrue;

import java.util.Date;
import java.util.Properties;

import org.mybatis.generator.api.CommentGenerator;
import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.IntrospectedTable;
import org.mybatis.generator.api.dom.java.CompilationUnit;
import org.mybatis.generator.api.dom.java.Field;
import org.mybatis.generator.api.dom.java.InnerClass;
import org.mybatis.generator.api.dom.java.InnerEnum;
import org.mybatis.generator.api.dom.java.Method;
import org.mybatis.generator.api.dom.xml.XmlElement;
import org.mybatis.generator.config.PropertyRegistry;
/**
 * 自定义注释生成器
 * @author 陈嘉豪
 *
 */
public class MyDefaultCommentGenerator implements CommentGenerator {

	private Properties properties;
	private boolean suppressDate;
	private boolean suppressAllComments;

	public MyDefaultCommentGenerator() {
		super();
		properties = new Properties();
		suppressDate = false;
		suppressAllComments = false;
	}
	
	/**
	 * 添加属性注释
	 * @author 陈嘉豪 
	 *(non-Javadoc)
	 * @see org.mybatis.generator.api.CommentGenerator#addFieldComment(org.mybatis.generator.api.dom.java.Field, org.mybatis.generator.api.IntrospectedTable, org.mybatis.generator.api.IntrospectedColumn)
	 */
	@Override
	public void addFieldComment(Field field, IntrospectedTable introspectedTable,
			IntrospectedColumn introspectedColumn) {
		if (suppressAllComments) {
			return;
		}
		field.addJavaDocLine("/**");
		field.addJavaDocLine(" * " + introspectedColumn.getRemarks());
		field.addJavaDocLine(" */");
	}
	@Override
	public void addFieldComment(Field field, IntrospectedTable introspectedTable) {
	}
	@Override
	public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable) {
		if (suppressAllComments) {
			return;
		}
		StringBuilder sb = new StringBuilder();
		innerClass.addJavaDocLine("/**"); 
		sb.append(introspectedTable.getFullyQualifiedTable());
		innerClass.addJavaDocLine(sb.toString());
		innerClass.addJavaDocLine(" */");
	}
	@Override
	public void addClassComment(InnerClass innerClass, IntrospectedTable introspectedTable, boolean markAsDoNotDelete) {
		if (suppressAllComments) {
			return;
		}
		StringBuilder sb = new StringBuilder();
		innerClass.addJavaDocLine("/**"); 
		sb.append(introspectedTable.getFullyQualifiedTable());
		innerClass.addJavaDocLine(sb.toString());
		innerClass.addJavaDocLine(" */");
	}
	@Override
	public void addConfigurationProperties(Properties properties) {
		 this.properties.putAll(properties);
	        suppressDate = isTrue(properties
	                .getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_DATE));
	        suppressAllComments = isTrue(properties
	                .getProperty(PropertyRegistry.COMMENT_GENERATOR_SUPPRESS_ALL_COMMENTS));
	}
	@Override
	public void addEnumComment(InnerEnum innerEnum, IntrospectedTable introspectedTable) {
	}
	@Override
	public void addGetterComment(Method method, IntrospectedTable introspectedTable,
			IntrospectedColumn introspectedColumn) {
	}
	@Override
	public void addSetterComment(Method method, IntrospectedTable introspectedTable,
			IntrospectedColumn introspectedColumn) {
	}
	@Override
	public void addGeneralMethodComment(Method method, IntrospectedTable introspectedTable) {
	}
	@Override
	public void addJavaFileComment(CompilationUnit compilationUnit) {
	}
	@Override
	public void addComment(XmlElement xmlElement) {
	}
	@Override
	public void addRootComment(XmlElement rootElement) {
	}
	
	protected String getDateString() {
        if (suppressDate) {
            return null;
        } else {
            return new Date().toString();
        }
    }

}

写完之后，还需在配置文件修改如下，指定type，值就是自定义注释生成类的全路径，如下：

<commentGenerator type="com.cjh.mybatis.generator.MyDefaultCommentGenerator">
			<property name="suppressDate" value="true" />
			<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
			<property name="suppressAllComments" value="false" />
		</commentGenerator>

4、可能出现的问题

（1）运行异常：Cannot instantiate object of type com.cjh.mybatis.generator.MyDefaultCommentGenerator

解决:将自定义的注释生成器类打包生成jar,然后在pom文件mybatis-generator-maven-plugin插件中添加该依赖。