maven mybatis generator的使用

一、 背景

　　在使用mybatis时我们需要重复的去创建pojo类、mapper文件以及dao类并且需要配置它们之间的依赖关系，比较麻烦且做了大量的重复工作，mybatis官方也发现了这个问题，因此给我们提供了mybatis generator工具来帮我们自动创建pojo类、mapper文件以及dao类并且会帮我们配置好它们的依赖关系。

二、 配置

　　1、引入mybatis generator插件

<build>
        <plugins>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.7</version>
                <configuration>
                    <configurationFile>generatorConfig.xml</configurationFile>
                    <verbose>true</verbose>
                    <overwrite>true</overwrite>
                </configuration>
                <executions>
                    <execution>
                        <id>Generate MyBatis Artifacts</id>
                        <phase>deploy</phase>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <overwrite>true</overwrite>
                        </configuration>
                    </execution>
                </executions>
                <dependencies>
                    <dependency>
                        <groupId>org.mybatis.generator</groupId>
                        <artifactId>mybatis-generator-core</artifactId>
                        <version>1.3.7</version>
                    </dependency>
                    <dependency>
                        <groupId>com.xxx</groupId>
                        <artifactId>my-generator</artifactId>
                        <version>0.1.0-SNAPSHOT</version>
                    </dependency>

                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>5.1.47</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>

　　说明：my-generator 是自己定义的模板配置包

　　

 　　2. generatorConfig.xml 配置

<?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" >
<!--使用方法:mvn mybatis-generator:generate-->
<generatorConfiguration>

    <context id="context" targetRuntime="MyBatis3">
        <property name="beginningDelimiter" value=""/>
        <property name="endingDelimiter" value=""/>
        <property name="javaFileEncoding" value="utf-8"/>
        <property name="useActualColumnNames" value="true"/>

        <commentGenerator type="com.xxx.common.generate.MyBatisCommentGenerator">
            <!--<commentGenerator>-->
            <property name="suppressDate" value="false"/>
            <!-- 是否去除自动生成的注释true：是： false:否 -->
            <property name = "suppressAllComments" value="false"/>
            <property name="addRemarkComments" value="true"/>
        </commentGenerator>

        <!--数据库链接URL，用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver"
                        connectionURL="jdbc:mysql://xxx.com:3306/xxx?useUnicode=true"
                        userId="xxx"
                        password="xxx"/>

        <javaTypeResolver type="com.xxx.common.generate.MyJavaTypeResolverImpl">
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 生成entity对象的包名和位置-->
        <javaModelGenerator targetPackage="com.xxx.demo.dal.model" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- 生成mapper xml文件的包名和位置-->
        <sqlMapGenerator targetPackage="mapper" targetProject="src/main/resources">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="com.xxx.demo.dal.mapper" targetProject="src/main/java">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>

        <!-- 要生成的表tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
        <table tableName="ssp_bill_dispatch"
               domainObjectName="SspBillDispatch"
               enableCountByExample="true" enableUpdateByExample="true"
               enableDeleteByExample="true" enableSelectByExample="true">
            <property name="useActualColumnNames" value="false"/>
            <generatedKey column="id" sqlStatement="Mysql" identity="true"/>
        </table>
    </context>

</generatorConfiguration>

MyBatisCommentGenerator

 MyJavaTypeResolverImpl

package com.xxx.common.generate;

import org.mybatis.generator.api.IntrospectedColumn;
import org.mybatis.generator.api.dom.java.FullyQualifiedJavaType;
import org.mybatis.generator.internal.types.JavaTypeResolverDefaultImpl;

import java.sql.Types;

/**
 * @author: xi
 * @Date: 2019-02-15 16:20
 * @Description: MyJavaTypeResolver
 */
public class MyJavaTypeResolverImpl extends JavaTypeResolverDefaultImpl {
    @Override
    public FullyQualifiedJavaType calculateJavaType(IntrospectedColumn introspectedColumn) {
        FullyQualifiedJavaType answer = null;
        JdbcTypeInformation jdbcTypeInformation = this.typeMap.get(introspectedColumn.getJdbcType());
        if (jdbcTypeInformation == null) {
            return answer;
        } else {
            switch (introspectedColumn.getJdbcType()) {
                case Types.INTEGER:
//                    if (introspectedColumn.getLength() > 9) {
//                        answer = new FullyQualifiedJavaType(Long.class.getName());
//                    } else {
                        answer = new FullyQualifiedJavaType(Integer.class.getName());
//                    }

                    break;
                case Types.BIT:
                    answer = new FullyQualifiedJavaType(Byte.class.getName());
                    break;
                default:
                    answer = jdbcTypeInformation.getFullyQualifiedJavaType();
                    answer = this.overrideDefaultType(introspectedColumn, answer);
            }

            return answer;
        }
    }
}

3. 执行命令：

　　mvn mybatis-generator:generate