MyBatis实战-8-代码生成工具MBG

2016-10-01

MyBatis代码生成工具MyBatis Generator

MyBatis Generator简介

MyBatis Generator (MBG) 是一个Mybatis的代码生成器 MyBatis 和 iBATIS. 它可以生成Mybatis各个版本的代码，和iBATIS 2.2.0版本以后的代码。它可以内省数据库的表（或多个表）然后生成可以用来访问（多个）表的基础对象。这样和数据库表进行交互时不需要创建对象和配置文件。 MBG的解决了对数据库操作有最大影响的一些简单的CRUD（插入，查询，更新，删除）操作。你仍然需要对联合查询和存储过程手写SQL和对象。

MBG生成对象说明

MyBatis Generator 会生成:

匹配表结构的Java POJO，可能包括:

一个和表主键匹配的类(如果存在主键[注:只有联合主键会有])
一个包含了非主键字段的类(BLOB字段除外[注:单字段做主键时这里会包含])
一个包含了BLOB字段的类 (如果表包含了BLOB字段)
一个允许动态查询、更新和删除的类[注:指的是Example查询]

这些类之间会有适当的继承关系。请注意可以配置生成器来生成不同类型的 POJO 的层次结构。例如，如果你愿意你可能会选择针对每个表生成一个单独的实体对象。

MBG映射文件说明

MyBatis/iBATIS 兼容 SQL 映射 XML 文件。MBG 在配置中为每个表简单的 CRUD 操作生成 SQL。生成的 SQL 语句包括：

insert (插入)
update by primary key (根据主键更新记录)
update by example (根据条件更新记录)
delete by primary key (根据主键删除记录)
delete by example (根据条件删除记录)
select by primary key (根据主键查询记录)
select by example (根据条件查询记录集)
count by example (根据条件查询记录总数)

根据表的结构，生成的这些语句会有不同的变化（例如，如果表中没有主键，那么 MBG 将不会生成update by primary key方法）。

项目依赖管理

当前MySQL的JDBC连接的jar包已经出到了6.0.3版本，但很遗憾的是，这个版本还存在很多问题，比如jdbc连接的方式的改变，原来的声明需要做大量的修改，此外，最新版的mybatis-generator-core也无法正常的工作，因为生成的映射文件不包含primary key选项，估计是最新的MySQL连接包作了限制。现在当前环境建议大家还是使用5.x版本比较靠谱。以下是相关依赖：

dom4j-1.6.1.jar
hamcrest-core-1.3.jar
junit-4.12.jar
mybatis-3.4.1.jar
mybatis-generator-core-1.3.5.jar
mysql-connector-java-5.1.39.jar

Maven地址（关于Maven相关的教程后续会陆续推出，这里提供给使用Maven的读者）

<dependency>
    <groupId>dom4j</groupId>
    <artifactId>dom4j</artifactId>
    <version>1.6.1</version>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>
<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest-core</artifactId>
    <version>1.3</version>
</dependency>
<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.4.1</version>
</dependency>
<dependency>
    <groupId>org.mybatis.generator</groupId>
    <artifactId>mybatis-generator-core</artifactId>
    <version>1.3.5</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.39</version>
</dependency>

（一）生成模板映射XML文件

CreateGenConfigXML.java

package com.qinjiangbo.gen.util;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.dom.DOMDocumentType;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import org.dom4j.tree.DefaultDocumentType;

import java.io.File;
import java.io.FileOutputStream;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * Date: 9/26/16
 * Author: [email protected]
 */
public class CreateGenConfigXML {

    /**
     * 获得数据库连接
     *
     * @return
     */
    public static Connection getConnection() {
        try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection connection =
                    DriverManager.getConnection("jdbc:mysql://localhost:3306/mybatis",
                            "Richard", "123456");
            return connection;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 获取全部的表名
     * @return
     * @throws SQLException
     */
    public static List<String> getTableNames() throws SQLException {
        List<String> names = new ArrayList<String>();
        Connection connection = getConnection();
        DatabaseMetaData databaseMetaData = connection.getMetaData();
        String[] types = {"TABLE"};
        ResultSet resultSet = databaseMetaData.getTables(null, null, "%", types);
        while (resultSet.next()) {
            String name = (String) resultSet.getObject("TABLE_NAME");
            if (name.contains("（") || name.contains("）")) {
                continue;
            }
            names.add(name);
        }
        connection.close();
        return names;
    }

    /**
     * 生成DOM文件
     * @return
     * @throws SQLException
     */
    private static Document createDom() throws SQLException {
        Document doc = DocumentHelper.createDocument();
        //创建DOCTYPE申明
        doc.setDocType(new DOMDocumentType("generatorConfiguration",
                "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN",
                "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd"));

        //创建根结点
        Element root = doc.addElement("generatorConfiguration");

        //创建上下文结点
        Element context = root.addElement("context");
        context.addAttribute("id", "MBG");
        context.addAttribute("targetRuntime", "Mybatis3");
        context.addAttribute("defaultModelType", "conditional");

        //创建插件结点(这里默认每个类序列化)
        Element plugin = context.addElement("plugin");
        plugin.addAttribute("type", "org.mybatis.generator.plugins.SerializablePlugin");

        //创建注释结点,判断是否生成注释
        Element commentGenerator = context.addElement("commentGenerator");
        Element property = commentGenerator.addElement("property");
        property.addAttribute("name", "suppressAllComments");
        property.addAttribute("value", "false");

        //创建jdbc连接结点
        Element jdbcConnection = context.addElement("jdbcConnection");
        jdbcConnection.addAttribute("driverClass", "com.mysql.jdbc.Driver");
        jdbcConnection.addAttribute("connectionURL", "jdbc:mysql://localhost:3306/mybatis");
        jdbcConnection.addAttribute("userId", "Richard");
        jdbcConnection.addAttribute("password", "123456");

        //创建java类型处理类结点
        Element javaTypeResolver = context.addElement("javaTypeResolver");
        Element property2 = javaTypeResolver.addElement("property");
        property2.addAttribute("name", "forceBigDecimals");
        property2.addAttribute("value", "false");

        //创建java模型结点
        Element javaModelGenerator = context.addElement("javaModelGenerator");
        javaModelGenerator.addAttribute("targetPackage", "com.qinjiangbo.gen.model");
        javaModelGenerator.addAttribute("targetProject", "src");
        Element property3 = javaModelGenerator.addElement("property");
        property3.addAttribute("name", "enableSubPackages");
        property3.addAttribute("value", "true");

        //创建sql映射文件结点
        Element sqlMapGenerator = context.addElement("sqlMapGenerator");
        sqlMapGenerator.addAttribute("targetPackage", "com.qinjiangbo.gen.mapper");
        sqlMapGenerator.addAttribute("targetProject", "src");
        Element property4 = sqlMapGenerator.addElement("property");
        property4.addAttribute("name", "enableSubPackages");
        property4.addAttribute("value", "true");

        //创建java客户端结点,这里声明了dao层的位置
        Element javaClientGenerator = context.addElement("javaClientGenerator");
        javaClientGenerator.addAttribute("type", "XMLMAPPER");
        javaClientGenerator.addAttribute("targetPackage", "com.qinjiangbo.gen.mapper");
        javaClientGenerator.addAttribute("targetProject", "src");
        Element property5 = javaClientGenerator.addElement("property");
        property5.addAttribute("name", "enableSubPackages");
        property5.addAttribute("value", "true");

        //创建表(table)结点
        List<String> names = getTableNames();
        for (String name : names) {
            String[] words = name.split("_");
            String entityName = "";
            for (String word : words) {
                word = word.substring(0, 1).toUpperCase() + word.substring(1);
                if (entityName == null || entityName.equals("")) {
                    entityName = word;
                } else {
                    entityName = entityName + word;
                }
            }
            Element tableNode = context.addElement("table");
            tableNode.addAttribute("tableName", name);
            tableNode.addAttribute("domainObjectName", entityName);
            tableNode.addAttribute("enableCountByExample", "true");
            tableNode.addAttribute("enableUpdateByExample", "true");
            tableNode.addAttribute("enableDeleteByExample", "true");
            tableNode.addAttribute("enableSelectByExample", "true");
            tableNode.addAttribute("selectByExampleQueryId", "true");
            tableNode.addAttribute("enableDeleteByPrimaryKey", "true");
            tableNode.addAttribute("enableSelectByPrimaryKey", "true");
            tableNode.addAttribute("enableUpdateByPrimaryKey", "true");
            tableNode.addAttribute("enableInsert", "true");
        }

        return doc;
    }

    /**
     * 写入到XML文件中
     * @throws Exception
     */
    public static void writeXML() throws Exception {
        XMLWriter xmlWriter = null;
        String userDir = System.getProperty("user.dir");
        String fileName = userDir + "/src/com/qinjiangbo/gen/util/generatorConfiguration.xml";
        OutputFormat format = OutputFormat.createPrettyPrint();
        FileOutputStream fos = new FileOutputStream(new File(fileName));
        format.setEncoding("utf-8");
        xmlWriter = new XMLWriter(fos, format);
        xmlWriter.write(createDom());
        xmlWriter.close();
    }

    public static void main(String[] args) throws Exception {
        writeXML();
        System.out.println("Completed!");
    }
}

（二）生成的GeneratorConfiguration.xml文件

由前一步生成的GeneratorConfiguration.xml文件如下：

<?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="MBG" targetRuntime="Mybatis3" defaultModelType="conditional">
    <plugin type="org.mybatis.generator.plugins.SerializablePlugin"/>
    <commentGenerator>
      <property name="suppressAllComments" value="false"/>
    </commentGenerator>
    <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://localhost:3306/mybatis"
                    userId="Richard" password="123456"/>
    <javaTypeResolver>
      <property name="forceBigDecimals" value="false"/>
    </javaTypeResolver>
    <javaModelGenerator targetPackage="com.qinjiangbo.gen.model" targetProject="src">
      <property name="enableSubPackages" value="true"/>
    </javaModelGenerator>
    <sqlMapGenerator targetPackage="com.qinjiangbo.gen.mapper" targetProject="src">
      <property name="enableSubPackages" value="true"/>
    </sqlMapGenerator>
    <javaClientGenerator type="XMLMAPPER" targetPackage="com.qinjiangbo.gen.mapper" targetProject="src">
      <property name="enableSubPackages" value="true"/>
    </javaClientGenerator>
    <table tableName="class" domainObjectName="Class" enableCountByExample="true" enableUpdateByExample="true"
           enableDeleteByExample="true" enableSelectByExample="true" selectByExampleQueryId="true"
           enableDeleteByPrimaryKey="true" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
           enableInsert="true"/>
    <table tableName="orders" domainObjectName="Orders" enableCountByExample="true" enableUpdateByExample="true"
           enableDeleteByExample="true" enableSelectByExample="true" selectByExampleQueryId="true"
           enableDeleteByPrimaryKey="true" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
           enableInsert="true"/>
    <table tableName="student" domainObjectName="Student" enableCountByExample="true" enableUpdateByExample="true"
           enableDeleteByExample="true" enableSelectByExample="true" selectByExampleQueryId="true"
           enableDeleteByPrimaryKey="true" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
           enableInsert="true"/>
    <table tableName="teacher" domainObjectName="Teacher" enableCountByExample="true" enableUpdateByExample="true"
           enableDeleteByExample="true" enableSelectByExample="true" selectByExampleQueryId="true"
           enableDeleteByPrimaryKey="true" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
           enableInsert="true"/>
    <table tableName="users" domainObjectName="Users" enableCountByExample="true" enableUpdateByExample="true"
           enableDeleteByExample="true" enableSelectByExample="true" selectByExampleQueryId="true"
           enableDeleteByPrimaryKey="true" enableSelectByPrimaryKey="true" enableUpdateByPrimaryKey="true"
           enableInsert="true"/>
  </context>
</generatorConfiguration>

关于这个文件的具体说明请移步MyBatis-Generator的官方说明，这里读者可以通过阅读XML获得相关属性的含义和作用。

（三）生成DAO层的SQL映射文件

package com.qinjiangbo.gen.util;

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;

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

/**
 * Date: 9/26/16
 * Author: [email protected]
 */
public class Generator {

    public static void main(String[] args) throws Exception {
        List<String> warnings = new ArrayList<String>();
        boolean overwrite = true;
        String userDir = System.getProperty("user.dir");
        File configFile = new File(userDir + "/src/com/qinjiangbo/gen/util/generatorConfiguration.xml");
        ConfigurationParser cp = new ConfigurationParser(warnings);
        Configuration config = cp.parseConfiguration(configFile);
        DefaultShellCallback callback = new DefaultShellCallback(overwrite);
        MyBatisGenerator myBatisGenerator = new MyBatisGenerator(config, callback, warnings);
        myBatisGenerator.generate(null);
        System.out.println("Completed!");
    }
}

针对上面这个文件需要说明的是需要指明配置文件的所在位置，然后回调函数设置为空，表示不做任何操作。就是静态地生成这些DAO层的SQL映射文件即可。

项目结构图

项目的结构会发生很大的变化，新生成的SQL映射文件包括Java文件和XML文件都在同一个包，在企业开发中通常这两个也是一直被放在一个包，便于管理，然后模型Model放在另一个包。结构图如下：

项目结构图

上面util包是前面生成映射文件所需要的工具包。读者可以根据自身的实际情况更改所在包。

项目测试

下面选择两个映射文件中的随机两个方法进行抽样测试（这个完全是为了节省版面，正规的还是需要做路径覆盖测试的，请读者自行在下面测试）。

package com.qinjiangbo.test;

import com.qinjiangbo.gen.mapper.StudentMapper;
import com.qinjiangbo.gen.mapper.TeacherMapper;
import com.qinjiangbo.gen.model.Student;
import com.qinjiangbo.gen.model.StudentExample;
import com.qinjiangbo.gen.model.Teacher;
import com.qinjiangbo.gen.model.TeacherExample;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

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

/**
 * Date: 27/09/2016
 * Author: [email protected]
 */
public class MyBatisTest7 {

    private SqlSession sqlSession = null;

    @Before
    public void init() {
        String config = "com/qinjiangbo/conf/configure.xml";
        InputStream inputStream = MyBatisTest2.class.getClassLoader().getResourceAsStream(config);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        sqlSession = sqlSessionFactory.openSession();
    }

    @Test
    public void testFindTeachers() {
        TeacherMapper mapper = sqlSession.getMapper(TeacherMapper.class);
        TeacherExample example = new TeacherExample();
        example.createCriteria().andTGenderIsNotNull();
        List<Teacher> teacherList = mapper.selectByExample(example);
        for (Teacher teacher : teacherList) {
            System.out.println(teacher.gettName() + " " + teacher.gettGender());
        }
    }

    @Test
    public void testFindStudents() {
        StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
        StudentExample example = new StudentExample();
        example.createCriteria().andCIdEqualTo(3);
        List<Student> studentList = mapper.selectByExample(example);
        for (Student student : studentList) {
            System.out.println(student.getsName() + " " + student.getsAge());
        }
    }

    @After
    public void commit() {
        sqlSession.commit();
    }
}

测试结果

testFindTeachers():

测试结果

Loris Male
Lily Female
QinJiangbo Female
Sony Male
Sarah Female
Toffy Male
Jeserf Male

testFindStudents():

测试结果

1 2	QinJiangbo 21 YuYing 21

以上测试全部通过！

DON'T BE THE SAME, BE BETTER!

开发技术Java

MyBatis实战-8-代码生成工具MBG

MyBatis代码生成工具MyBatis Generator

MyBatis Generator简介

MBG生成对象说明

MBG映射文件说明

项目依赖管理

（一）生成模板映射XML文件

（二）生成的GeneratorConfiguration.xml文件

（三）生成DAO层的SQL映射文件

项目结构图

项目测试

测试结果