Spring 学习小记（八）

本小记学习标

   

    了解MyBatis Generator插件的使用

 

一、MyBatis Generator

    我们在使用Spring集成MyBatis时发现，除了配置外我们还需要编写Dao接口、实体类、Mapping映射文件，这个过程是比较繁琐的，对于这些内容我们可以使用MyBatis Generator插件帮忙我们生成，从而使用我们的更加专注于业务逻辑代码的编写上。

 

    MyBatis Generator有三种常用的方法来自动生成代码

1. 命令行
2. Eclipse插件
3. Maven插件

 

Eclipse插件安装

在线安装插件

1.Help-->Install New Software...

 

在上面弹出的对话框Name后的输入框中输出一个名称（自定义）、在Location后的输入框中输入在线地址

Name:MyBatis-Generator

Location:https://dl.bintray.com/mybatis/mybatis-generator/

 

 

接下来Next--->accept--->install

安装完成后，会提示重新启动Eclipse，在重启完成后可以验证是否安装成功

File--->New--->other--->在向导中输入MyBatis，如果可以看到如下信息则表示安装成功

为了使用方便可以把这个选项集成到New而不需要进入Other中去选择，按如下操作去配置

我们新增一个实例进行测试

 

我们mysql数据库中存在一个表student,表信息如下：

 

1.新增一个Maven的jar工程，在对应的pom.xml中新增如下依赖

< dependencies >

       <!-- mysql -connector-java -->

             < dependency >

                < groupId > mysql </ groupId >

                < artifactId > mysql-connector-java </ artifactId >

                < version >5.1.45 </ version >

             </ dependency >

            

             <!-- mybatis -->

             < dependency >

                < groupId >org.mybatis </ groupId >

                < artifactId > mybatis </ artifactId >

                < version >3.4.5 </ version >

             </ dependency >

            

             <!-- https://mvnrepository.com/artifact/org.mybatis.dynamic-sql/mybatis-dynamic-sql -->

             < dependency >

                < groupId >org.mybatis.dynamic- sql </ groupId >

                < artifactId > mybatis-dynamic- sql </ artifactId >

                < version >1.1.4 </ version >

             </ dependency >

            

             < dependency >

                   < groupId >javax.annotation </ groupId >

                   < artifactId >jsr250- api </ artifactId >

                   < version >1.0 </ version >

             </ dependency >

  </ dependencies >

2.新增配置文件，首先我们新增一个包com.xiaoxie.dao.mybatis.config，在这个包上点击右键选择New-->MyBatis Generator Configuration File,在弹出的对话框中直接点击Finish

 

3.编辑刚才生成的配置文件generatorConfig.xml

<? 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= "context1" >

    < jdbcConnection connectionURL= "jdbc:mysql://localhost:3306/test?characterEncoding=utf8"

    driverClass= "com.mysql.jdbc.Driver" password= "root" userId= "root" />

    <!-- 实体 -->

    < javaModelGenerator targetPackage= "com.xiaoxie.pojo" targetProject= "SSM_10" >

       < property name= "enableSubPackages" value= "true" />

    </ javaModelGenerator >

    <!-- XMLMapper -->

    < javaClientGenerator targetPackage= "com.xiaoxie.dao" targetProject= "SSM_10" type= "XMLMAPPER" >

       < property name= "enableSubPackages" value= "true" />

    </ javaClientGenerator >

    < table schema= "test" tableName= "student" enableCountByExample= "true"

    enableUpdateByExample= "true" enableDeleteByExample= "true" enableSelectByExample= "true"

    enableSelectByPrimaryKey= "true" >

    </ table >

  </ context >

</ generatorConfiguration >

配置中主要有四部分信息

    （1）由于自动生成时需要读取数据库的信息所以需要配置数据的连接信息

    （2）需要指定实体生成在哪里，指定生成的目标包targetPackage

     (3) 需要指定xmlMapper生成在哪里，指定生成的目标包targetPackage

     (4) 指定数据库及表信息

注意：这里面的配置信息中有一个targetProject,这里指定的是项目的名称，表示在哪个项目中生成，这里不能写错如果找不到则在生成时会出错

 

4.在刚才编写的这个配置文件上点击右键，选择Run As---->Run MyBatis Generator

运行后会开始根据配置的信息生成对应的信息，并且在控制台会打印出生成的日志信息

MyBatis Generator Started...

  Buildfile: D:\STSProject\.metadata\.plugins\org.mybatis.generator.eclipse.ui\.generatedAntScripts\SSM_10-generatorConfig.xml.xml

  BUILD SUCCESSFUL

MyBatis Generator Finished

这个时候会生成如下信息：

com.xiaoie.pojo下会生成Student实体类

package com.xiaoxie.pojo;

import javax.annotation.Generated;

public class Student {

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1263811+08:00", comments = "Source field: student.ID")

       private Integer id;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1263811+08:00", comments = "Source field: student.NAME")

       private String name;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1273821+08:00", comments = "Source field: student.AGE")

       private Integer age;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1263811+08:00", comments = "Source field: student.ID")

       public Integer getId() {

             return id;

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1263811+08:00", comments = "Source field: student.ID")

       public void setId(Integer id) {

             this. id = id;

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1263811+08:00", comments = "Source field: student.NAME")

       public String getName() {

             return name;

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1273821+08:00", comments = "Source field: student.NAME")

       public void setName(String name) {

             this. name = name;

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1273821+08:00", comments = "Source field: student.AGE")

       public Integer getAge() {

             return age;

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1273821+08:00", comments = "Source field: student.AGE")

       public void setAge(Integer age) {

             this. age = age;

      }

       /*这个是手工添加的，目的打印对象时可以看到对象信息辨识度更高*/

       public String toString() {

             return "Student[id="+ id+ ",name="+ name+ ",age="+ age+ "]";

      }

}

注意：toString方法是手工添加上去的

com.xiaoxie.dao下生成StudentMapper的接口

package com.xiaoxie.dao;

import static com.xiaoxie.dao.StudentDynamicSqlSupport.*;

import static org.mybatis.dynamic.sql.SqlBuilder.*;

import com.xiaoxie.pojo.Student;

import java.util.Collection;

import java.util.List;

import java.util.Optional;

import javax.annotation.Generated;

import org.apache.ibatis.annotations.DeleteProvider;

import org.apache.ibatis.annotations.InsertProvider;

import org.apache.ibatis.annotations.Mapper;

import org.apache.ibatis.annotations.Result;

import org.apache.ibatis.annotations.ResultMap;

import org.apache.ibatis.annotations.Results;

import org.apache.ibatis.annotations.SelectProvider;

import org.apache.ibatis.annotations.UpdateProvider;

import org.apache.ibatis.type.JdbcType;

import org.mybatis.dynamic.sql.BasicColumn;

import org.mybatis.dynamic.sql.delete.DeleteDSLCompleter;

import org.mybatis.dynamic.sql.delete.render.DeleteStatementProvider;

import org.mybatis.dynamic.sql.insert.render.InsertStatementProvider;

import org.mybatis.dynamic.sql.insert.render.MultiRowInsertStatementProvider;

import org.mybatis.dynamic.sql.select.CountDSLCompleter;

import org.mybatis.dynamic.sql.select.SelectDSLCompleter;

import org.mybatis.dynamic.sql.select.render.SelectStatementProvider;

import org.mybatis.dynamic.sql.update.UpdateDSL;

import org.mybatis.dynamic.sql.update.UpdateDSLCompleter;

import org.mybatis.dynamic.sql.update.UpdateModel;

import org.mybatis.dynamic.sql.update.render.UpdateStatementProvider;

import org.mybatis.dynamic.sql.util.SqlProviderAdapter;

import org.mybatis.dynamic.sql.util.mybatis3.MyBatis3Utils;

@Mapper

public interface StudentMapper {

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

      BasicColumn[] selectList = BasicColumn.columnList(id, name, age);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @SelectProvider(type = SqlProviderAdapter. class, method = "select")

       long count(SelectStatementProvider selectStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @DeleteProvider(type = SqlProviderAdapter. class, method = "delete")

       int delete(DeleteStatementProvider deleteStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @InsertProvider(type = SqlProviderAdapter. class, method = "insert")

       int insert(InsertStatementProvider<Student> insertStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @InsertProvider(type = SqlProviderAdapter. class, method = "insertMultiple")

       int insertMultiple(MultiRowInsertStatementProvider<Student> multipleInsertStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @SelectProvider(type = SqlProviderAdapter. class, method = "select")

       @ResultMap( "StudentResult")

      Optional<Student> selectOne(SelectStatementProvider selectStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @SelectProvider(type = SqlProviderAdapter. class, method = "select")

       @Results(id = "StudentResult", value = {

                   @Result(column = "ID", property = "id", jdbcType = JdbcType.INTEGER, id = true),

                   @Result(column = "NAME", property = "name", jdbcType = JdbcType.VARCHAR),

                   @Result(column = "AGE", property = "age", jdbcType = JdbcType.INTEGER) })

      List<Student> selectMany(SelectStatementProvider selectStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       @UpdateProvider(type = SqlProviderAdapter. class, method = "update")

       int update(UpdateStatementProvider updateStatement);

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       default long count(CountDSLCompleter completer) {

             return MyBatis3Utils.countFrom( this::count, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       default int delete(DeleteDSLCompleter completer) {

             return MyBatis3Utils.deleteFrom( this::delete, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       default int deleteByPrimaryKey(Integer id_) {

             return delete(c -> c.where(id, isEqualTo(id_)));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source Table: student")

       default int insert(Student record) {

             return MyBatis3Utils.insert( this::insert, record, student,

                        c -> c.map(id).toProperty( "id").map(name).toProperty( "name").map(age).toProperty( "age"));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default int insertMultiple(Collection<Student> records) {

             return MyBatis3Utils.insertMultiple( this::insertMultiple, records, student,

                        c -> c.map(id).toProperty( "id").map(name).toProperty( "name").map(age).toProperty( "age"));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default int insertSelective(Student record) {

             return MyBatis3Utils.insert( this::insert, record, student,

                        c -> c.map(id).toPropertyWhenPresent( "id", record::getId).map(name)

                                    .toPropertyWhenPresent( "name", record::getName).map(age)

                                    .toPropertyWhenPresent( "age", record::getAge));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default Optional<Student> selectOne(SelectDSLCompleter completer) {

             return MyBatis3Utils.selectOne( this::selectOne, selectList, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default List<Student> select(SelectDSLCompleter completer) {

             return MyBatis3Utils.selectList( this::selectMany, selectList, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default List<Student> selectDistinct(SelectDSLCompleter completer) {

             return MyBatis3Utils.selectDistinct( this::selectMany, selectList, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default Optional<Student> selectByPrimaryKey(Integer id_) {

             return selectOne(c -> c.where(id, isEqualTo(id_)));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default int update(UpdateDSLCompleter completer) {

             return MyBatis3Utils.update( this::update, student, completer);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       static UpdateDSL<UpdateModel> updateAllColumns(Student record, UpdateDSL<UpdateModel> dsl) {

             return dsl.set(id).equalTo(record::getId).set(name).equalTo(record::getName).set(age).equalTo(record::getAge);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       static UpdateDSL<UpdateModel> updateSelectiveColumns(Student record, UpdateDSL<UpdateModel> dsl) {

             return dsl.set(id).equalToWhenPresent(record::getId).set(name).equalToWhenPresent(record::getName).set(age)

                        .equalToWhenPresent(record::getAge);

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default int updateByPrimaryKey(Student record) {

             return update(c -> c.set(name).equalTo(record::getName).set(age).equalTo(record::getAge).where(id,

                        isEqualTo(record::getId)));

      }

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1323683+08:00", comments = "Source Table: student")

       default int updateByPrimaryKeySelective(Student record) {

             return update(c -> c.set(name).equalToWhenPresent(record::getName).set(age).equalToWhenPresent(record::getAge)

                        .where(id, isEqualTo(record::getId)));

      }

}

com.xiaoxie.dao下会生成StudentDynamicSqlSupport

package com.xiaoxie.dao;

import java.sql.JDBCType;

import javax.annotation.Generated;

import org.mybatis.dynamic.sql.SqlColumn;

import org.mybatis.dynamic.sql.SqlTable;

public final class StudentDynamicSqlSupport {

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1303739+08:00", comments = "Source Table: student")

       public static final Student student = new Student();

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source field: student.ID")

       public static final SqlColumn<Integer> id = student. id;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source field: student.NAME")

       public static final SqlColumn<String> name = student. name;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1313709+08:00", comments = "Source field: student.AGE")

       public static final SqlColumn<Integer> age = student. age;

       @Generated(value = "org.mybatis.generator.api.MyBatisGenerator", date = "2020-11-24T23:45:23.1303739+08:00", comments = "Source Table: student")

       public static final class Student extends SqlTable {

             public final SqlColumn<Integer> id = column( "ID", JDBCType. INTEGER);

             public final SqlColumn<String> name = column( "NAME", JDBCType. VARCHAR);

             public final SqlColumn<Integer> age = column( "AGE", JDBCType. INTEGER);

             public Student() {

                   super( "student");

            }

      }

}

 

5.接下来配置MyBatis的配置信息（src/main/resources下）

新增一个jdbc.properties(配置数据库的连接信息)

jdbc.driverClass= com.mysql.jdbc.Driver

jdbc.url= jdbc:mysql:// localhost :3306/test?characterEncoding=utf8

jdbc.username= root

jdbc.password= root

 

新增一个mybatis-config.xml的全局配置文件

<? xml version= "1.0" encoding= "UTF-8" ?>

<! DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd" >

< configuration >

       <!-- 引入外部资源文件 -->

       < properties resource= "jdbc.properties" />

       <!-- 配置 mybatis 的全局环境 -->

       < environments default= "development" >

             < environment id= "development" >

                   < transactionManager type= "JDBC" />

                   < dataSource type= "POOLED" >

                         <!-- 连接信息 -->

                         < property name= "driver" value= "${jdbc.driverClass}" />

                         < property name= "url" value= "${jdbc.url}" />

                         < property name= "username" value= "${jdbc.username}" />

                         < property name= "password" value= "${jdbc.password}" />

                   </ dataSource >

             </ environment >

       </ environments >

       <!-- 映射文件 -->

       < mappers >

             < mapper class= "com.xiaoxie.dao.StudentMapper" />

       </ mappers >

      

</ configuration >

 

6.新增测试类com.xiaoxie.test.Application,在其中新增测试方法

@SuppressWarnings( "deprecation")

       private static void generatorMybatis() throws IOException {

            String mybatisConfigPath = "mybatis-config.xml";

             //读取配置文件

            InputStream config = Resources. getResourceAsStream( mybatisConfigPath);

             //构建SqlSessionFactory

            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build( config);

             //创建SqlSession对象

            SqlSession sqlSession = sqlSessionFactory.openSession();

            StudentMapper studentMapper = sqlSession.getMapper(StudentMapper. class);

            SelectStatementProvider selectStatement = select( id, name, age).from( student).where().build().render(RenderingStrategy. MYBATIS3);

            List<Student> students = studentMapper.selectMany( selectStatement);

             for (Student stu : students) {

                  System. out.println( stu);

            }

      }

 

7.在main方法中调用上述方法，运行后控制打印结果如下

Student[id=2,name=关公,age=29]

Student[id=3,name=张飞,age=26]

Student[id=10,name=诸葛亮,age=23]

Student[id=11,name=赵云,age=23]

Student[id=12,name=黄忠,age=35]