什么是逆向工程
Mybatis需要程序员自己编写SQL语句,mybatis官网提供逆向工程,可以针对单表自动生成mybatis执行所有需要代码(mapper.java,mapper.xml,po)
企业实际开发中,常用的逆向工程方式:
数据库表来生产Java代码,
企业开发中,是先对数据库进行设计,也就是编码之前数据库已经有了。
实现步骤如下:
首先:建立一个Maven项目
目录结构如下:
先进行配置pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>hyx.revorse</groupId>
<artifactId>revorse-project</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<junit.version>4.12</junit.version>
<mybatis.version>3.4.4</mybatis.version>
<mysql.version>5.1.34</mysql.version>
<log4j.version>1.2.17</log4j.version>
<fastjson.version>1.2.35</fastjson.version>
<slf4j.version>1.7.25</slf4j.version>
</properties>
<dependencies>
<!-- mybatis核心包 -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>${mybatis.version}</version>
</dependency>
<!--mysql包-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<!-- 日志文件管理包 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<!-- 格式化对象,方便输出日志 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>${fastjson.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<!--测试包-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>RELEASE</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>RELEASE</version>
<scope>compile</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.5</version>
<configuration>
<verbose>true</verbose>
<overwrite>true</overwrite>
</configuration>
</plugin>
</plugins>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
</build>
</project>
建立generatorConfig.xml配置文件
<?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>
<!-- (1)配置mysql 驱动jar包路径.用了绝对路径 -->
<classPathEntry location="E:\Linux\repository-big\repository\mysql\mysql-connector-java\5.1.38\mysql-connector-java-5.1.38.jar" />
<context id="scm_mysql_tables" targetRuntime="MyBatis3">
<!-- 防止生成的代码中有很多注释,加入下面的配置控制 -->
<commentGenerator>
<property name="suppressAllComments" value="true" />
<property name="suppressDate" value="true" />
</commentGenerator>
<!-- (2)数据库连接 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mybatis01?characterEncoding=UTF-8"
userId="root"
password="123">
</jdbcConnection>
<javaTypeResolver >
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- (3)数据表对应的model层 -->
<javaModelGenerator targetPackage="com.hd.po"
targetProject="src\main\java">
<property name="enableSubPackages" value="true" />
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!-- (4)sql mapper 映射配置文件 -->
<sqlMapGenerator targetPackage="com.hd.mapper"
targetProject="src\main\java">
<property name="enableSubPackages" value="true" />
</sqlMapGenerator>
<!-- (5)mybatis3中的mapper接口 -->
<javaClientGenerator type="XMLMAPPER"
targetPackage="com.hd.mapper"
targetProject="src\main\java">
<property name="enableSubPackages" value="true" />
</javaClientGenerator>
<!-- (5)数据表进行生成操作 schema:相当于库名; tableName:表名;
domainObjectName:对应的DO
-->
<table schema="mybatis" tableName="user" domainObjectName="User"
enableCountByExample="false" enableUpdateByExample="false"
enableDeleteByExample="false" enableSelectByExample="false"
selectByExampleQueryId="false">
</table>
<table schema="mybatis" tableName="orders" domainObjectName="Orders"
enableCountByExample="false" enableUpdateByExample="false"
enableDeleteByExample="false" enableSelectByExample="false"
selectByExampleQueryId="false">
</table>
</context>
</generatorConfiguration>
开始生成实体类与DAO层
生成成功如下图所示,查看Mapper.interface接口可以看到很多增删改查的方法
开始测试:.
先进行配置sqlMapconfig.xml
<?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>
<settings>
<setting name="lazyLoadingEnabled" value="true"/>
<setting name="aggressiveLazyLoading" value="false"/>
</settings>
<typeAliases>
<package name="com.hd.po"></package>
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"></transactionManager>
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"></property>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis01"></property>
<property name="username" value="root"></property>
<property name="password" value="123"></property>
</dataSource>
</environment>
</environments>
<mappers>
<!--<mapper resource="com/huadian/c_dao_mapper/mapper/OrdersMapper.xml"></mapper>-->
<package name="com.hd.mapper"></package>
</mappers>
</configuration>
配置日志输出配置文件
# Global logging configuration
#在开发环境下日志级别设置为debug,生产环境下设置成info或error
log4j.rootLogger=debug, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
测试代码:
package com.hd.test;
import com.hd.mapper.UserMapper;
import com.hd.po.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;
import java.io.IOException;
import java.io.InputStream;
public class Demo01 {
private SqlSessionFactory sqlSessionFactory;
@Before
public void fun0() throws IOException {
InputStream inputStream = Resources.getResourceAsStream( "sqlMapconfig.xml" );
//通过配置创建会话工厂
sqlSessionFactory = new SqlSessionFactoryBuilder().build( inputStream );
}
@Test
public void fun1(){
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper mapper = sqlSession.getMapper(UserMapper.class);
User user = mapper.selectByPrimaryKey(1);
System.out.println(user);
}
}