Mybatis 提供了逆向工程,通過逆向工程,可以幫助程序員根據單表來生成pojo類,mappper映射文件、mapper接口。
- 新建maven項目,在pom中添加如下依賴:
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.0</version>
</dependency>
<!-- mysql驅動包 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.16.10</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-core</artifactId>
<version>1.3.6</version>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/resources/</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
</resources>
<plugins>
<!-- mybatis-generator自動生成代碼插件 -->
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.6</version>
</plugin>
</plugins>
</build>
- 在resource config目錄下新建 generatorConfig.xml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>
<context id="mybatisGenerator" targetRuntime="MyBatis3">
<commentGenerator>
<!-- 是否去除自動生成的註釋 true:是 : false:否 -->
<property name="suppressAllComments" value="true" />
</commentGenerator>
<!-- 拉取表信息的數據庫鏈接URL、驅動類、用戶名、密碼 -->
<jdbcConnection driverClass="com.mysql.jdbc.Driver"
connectionURL="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC"
userId="root"
password="rhwl1234,">
</jdbcConnection>
<!-- 默認false,把JDBC DECIMAL 和 NUMERIC 類型解析爲 Integer,爲 true時把JDBC DECIMAL 和
NUMERIC 類型解析爲java.math.BigDecimal -->
<javaTypeResolver>
<property name="forceBigDecimals" value="false" />
</javaTypeResolver>
<!-- targetProject:指定javaBean的生成策略
targetPackage :目標包名
targetProject: 目標工程
-->
<javaModelGenerator targetPackage="com.diligentkong.mybatis.bean"
targetProject="./src/main/java">
<!-- enableSubPackages:是否讓schema作爲包的後綴 -->
<property name="enableSubPackages" value="false" />
<!-- 從數據庫返回的值被清理前後的空格 -->
<property name="trimStrings" value="true" />
</javaModelGenerator>
<!--
對應的mapper.xml文件
sqlMapGenerator:sql映射生成策略
targetProject:mapper映射文件生成的位置 -->
<sqlMapGenerator targetPackage="mapper"
targetProject="./src/main/resources">
<!-- enableSubPackages:是否讓schema作爲包的後綴 -->
<property name="enableSubPackages" value="false" />
</sqlMapGenerator>
<!-- javaClientGenerator:指定mapper接口所在的位置
targetPackage:mapper接口生成的位置
-->
<javaClientGenerator type="XMLMAPPER"
targetPackage="com.diligentkong.mybatis.mapper"
targetProject="./src/main/java">
<!-- enableSubPackages:是否讓schema作爲包的後綴 -->
<property name="enableSubPackages" value="false" />
</javaClientGenerator>
<!--指定逆向分析哪些表 根據表要創建javaBean -->
<table tableName="employee" domainObjectName="Employee"></table>
<table tableName="dept" domainObjectName="Department"></table>
</context>
</generatorConfiguration>
- 運行函數:
public static void main(String[] args) throws Exception{
List<String> warnings = new ArrayList<String>();
boolean overwrite = true;
File configFile = new File("src/main/resources/config/generationConfig.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);
}
項目生成目錄如下:
- 項目測試代碼:
public SqlSessionFactory getSqlSeeionFactory() throws IOException {
String resource = "config/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
return new SqlSessionFactoryBuilder().build(inputStream);
}
@Test
public void myTestif() throws IOException {
// 1.獲取sqlSessionFactory對象
SqlSessionFactory sqlSessionFactory = getSqlSeeionFactory();
// 2、獲取sqlSession對象
SqlSession openSession = sqlSessionFactory.openSession(true);
try {
// 3、獲取接口的實現類對象
//會爲接口自動的創建一個代理對象,代理對象去執行增刪改查方法
EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class);
// XXXExample就是封裝查詢條件,相當於where後面部分
EmployeeExample example = new EmployeeExample();
// 創建一個Criteria,這個Criteria就是拼裝查詢條件
//select id,username,age,email from employee where (username like "%k%" and age = 20) or eamil like "%e%"
EmployeeExample.Criteria criteria = example.createCriteria();
criteria.andUserNameLike("%k%");
criteria.andAgeEqualTo(20);
EmployeeExample.Criteria criteria2 = example.createCriteria();
criteria2.andEmailLike("%e%");
example.or(criteria2);
List<Employee> list = mapper.selectByExample(example);
for (Employee employee : list){
System.out.println(employee.getId());
}
} finally {
openSession.close();
}
}