MyBatis 逆向工程的使用

什么是逆向工程
mybaits需要程序员自己编写sql语句，mybatis官方提供逆向工程 可以针对单表自动生成mybatis执行所需要的代码（mapper.java,mapper.xml、po…）
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="testTables" targetRuntime="MyBatis3">
		<commentGenerator>
			<!-- 是否去除自动生成的注释 true：是 ： false:否 -->
			<property name="suppressAllComments" value="true" />
		</commentGenerator>
		<!--数据库连接的信息：驱动类、连接地址、用户名、密码 -->
		<jdbcConnection driverClass="com.mysql.jdbc.Driver"
			connectionURL="jdbc:mysql://localhost:3306/mybatis" userId="root"
			password="mysql">
		</jdbcConnection>
		<!-- <jdbcConnection driverClass="oracle.jdbc.OracleDriver"
			connectionURL="jdbc:oracle:thin:@127.0.0.1:1521:yycg" 
			userId="yycg"
			password="yycg">
		</jdbcConnection> -->

		<!-- 默认false，把JDBC DECIMAL 和 NUMERIC 类型解析为 Integer，为 true时把JDBC DECIMAL 和 
			NUMERIC 类型解析为java.math.BigDecimal -->
		<javaTypeResolver>
			<property name="forceBigDecimals" value="false" />
		</javaTypeResolver>

		<!-- targetProject:生成PO类的位置 -->
		<javaModelGenerator targetPackage="cn.itcast.ssm.po"
			targetProject=".\src">
			<!-- enableSubPackages:是否让schema作为包的后缀 -->
			<property name="enableSubPackages" value="false" />
			<!-- 从数据库返回的值被清理前后的空格 -->
			<property name="trimStrings" value="true" />
            <!-- 是否对model添加 构造函数 -->
           <property name="constructorBased" value="true"/>
		</javaModelGenerator>
        <!-- targetProject:mapper映射文件生成的位置 -->
		<sqlMapGenerator targetPackage="cn.itcast.ssm.mapper" 
			targetProject=".\src">
			<!-- enableSubPackages:是否让schema作为包的后缀 -->
			<property name="enableSubPackages" value="false" />
		</sqlMapGenerator>
		<!-- targetPackage：mapper接口生成的位置 -->
		<javaClientGenerator type="XMLMAPPER"
			targetPackage="cn.itcast.ssm.mapper" 
			targetProject=".\src">
			<!-- enableSubPackages:是否让schema作为包的后缀 -->
			<property name="enableSubPackages" value="false" />
		</javaClientGenerator>
		<!-- 指定数据库表 -->
		<table tableName="items"></table>
		<table tableName="orders"></table>
		<table tableName="orderdetail"></table>
		<table tableName="user"></table>

		
	</context>
</generatorConfiguration>

执行生成程序

public class GeneratorSqlMapDemo01 {

public static void main(String[] args) throws Exception {
	List<String> warnings = new ArrayList<String>();
	boolean overwrite = true;
	File configFile = new File("src/generatorConfig.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);

}

}

根据数据库一张表完成逆向工程的例子

逆向工程生成的student类

public class Student {
    private Integer id;

    private String name;

    private Integer age;

    private String sex;

    private String email;
    .............

对逆向工程生成的StudentMapper建立测试类进行测试

/**
 * 凡是带selective的方法的特点：遇到null字段忽略。
 * 
 * @author h
 *
 */
public class StudentMapperTest {

	private StudentMapper studentMapper;
	
	@Before
	public void setUp() throws Exception {
		SqlSession sqlSession=MyBatisUtils.getSqlSession();
		this.studentMapper=sqlSession.getMapper(StudentMapper.class);
		System.out.println("this.studentMapper="+this.studentMapper);
	}

	@Test
	public void testCountByExample() {
		StudentExample studentExample=new StudentExample();
		
		studentExample.setDistinct(true);
		studentExample.setOrderByClause("id desc");
		int count=this.studentMapper.countByExample(studentExample);
		System.out.println("count="+count);
	}

	@Test
	public void testDeleteByExample() {
		StudentExample example=new StudentExample();
		Criteria criteria=example.createCriteria();
		criteria.andNameEqualTo("小丽");
		int count=this.studentMapper.deleteByExample(example);
		System.out.println("count="+count);
	}

	@Test
	public void testDeleteByPrimaryKey() {
		int id=10;
		int count=this.studentMapper.deleteByPrimaryKey(id);
		System.out.println("count="+count);
	}

	@Test
	public void testInsert() {
		Student student=new Student();
		student.setName("小娥");
		int count=this.studentMapper.insert(student);
		System.out.println("count="+count);
	}

	@Test
	public void testInsertSelective() {
		Student student=new Student();
		student.setName("小静");
		int count=this.studentMapper.insertSelective(student);
		System.out.println("count="+count);
	}

	@Test
	public void testSelectByExample() {
		StudentExample example=new StudentExample();
		
		Criteria criteria=example.createCriteria();
		String condition="小";
		criteria.andNameLike("%"+condition+"%");
		criteria.andSexEqualTo("男");
		List<Student> list=this.studentMapper.selectByExample(example);
		System.out.println(list);
	}

	@Test
	public void testSelectByPrimaryKey() {
		int id=1;
		Student student=this.studentMapper.selectByPrimaryKey(id);
		System.out.println(student);
	}

	@Test
	public void testUpdateByExampleSelective() {
		int id=8;
		Student student=this.studentMapper.selectByPrimaryKey(id);
		if(student!=null){
			student.setName("丽儿");
			student.setAge(18);
			int count=this.studentMapper.updateByPrimaryKeySelective(student);
			System.out.println("count="+count);
		}else{
			System.out.println("学生不存在！");
		}
		
	}

	@Test
	public void testUpdateByExample() {
		int id=8;
		Student student=this.studentMapper.selectByPrimaryKey(id);
		if(student!=null){
			StudentExample studentExample=new StudentExample();
			Criteria criteria=studentExample.createCriteria();
			criteria.andNameEqualTo("丽儿");
			student.setName("妹儿");
			student.setAge(18);
			int count=this.studentMapper.updateByExample(student, studentExample);
			System.out.println("count="+count);
		}else{
			System.out.println("学生不存在！");
		}
	}

	@Test
	public void testUpdateByPrimaryKeySelective() {
		int id=8;
		Student student=this.studentMapper.selectByPrimaryKey(id);
		if(student!=null){
			student.setName("小美");
			int count=this.studentMapper.updateByPrimaryKeySelective(student);
			System.out.println("count="+count);
		}
		
	}

	@Test
	public void testUpdateByPrimaryKey() {
		int id=8;
		Student student=this.studentMapper.selectByPrimaryKey(id);
		if(student!=null){
			student.setName("妹儿");
			int count=this.studentMapper.updateByPrimaryKey(student);
			System.out.println("count="+count);
		}
	}

}