MyBatis参数处理及测试增删改查
POJO
private Integer id; private String lastName; private String email; private String gender; //getter and setter
接口
public interface EmployeeMapper { //查询 public Employee getEmployeeById(Integer id); //多条件查询 public Employee getEmpLoyeeByIdAndName(@Param("id") Integer id, @Param("lastName") String lastName); //添加 public void addEmp(Employee employee); //修改 public void updateEmp(Employee employee); //删除 public void deleteEmpById(Integer id);}
MyBatis主配置文件
<?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> <environments default="development"> <environment id="test"> <transactionManager type=""></transactionManager> <dataSource type=""></dataSource> </environment> <environment id="development"> <transactionManager type="JDBC" /> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false" /> <property name="username" value="root" /> <property name="password" value="123456" /> </dataSource> </environment> </environments> <!-- 将我们写好的sql映射文件(testEmployeeMapper.xml)注册到全局配置文件(mybatis-config.xml)中 --> <mappers> <mapper resource="testEmployeeMapper.xml" /> </mappers></configuration>
测试类
public class MyBatisTest { // 获取SqlSessionFactory对象 private SqlSessionFactory getSqlSessionFactory() throws IOException { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); return new SqlSessionFactoryBuilder().build(inputStream); } /** * 测试增删改 * 1. 需要手动提交数据 * sqlSessionFactory.openSession(); ===》 手动提交 * sqlSessionFactory.openSession(true); ===》 自动提交 * 2. 可以有返回值,返回值类型是一下几种: * Long, Integer,Boolean,void * @throws IOException */ @Test public void test03() throws IOException { SqlSessionFactory sqlSessionFactory = getSqlSessionFactory(); //获取到的SqlSession对象不会自动提交数据 SqlSession openSession = sqlSessionFactory.openSession(); try { EmployeeMapper mapper = openSession.getMapper(EmployeeMapper.class); //测试单个参数查询// Employee employee = mapper.getEmployeeById(2);// System.out.println(employee); //测试多个参数查询 Employee employee = mapper.getEmpLoyeeByIdAndName(2, "xiaobai"); System.out.println(employee); //添加一条数据// Employee employee = new Employee(null, "xiaobai", "xiaobai@zgz.com", "0");// mapper.addEmp(employee);// System.out.println(employee.getId()); //更新数据// Employee employee = new Employee(1, "xiaobai", "xiaobai@zgz.com", "0");// mapper.updateEmp(employee); //删除数据// mapper.deleteEmpById(1); //手动提交数据// openSession.commit(); } finally { openSession.close(); } }}
Sql映射文件
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.zgz.MyBatis.dao.EmployeeMapper"><!-- namespace: 名称空间 id: 唯一标识 resultType: 返回值类型 #{id}: 从传递过来的参数中取出id值 在MyBatis中,接口可以与配置文件实现动态绑定,绑定方式: 1. 把namespace指定为接口的全类名 2. 把id换成接口中的方法,可以把select标签和接口中的方法进行绑定 --> <!-- 使用#{}取值和${}取值的区别: #{}:是以预编译的形式,将参数设置到sql语句中,防止sql注入,一般均使用#{} ${}:取出的值直接拼装在sql语句中,会有安全问题,对于不支持预编译(不支持占位符)的原生jdbc,可以使用${},比如${tableName}; eg: select * from test where id = #{id} and name = ${name}; select * from test where id = ? and name = xiaoming; --> <!-- 参数传递: 单个参数:mybatis不会做特殊处理 用#{参数名}的形式去除参数值,参数名可以随便起,但最好要直观 多个参数:mybatis会对其进行特殊处理 多个参数会被封装成一个map key:param1...paramN value:传入的参数值 #{}就是从map中取出参数值,用 #{param1}或#{0}取出第一个值,以此类推取出n个值 命名参数:#{param1},可读性不好,采用注解的形式增加可读性 public Employee getEmpLoyeeByIdAndName(@Param("id") Integer id, @Param("lastName") String lastName); 传递多个参数: 1. POJO: 如果参数正好是业务逻辑的数据模型,可以直接传入pojo;#{属性名}:取出传入的pojo的属性值 2. Map: 如果多个参数不是业务逻辑的数据模型,没有对应的pojo,为了方便可以传入map;#{key}:取出map中的值 Collection类型:key为collection List类型:key为list 数组类型:key为array 3. TO: 如果多个参数不是业务模型中的数据,但是经常使用,可以编写一个TO(Transfer Object)数据传输对象 例如:做分页的时候可以传入一个 Page{ int index; int size; } --> <!-- 单个参数查询 --> <select id="getEmployeeById" resultType="com.zgz.MyBatis.bean.Employee"> select id,last_name lastName,email,gender from tbl_employee where id = #{id} </select> <!-- 多个参数查询 --> <select id="getEmpLoyeeByIdAndName" resultType="com.zgz.MyBatis.bean.Employee"> select id, last_name lastName, email, gender from tbl_employee where id = #{id} and last_name = #{lastName} </select> <!-- MyBatis获取自增主键: 1. useGeneratedKeys="true",使用主键自增策略 2. keyProperty="id",指定对应主键属性,也就是mybatis获取到主键后将这个值封装给javaBean的哪个属性 Oracle不支持主键自增:Oracle使用序列来模拟自增 每次插入的数据的主键是从序列中拿到的值,如何获取到这个值 --> <!-- 增删改时返回的是影响的行数 --> <insert id="addEmp" parameterType="com.zgz.MyBatis.bean.Employee" useGeneratedKeys="true" keyProperty="id"> insert into tbl_employee(last_name, email, gender) values(#{lastName},#{email},#{gender}) </insert> <update id="updateEmp" parameterType="com.zgz.MyBatis.bean.Employee"> update tbl_employee set last_name=#{lastName},email=#{email},gender=#{gender} where id = #{id} </update> <delete id="deleteEmpById" parameterType="com.zgz.MyBatis.bean.Employee"> delete from tbl_employee where id = #{id} </delete></mapper>
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