映射参数

1、参数 a、当只有一个参数时，则在xml映射文件中获取改参数数据时没有要求 b、当有多个参数时，则默认将这些参数放到Map集合中，key为arg0…argn或param1…paramn；为了在获取参数值时xml映射文件中的key有意义，可以通过@Param注解的方式指定key的值 c、当参数为自定义引用类型时，则直接使用#{成员变量名} d、{}与#{}区别:{}直接将数据和sql进行拼接，无法防止SQL注入；#{}以？方式作为占位符，可以防止SQL注入

对数据进行添加，修改或者删除时方法返回值可以是布尔，int，long,及其包装类，如果为Boolean或其包装类则表示是否修改成功，如果为int或long类型，及其包装类，则返回受影响的行数

1、 有两个参数实质是用map实现的，mybatis自动转换（转下面的2）

package com.lq.userinfo; import org.apache.ibatis.annotations.Param; import com.lq.vo.UserInfo; public interface IUserInfoDao{ UserInfo selectById(@Param("id")String id,@Param("name")String name); } package com.lq.userinfo; import com.lq.vo.UserInfo; public interface IUserInfoService { UserInfo selectById(String id,String name); } <?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.lq.userinfo.IUserInfoDao"> <select id="selectById" resultType="com.lq.vo.UserInfo"> select * from employee where id=#{id} and user_name=#{name} </select> </mapper> package com.lq.userinfo.imp; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import com.lq.userinfo.IUserInfoDao; import com.lq.userinfo.IUserInfoService; import com.lq.vo.UserInfo; @Service public class UserInfoService implements IUserInfoService{ @Autowired IUserInfoDao userInfoDao; @Override public UserInfo selectById(String id,String name) { return userInfoDao.selectById(id,name); } }

2、

package com.lq.test; import java.util.HashMap; import java.util.Map; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.lq.userinfo.IUserInfoDao; import com.lq.vo.UserInfo; public class Test { public static void main(String[] args){ ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application.xml"); IUserInfoDao userInfoDao = applicationContext.getBean(IUserInfoDao.class); Map<String,String> map = new HashMap<>(); map.put("param1", "9c702712-cc24-4573-accf-c3c9bcd9daf7"); map.put("param2", "丹"); UserInfo userInfo= userInfoDao.selectById(map); System.out.println(userInfo); applicationContext.close(); } } package com.lq.userinfo; import java.util.Map; import com.lq.vo.UserInfo; public interface IUserInfoDao{ UserInfo selectById(Map<String,String> map); } <?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.lq.userinfo.IUserInfoDao"> <select id="selectById" resultType="com.lq.vo.UserInfo"> select * from employee where id=#{param1} and user_name=#{param2} </select> </mapper>

3、 参数为自定义类型

package com.lq.userinfo; import com.lq.vo.UserInfo; public interface IUserInfoDao{ UserInfo selectById(UserInfo userInfo); } <?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.lq.userinfo.IUserInfoDao"> <select id="selectById" resultType="com.lq.vo.UserInfo"> select * from employee where id=#{id} and user_name=#{userName} </select> </mapper> package com.lq.test; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.lq.userinfo.IUserInfoDao; import com.lq.vo.UserInfo; public class Test { public static void main(String[] args){ ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext("application.xml"); IUserInfoDao userInfoDao = applicationContext.getBean(IUserInfoDao.class); UserInfo userInfo = new UserInfo(); userInfo.setId("9c702712-cc24-4573-accf-c3c9bcd9daf7"); userInfo.setUserName("丹"); userInfo = userInfoDao.selectById(userInfo); System.out.println(userInfo); applicationContext.close(); } }