Mybatis培训教程
3. 操作users表的CRUD
3.1. XML的实现
1). 定义sql映射xml文件：
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<insert id="insertUser" parameterType="com.atguigu.ibatis.bean.User"> insert into users(name, age) values(#{name}, #{age}); </insert>
<delete id="deleteUser" parameterType="int"> delete from users where id=#{id} </delete> <update id="updateUser" parameterType="com.atguigu.ibatis.bean.User"> update users set name=#{name},age=#{age} where id=#{id} </update> <select id="selectUser" parameterType="int" resultType="com.atguigu.ibatis.bean.User"> select * from users where id=#{id} </select> <select id="selectAllUsers" resultType="com.atguigu.ibatis.bean.User"> select * from users </select> |
2). 在config.xml中注册这个映射文件
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<mapper resource="net/lamp/java/ibatis/bean/userMapper.xml"/> |
3). 在dao中调用：
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public User getUserById(int id) { SqlSession session = sessionFactory.openSession(); User user = session.selectOne(URI+".selectUser", id); return user; } |
3.2. 注解的实现
1). 定义sql映射的接口
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public interface UserMapper { @Insert("insert into users(name, age) values(#{name}, #{age})") public int insertUser(User user);
@Delete("delete from users where id=#{id}") public int deleteUserById(int id); @Update("update users set name=#{name},age=#{age} where id=#{id}") public int updateUser(User user);
@Select("select * from users where id=#{id}") public User getUserById(int id);
@Select("select * from users") public List<User> getAllUser(); }
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2). 在config中注册这个映射接口
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<mapper class="com.atguigu.ibatis.crud.ano.UserMapper"/> |
3). 在dao类中调用
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public User getUserById(int id) { SqlSession session = sessionFactory.openSession(); UserMapper mapper = session.getMapper(UserMapper.class); User user = mapper.getUserById(id); return user; } |
4. 几个可以优化的地方
4.1. 连接数据库的配置单独放在一个properties文件中
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## db.properties
<properties resource="db.properties"/>
<property name="driver" value="${driver}" /> <property name="url" value="${url}" /> <property name="username" value="${username}" /> <property name="password" value="${password}" /> |
4.2. 为实体类定义别名,简化sql映射xml文件中的引用
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<typeAliases> <typeAlias type="com.atguigu.ibatis.bean.User" alias="_User"/> </typeAliases> |
4.3. 可以在src下加入log4j的配置文件,打印日志信息
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1. 添加jar: log4j-1.2.16.jar
2.1. log4j.properties(方式一)
log4j.properties， log4j.rootLogger=DEBUG, Console #Console log4j.appender.Console=org.apache.log4j.ConsoleAppender log4j.appender.Console.layout=org.apache.log4j.PatternLayout log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n log4j.logger.java.sql.ResultSet=INFO log4j.logger.org.apache=INFO log4j.logger.java.sql.Connection=DEBUG log4j.logger.java.sql.Statement=DEBUG log4j.logger.java.sql.PreparedStatement=DEBUG
2.2. log4j.xml(方式二)
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd"> <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/"> <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender"> <layout class="org.apache.log4j.PatternLayout"> <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" /> </layout> </appender> <logger name="java.sql"> <level value="debug" /> </logger> <logger name="org.apache.ibatis"> <level value="debug" /> </logger> <root> <level value="debug" /> <appender-ref ref="STDOUT" /> </root> </log4j:configuration> |
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