数据库CRUD操作以及MyBatisd的配置使用

• 业务字段设计

• 数据库创建 • CRUD操作 • MyBatis集成 • 注解和XML定义 • ViewObject和DateTool • 首页开发     • 业务字段设计 实体：

 

• 数据库创建 GUI版本管理工具创建，然后通过GUI转SQL； • CRUD操作   insert into table_name (列1, 列2,...) VALUES (值1, 值2,....)； select 列名1，列名2 from 表名称 where 条件； 条件： between 1 and 2 order by 3 desc UPDATE 表名称 SET 列名称 = 新值 WHERE 列名称 = 某值   • MyBatis集成 1. application.properties增加spring配置数据库链接地址 spring.datasource.url = jdbc:mysql://localhost:3306/wenda?useUnicode=true&characterEncoding=utf8&useSSL=false spring.datasource.username = root spring.datasource.password = qwertyuiop mybatis.config-location = classpath:mybatis-config.xml 同时：在配置的同级别目录下：resources/templates建立粘贴建立官网有：mybatis-config.xml <? 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 >   < settings > <!-- Globally enables or disables any caches configured in any mapper under this configuration --> < setting name ="cacheEnabled" value ="true" /> <!-- Sets the number of seconds the driver will wait for a response from the database --> < setting name ="defaultStatementTimeout" value ="3000" /> <!-- Enables automatic mapping from classic database column names A_COLUMN to camel case classic Java property names aColumn --> < setting name ="mapUnderscoreToCamelCase" value ="true" /> <!-- Allows JDBC support for generated keys. A compatible driver is required. This setting forces generated keys to be used if set to true, as some drivers deny compatibility but still work --> < setting name ="useGeneratedKeys" value ="true" /> </ settings >   <!-- Continue going here -->   </ configuration > 2. pom.xml引入mybatis-spring-boot-starter和mysql-connector-java <dependency> <groupId> org.mybatis </groupId> <artifactId> mybatis </artifactId> <version>1.1.1 </version> </dependency>   < dependency > < groupId > mysql </ groupId > < artifactId > mysql-connector-java </ artifactId > < scope > runtime </ scope > </ dependency >       3. 官网： http://www.mybatis.org/mybatis3/zh/index.html DAO层建立modul相关的userDao来通过mybatis访问数据库库: //注解配置； @Mapper public interface UserDAO { String TABLE_NAME = "user" ; String INSET_FIELDS = " name, password, salt, head_url " ; String SELECT_FIELDS = " id, name, password, salt, head_url" ; //通过抽象，实现crud的复用； @Insert ( { "insert into " , TABLE_NAME , "(" , INSET_FIELDS , ") values (#{name},#{password},#{salt},#{headUrl})" } ) int addUser ( User user ) ;   @Select ( { "select " , SELECT_FIELDS , " from " , TABLE_NAME , " where id=#{id}" } ) User selectById ( int id ) ;   @Select ( { "select " , SELECT_FIELDS , " from " , TABLE_NAME , " where name=#{name}" } ) User selectByName ( String name ) ;   @Update ( { "update " , TABLE_NAME , " set password=#{password} where id=#{id}" } ) void updatePassword ( User user ) ;   @Delete ( { "delete from " , TABLE_NAME , " where id=#{id}" } ) void deleteById ( int id ) ; } //xml配置，在相应的resources下建立DAO相应目录的的xml； <mapper namespace="com.nowcoder.dao.QuestionDAO"> <sql id="table">question</sql> <sql id="selectFields">id,title, content,comment_count,created_date,user_id </sql> <select id="selectByUserIdAndOffset" resultType="com.nowcoder.model.Question"> SELECT <include refid="selectFields"/> FROM <include refid="table"/> <if test="userId != 0"> WHERE user_id = #{userId} </if> ORDER BY id DESC LIMIT #{offset},#{limit} </select> </mapper>     • 注解和XML定义 • ViewObject和DateTool • 首页开发