近日做项目，表很多，不想一一写CRUD操作，所以整理了下实现方法，mybatis框架，具体配置此处不提，只说核心思想，有兴趣的欢迎一起讨论。
=================以下例子均用User为范例==============
1.实体类
public class User { private Integer id; private String username; private String mobile; //其他属性……get/set方法省略 } 2.dao层（此处命名为mapper后缀）
BaseMapper.java文件，为dao层所有父类接口：
public interface BaseMapper<T,ID extends Serializable> { int deleteByPrimaryKey(ID id); int insert(T record); int insertSelective(T record); T selectByPrimaryKey(ID id); int updateByPrimaryKeySelective(T record); int updateByPrimaryKey(T record); List<T> selectAll(); }
参数说明：T为实现类对应类型，ID为主键类型，具体方法不再具体介绍
UserMapper.java，BaseMapper的子接口，此处添加三个新方法
public interface UserMapper extends BaseMapper<User, Integer>{ User selectByMobile(String mobile); int updateByMobileSelective(User user); List<User> selectStudents(); } UserMapper.xml，由插件生成，很长，但 不重要，无需细看，注意映射路径即可，不再详细说明 <?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.mingxu.mapper.UserMapper"> <resultMap id="BaseResultMap" type="com.mingxu.entity.User"> <id column="id" jdbcType="INTEGER" property="id" /> <result column="username" jdbcType="VARCHAR" property="username" /> <result column="mobile" jdbcType="VARCHAR" property="mobile" /> <result column="password" jdbcType="VARCHAR" property="password" /> <result column="head_img" jdbcType="VARCHAR" property="headImg" /> <result column="open_id" jdbcType="VARCHAR" property="openId" /> <result column="id_bind" jdbcType="CHAR" property="idBind" /> <result column="insert_time" jdbcType="TIMESTAMP" property="insertTime" /> <result column="update_time" jdbcType="TIMESTAMP" property="updateTime" /> <result column="real_name" jdbcType="VARCHAR" property="realName" /> <result column="user_role" jdbcType="CHAR" property="userRole" /> <result column="is_trained" jdbcType="CHAR" property="isTrained" /> <result column="gender" jdbcType="CHAR" property="gender" /> <result column="grade" jdbcType="VARCHAR" property="grade" /> <result column="major" jdbcType="VARCHAR" property="major" /> <result column="id_card" jdbcType="VARCHAR" property="idCard" /> <result column="email" jdbcType="VARCHAR" property="email" /> </resultMap> <sql id="Base_Column_List"> id, username, mobile, password, head_img, open_id, id_bind, insert_time, update_time, real_name, user_role, is_trained, gender, grade, major, id_card, email </sql> <select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap"> select <include refid="Base_Column_List" /> from user where id = #{id,jdbcType=INTEGER} </select> <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer"> delete from user where id = #{id,jdbcType=INTEGER} </delete> <insert id="insert" parameterType="com.mingxu.entity.User"> insert into user (id, username, mobile, password, head_img, open_id, id_bind, insert_time, update_time, real_name, user_role, is_trained, gender, grade, major, id_card, email) values (#{id,jdbcType=INTEGER}, #{username,jdbcType=VARCHAR}, #{mobile,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR}, #{headImg,jdbcType=VARCHAR}, #{openId,jdbcType=VARCHAR}, #{idBind,jdbcType=CHAR}, #{insertTime,jdbcType=TIMESTAMP}, #{updateTime,jdbcType=TIMESTAMP}, #{realName,jdbcType=VARCHAR}, #{userRole,jdbcType=CHAR}, #{isTrained,jdbcType=CHAR}, #{gender,jdbcType=CHAR}, #{grade,jdbcType=VARCHAR}, #{major,jdbcType=VARCHAR}, #{idCard,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR}) </insert> <insert id="insertSelective" parameterType="com.mingxu.entity.User"> insert into user <trim prefix="(" suffix=")" suffixOverrides=","> <if test="id != null"> id, </if> <if test="username != null"> username, </if> <if test="mobile != null"> mobile, </if> <if test="password != null"> password, </if> <if test="headImg != null"> head_img, </if> <if test="openId != null"> open_id, </if> <if test="idBind != null"> id_bind, </if> <if test="insertTime != null"> insert_time, </if> <if test="updateTime != null"> update_time, </if> <if test="realName != null"> real_name, </if> <if test="userRole != null"> user_role, </if> <if test="isTrained != null"> is_trained, </if> <if test="gender != null"> gender, </if> <if test="grade != null"> grade, </if> <if test="major != null"> major, </if> <if test="idCard != null"> id_card, </if> <if test="email != null"> email, </if> </trim> <trim prefix="values (" suffix=")" suffixOverrides=","> <if test="id != null"> #{id,jdbcType=INTEGER}, </if> <if test="username != null"> #{username,jdbcType=VARCHAR}, </if> <if test="mobile != null"> #{mobile,jdbcType=VARCHAR}, </if> <if test="password != null"> #{password,jdbcType=VARCHAR}, </if> <if test="headImg != null"> #{headImg,jdbcType=VARCHAR}, </if> <if test="openId != null"> #{openId,jdbcType=VARCHAR}, </if> <if test="idBind != null"> #{idBind,jdbcType=CHAR}, </if> <if test="insertTime != null"> #{insertTime,jdbcType=TIMESTAMP}, </if> <if test="updateTime != null"> #{updateTime,jdbcType=TIMESTAMP}, </if> <if test="realName != null"> #{realName,jdbcType=VARCHAR}, </if> <if test="userRole != null"> #{userRole,jdbcType=CHAR}, </if> <if test="isTrained != null"> #{isTrained,jdbcType=CHAR}, </if> <if test="gender != null"> #{gender,jdbcType=CHAR}, </if> <if test="grade != null"> #{grade,jdbcType=VARCHAR}, </if> <if test="major != null"> #{major,jdbcType=VARCHAR}, </if> <if test="idCard != null"> #{idCard,jdbcType=VARCHAR}, </if> <if test="email != null"> #{email,jdbcType=VARCHAR}, </if> </trim> </insert> <update id="updateByPrimaryKeySelective" parameterType="com.mingxu.entity.User"> update user <set> <if test="username != null"> username = #{username,jdbcType=VARCHAR}, </if> <if test="mobile != null"> mobile = #{mobile,jdbcType=VARCHAR}, </if> <if test="password != null"> password = #{password,jdbcType=VARCHAR}, </if> <if test="headImg != null"> head_img = #{headImg,jdbcType=VARCHAR}, </if> <if test="openId != null"> open_id = #{openId,jdbcType=VARCHAR}, </if> <if test="idBind != null"> id_bind = #{idBind,jdbcType=CHAR}, </if> <if test="insertTime != null"> insert_time = #{insertTime,jdbcType=TIMESTAMP}, </if> <if test="updateTime != null"> update_time = #{updateTime,jdbcType=TIMESTAMP}, </if> <if test="realName != null"> real_name = #{realName,jdbcType=VARCHAR}, </if> <if test="userRole != null"> user_role = #{userRole,jdbcType=CHAR}, </if> <if test="isTrained != null"> is_trained = #{isTrained,jdbcType=CHAR}, </if> <if test="gender != null"> gender = #{gender,jdbcType=CHAR}, </if> <if test="grade != null"> grade = #{grade,jdbcType=VARCHAR}, </if> <if test="major != null"> major = #{major,jdbcType=VARCHAR}, </if> <if test="idCard != null"> id_card = #{idCard,jdbcType=VARCHAR}, </if> <if test="email != null"> email = #{email,jdbcType=VARCHAR}, </if> </set> where id = #{id,jdbcType=INTEGER} </update> <update id="updateByPrimaryKey" parameterType="com.mingxu.entity.User"> update user set username = #{username,jdbcType=VARCHAR}, mobile = #{mobile,jdbcType=VARCHAR}, password = #{password,jdbcType=VARCHAR}, head_img = #{headImg,jdbcType=VARCHAR}, open_id = #{openId,jdbcType=VARCHAR}, id_bind = #{idBind,jdbcType=CHAR}, insert_time = #{insertTime,jdbcType=TIMESTAMP}, update_time = #{updateTime,jdbcType=TIMESTAMP}, real_name = #{realName,jdbcType=VARCHAR}, user_role = #{userRole,jdbcType=CHAR}, is_trained = #{isTrained,jdbcType=CHAR}, gender = #{gender,jdbcType=CHAR}, grade = #{grade,jdbcType=VARCHAR}, major = #{major,jdbcType=VARCHAR}, id_card = #{idCard,jdbcType=VARCHAR}, email = #{email,jdbcType=VARCHAR} where id = #{id,jdbcType=INTEGER} </update> <select id="selectByMobile" parameterType="String" resultMap="BaseResultMap"> select <include refid="Base_Column_List" /> from user where mobile = #{mobile,jdbcType=VARCHAR} </select> <update id="updateByMobileSelective" parameterType="com.mingxu.entity.User"> update user <set> <if test="username != null"> username = #{username,jdbcType=VARCHAR}, </if> <if test="password != null"> password = #{password,jdbcType=VARCHAR}, </if> <if test="headImg != null"> head_img = #{headImg,jdbcType=VARCHAR}, </if> <if test="openId != null"> open_id = #{openId,jdbcType=VARCHAR}, </if> <if test="idBind != null"> id_bind = #{idBind,jdbcType=CHAR}, </if> <if test="insertTime != null"> insert_time = #{insertTime,jdbcType=TIMESTAMP}, </if> <if test="updateTime != null"> update_time = #{updateTime,jdbcType=TIMESTAMP}, </if> <if test="realName != null"> real_name = #{realName,jdbcType=VARCHAR}, </if> <if test="userRole != null"> user_role = #{userRole,jdbcType=CHAR}, </if> <if test="isTrained != null"> is_trained = #{isTrained,jdbcType=CHAR}, </if> <if test="gender != null"> gender = #{gender,jdbcType=CHAR}, </if> <if test="grade != null"> grade = #{grade,jdbcType=VARCHAR}, </if> <if test="major != null"> major = #{major,jdbcType=VARCHAR}, </if> <if test="idCard != null"> id_card = #{idCard,jdbcType=VARCHAR}, </if> <if test="email != null"> email = #{email,jdbcType=VARCHAR}, </if> </set> where mobile = #{mobile,jdbcType=VARCHAR} </update> <select id="selectStudents" parameterType="String" resultMap="BaseResultMap"> select <include refid="Base_Column_List" /> from user where user_role='1' and is_trained='1' ORDER BY insert_time DESC </select> </mapper> 3.service层3.1接口定义
BaseService.java，此处与dao层统一
public interface BaseService<T,ID extends Serializable> { boolean removeByPrimaryKey(ID id); boolean add(T record); boolean addSelective(T record); T findByPrimaryKey(ID id); boolean saveByPrimaryKeySelective(T record); boolean saveByPrimaryKey(T record); List<T> findAll(); } UserService.java public interface UserService extends BaseService<Dept, Integer> { } 3.2接口实现
BaseServiceImpl.java这个类很重要，是数据库操作的实现
@Service public abstract class BaseServiceImpl<T, ID extends Serializable> implements BaseService<T, ID> { public abstract BaseMapper<T, ID> getMapper(); @Override public boolean removeByPrimaryKey(ID id) { return getMapper().deleteByPrimaryKey(id) > 0; } @Override public boolean add(T record) { return getMapper().insert(record) > 0; } @Override public boolean addSelective(T record) { return getMapper().insertSelective(record) > 0; } @Override public T findByPrimaryKey(ID id) { return getMapper().selectByPrimaryKey(id); } @Override public boolean saveByPrimaryKeySelective(T record) { return getMapper().updateByPrimaryKeySelective(record) > 0; } @Override public boolean saveByPrimaryKey(T record) { return getMapper().updateByPrimaryKey(record) > 0; } @Override public List<T> findAll() { return getMapper().selectAll(); } } UserServiceImpl.java @Service public class UserServiceImpl extends BaseServiceImpl<Archives, Integer> implements ArchivesService{ @Resource private UserMapper mapper; @Override public BaseMapper<Archives, Integer> getMapper() { return mapper; } }