SSM实现简单的CRUD之DAO层
前言
在阅读这篇文章之前如果对SSM整合不了解的同学可以先看一下我的这篇文章http://blog.csdn.net/qq_33524158/article/details/78360268
对MyBatis-逆向工程不了解的可以看我这篇文章http://blog.csdn.net/qq_33524158/article/details/78442664
本篇文章CRUD之DAO层 的sql 也是用MyBatis-逆向工程生成的 ，但是我也在生成的基础上进行了更改。
逆向工程生成的源代码我已经发布到github上了https://github.com/hfbin/MyBatis-Benerator 所有生成代码没改动过（最好都看一下生成的源代码 后面我只会附上我改动的代码，不在生成的源码与改动模块的代码进行讲解）
创建数据库
注意：如果你已经看了MyBatis-逆向工程的这篇文章了下面的数据库就不要再创建啦！！！
创建数据库
CREATE SCHEMA `ssm_crud` ;创建部门表
CREATE TABLE `tbl_dept` (
`dept_id` int(11) NOT NULL AUTO_INCREMENT,
`dept_name` varchar(45) DEFAULT NULL,
PRIMARY KEY (`dept_id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;初始化数据
INSERT INTO `tbl_dept` VALUES (1,'运营部'),(2,'技术部'),(3,'运维部'),(4,'测试部');创建员工表
CREATE TABLE `tbl_emp` (
`emp_id` int(11) NOT NULL AUTO_INCREMENT,
`emp_name` varchar(225) DEFAULT NULL,
`gender` char(1) DEFAULT NULL,
`email` varchar(45) DEFAULT NULL,
`d_id` int(11) NOT NULL,
PRIMARY KEY (`emp_id`),
KEY `fk_emp_dept_idx` (`d_id`),
CONSTRAINT `fk_emp_dept` FOREIGN KEY (`d_id`) REFERENCES `tbl_dept` (`dept_id`) ON DELETE NO ACTION ON UPDATE NO ACTION
) ENGINE=InnoDB AUTO_INCREMENT=2610 DEFAULT CHARSET=utf8;注意：这里创建了一个外键d_id与tbl_emp的dept_id关联起来
AUTO_INCREMENT=2610 代表自增的初始值
这里初始化数据在后面教用一个批量插入
到这数据库创建完成
MyBatis-逆向工程
在这不做说明具体看前言
在这并不建议使用MyBatis-逆向工程，因为使用得到的sql语句不算多， 但是由于上一章介绍了MyBatis-逆向工程，使用到的表也是一样，那就凑合用，下面一节主要介绍代码修改
MyBatis-逆向工程生成的代码更改
mapper xml 中 sql 修改
DepartmentMapper.xml
<mapper namespace="cn.hfbin.crud.dao.DepartmentMapper">
<resultMap id="BaseResultMap" type="cn.hfbin.crud.bean.Department">
<id column="dept_id" jdbcType="INTEGER" property="deptId" />
<result column="dept_name" jdbcType="VARCHAR" property="deptName" />
resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
foreach>
when>
choose>
foreach>
trim>
if>
foreach>
where>
sql>
<sql id="Base_Column_List">
dept_id, dept_name
sql>
<select id="selectByExample" parameterType="cn.hfbin.crud.bean.DepartmentExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
if>
<include refid="Base_Column_List" />
from tbl_dept
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
<if test="orderByClause != null">
order by ${orderByClause}
if>
select>
mapper>EmployeeMapper.xml
注意：这里我自己添加了多一个带部门的查询 sql语句也不难 使用左外链接
<mapper namespace="cn.hfbin.crud.dao.EmployeeMapper">
<resultMap id="BaseResultMap" type="cn.hfbin.crud.bean.Employee">
<id column="emp_id" jdbcType="INTEGER" property="empId" />
<result column="emp_name" jdbcType="VARCHAR" property="empName" />
<result column="gender" jdbcType="CHAR" property="gender" />
<result column="email" jdbcType="VARCHAR" property="email" />
<result column="d_id" jdbcType="INTEGER" property="dId" />
resultMap>
<resultMap type="cn.hfbin.crud.bean.Employee" id="WithDeptResultMap">
<id column="emp_id" jdbcType="INTEGER" property="empId" />
<result column="emp_name" jdbcType="VARCHAR" property="empName" />
<result column="gender" jdbcType="CHAR" property="gender" />
<result column="email" jdbcType="VARCHAR" property="email" />
<result column="d_id" jdbcType="INTEGER" property="dId" />
<association property="department" javaType="cn.hfbin.crud.bean.Department">
<id column="dept_id" property="deptId"/>
<result column="dept_name" property="deptName"/>
association>
resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
foreach>
when>
choose>
foreach>
trim>
if>
foreach>
where>
sql>
<sql id="Update_By_Example_Where_Clause">
<where>
<foreach collection="example.oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
foreach>
when>
choose>
foreach>
trim>
if>
foreach>
where>
sql>
<sql id="Base_Column_List">
emp_id, emp_name, gender, email, d_id
sql>
<sql id="WithDept_Column_List">
e.emp_id, e.emp_name, e.gender, e.email, e.d_id,d.dept_id,d.dept_name
sql>
<select id="selectByExampleWithDept" resultMap="WithDeptResultMap">
select
<if test="distinct">
distinct
if>
<include refid="WithDept_Column_List" />
FROM tbl_emp e
left join tbl_dept d on e.`d_id`=d.`dept_id`
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
order by e.emp_id
select>
<select id="selectByExample" parameterType="cn.hfbin.crud.bean.EmployeeExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
if>
<include refid="Base_Column_List" />
from tbl_emp
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
<if test="orderByClause != null">
order by ${orderByClause}
if>
select>
<select id="selectByPrimaryKey" parameterType="java.lang.Integer" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from tbl_emp
where emp_id = #{empId,jdbcType=INTEGER}
select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.Integer">
delete from tbl_emp
where emp_id = #{empId,jdbcType=INTEGER}
delete>
<delete id="deleteByExample" parameterType="cn.hfbin.crud.bean.EmployeeExample">
delete from tbl_emp
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
delete>
<insert id="insertSelective" parameterType="cn.hfbin.crud.bean.Employee">
insert into tbl_emp
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="empId != null">
emp_id,
if>
<if test="empName != null">
emp_name,
if>
<if test="gender != null">
gender,
if>
<if test="email != null">
email,
if>
<if test="dId != null">
d_id,
if>
trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="empId != null">
#{empId,jdbcType=INTEGER},
if>
<if test="empName != null">
#{empName,jdbcType=VARCHAR},
if>
<if test="gender != null">
#{gender,jdbcType=CHAR},
if>
<if test="email != null">
#{email,jdbcType=VARCHAR},
if>
<if test="dId != null">
#{dId,jdbcType=INTEGER},
if>
trim>
insert>
<select id="countByExample" parameterType="cn.hfbin.crud.bean.EmployeeExample" resultType="java.lang.Long">
select count(*) from tbl_emp
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
if>
select>
<update id="updateByPrimaryKeySelective" parameterType="cn.hfbin.crud.bean.Employee">
update tbl_emp
<set>
<if test="empName != null">
emp_name = #{empName,jdbcType=VARCHAR},
if>
<if test="gender != null">
gender = #{gender,jdbcType=CHAR},
if>
<if test="email != null">
email = #{email,jdbcType=VARCHAR},
if>
<if test="dId != null">
d_id = #{dId,jdbcType=INTEGER},
if>
set>
where emp_id = #{empId,jdbcType=INTEGER}
update>
mapper>
dao接口修改
EmployeeMapper.java
package cn.hfbin.crud.dao;
import cn.hfbin.crud.bean.Employee;
import cn.hfbin.crud.bean.EmployeeExample;
import org.apache.ibatis.annotations.Param;
import java.util.List;
public interface EmployeeMapper {
/**
* 检验用户名是否可用
*/
long countByExample(EmployeeExample example);
/**
* 批量删除员工
*/
int deleteByExample(EmployeeExample example);
/**
* 员工删除
*/
int deleteByPrimaryKey(Integer empId);
/**
* 员工保存
*/
int insertSelective(Employee record);
/**
* 按照员工id查询员工
*/
Employee selectByPrimaryKey(Integer empId);
/**
* 查询所有员工
*/
List selectByExampleWithDept(EmployeeExample example);
/**
* 员工更新
*/
int updateByPrimaryKeySelective(Employee record);
} DepartmentMapper.java
package cn.hfbin.crud.dao;
import cn.hfbin.crud.bean.Department;
import cn.hfbin.crud.bean.DepartmentExample;
import java.util.List;
public interface DepartmentMapper {
//所有部门
List selectByExample(DepartmentExample example);
} bean 修改
Employee.java
package cn.hfbin.crud.bean;
public class Employee {
private Integer empId;
private String empName;
private String gender;
private String email;
private Integer dId;
//查询员工的同时部门信息也是查询好的
private Department department;
@Override
public String toString() {
return "Employee [empId=" + empId + ", empName=" + empName
+ ", gender=" + gender + ", email=" + email + ", dId=" + dId
+ "]";
}
public Employee() {
super();
}
public Employee(Integer empId, String empName, String gender, String email,
Integer dId) {
super();
this.empId = empId;
this.empName = empName;
this.gender = gender;
this.email = email;
this.dId = dId;
}
public Department getDepartment() {
return department;
}
public void setDepartment(Department department) {
this.department = department;
}
public Integer getEmpId() {
return empId;
}
public void setEmpId(Integer empId) {
this.empId = empId;
}
public String getEmpName() {
return empName;
}
public void setEmpName(String empName) {
this.empName = empName == null ? null : empName.trim();
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender == null ? null : gender.trim();
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email == null ? null : email.trim();
}
public Integer getdId() {
return dId;
}
public void setdId(Integer dId) {
this.dId = dId;
}
}好修改就那么多
其它没有修改的默认不动
测试
在这只测试所有部门跟批量插入， 原则上是需要所有的service里面的方法都要进行测试的
package cn.hfbin.crud.test;
import cn.hfbin.crud.bean.Employee;
import cn.hfbin.crud.dao.DepartmentMapper;
import cn.hfbin.crud.dao.EmployeeMapper;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import java.util.UUID;
/**
*使用Spring的单元测试，可以自动注入我们需要的组件
*1、导入SpringTest模块
*2、@ContextConfiguration指定Spring配置文件的位置
*3、直接autowired要使用的组件即可
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"classpath:applicationContext.xml"})
public class MapperTest {
@Autowired
DepartmentMapper departmentMapper;
@Autowired
EmployeeMapper employeeMapper;
@Autowired
SqlSession sqlSession;
/**
* 获取所有部门
*/
@Test
public void text01(){
System.out.println("所有部门 "+departmentMapper.selectByExample(null));
}
/**
* 批量插入
* 为了插入不同的性别 跟部门我做了四个不同的循环
*/
@Test
public void testCRUD(){
EmployeeMapper mapper = sqlSession.getMapper(EmployeeMapper.class);
for(int i = 0;i<200;i++){
String uid = UUID.randomUUID().toString().substring(0,5)+i;
mapper.insertSelective(new Employee(null,uid, "f", uid+"@hfbin.com", 1));
}
for(int i = 0;i<200;i++){
String uid = UUID.randomUUID().toString().substring(0,5)+i;
mapper.insertSelective(new Employee(null,uid, "M", uid+"@hfbin.com", 2));
}
for(int i = 0;i<200;i++){
String uid = UUID.randomUUID().toString().substring(0,5)+i;
mapper.insertSelective(new Employee(null,uid, "f", uid+"@hfbin.com", 3));
}
for(int i = 0;i<200;i++){
String uid = UUID.randomUUID().toString().substring(0,5)+i;
mapper.insertSelective(new Employee(null,uid, "M", uid+"@hfbin.com", 4));
}
System.out.println("批量完成");
}
}
控制台打印结果：
text01()运行结果如下图： 
testCRUD()运行结果如下图：
这个批量插入数据需要些时间 因为插入的数据量较大
到数据库查看插入的数据 如图：
好了剩下的方法希望各位老哥能够一个一个的测试
DAO层就编写到这 下一章将介绍service层
SSM整合 http://blog.csdn.net/qq_33524158/article/details/78360268
MyBatis-逆向工程讲解 http://blog.csdn.net/qq_33524158/article/details/78442664
SSM实现简单的CRUD之DAO层 http://blog.csdn.net/qq_33524158/article/details/78442771
SSM实现简单的CRUD之Service层 http://blog.csdn.net/qq_33524158/article/details/78449897
SSM实现简单的CRUD之Web层http://blog.csdn.net/qq_33524158/article/details/78462932