SpringBoot---使用Mybatis配置文件实现数据的增删查改

SpringBoot---使用Mybatis配置文件实现数据的增删查改

1、新建一个Maven项目，在pom.xml中添加必要的依赖：<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>

<groupId>com.etc</groupId>
<artifactId>springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>springboot</name>
<url>http://maven.apache.org</url>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.7.RELEASE</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8
4000
</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.7</java.version>
</properties>

<dependencies>
<!-- SpringBoot导入的jar包 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- freemarker模版 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-freemarker</artifactId>
</dependency>
<!-- jdbc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- mybatis -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.0</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8080</configuration>
</plugin>

<!-- mybatis generator 自动生成代码插件 -->
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<configuration>
<configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
<overwrite>true</overwrite>
<verbose>true</verbose>
</configuration>
</plugin>
</plugins>
</build>

</project>2、新建一个SpringBootBaseApplication.java启动类package com.etc.springboot;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan(basePackages="com.etc.*")
@MapperScan(value = "com.etc.mapper")//这样才能找到mapper文件
public class SpringBootBaseApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootBaseApplication.class,args);
System.out.println("启动完成");
}
}3、在数据库中新建一个表t_student，添加一些简单的数据，如下图所示：



4、新建src/main/resource源文件夹，在该文件夹下新建application.properties文件，配置一些参数如下：spring.datasource.name=test
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.jdbc.Driver

###########################mybatis配置###############################
#全局映射器启用缓存
mybatis.configuration.cache-enabled=true
#查询时,关闭关联对象及时加载以提高性能
mybatis.configuration.lazy-loading-enabled=false
#按需加载字段(加载字段由SQL指定),不会加载关联表的所有字段,以提高性能
mybatis.configuration.aggressive-lazy-loading=false
#允许返回不同的结果集以达到通用的效果
mybatis.configuration.multiple-result-sets-enabled=true
#对于批量更新操作缓存SQL以提高性能
mybatis.configuration.default-executor-type=REUSE
#数据库执行超时时间
mybatis.configuration.default-statement-timeout=25000
mybatis.mapper-locations=classpath:mapping/*.xml
mybatis.type-aliases-package=com.etc.po5、在com.etc.po包下新建一个Student.java类：package com.etc.po;
/**
* @Description:学生实体类
* @author zoey
* @date:2018年3月6日
*/
public class Student {
private int sno;
private String sname;
private int sage;

public int getSno() {
return sno;
}
public void setSno(int sno) {
this.sno = sno;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public int getSage() {
return sage;
}
public void setSage(int sage) {
this.sage = sage;
}
@Override
public String toString() {
return "Student [sno=" + sno + ", sname=" + sname + ", sage=" + sage + "]";
}

public Student(String sname, int sage) {
super();
this.sname = sname;
this.sage = sage;
}
public Student() {
super();
}
}6、在src/main/resources下新建一个mapping文件夹，然后新建StudentMapper.xml文件如下：<?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.etc.mapper.StudentMapper">
<!-- 结果集 -->
<resultMap id="studentMap" type="com.etc.po.Student">
<id column="sno" property="sno" />
<result column="sname" property="sname" />
<result column="sage" property="sage" />
</resultMap>

<select id="findAll" resultMap="studentMap" parameterType="com.etc.po.Student"> select sno, sname, sage from t_student </select>

<insert id="insertStudent" parameterType="com.etc.po.Student" useGeneratedKeys="true" keyProperty="sno">
insert into
t_student(sname,sage)
values
(#{sname},#{sage})
</insert>

<select id="findById" resultMap="studentMap" parameterType="java.lang.Integer">
select
sno,
sname,
sage
from
t_student
where
sno = #{sno}

</select>
<!--
报错：Result Maps collection does not contain value for com.etc.po.Student
解决方法：将findById查询方法的 resultMap="com.etc.po.Student" 改为 resultMap="studentMap"
-->

<update id="updateStudent" parameterType="com.etc.po.Student">
update
t_student
set
sname = #{sname},sage=#{sage}
where
sno = #{sno}
</update>

<delete id="deleteStudent" parameterType="java.lang.Integer">
delete from
t_student
where
sno = #{sno}
</delete>

<delete id="delteStudent2" parameterType="com.etc.po.Student">
delete from
t_student
where
sno = #{sno}
</delete>

</mapper>7、在com.etc.mapper包下新建一个StudentMapper.java类：package com.etc.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Mapper;

import com.etc.po.Student;
/**
* @Description:一个接口，方法名称和
* @author zoey
* @date:2018年3月6日
*/
public interface StudentMapper {
List<Student> findAll();

int insertStudent(Student student);

Student findById(int i);

int updateStudent(Student student);

int deleteStudent(int i);

int delteStudent2(Student student);
}8、在com.etc.service包下新建一个StudentService.java类：package com.etc.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.etc.mapper.StudentMapper;
import com.etc.po.Student;
/**
* @Description:Service层，调用mapper层的方法
* @author zoey
* @date:2018年3月6日
*/
@Service(value="studentService")
public class StudentService {
@Autowired
private StudentMapper studentMapper;

public List<Student> findAll(){
return studentMapper.findAll();
}

public int insertStudent(Student student) {
return studentMapper.insertStudent(student);
}

public Student findById(int i) {
return studentMapper.findById(i);
}

public int updateStudent(Student student) {
return studentMapper.updateStudent(student);
}

public int deleteStudent(int i) {
return studentMapper.deleteStudent(i);
}

public int deleteStudent2(Student student) {
return studentMapper.delteStudent2(student);
}
}9、在com.etc.controller包下新建一个StudentController.java类：package com.etc.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.etc.po.Student;
import com.etc.service.StudentService;
/**
* @Description:Controller层，调用Service层的方法，返回执行结果
* @author zoey
* @date:2018年3月6日
*/
@Controller
@RequestMapping("/student")
public class StudentController {
@Autowired
private StudentService studentService;

/**
* @Description:查询所有的学生信息
* 访问地址：http://localhost:8080/student/findAll
* @return 返回字符串信息，直接显示在页面
* @author zoey
* @date:2018年3月6日
*/
@RequestMapping("/findAll")
@ResponseBody //使得返回结果为字符串，而不是进入某一个指定的页面
public String findAll() {
System.out.println("进入查询方法");
List<Student> list = studentService.findAll();
for(int i=0;i<list.size();i++) {
System.out.println("学生:"+list.get(i));
}
return "findAll";
}
/**
* @Description:根据学生id查询学生信息(使用@PathVariable注解接收传入的参数)
* 访问地址：http://localhost:8080/student/findById/3
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping(value="/findById/{sno}",method=RequestMethod.GET)
@ResponseBody
public String findById(@PathVariable("sno") Integer sno) {
System.out.println("进入根据id查询学生信息方法");
Student student = studentService.findById(sno);
System.out.println(student);
return "findById";
}
/**
* @Description:根据学生id查询学生信息(使用@RequestParam注解接收传入的参数)
* 访问地址：http://localhost:8080/student/findById?sno=3
* @param sno
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping(value="/findById")
@ResponseBody
public String findById2(@RequestParam("sno") Integer sno) {
System.out.println("进入根据id查询学生信息方法");
Student student = studentService.findById(sno);
System.out.println(student);
return "findById";
}
/**
* @Description:新增学生信息
* 访问地址：http://localhost:8080/student/insertStudent(数据写死)
* http://localhost:8080/student/insertStudent?sname=zoey&sage=18(传递参数) * @return 返回字符串信息，直接显示在页面
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping("/insertStudent")
@ResponseBody
public String insertStudent(Student student) {
System.out.println("进入新增方法");
//Student student = new Student("lan",20);//数据写死
int result = studentService.insertStudent(student);
if(result==1) {
System.out.println("新增学生成功!");
}else {
System.out.println("新增学生失败!");
}
return "insert";
}
/**
* @Description:修改学生信息
* 访问地址：http://localhost:8080/student/updateStudent?sno=1&sname=change
* @param student
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping("/updateStudent")
@ResponseBody
public String updateStudent(Student student) {
System.out.println("进入更新方法");
int result = studentService.updateStudent(student);
if(result==1) {
System.out.println("修改学生成功!");
}else {
System.out.println("修改学生失败!");
}
return "update";
}
/**
* @Description:删除学生信息(数据写死)
* 访问地址：http://localhost:8080/student/deleteStudent
* http://localhost:8080/student/deleteStudent?sno=2(报错) * 报错如下：
* Optional int parameter 'i' is present but cannot be translated into a null value
* due to being declared as a primitive type.
* Consider declaring it as object wrapper for the corresponding primitive type.
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping("/deleteStudent")
@ResponseBody
public String deleteStudent() {
System.out.println("进入删除方法");
int result = studentService.deleteStudent(1);//传入的参数是一个整型，不能从地址栏的参数中传递过去
if(result==1) {
System.out.println("删除学生成功!");
}else {
System.out.println("删除学生失败！");
}
return "delete";
}
/**
* @Description:根据学生id删除学生信息
* 访问地址：http://localhost:8080/student/deleteStudent?sno=2
* @param student
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping("/deleteStudent2")
@ResponseBody
public String delelteStudent2(Student student) {
int result = studentService.deleteStudent2(student);//传递的参数是一个对象，可以从地址栏的参数中传递过去
if(result==1) {
System.out.println("删除学生成功!");
}else {
System.out.println("删除学生失败！");
}
return "delete2";
}
}

项目结构图如下：

错误总结：

1、启动SpringBootBaseApplication.java类失败，报错如下：Description:

Field studentService in com.etc.controller.StudentController required a bean of type 'com.etc.service.StudentService' that could not be found.

Action:

Consider defining a bean of type 'com.etc.service.StudentService' in your configuration.找不到Service类，解决方法如下：
    在StudentService类上面增加注解如下： @Service(value="studentService")2、启动SpringBootBaseApplication.java类失败，报错如下：D
d3c9
escription:

Field studentMapper in com.etc.service.StudentService required a bean of type 'com.etc.mapper.StudentMapper' that could not be found.

Action:

Consider defining a bean of type 'com.etc.mapper.StudentMapper' in your configuration.找不到mapper类，解决方法如下：
    在SpringBootBaseApplication启动类的上面增加注解如下：
@MapperScan(value = "com.etc.mapper")//这样才能找到mapper文件
3、启动成功，报错如下：Invalid bound statement (not found): com.etc.mapper.StudentMapper.findAll找不到StudentMapper.java类
解决方法，步骤如下：
(1)pom.xml中增加mybatis的依赖如下：<!-- mybatis -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.0</version>
</dependency>(2)pom.xml中增加mybatis的自动生成代码如下：<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8080</configuration>
</plugin>

<!-- mybatis generator 自动生成代码插件 -->
<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.2</version>
<configuration>
<configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
<overwrite>true</overwrite>
<verbose>true</verbose>
</configuration>
</plugin>
</plugins>
</build>(3)application.properties中增加mybatis的配置如下：###########################mybatis配置###############################
#全局映射器启用缓存
mybatis.configuration.cache-enabled=true
#查询时,关闭关联对象及时加载以提高性能
mybatis.configuration.lazy-loading-enabled=false
#按需加载字段(加载字段由SQL指定),不会加载关联表的所有字段,以提高性能
mybatis.configuration.aggressive-lazy-loading=false
#允许返回不同的结果集以达到通用的效果
mybatis.configuration.multiple-result-sets-enabled=true
#对于批量更新操作缓存SQL以提高性能
mybatis.configuration.default-executor-type=REUSE
#数据库执行超时时间
mybatis.configuration.default-statement-timeout=25000
mybatis.mapper-locations=classpath:mapping/*.xml
mybatis.type-aliases-package=com.etc.po

经验总结：

1、要读取数据库中的数据，需要进行如下操作：
(1)pom.xml中引入数据库相关的依赖包： <!-- jdbc -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- mysql -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.0</version>
</dependency>(2)application.properties文件中需要配置数据库相关的信息：###############################数据库配置：连接本地数据库###############################
spring.datasource.name=test
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.jdbc.Driver
2、进行增删查改操作，结构如下：
Controller类--->Service类--->Mapper类--->Mapper.xml配置文件
(1)Controller类中需要访问Service类的方法，则在Controller类中添加@Autowired注解，自动注入Service类：@Autowired
private StudentService studentService;(2)Service类中需要访问Mapper类的方法，则在Service类中添加@Autowired注解，自动注入Mapper类：@Autowired
private StudentMapper studentMapper;(3)Mapper类中需要访问Mapper.xml中的方法，需要保持Mapper类中方法的名称和Mapper.xml中的id保持一致：List<Student> findAll();

<select id="findAll" resultMap="studentMap" parameterType="com.etc.po.Student">
select
sno,
sname,
sage
from
t_student
</select>

3、StudentMapper.xml文件的编写细节：
(1)查询标签：<select>、新增标签：<insert>、更新标签：<update>、删除标签：<delete>
(2)resultMap标签，结果与数据库中的字段相对应<!-- 结果集 -->
<resultMap id="studentMap" type="com.etc.po.Student">
<id column="sno" property="sno" />
<result column="sname" property="sname" />
<result column="sage" property="sage" />
</resultMap>(3)parameterType需要指定详细的类型，比如 传递的参数类型是int，那么parameterType的值不能是int或者Integer,而必须是java.lang.Integer<select id="findById" resultMap="studentMap" parameterType="java.lang.Integer">
select
sno,
sname,
sage
from
t_student
where
sno = #{sno}
</select>其中，动态值，需要传入的参数sno，使用#{sno}来获取
4、通过url传递参数的几种方式：
(1)第一种方法：传递一个Student对象：
(a)StudentMapper.xml中定义如下：<update id="updateStudent" parameterType="com.etc.po.Student">
update
t_student
set
sname = #{sname},sage=#{sage}
where
sno = #{sno}
</update>(2)StudentController.java类中编写如下：/**
* @Description:修改学生信息
* 访问地址：http://localhost:8080/student/updateStudent?sno=1&sname=change
* @param student
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping("/updateStudent")
@ResponseBody
public String updateStudent(Student student) {
System.out.println("进入更新方法");
int result = studentService.updateStudent(student);
if(result==1) {
System.out.println("修改学生成功!");
}else {
System.out.println("修改学生失败!");
}
return "update";
}访问地址：

http://localhost:8080/student/updateStudent?sno=1&sname=change

传入一个学生对象，进行更改。
运行结果：修改学生成功！这种方式，不能直接传入一个sno，也就是参数类型改为java.lang.Integer,无法实现，报错如下：Optional int parameter 'i' is present but cannot be translated into a null value
due to being declared as a primitive type.
Consider declaring it as object wrapper for the corresponding primitive type.那么，如果我们想要直接传入一个sno，然后进行操作，就使用第二种方法或者第三种方法。
(2)第二种方法：传递一个Integer类型，使用@PathVariable注解
(a)StudentMapper.xml中定义如下：<select id="findById" resultMap="studentMap" parameterType="java.lang.Integer">
select
sno,
sname,
sage
from
t_student
where
sno = #{sno}

</select>(b)StudentController.java类中编写如下：/**
* @Description:根据学生id查询学生信息
* 访问地址：http://localhost:8080/student/findById/3
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping(value="/findById/{sno}",method=RequestMethod.GET)
@ResponseBody
public String findById(@PathVariable("sno") Integer sno) {
System.out.println("进入根据id查询学生信息方法");
Student student = studentService.findById(sno);
System.out.println(student);
return "findById";
}访问地址：

http://localhost:8080/student/findById/3

运行结果如下：进入根据id查询学生信息方法
Student [sno=3, sname=StudentC, sage=3](3)第三种方法：传递一个Integer类型,使用@RequestParam注解(a)StudentMapper.xml中定义如下：<select id="findById" resultMap="studentMap" parameterType="java.lang.Integer">
select
sno,
sname,
sage
from
t_student
where
sno = #{sno}

</select>(b)StudentController.java类中编写如下：/**
* @Description:根据学生id查询学生信息
* 访问地址：http://localhost:8080/student/findById?sno=3
* @param sno
* @return
* @author:zoey
* @date:2018年3月6日
*/
@RequestMapping(value="/findById")
@ResponseBody
public String findById(@RequestParam("sno") Integer sno) {
System.out.println("进入根据id查询学生信息方法");
Student student = studentService.findById(sno);
System.out.println(student);
return "findById";
}访问地址：

http://localhost:8080/student/findById?sno=3

运行结果如下：进入根据id查询学生信息方法
Student [sno=3, sname=StudentC, sage=3]