SpringBoot整合mybatis實現mapper.xml方式訪問數據庫

       SpringBoot整合mybatis實現mapper.xml方式訪問數據庫

一、項目架構

二、代碼

## pom文件

<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.yuyou</groupId>
  <artifactId>springboot-mybatis-demo</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.1.RELEASE</version>
    </parent>
    
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>1.11</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
    </dependencies>
</project>

##mapper層

---------------------mapper接口-----------------------
package com.yuyou.demo.mapper;

import java.util.List;

import org.apache.ibatis.annotations.Mapper;

import com.yuyou.demo.po.User;

public interface UserMapper {
	
	List<User> getUserList(User user);

}
---------------------mapper接口sql------------------------

<?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.yuyou.demo.mapper.UserMapper" >
    <select id="getUserList" resultType="User">
        select *
        from t_user
        <where>
            <if test="type != null">
                and type = #{type}
            </if>
             <if test ="age != null">
                and age > #{age}
            </if>
        </where>
    </select>
</mapper

##service層

---------------------service接口-----------
import java.util.List;

import com.yuyou.demo.po.User;

public interface UserService {

	List<User> selectUser(); 
}
---------------------service接口實現-----------
package com.yuyou.demo.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.yuyou.demo.mapper.UserMapper;
import com.yuyou.demo.po.User;
import com.yuyou.demo.service.UserService;

@Service
public class UserServiceImpl implements UserService{

	@Autowired
	private UserMapper userMapper;
	
	@Override
	public List<User> selectUser() {
		User user = new User();
		user.setType(1);
		user.setAge(16);
		return userMapper.getUserList(user);
	}

}

##controller層

package com.yuyou.demo.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import com.yuyou.demo.po.User;
import com.yuyou.demo.service.UserService;

@RestController
public class IndexController {

	@Autowired
	private UserService userService;
	
	@GetMapping("/getUser")
	public List<User> getUser(){
		return userService.selectUser();
	}
}

## 配置文件application.yml

server: 
  port: 8080
spring:
  datasource: 
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://ip_address:port/db_name?useUnicode=true&characterEncoding=utf8&useSSL=false&allowMultiQueries=true
    username: username
    password: password
mybatis:
    mapper-locations: classpath:mapper/**/*.xml
    type-aliases-package: com.yuyou.demo.po

##啓動類

package com.yuyou.demo;

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

@SpringBootApplication
@MapperScan("com.yuyou.demo.mapper")
public class StartUp {

	public static void main(String[] args) {
		SpringApplication.run(StartUp.class, args);
	}
}

三、注意事項

一、可以在每個mapper接口上添加@Mapper註解，這樣啓動類就不需要@MapperScan

二、mapper.xml文件中寫sql語句注意點

1、where 1==1  and col = '#' 和 <where><if test="col != null"> and col = '#'</if></where>

2、再進行數值比較時,>可以直接使用,<必須轉義&lt;,否者編譯異常

三、異常org.apache.ibatis.binding.BindingException: Invalid bound statement (not found):

1、配置文件mybatis.mapper-locations配置有誤

2、檢查xml文件所在package名稱是否和Mapper interface所在的包名一一對應

3、檢查xml的namespace是否和xml文件的package名稱一一對應

4、檢查方法名稱是否對應

5、去除xml文件中的中文註釋