Spring Boot乾貨系列：（九）數據存儲篇-SQL關係型數據庫之MyBatis的使用

時間 2019-11-11

標籤 spring boot 乾貨系列數據存儲 sql 關係數據庫 mybatis 使用欄目 Spring 简体版

原文原文鏈接

前言

上篇咱們介紹了Spring Boot對傳統JdbcTemplate的集成，此次換一下，介紹下Spring Boot中如何集成MyBatis。這裏分別介紹註解方式以及XML方式的整合。喜歡哪一種方式本身選擇。html

正文

項目框架仍是跟上一篇同樣使用Spring Boot的ace後端模板，你能夠基於它來跟着博主一塊兒來調整代碼，若是沒看過上一篇，那就下載本篇源碼研究吧。java

跟上篇同樣先添加基礎的依賴和數據源。mysql

添加依賴

這裏須要添加mybatis-spring-boot-starter依賴跟mysql依賴git

<!--最新版本，匹配spring Boot1.5 or higher-->
<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>
</dependency>

這裏不引入spring-boot-starter-jdbc依賴，是因爲mybatis-spring-boot-starter中已經包含了此依賴。 github

博主開始整理的時候發現mybatis-spring-boot-starter有新版本了，這裏就集成最新的，匹配Spring Boot1.5版本。
spring

MyBatis-Spring-Boot-Starter依賴將會提供以下：sql

自動檢測現有的DataSource
將建立並註冊SqlSessionFactory的實例，該實例使用SqlSessionFactoryBean將該DataSource做爲輸入進行傳遞
將建立並註冊從SqlSessionFactory中獲取的SqlSessionTemplate的實例。
自動掃描您的mappers，將它們連接到SqlSessionTemplate並將其註冊到Spring上下文，以便將它們注入到您的bean中。

就是說，使用了該Starter以後，只須要定義一個DataSource便可（application.properties中可配置），它會自動建立使用該DataSource的SqlSessionFactoryBean以及SqlSessionTemplate。會自動掃描你的Mappers，鏈接到SqlSessionTemplate，並註冊到Spring上下文中。數據庫

數據源配置

在src/main/resources/application.properties中配置數據源信息。編程

spring.datasource.url = jdbc:mysql://localhost:3306/spring?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driver-class-name = com.mysql.jdbc.Driver

自定義數據源

Spring Boot默認使用tomcat-jdbc數據源，若是你想使用其餘的數據源，好比這裏使用了阿里巴巴的數據池管理,除了在application.properties配置數據源以外，你應該額外添加如下依賴：json

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.0.19</version>
</dependency>

修改Application.java

@SpringBootApplication
public class Application {

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

    @Autowired
    private Environment env;

    //destroy-method="close"的做用是當數據庫鏈接不使用的時候,就把該鏈接從新放到數據池中,方便下次使用調用.
    @Bean(destroyMethod =  "close")
    public DataSource dataSource() {
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setUrl(env.getProperty("spring.datasource.url"));
        dataSource.setUsername(env.getProperty("spring.datasource.username"));//用戶名
        dataSource.setPassword(env.getProperty("spring.datasource.password"));//密碼
        dataSource.setDriverClassName(env.getProperty("spring.datasource.driver-class-name"));
        dataSource.setInitialSize(2);//初始化時創建物理鏈接的個數
        dataSource.setMaxActive(20);//最大鏈接池數量
        dataSource.setMinIdle(0);//最小鏈接池數量
        dataSource.setMaxWait(60000);//獲取鏈接時最大等待時間，單位毫秒。
        dataSource.setValidationQuery("SELECT 1");//用來檢測鏈接是否有效的sql
        dataSource.setTestOnBorrow(false);//申請鏈接時執行validationQuery檢測鏈接是否有效
        dataSource.setTestWhileIdle(true);//建議配置爲true，不影響性能，而且保證安全性。
        dataSource.setPoolPreparedStatements(false);//是否緩存preparedStatement，也就是PSCache
        return dataSource;
    }
}

ok這樣就算本身配置了一個DataSource，Spring Boot會智能地選擇咱們本身配置的這個DataSource實例。

腳本初始化

CREATE DATABASE /*!32312 IF NOT EXISTS*/`spring` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `spring`;
DROP TABLE IF EXISTS `learn_resource`;

CREATE TABLE `learn_resource` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'ID',
  `author` varchar(20) DEFAULT NULL COMMENT '做者',
  `title` varchar(100) DEFAULT NULL COMMENT '描述',
  `url` varchar(100) DEFAULT NULL COMMENT '地址連接',
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=1029 DEFAULT CHARSET=utf8;

insert into `learn_resource`(`id`,`author`,`title`,`url`) values (999,'官方SpriongBoot例子','官方SpriongBoot例子','https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1000,'龍果學院','Spring Boot 教程系列學習','http://www.roncoo.com/article/detail/124661');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1001,'嘟嘟MD獨立博客','Spring Boot乾貨系列','http://tengj.top/');
insert into `learn_resource`(`id`,`author`,`title`,`url`) values (1002,'後端編程嘟','Spring Boot視頻教程','http://www.toutiao.com/m1559096720023553/');

註解方式跟XML配置方式共同的模塊編碼

不論是註解方式仍是XML配置的方式，如下代碼模塊都是同樣的

實體對象

public class LearnResouce {
    private Long id;
    private String author;
    private String title;
    private String url;
    // SET和GET方法
}

Controller層

/** 教程頁面
 * Created by tengj on 2017/3/13.
 */
@Controller
@RequestMapping("/learn")
public class LearnController {
    @Autowired
    private LearnService learnService;
    private Logger logger = LoggerFactory.getLogger(this.getClass());

    @RequestMapping("")
    public String learn(){
        return "learn-resource";
    }

    @RequestMapping(value = "/queryLeanList",method = RequestMethod.POST,produces="application/json;charset=UTF-8")
    @ResponseBody
    public void queryLearnList(HttpServletRequest request ,HttpServletResponse response){
        String page = request.getParameter("page"); // 取得當前頁數,注意這是jqgrid自身的參數
        String rows = request.getParameter("rows"); // 取得每頁顯示行數，,注意這是jqgrid自身的參數
        String author = request.getParameter("author");
        String title = request.getParameter("title");
        Map<String,Object> params = new HashMap<String,Object>();
        params.put("page", page);
        params.put("rows", rows);
        params.put("author", author);
        params.put("title", title);
        List<LearnResouce> learnList=learnService.queryLearnResouceList(params);
        PageInfo<LearnResouce> pageInfo =new PageInfo<LearnResouce>(learnList);
        JSONObject jo=new JSONObject();
        jo.put("rows", learnList);
        jo.put("total", pageInfo.getPages());//總頁數
        jo.put("records",pageInfo.getTotal());//查詢出的總記錄數
        ServletUtil.createSuccessResponse(200, jo, response);
    }
    /**
     * 新添教程
     * @param request
     * @param response
     */
    @RequestMapping(value = "/add",method = RequestMethod.POST)
    public void addLearn(HttpServletRequest request , HttpServletResponse response){
        JSONObject result=new JSONObject();
        String author = request.getParameter("author");
        String title = request.getParameter("title");
        String url = request.getParameter("url");
        if(StringUtil.isNull(author)){
            result.put("message","做者不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        if(StringUtil.isNull(title)){
            result.put("message","教程名稱不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        if(StringUtil.isNull(url)){
            result.put("message","地址不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        LearnResouce learnResouce = new LearnResouce();
        learnResouce.setAuthor(author);
        learnResouce.setTitle(title);
        learnResouce.setUrl(url);
        int index=learnService.add(learnResouce);
        if(index>0){
            result.put("message","教程信息添加成功!");
            result.put("flag",true);
        }else{
            result.put("message","教程信息添加失敗!");
            result.put("flag",false);
        }
        ServletUtil.createSuccessResponse(200, result, response);
    }
    /**
     * 修改教程
     * @param request
     * @param response
     */
    @RequestMapping(value = "/update",method = RequestMethod.POST)
    public void updateLearn(HttpServletRequest request , HttpServletResponse response){
        JSONObject result=new JSONObject();
        String id = request.getParameter("id");
        LearnResouce learnResouce=learnService.queryLearnResouceById(Long.valueOf(id));
        String author = request.getParameter("author");
        String title = request.getParameter("title");
        String url = request.getParameter("url");
        if(StringUtil.isNull(author)){
            result.put("message","做者不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        if(StringUtil.isNull(title)){
            result.put("message","教程名稱不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        if(StringUtil.isNull(url)){
            result.put("message","地址不能爲空!");
            result.put("flag",false);
            ServletUtil.createSuccessResponse(200, result, response);
            return;
        }
        learnResouce.setAuthor(author);
        learnResouce.setTitle(title);
        learnResouce.setUrl(url);
        int index=learnService.update(learnResouce);
        System.out.println("修改結果="+index);
        if(index>0){
            result.put("message","教程信息修改爲功!");
            result.put("flag",true);
        }else{
            result.put("message","教程信息修改失敗!");
            result.put("flag",false);
        }
        ServletUtil.createSuccessResponse(200, result, response);
    }
    /**
     * 刪除教程
     * @param request
     * @param response
     */
    @RequestMapping(value="/delete",method = RequestMethod.POST)
    @ResponseBody
    public void deleteUser(HttpServletRequest request ,HttpServletResponse response){
        String ids = request.getParameter("ids");
        System.out.println("ids==="+ids);
        JSONObject result = new JSONObject();
        //刪除操做
        int index = learnService.deleteByIds(ids.split(","));
        if(index>0){
            result.put("message","教程信息刪除成功!");
            result.put("flag",true);
        }else{
            result.put("message","教程信息刪除失敗!");
            result.put("flag",false);
        }
        ServletUtil.createSuccessResponse(200, result, response);
    }
}

Service層

package com.dudu.service;
public interface LearnService {
    int add(LearnResouce learnResouce);
    int update(LearnResouce learnResouce);
    int deleteByIds(String[] ids);
    LearnResouce queryLearnResouceById(Long learnResouce);
    List<LearnResouce> queryLearnResouceList(Map<String, Object> params);
}

實現類

package com.dudu.service.impl;

/**
 * Created by tengj on 2017/4/7.
 */
@Service
public class LearnServiceImpl implements LearnService {

    @Autowired
    LearnMapper learnMapper;
    @Override
    public int add(LearnResouce learnResouce) {
        return this.learnMapper.add(learnResouce);
    }

    @Override
    public int update(LearnResouce learnResouce) {
        return this.learnMapper.update(learnResouce);
    }

    @Override
    public int deleteByIds(String[] ids) {
        return this.learnMapper.deleteByIds(ids);
    }

    @Override
    public LearnResouce queryLearnResouceById(Long id) {
        return this.learnMapper.queryLearnResouceById(id);
    }

    @Override
    public List<LearnResouce> queryLearnResouceList(Map<String,Object> params) {
        PageHelper.startPage(Integer.parseInt(params.get("page").toString()), Integer.parseInt(params.get("rows").toString()));
        return this.learnMapper.queryLearnResouceList(params);
    }
}

Mybatis集成

接下來，咱們分別來介紹下註解方式以及XML配置方式。

方案一：註解方式

Mybatis註解的方式好簡單，只要定義一個dao接口，而後sql語句經過註解寫在接口方法上。最後給這個接口添加@Mapper註解或者在啓動類上添加@MapperScan(「com.dudu.dao」)註解都行。

以下：

package com.dudu.dao;
/**
 * Created by tengj on 2017/4/22.
 * Component註解不添加也沒事，只是不加service那邊引入LearnMapper會有錯誤提示，但不影響
 */
@Component
@Mapper
public interface LearnMapper {
    @Insert("insert into learn_resource(author, title,url) values(#{author},#{title},#{url})")
    int add(LearnResouce learnResouce);

    @Update("update learn_resource set author=#{author},title=#{title},url=#{url} where id = #{id}")
    int update(LearnResouce learnResouce);

    @DeleteProvider(type = LearnSqlBuilder.class, method = "deleteByids")
    int deleteByIds(@Param("ids") String[] ids);


    @Select("select * from learn_resource where id = #{id}")
    @Results(id = "learnMap", value = {
            @Result(column = "id", property = "id", javaType = Long.class),
            @Result(property = "author", column = "author", javaType = String.class),
            @Result(property = "title", column = "title", javaType = String.class)
    })
    LearnResouce queryLearnResouceById(@Param("id") Long id);

    @SelectProvider(type = LearnSqlBuilder.class, method = "queryLearnResouceByParams")
    List<LearnResouce> queryLearnResouceList(Map<String, Object> params);

    class LearnSqlBuilder {
        public String queryLearnResouceByParams(final Map<String, Object> params) {
            StringBuffer sql =new StringBuffer();
            sql.append("select * from learn_resource where 1=1");
            if(!StringUtil.isNull((String)params.get("author"))){
                sql.append(" and author like '%").append((String)params.get("author")).append("%'");
            }
            if(!StringUtil.isNull((String)params.get("title"))){
                sql.append(" and title like '%").append((String)params.get("title")).append("%'");
            }
            System.out.println("查詢sql=="+sql.toString());
            return sql.toString();
        }

        //刪除的方法
        public String deleteByids(@Param("ids") final String[] ids){
            StringBuffer sql =new StringBuffer();
            sql.append("DELETE FROM learn_resource WHERE id in(");
            for (int i=0;i<ids.length;i++){
                if(i==ids.length-1){
                    sql.append(ids[i]);
                }else{
                    sql.append(ids[i]).append(",");
                }
            }
            sql.append(")");
            return sql.toString();
        }
    }
}

須要注意的是，簡單的語句只須要使用@Insert、@Update、@Delete、@Select這4個註解便可，可是有些複雜點須要動態SQL語句，就好比上面方法中根據查詢條件是否有值來動態添加sql的，就須要使用@InsertProvider、@UpdateProvider、@DeleteProvider、@SelectProvider等註解。

這些可選的 SQL 註解容許你指定一個類名和一個方法在執行時來返回運行容許建立動態的 SQL。基於執行的映射語句, MyBatis 會實例化這個類,而後執行由 provider 指定的方法. 該方法能夠有選擇地接受參數對象.(In MyBatis 3.4 or later, it’s allow multiple parameters) 屬性: type,method。type 屬性是類。method 屬性是方法名。注意: 這節以後是對類的討論,它能夠幫助你以乾淨,容於閱讀的方式來構建動態 SQL。

方案二：XML配置方式

xml配置方式保持映射文件的老傳統，優化主要體如今不須要實現dao的是實現層，系統會自動根據方法名在映射文件中找對應的sql，具體操做以下：

編寫Dao層的代碼
新建LearnMapper接口，無需具體實現類。

package com.dudu.dao;
@Mapper
public interface LearnMapper {
    int add(LearnResouce learnResouce);
    int update(LearnResouce learnResouce);
    int deleteByIds(String[] ids);
    LearnResouce queryLearnResouceById(Long id);
    public List<LearnResouce> queryLearnResouceList(Map<String, Object> params);
}

修改application.properties 配置文件

#指定bean所在包
mybatis.type-aliases-package=com.dudu.domain
#指定映射文件
mybatis.mapperLocations=classpath:mapper/*.xml

添加LearnMapper的映射文件

在src/main/resources目錄下新建一個mapper目錄，在mapper目錄下新建LearnMapper.xml文件。

經過mapper標籤中的namespace屬性指定對應的dao映射，這裏指向LearnMapper。

<?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.dudu.dao.LearnMapper">
  <resultMap id="baseResultMap" type="com.dudu.domain.LearnResouce">
    <id column="id" property="id" jdbcType="BIGINT"  />
    <result column="author" property="author" jdbcType="VARCHAR"/>
    <result column="title" property="title" jdbcType="VARCHAR"/>
    <result column="url" property="url" jdbcType="VARCHAR"/>
  </resultMap>

  <sql id="baseColumnList" >
    id, author, title,url
  </sql>

  <select id="queryLearnResouceList" resultMap="baseResultMap" parameterType="java.util.HashMap">
    select
    <include refid="baseColumnList" />
    from learn_resource
    <where>
      1 = 1
      <if test="author!= null and author !=''">
        AND author like CONCAT(CONCAT('%',#{author,jdbcType=VARCHAR}),'%')
      </if>
      <if test="title != null and title !=''">
        AND title like  CONCAT(CONCAT('%',#{title,jdbcType=VARCHAR}),'%')
      </if>

    </where>
  </select>

  <select id="queryLearnResouceById"  resultMap="baseResultMap" parameterType="java.lang.Long">
    SELECT
    <include refid="baseColumnList" />
    FROM learn_resource
    WHERE id = #{id}
  </select>

  <insert id="add" parameterType="com.dudu.domain.LearnResouce" >
    INSERT INTO learn_resource (author, title,url) VALUES (#{author}, #{title}, #{url})
  </insert>

  <update id="update" parameterType="com.dudu.domain.LearnResouce" >
    UPDATE learn_resource SET author = #{author},title = #{title},url = #{url} WHERE id = #{id}
  </update>

  <delete id="deleteByIds" parameterType="java.lang.String" >
    DELETE FROM learn_resource WHERE id in
    <foreach item="idItem" collection="array" open="(" separator="," close=")">
      #{idItem}
    </foreach>
  </delete>
</mapper>

更多mybatis數據訪問操做的使用請參考：mybatis官方中文參考文檔

分頁插件

上面我有使用到物理分頁插件pagehelper，用法還算簡單，配置以下
pom.xml中添加依賴

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.1.0</version>
</dependency>

而後你只需在查詢list以前使用PageHelper.startPage(int pageNum, int pageSize)方法便可。pageNum是第幾頁，pageSize是每頁多少條。

@Override
    public List<LearnResouce> queryLearnResouceList(Map<String,Object> params) {
        PageHelper.startPage(Integer.parseInt(params.get("page").toString()), Integer.parseInt(params.get("rows").toString()));
        return this.learnMapper.queryLearnResouceList(params);
    }

分頁插件PageHelper項目地址： https://github.com/pagehelper/Mybatis-PageHelper

最終項目效果以下,增刪改查分頁一個都很多：