SpringBoot+MyBatis簡單數據訪問應用

由於實習用的是MyBatis框架,因此寫一篇關於SpringBoot整合MyBatis框架的總結。前端

一,Pom文件java

<?xml version="1.0" encoding="UTF-8"?>

<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.example</groupId>
    <artifactId>example</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging> //這裏設置爲jar,由於咱們會使用jar包部署運行

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId> //Mybatis的jar包
            <version>1.1.1</version>
        </dependency>

        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId> //json數據格式和對象的轉換jar包
            <version>1.9.8</version>
            <type>jar</type>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId> //內嵌數據庫
            <artifactId>h2</artifactId> 
            <version>1.3.156</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId> //lombok插件,方便model對象的處理
            <version>1.16.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId> //mysql驅動
            <version>5.1.18</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>example</finalName> //打包後的jar包名稱

        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId> //必需要的SpringBoot繼承的maven插件,缺乏了沒法打包jar。
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <artifactId>maven-resources-plugin</artifactId> //由於jar包中可能存在不少其餘的配置資源,例如mapper文件因此打包爲jar包須要將其加入,因此須要此資源打包插件
                <version>2.5</version>
                <executions>
                    <execution>
                        <id>copy-xmls</id>
                        <phase>process-sources</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${basedir}/target/classes</outputDirectory>
                            <resources>
                                <resource>
                                    <directory>${basedir}/src/main/java</directory>
                                    <includes>
                                        <include>**/*.xml</include>
                                    </includes>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>

        <resources> //打包包含相應的資源文件
            <resource>
                <directory>src/main/resources</directory> 
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.tld</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                    <include>**/*.tld</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>
    <repositories>//設置倉庫
        <repository>
            <id>spring-milestone</id>
            <url>http://repo.spring.io/libs-release</url>
        </repository>
    </repositories>

</project>

好了簡單的SpringBoot整合Mybatis框架的基礎環境已經搭建完成了,一個Pom文件搞定,接下來咱們配置咱們的配置文件。mysql

二,配置文件web

咱們寫在resources目錄下的application.properties文件中。ajax

spring.datasource.url=jdbc:mysql://localhost:3306/數據庫名稱?useUnicode=true&characterEncoding=UTF8
spring.datasource.username=用戶名
spring.datasource.password=用戶密碼
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
mybatis.mapper-locations=classpath*:/mapper/*Mapper.xml //mapper文件的路徑
mybatis.type-aliases-package=map.model //mapper文件中的前綴
server.port=監聽端口號,不設置默認8080

ok,如今環境已經完全搭建完成咱們能夠編寫本身的代碼了。spring

三,編寫代碼sql

Model對象
數據庫

 

@Data//@Data lombok插件的註解自動添加get set方法
public class ExampleModel {
    private Long id;
    private String name;
   
}
//一個簡單的model對象

Dao層apache

這裏須要注意的是,推薦公司使用的一種作法,由於不少的Dao對象都是簡單的增刪改查功能,因此咱們抽象出一個最基本的父類,這個父類實現最基本的增刪改查功能,每一個新的Dao對象能夠繼承這個類,而後自定義實現特殊的數據庫訪問功能,咱們能夠把這個基本的父類成爲MyBatisHelper並用上泛型,具體實現以下:json

@Data
public class MybatisHelper<T> {
    @Autowired
    private SqlSession sqlSession; //這裏自動注入mybatis的SqlSession

    private String nameSpace;

    public MybatisHelper(String nameSpace) {
        this.nameSpace = nameSpace;
    }

    public String getSqlName(String sqlName) {
        return  nameSpace +"."+ sqlName;
    }

    public Integer create(String name, T obj) {
        return sqlSession.insert(getSqlName(name), obj);
    }

    public Boolean update(String name, T obj) {
        return Boolean.valueOf(sqlSession.update(getSqlName(name), obj) > 0);
    }

    public T findById(String name, Long id) {
        return sqlSession.selectOne(getSqlName(name), id);
    }

    public Boolean delete(String name, Long id) {
        return Boolean.valueOf(sqlSession.delete(getSqlName(name), id) > 0);
    }

    public List<T> findAll(String name){return  sqlSession.selectList(getSqlName(name));}

}

須要說明的是由於sqlSession的執行回去尋找相應的mapper文件,因此namespace+方法名稱很重要,這個必定要注意不要弄錯了,弄錯了就會沒法正確調用。

而後咱們的Dao層實現繼承此類

@Component
public class ExampleModelDao extends MybatisHelper<ExampleModel>{
    public ExampleModelDao() {
        super("example.dao.");
    }
//todo 自定義操做
public Integer findDataCounts(){
return getSqlSession().selectOne(getSqlName("findDataCounts"));//他會尋找example.dao.findDataCounts對應的方法執行
}
}

這樣是否是很簡單,也能大量複用很省事,關於service層我就不寫了很簡單。

四,mapper文件

<?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="example.dao">//這裏很重要就是前綴
    <resultMap id="ExampleModelMap" type="ExampleMode">
        <id column="id" property="id"/>
        <result column="name" property="name"/>
    </resultMap> //自定義resultMap對象,利於對象的操做

    <sql id="tb"> //數據表標籤
        example_data
    </sql>

    <sql id="value_exclude_id"> //除了主鍵覺得的字段集合標籤
        name
    </sql>
 
    <sql id="vls"> //插入屬性的字段集合標籤
        id,name
    </sql>

    <sql id="insert_value">//插入輸入進來的字段值標籤
       #{name}
    </sql>

    <insert id="create" parameterType="ExampleModel">
        INSERT INTO <include refid="tb"/> (<include refid="value_exclude_id"/>) VALUES (<include refid="insert_value"/>)
    </insert>//一看就明白了建立一個對象

    <select id="findById" parameterType="long" resultMap="ExampleModelMap">//返回咱們定義的resultMap
        SELECT <include refid="vls"/> FROM <include refid="tb"/> WHERE id = #{id}
    </select>

    <select id="findAll"  resultMap="ExampleModelMap">
        SELECT <include refid="vls"/> FROM <include refid="tb"/>
    </select>

    <select id="findDataCounts"  resultType="int">
        SELECT count(1)  FROM <include refid="tb"/>
    </select>//自定義的操做

</mapper>

ok,對應的mapper文件已經有了,咱們就能夠調用了,調用很簡單通常寫在service層中調用,下面咱們去編寫對應的controller。

五,控制器編寫

推薦使用restful風格,所以咱們控制器編寫代碼以下:

@RestController
@CrossOrigin //這個是ajax跨域請求容許的註解,不用能夠去掉
public class DigMapDataController {

    @Autowired
    private ExampleService exampleService;//service對象

   

    @RequestMapping(value = "/create", method = RequestMethod.POST)
    public String create(@requestBody ExampleModel exampleModel) {
        return String.valueOf(exampleService.create(exampleModel));
}
//@requestBody註解會接受前端的JSON數據並配合jackson自動轉換爲相應的對象

    @RequestMapping(value = "/find/count",method = RequestMethod.GET)
    public Integer findCounts() {
        return exampleService.findDataCounts();

    }

}

一個簡單的控制器就編寫完成了,這個時候咱們能夠啓動應用進行數據訪問了,是否是很簡單。

六,應用的部署

直接在終端中使用命令,將應用打包爲jar文件

1.maven  [clean]  package ;打包後的文件在target目錄下

2.java -jar example.jar ; 運行咱們的jar包程序

ok 大功告成!

下一章,我會總結一些關於mapper文件的特殊技巧。

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