IntelliJ IDEA ，springboot 2.0 +mybatis 創建和訪問數據庫

環境：

JDK8+windows10

步驟 New Module —>Spring Initializr—>next

1

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2.

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3。web勾選web，sql里面可以不勾，后續添加，另外，勾選了MyBatis會報錯Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required 這樣的錯誤。這里我勾選了是為了待會解決這個錯誤

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選完直接下一步到最后就行了

自動生成的pom文件如下

<?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> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.8.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.example</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.0.0</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project> 

## 目錄結構​

因為沒有配置數據庫和任何文件，application是空的 ，默認端口是8080

我們需要在 在啟動累忽略數據庫配置

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})

然后 用postman訪問一下  說明項目是正常的

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4.配置數據庫 application.yml 文件

server:
  port: 8080
  tomcat:
    uri-encoding: UTF-8
  servlet:
    context-path: /
spring:
  dataSource:
    url: jdbc:mysql://localhost:3306/db-test?useUnicode=true&characterEncoding=utf8&tinyInt1isBit=false
    username: root
    password: 123456
    driverClassName: com.mysql.jdbc.Driver
mybatis:
  mapper-locations: classpath:com/example/demo/mapper/*Mapper.xml #注意：一定要對應mapper映射xml文件的所在路徑
  type-aliases-package: com.example.demo.model # 注意：對應實體類的路徑
  configuration:
    call-setters-on-nulls: true # 解決使用map類型接收查詢結果的時候為null的字段會沒有的情況

這時候 com.mysql.jdbc.Driver 標紅 說明mysql架包找不到

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把<scope>runtime</scope> 去掉，  他的意思是運行時不需要，實際上是需要的

<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope> </dependency>

改成  版本默認就行

<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency>

然后driverClassName 恢復正常

導入 service dao xml (這里沒有使用實體類返回，使用的是map返回，所以表我們可以隨意自建)

UserController

@Controller @RequestMapping("/usersDemo") public class UserController { private static Logger log = LoggerFactory.getLogger(UserController.class); @Resource UserService userService; @ResponseBody @RequestMapping(value = "/test", produces = "application/json;charset=UTF-8", method = {RequestMethod.POST, RequestMethod.GET}) public List<Map<String, Object>> test(){ log.info("進入了test方法！"); List<Map<String,Object>> list=userService.userQueryAll(); return list; } }

UserService

public interface UserService { List<Map<String, Object>> userQueryAll(); }

UserserviceImpl

@Service public class UserserviceImpl implements UserService { @Resource UserMapper userDao; @Override public List<Map<String, Object>> userQueryAll() { return userDao.userQueryAll(); } }

 UserMapper

@Mapper public interface UserMapper { List<Map<String, Object>> userQueryAll(); }

UserMapper.xml

<?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.example.demo.dao.UserMapper">
    <select id="userQueryAll" parameterType="Map" resultType="Map">
        SELECT * FROM `users`
    </select>
</mapper>

 

DemoApplication

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class}) @MapperScan("com.example.demo.dao") @ComponentScan(basePackages = {"com.example.demo.*"}) public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); } }

好了 ，

接下來就是啟動了  

5啟動

注意 ：依賴注入后 如果沒有去掉 exclude = {DataSourceAutoConfiguration.class}

啟動會報如下錯誤：

Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required

錯誤原因1：

很多人說 創建項目的時候勾選了mybatis導致
  實際上是這個架包的原因
如果不要的話也不能使用mybatis了 
<dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.0.0</version> </dependency>

錯誤原因2 ，

dataSource.type 使用默認的連接池導致的

解決方案1 ：去掉 exclude = {DataSourceAutoConfiguration.class} ，就能正常啟動

 

解決方案2 :使用其他連接池 ，比如阿里 druid 連接池 

<dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.13</version> </dependency>

然后修改application.yml  里面的  spring.dataSource.type=com.alibaba.druid.pool.DruidDataSource

就可以不刪除 exclude = {DataSourceAutoConfiguration.class}了 ，實際上意義不大，屬於低級錯誤

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6 繼續啟動，

日志是沒錯了， 然后訪問數據庫的時候 可能會出現

這樣的錯誤

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.example.demo.dao.UserMapper.userQueryAll

錯誤可能原因 1.   mapper.xml   select 的 id寫錯了   

解決方案：檢查代碼

錯誤可能原因 2. 程序沒有編譯xml文件 

解決方案：pom.xml 文件 build里面 增加代碼 

<resources>
<resource>
    <directory>src/main/java</directory>
    <includes>
        <include>**/*.xml</include>
    </includes>
    <filtering>false</filtering>
</resource>
</resources>

再次啟動 ：

成功 

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最終 pom.xml文件如下

<?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>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.8.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>
        <!-- alibaba的druid數據庫連接池監控依賴 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.13</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
        <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
            <filtering>false</filtering>
        </resource>
        </resources>
    </build>

</project>

 

跳轉網頁404 錯誤解決方案 ：https://blog.csdn.net/q18771811872/article/details/88051260

 轉載請附帶原地址：https://blog.csdn.net/q18771811872/article/details/88126835