快速搭建springboot项目，并整合mybatis+druid以及thymeleaf模板引擎

1.新建maven项目

1.1 Eclipse新建maven项目

1.2点击下一步
选择标红选项，点击下一步
点击finish,完成项目初步搭建

2.整合springboot

2.1.在pom文件里添加springboot相关依赖

<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.pc</groupId>
<artifactId>springbootDemo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

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

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.RELEASE</version>
<relativePath/>
</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>
<!-- 引入springboot相关依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>

此时你会发现Maven Dependencies下多了好多spring相关jar包和日志相关jar包，这就体现出了springboot配置简单的优点了，明明只引入一个依赖，却相关jar包都已经引入工程。
此时jar包我们已经添加完毕，接下来创建程序入口，在springbootDemo包下创建MainApplication类

package com.pc.springbootDemo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;
@SpringBootApplication
@ComponentScan(basePackages={"com.pc.controller"})//此注解将扫描指定包下的注解，若不添加，则在spring容器内找不到相关bean,默认扫描路径为入口类同包路径
public class MainApplication {
public static void main(String[] args) throws Exception {
SpringApplication.run(MainApplication.class, args);
}
}

2.2新建测试Action

package com.pc.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/test")
public class TestController {

@RequestMapping("/hello")
@ResponseBody
public String hello(){
return "hello my name is springboot";
}
}

此时直接运行MainApplication中的main方法会看到控制台出现以下内容则启动成功
打开浏览器输入http://localhost:8080/test/hello

3.此时你已经搭建了一半了，接下来整合mybatis和druid,以及thymeleaf

3.1在pom文件中添加相关依赖

<!-- 引入模板引擎thymeleaf框架 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<!--添加mybatis依赖  -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.3.2</version>
</dependency>
<!--mybatis的分页插件-->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.2.3</version>
</dependency>
<!--mysql连接-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
<!--druid包-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.9</version>
</dependency>

3.2此时我们需要在配置文件中添加相关配置，这时有小伙伴会纳闷了，在哪添加配置文件呢？
在项目下新建src/main/resources文件夹
在resources文件夹下新建application.properties在配置文件中添加如下配置

#thymeleaf
spring.thymeleaf.cache=false  #默认开启缓存，开发环境建议关闭
spring.thymeleaf.servlet.content-type=text/html
spring.thymeleaf.enabled=true
spring.thymeleaf.encoding=UTF-8
spring.thymeleaf.mode=HTML5
spring.thymeleaf.prefix=classpath:/templates/  #模板前缀，在此路径下存放模板
spring.thymeleaf.suffix=.html		#模板后缀

#mybatis
mybatis.type-aliases-package=com.pc.pojo
mybatis.configuration.map-underscore-to-camel-case=true
mybatis.configuration.default-fetch-size=100
mybatis.configuration.default-statement-timeout=3000
mybatis.mapperLocations=classpath:/com/pc/dao/*.xml
#druid
spring.datasource.url = jdbc:mysql://localhost:3306/bank?useUnicode=true&characterEncoding=utf-8
spring.datasource.username = root
spring.datasource.password = root
spring.datasource.driverClassName = com.mysql.jdbc.Driver
#druid 连接池的配置 可以是默认的
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.druid.filters=stat
spring.datasource.druid.max-active=20
spring.datasource.druid.initial-size=1
spring.datasource.druid.min-idle=1
spring.datasource.druid.max-wait=60000
spring.datasource.druid.time-between-eviction-runs-millis=60000
spring.datasource.druid.min-evictable-idle-time-millis=300000
spring.datasource.druid.validation-query=select 'x'
spring.datasource.druid.test-while-idle=true
spring.datasource.druid.test-on-borrow=false
spring.datasource.druid.test-on-return=false
spring.datasource.druid.pool-prepared-statements=true
spring.datasource.druid.max-open-prepared-statements=20

接下来我们做一个测试，测试是否连接上数据库
编写pojo

package com.pc.pojo;

public class Customer {
private Integer custNumber;
private String custName;
private String custPwd;
public Integer getCustNumber() {
return custNumber;
}
public void setCustNumber(Integer custNumber) {
this.custNumber = custNumber;
}
public String getCustName() {
return custName;
}
public void setCustName(String custName) {
this.custName = custName;
}
public String getCustPwd() {
return custPwd;
}
public void setCustPwd(String custPwd) {
this.custPwd = custPwd;
}
}

编写dao

package com.pc.dao;

import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import com.pc.pojo.Customer;

@Mapper
public interface CustomerDao {
@Select("select * from customer where custNumber=#{id}")
public Customer findById(@Param("id")int id);
}

编写service接口和实现类

package com.pc.service;

import com.pc.pojo.Customer;

public interface CustomerService {
public Customer findById(int id);
}

实现类

package com.pc.service.impl;

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

import com.pc.dao.CustomerDao;
import com.pc.pojo.Customer;
import com.pc.service.CustomerService;

@Service
public class CustomerServiceImpl implements CustomerService{
@Autowired
private CustomerDao customerDao;

public Customer findById(int id) {
return customerDao.findById(id);
}

}

接下来编写控制层Action

package com.pc.controller;

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

import com.pc.pojo.Customer;
import com.pc.service.CustomerService;

@Controller
@RequestMapping("/test")
public class TestController {
@Autowired
private CustomerService customerService;
@RequestMapping("/hello")
@ResponseBody
public String hello(){
return "hello my name is springboot";
}
@RequestMapping("/db")
@ResponseBody
public Customer getDb(){
return customerService.findById(1);
}
}

启动项目报如下错误

. ____ _ __ _ _
/\ / ’ __ _ () __ __ _ \ \ \
( ( )__ | '_ | '| | ’ / ` | \ \ \
\/ )| |)| | | | | || (| | ) ) ) )
’ || .__|| ||| |__, | / / / /
=|_|======|/=////
:: Spring Boot :: (v2.0.1.RELEASE)

2019-03-27 10:26:21.651 INFO 9272 — [ main] com.pc.springbootDemo.MainApplication : Starting MainApplication on Pei-PC with PID 9272 (G:\MavenEclipseWorkSpace\springbootDemo\target\classes started by PC in G:\MavenEclipseWorkSpace\springbootDemo)
2019-03-27 10:26:21.657 INFO 9272 — [ main] com.pc.springbootDemo.MainApplication : No active profile set, falling back to default profiles: default
2019-03-27 10:26:21.784 INFO 9272 — [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@e50a6f6: startup date [Wed Mar 27 10:26:21 CST 2019]; root of context hierarchy
2019-03-27 10:26:23.233 WARN 9272 — [ main] o.m.s.mapper.ClassPathMapperScanner : No MyBatis mapper was found in ‘[com.pc.springbootDemo]’ package. Please check your configuration.
2019-03-27 10:26:24.411 INFO 9272 — [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2019-03-27 10:26:24.460 INFO 9272 — [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2019-03-27 10:26:24.462 INFO 9272 — [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.29
2019-03-27 10:26:24.477 INFO 9272 — [ost-startStop-1] o.a.catalina.core.AprLifecycleListener : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\Program Files\Java\jdk1.8.0_171\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jdk1.8.0_171/bin/…/jre/bin/server;C:/Program Files/Java/jdk1.8.0_171/bin/…/jre/bin;C:/Program Files/Java/jdk1.8.0_171/bin/…/jre/lib/amd64;F:\app\PC\product\11.1.0\db_1\bin;C:\Program Files\Java\jdk1.8.0_171\bin;C:\Program Files\Java\jdk1.8.0_171\jre\bin;c:\windows\system32;C:\Program Files\TortoiseSVN\bin;D:\maven\apache-maven-3.3.9\bin;C:\Program Files (x86)\VanDyke Software\Clients;E:\nodejs;E:\nodejs\node_cache;C:\Users\PC\AppData\Local\Microsoft\WindowsApps;C:\Program Files (x86)\VanDyke Software\Clients;E:\nodejs\node_global;;D:\Eclipse\eclipse;;.]
2019-03-27 10:26:24.639 INFO 9272 — [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2019-03-27 10:26:24.640 INFO 9272 — [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2860 ms
2019-03-27 10:26:24.891 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet dispatcherServlet mapped to [/]
2019-03-27 10:26:24.893 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Servlet statViewServlet mapped to [/druid/]
2019-03-27 10:26:24.898 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: ‘characterEncodingFilter’ to: [/]
2019-03-27 10:26:24.899 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: ‘hiddenHttpMethodFilter’ to: [/]
2019-03-27 10:26:24.899 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: ‘httpPutFormContentFilter’ to: [/]
2019-03-27 10:26:24.900 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: ‘requestContextFilter’ to: [/]
2019-03-27 10:26:24.901 INFO 9272 — [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: ‘webStatFilter’ to urls: [/]
2019-03-27 10:26:24.962 WARN 9272 — [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name ‘testController’: Unsatisfied dependency expressed through field ‘customerService’; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type ‘com.pc.service.CustomerService’ available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
2019-03-27 10:26:24.966 INFO 9272 — [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]
2019-03-27 10:26:24.988 WARN 9272 — [ost-startStop-1] o.a.c.loader.WebappClassLoaderBase : The web application [ROOT] appears to have started a thread named [Abandoned connection cleanup thread] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
java.lang.Object.wait(Native Method)
java.lang.ref.ReferenceQueue.remove(ReferenceQueue.java:143)
com.mysql.jdbc.AbandonedConnectionCleanupThread.run(AbandonedConnectionCleanupThread.java:43)
2019-03-27 10:26:25.002 INFO 9272 — [ main] ConditionEvaluationReportLoggingListener :

Error starting ApplicationContext. To display the conditions report re-run your application with ‘debug’ enabled.
2019-03-27 10:26:25.168 ERROR 9272 — [ main] o.s.b.d.LoggingFailureAnalysisReporter :

APPLICATION FAILED TO START

Description:

Field customerService in com.pc.controller.TestController required a bean of type ‘com.pc.service.CustomerService’ that could not be found.

Action:

Consider defining a bean of type ‘com.pc.service.CustomerService’ in your configuration.
分析原因，在启动类上忘记添加扫描包在启动类上添加扫描包

@MapperScan("com.pc.dao")
@ComponentScan(basePackages={"com.pc.controller","com.pc.service"})

再次启动，启动成功，在浏览器输入http://localhost:8080/test/db