Spring Boot入门

使用ssh，ssm等框架写项目会发现从开始到结束一直在配置配置不停地配置，spring boot的出现，是我们脱离了繁琐的配置文件，spring boot帮我们完成了这些默认的配置

pom配置文件

<?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>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>dangdang</name>
<description>Demo project for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.9.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</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>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>

<!-- 添加Spring-data-jpa依赖. -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<!-- servlet依赖-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<scope>provided</scope>
</dependency>

<!--jstl标签-->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
</dependency>

<!-- tomcat 的支持.-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provide</scope>
</dependency>
<dependency>
<groupId>org.apache.tomcat.embed</groupId>
<artifactId>tomcat-embed-jasper</artifactId>
<scope>provided</scope>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>

启动类（一般放在根路径下）

//web工程需要继承SpringBootServletInitializer重写configure方法
//@SpringBootApplication会自动扫描此类所在包和此包的子包下的所有注解
@SpringBootApplication
public class DangdangApplication extends SpringBootServletInitializer{

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

@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
return builder.sources(DangdangApplication.class);
}
}

配置文件application.properties(根路径下)

#配置数据库连接信息
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/shop
spring.datasource.username=xxxxxx
spring.datasource.password=xxxxxxx
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.max-active=20
spring.datasource.max-idle=8
spring.datasource.min-idle=8
spring.datasource.initial-size=10
#指定自定义连接池
#spring.datasource.type=org.apache.commons.dbcp2.BasicDataSource

########################################################
### Java Persistence Api --  Spring jpa\u7684\u914d\u7f6e\u4fe1\u606f.
########################################################
# Specify the DBMS
spring.jpa.database = MYSQL
# Show or not log for each sql query
spring.jpa.show-sql = true
# Hibernate ddl auto (create, create-drop, update)
spring.jpa.hibernate.ddl-auto = update
# Naming strategy
#[org.hibernate.cfg.ImprovedNamingStrategy  #org.hibernate.cfg.DefaultNamingStrategy]
spring.jpa.hibernate.naming-strategy = org.hibernate.cfg.ImprovedNamingStrategy
# stripped before adding them to the entity manager)
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

# 页面默认前缀目录
spring.mvc.view.prefix=/WEB-INF/jsp/
#相应页面默认后缀
spring.mvc.view.suffix=.jsp

bean层省略

dao层编写（JpaRepository会在下篇讲解，只要记者他就相当于简洁的hibernate）

//CrudRepository<User,Integer>第一个参数查询类型 第二个参数主键类型
@Repository
public interface UserDao extends JpaRepository<User,Integer> {
public User findByNicknameAndPassword(String nickname,String password);
}

service层编写

@Service
public class UserService {
public UserService(){
System.out.println("==============================================================================================");
}
@Autowired
private UserDao userDao;
public User login(String nickname,String password){
return userDao.findByNicknameAndPassword(nickname,password);
}
}

controller层编写

//@Controller
@RestController
public class UserController {
@Autowired
private UserService userService;

@RequestMapping("/")
private String index(){

return "================json=================";
}
@RequestMapping("/login")
private ModelAndView login( String nickname, String password){
//User user=userService.login(nickname,password);
ModelAndView mv=new ModelAndView();
//没有此用户
if (true){
System.out.println("================进入Controller=============================");
//mv.setViewName("success");
// return mv;
mv.setViewName("redirect:/indext.jsp");
return mv;
}else{
//成功

//request.getSession().setAttribute("user",user);
// mv.addObject("user",request.getSession().getAttribute("user"));
mv.setViewName("success");
return mv;//返回视图页面
}
}
@RequestMapping("/show")
private String show(){
return "success";//返回json字符串
}
}

RestController注解会自动将返回的字符串解析为json文本返回（ModelAndView返回视图）

Controller注解为基于视图的注解，会把返回的字符串解析为视图路径

基于spring boot应用，由于当前应用包含了一个可直接运行的Application类，所以在开发过程中，大家很容易在IDE（IDEA工具）中单机鼠标右键运行当前类。虽然可以启动当前应用，在非web应用中可能不会有什么问题，但在web应用中，如果采用上述方法直接运行应用，那么在访问有视图的页面时（如jsp）会一直报404错误。 因为直接运行当前启动类，spring boott无法找到当前页面资源。因此，基于spring boot的应用在开发调试的时候，一定要基于spring boot提供的spring-boot-maven-plugin插件命令来运行应用或通过spring boot命令行来运行应用（spring-boot:run）