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@SpringBootApplicationpublic 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/shopspring.datasource.username=xxxxxxspring.datasource.password=xxxxxxxspring.datasource.driver-class-name=com.mysql.jdbc.Driverspring.datasource.max-active=20spring.datasource.max-idle=8spring.datasource.min-idle=8spring.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 DBMSspring.jpa.database = MYSQL# Show or not log for each sql queryspring.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@Repositorypublic interface UserDao extends JpaRepository<User,Integer> {    public User findByNicknameAndPassword(String nickname,String password);}

service层编写

@Servicepublic 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@RestControllerpublic 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）