1、springboot入门案例helloworld与集成hibernate

Spring Boot使我们更容易去创建基于Spring的独立和产品级的可以”即时运行“的应用和服务。支持约定大于配置，目的是尽可能快地构建和运行Spring应用。

之前我们创建基于Spring的项目需要考虑添加哪些Spring依赖和第三方的依赖。使用Spring Boot后，我们可以以最小化的依赖开始spring应用。大多数Spring Boot应用需要很少的配置即可运行，比如我们可以创建独立独立大Java应用，然后通过java -jar运行启动或者传统的WAR部署。其也提供了命令行工具来直接运行Spring脚本（如groovy脚本）。也就是说Spring Boot让Spring应用从配置到运行变的更加简单，但不对Spring本身提供增强（即额外的功能）。

目的：
让所有Spring开发变得更快，且让更多的人更快的进行Spring入门体验，提供“starter” POM来简化我们的Maven配置（也就是说使用Spring Boot只有配合maven/gradle等这种依赖管理工具才能发挥它的能力），不像以前，构建一个springmvc项目需要进行好多配置等
开箱即用，快速开始需求开发而不被其他方面影响（如果可能会自动配置Spring）

提供一些非功能性的常见的大型项目类特性（如内嵌服务器、安全、度量、健康检查、外部化配置），如可以直接地内嵌Tomcat/Jetty（不需要单独去部署war包）
绝无代码生成，且无需XML配置

一、创建一个普通maven的Jar项目，在pom.xml中引入springboot的依赖包

  <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>1.3.3.RELEASE</version>
        </dependency>
    </dependencies>

二、创建Controller类

package com.chen.controller;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@EnableAutoConfiguration
public class HelloWorldController {

    @RequestMapping(value="/hello",method=RequestMethod.GET)
    @ResponseBody
    public String sayHello(){

        return "hello world!";
    }

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

运行HelloWorldController类，在浏览器上输入http://localhost:8080/hello
即可查看到调用结果。

常遇问题：
1、引入parent失败
     <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.3.3.RELEASE</version>
</parent>
配置仓库即可

    <repositories>
        <repository>
            <id>spring-snapshots</id>
            <url>http://repo.spring.io/libs-snapshot</url>
        </repository>
    </repositories>

    <pluginRepositories>
        <pluginRepository>
            <id>spring-snapshots</id>
            <url>http://repo.spring.io/libs-snapshot</url>
        </pluginRepository>
    </pluginRepositories>

2、
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>
继承spring-boot-starter-parent后我们可以继承一些默认的依赖，这样就无需添加一堆相应的依赖，把依赖配置最小化；spring-boot-starter-web提供了对web的支持，spring-boot-maven-plugin提供了直接运行项目的插件，我们可以直接mvn spring-boot:run运行。

二、运行

第一种方式
通过在UserController中加上@EnableAutoConfiguration开启自动配置，然后通过SpringApplication.run(UserController.class);运行这个控制器；这种方式只运行一个控制器比较方便；
第二种方式
通过@Configuration+@ComponentScan开启注解扫描并自动注册相应的注解Bean

package com.chen.controller;

import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@EnableConfigurationProperties
public class WelcomeController {

    @RequestMapping(value="/welcome",method=RequestMethod.GET)
    @ResponseBody
    public String welcome(){
        return "welcome";
    }
}


package com.chen.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan(basePackages="com")
@EnableAutoConfiguration
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

运行Application类即可发布整个应用

三、springboot应用添加hibernate持久层框架

1、引入依赖包
<dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
         <dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>4.3.7.Final</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.34</version>
    </dependency>

2、添加application.properties配置文件

spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.jpa.database = MYSQL
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql = true
spring.jpa.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5Dialect

3、写POJO

package com.chen.pojo;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="t_user")
public class User {
    private Long id ;
    private String username;
    private Date birthday;
    private String sex ;
    private String address;
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name="id")
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    @Column(name="username")
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    @Column(name="birthday")
    public Date getBirthday() {
        return birthday;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    @Column(name="sex")
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    @Column(name="adress")
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    @Override
    public String toString() {
        return "User [id=" + id + ", username=" + username + ", birthday="
                + birthday + ", sex=" + sex + ", address=" + address + "]";
    }

}

4、写repository

package com.chen.repository;

import javax.persistence.Table;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.CrudRepository;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Repository;

import com.chen.pojo.User;

@Repository
@Table(name="t_user")
@Qualifier("userRepository")
public interface UserRepository extends CrudRepository<User,Long>{
    public User findOne(Long id);

    @Query("select t from User t where t.username=:name")
    public User findUserByName(@Param("name") String name);
}

5、在启动类添加注解

package com.chen.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.orm.jpa.EntityScan;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration
@ComponentScan(basePackages="com.chen")
@EnableAutoConfiguration
@EntityScan(basePackages="com.chen.pojo")
@EnableJpaRepositories(basePackages="com.chen.repository")
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

6、添加控制器类

package com.chen.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.data.repository.query.Param;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

import com.chen.pojo.User;
import com.chen.repository.UserRepository;

@Controller
@EnableAutoConfiguration
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @RequestMapping(value="/user/getUserById")
    @ResponseBody
    public User getUserById(@RequestParam Long id){
        System.out.println("hello user");
        User u = userRepository.findOne(id);
        System.out.println(userRepository);
        System.out.println(u);
        return u;
    }

    @RequestMapping(value="/user/findUserByName")
    @ResponseBody
    public User findUserByName(@RequestParam String name){
        System.out.println("hello user");
        User u = userRepository.findUserByName(name);
        System.out.println(u);
        return u;
    }
}

源码见附件

1、springboot入门案例helloworld与集成hibernate

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