springboot系类代码：spring-boot-starter-data-jpa

JPA由EJB 3.0软件专家组开发，作为JSR-220实现的一部分。但它又不限于EJB 3.0，你可以在Web应用、甚至桌面应用中使用。JPA的宗旨是为POJO提供持久化标准规范，由此可见，经过这几年的实践探索，能够脱离容器独立运行，方便开发和测试的理念已经深入人心了。Hibernate3.2+、TopLink 10.1.3以及OpenJPA都提供了JPA的实现。

package com.programb;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@SpringBootApplication
@EnableJpaRepositories("com.programb.repository")
public class JpaApplication {

	@Bean
	public ObjectMapper objectMapper() {
		return new ObjectMapper().disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);
	}

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

package com.programb.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.programb.entity.R;
import com.programb.service.UserService;

@RestController
@RequestMapping("/user/*")
public class UserController {

    @Autowired
    UserService userService;

    @GetMapping("list")
    public R list() {
        try {
           return R.isOk().data(userService.list());
        } catch (Exception e) {
            return R.isFail(e);
        }
    }

    @GetMapping("list/{username}")
    public R listbyname(@PathVariable("username")  String username) {
        try {
            return R.isOk().data(userService.findByUsername(username));
        } catch (Exception e) {
            return R.isFail(e);
        }
    }

    @GetMapping("get/{userId}")
    public R get(@PathVariable("userId") String userId) {
        try {
            return R.isOk().data(userService.get(userId));
        } catch (Exception e) {
            return R.isFail(e);
        }
    }
}

package com.programb.entity;

import java.io.Serializable;
public class R<T> implements Serializable {

    private static final long serialVersionUID = -4577255781088498763L;
    private static final int OK = 0;
    private static final int FAIL = 1;
    private static final int UNAUTHORIZED = 2;
    private T data; //服务端数据
    private int status = OK; //状态码
    private String msg = ""; //描述信息

    public static R isOk(){
        return new R();
    }
    public static R isFail(){
        return new R().status(FAIL);
    }
    public static R isFail(Throwable e){
        return isFail().msg(e);
    }
    public R msg(Throwable e){
        this.setMsg(e.toString());
        return this;
    }
    public R data(T data){
        this.setData(data);
        return this;
    }
    public R status(int status){
       this.setStatus(status);
       return this;
    }

    public R() {

    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

package com.programb.entity;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "T_USER")
@JsonIgnoreProperties({"handler","hibernateLazyInitializer"})
public class User {

    @Id
    @Column(name = "USER_ID")
    private String userId;
    @Column(name = "USERNAME")
    private String username;
    @Column(name = "PASSWORD")
    private String password;

    public User() {

    }

    public User(String userId, String username, String password) {
        this.userId = userId;
        this.username = username;
        this.password = password;
    }

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "userId='" + userId + '\'' +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

package com.programb.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import com.programb.entity.User;
import java.util.List;


public interface UserRepository extends JpaRepository<User, String> {

    List<User> findByUsername(String username);
}

package com.programb.service;

import java.util.List;

import com.programb.entity.User;

public interface UserService  {

    List<User> list();
    List<User> findByUsername(String username);
    User get(String userId);

}

package com.programb.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.programb.entity.User;
import com.programb.repository.UserRepository;

import java.util.List;

@Service
public class UserServiceImpl  implements UserService {

    @Autowired
    UserRepository userRepository;

    @Override
    public List<User> list() {
        return userRepository.findAll();
    }

    @Override
    public List<User> findByUsername(String username) {
        return userRepository.findByUsername(username);
    }

    @Override
    public User get(String userId) {
        return userRepository.getOne(userId);
    }
}

spring:
  datasource:
    url: jdbc:mysql://localhost:3306/socks?useSSL=false
    username: root
    password: root
    driver-class-name: com.mysql.jdbc.Driver

DROP DATABASE IF EXISTS `socks`;
CREATE DATABASE `socks`;
USE `SOCKS`;
DROP TABLE IF EXISTS `t_user`;
CREATE TABLE `t_user` (
  `USER_ID` varchar(50) ,
  `USERNAME` varchar(50) ,
  `PASSWORD` varchar(50) 
) ;

INSERT INTO `t_user` VALUES ('1', 'admin', 'admin');
INSERT INTO `t_user` VALUES ('2', 'programb', '123456');

<?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.hehe</groupId>
	<artifactId>springboot-data-jpa</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>
	<name>springboot-data-jpa</name>
	<description>SpringBoot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.0.M4</version>
		<relativePath/>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-jpa</artifactId>
		</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>

	<repositories>
		<repository>
			<id>spring-snapshots</id>
			<url>http://repo.spring.io/snapshot</url>
			<snapshots><enabled>true</enabled></snapshots>
		</repository>
		<repository>
			<id>spring-milestones</id>
			<url>http://repo.spring.io/milestone</url>
		</repository>
	</repositories>
	<pluginRepositories>
		<pluginRepository>
			<id>spring-snapshots</id>
			<url>http://repo.spring.io/snapshot</url>
		</pluginRepository>
		<pluginRepository>
			<id>spring-milestones</id>
			<url>http://repo.spring.io/milestone</url>
		</pluginRepository>
	</pluginRepositories>

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

</project>