SpringBoot学习-支持JPA

前面MyBaties玩的差不多了，因为新公司的项目用的是JPA，所以现在再来玩玩spring-data-jpa~
其实也是比较简单的，老规矩，首先是Maven配置

<dependency>    <groupId>org.springframework.boot</groupId>    <artifactId>spring-boot-starter-data-jpa</artifactId></dependency><!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa --><dependency>    <groupId>org.springframework.data</groupId>    <artifactId>spring-data-jpa</artifactId></dependency>

然后是在配置文件中的参数设置

#打印SQLspring.jpa.show-sql=truelogging.level.org.hibernate.type.descriptor.sql.BasicBinder = tracelogging.level.org.springframework.data=DEBUGspring.jpa.hibernate.ddl-auto=updatespring.jpa.database-platform=org.hibernate.dialect.MySQLDialect#数据源spring.datasource.url=jdbc:mysql://localhost:3306/testspring.datasource.username=rootspring.datasource.password=123456spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.jpa.hibernate.ddl-auto参数的作用主要用于：自动创建|更新|验证数据库表结构

validate 加载hibernate时，验证创建数据库表结构
create 每次加载hibernate，重新创建数据库表结构，这就是导致数据库表数据丢失的原因。
create-drop 加载hibernate时创建，退出是删除表结构
update 加载hibernate自动更新数据库结构

spring.jpa.database-platform参数是指定数据库方言

这样配置部分就完成了，再来瞅瞅怎么使用
文件目录：

User实体类：

package com.example.demo.entities;import org.hibernate.annotations.GenericGenerator;import org.springframework.data.annotation.CreatedDate;import org.springframework.data.annotation.LastModifiedDate;import javax.persistence.*;import java.util.Date;import static javax.persistence.GenerationType.TABLE;import static javax.persistence.TemporalType.TIMESTAMP;/** * Created by lean on 2017/9/18. */@Entity@Table(name = "tab_user")public class User {    @Id    @Column(name = "user_id")    @GeneratedValue(strategy = TABLE, generator = "sequence_generator")    @GenericGenerator(            name = "sequence_generator",            strategy = "org.hibernate.id.enhanced.TableGenerator",            parameters = {                    @org.hibernate.annotations.Parameter(name = "segment_value", value = "user"),                    @org.hibernate.annotations.Parameter(name = "increment_size", value = "100"),                    @org.hibernate.annotations.Parameter(name = "optimizer", value = "pooled")            })    private Long id;    @Column(name = "user_name",nullable = false)    private String name;    @Column(name = "password",nullable = false)    private String password;    @CreatedDate    @Temporal(TIMESTAMP)    @Column(name = "create_time")    private Date createTime = new Date();    @LastModifiedDate    @Temporal(TIMESTAMP)    @Column(name = "modified_date")    protected Date modifiedDate;    public Long getId() {        return id;    }    public void setId(Long id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public Date getCreateTime() {        return createTime;    }    public void setCreateTime(Date createTime) {        this.createTime = createTime;    }    public Date getModifiedDate() {        return modifiedDate;    }    public void setModifiedDate(Date modifiedDate) {        this.modifiedDate = modifiedDate;    }}

InitRepository初始数据层：（作为公用父类，可以放置一些通用查询方法）

package com.example.demo.repository;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.JpaSpecificationExecutor;import org.springframework.data.repository.NoRepositoryBean;import java.io.Serializable;/** * @param <T>  Entity * @param <ID> ID * Created by lean on 2017/9/18. */@NoRepositoryBeanpublic interface InitRepository<T,ID extends Serializable>        extends JpaRepository<T,ID>,JpaSpecificationExecutor<T> {}

UserRepository用户实体类对应数据层:

package com.example.demo.repository;import com.example.demo.entities.User;import org.springframework.data.jpa.domain.Specification;import org.springframework.data.jpa.repository.JpaRepository;import org.springframework.data.jpa.repository.JpaSpecificationExecutor;import org.springframework.data.jpa.repository.Query;import org.springframework.data.repository.CrudRepository;import org.springframework.stereotype.Repository;import java.util.HashMap;import java.util.List;/** * Created by lean on 2017/9/18. */@Repositorypublic interface UserRepository extends InitRepository<User,Long> {}

接口：

package com.example.demo.service;import java.util.HashMap;/** * Created by lean on 2017/9/18. */public interface TestService {    HashMap<String,Object> testQuery(HashMap<String, Object> request);    HashMap<String,Object> testQueryOne(HashMap<String, Object> request);}

接口实现类：

package com.example.demo.service.impl;import com.example.demo.entities.User;import com.example.demo.repository.UserRepository;import com.example.demo.service.TestService;import com.example.demo.utils.DataTransUtil;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.data.jpa.domain.Specification;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Transactional;import org.springframework.util.StringUtils;import javax.persistence.criteria.CriteriaBuilder;import javax.persistence.criteria.CriteriaQuery;import javax.persistence.criteria.Predicate;import javax.persistence.criteria.Root;import java.util.ArrayList;import java.util.HashMap;import java.util.List;/** * Created by lean on 2017/9/18. */@Servicepublic class TestServiceImpl implements TestService {    @Autowired    private UserRepository userRepository;    @Override    @Transactional(readOnly = true)    public HashMap<String, Object> testQuery(HashMap<String, Object> request) {        List<User> users = userRepository.findAll(new Specification<User>() {            @Override            public Predicate toPredicate(Root<User> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {                List<Predicate> predicateList = new ArrayList<>();                predicateList.add(criteriaBuilder.equal(root.get("id"),request.get("id")));                String str = "";                if(request.get("name") != null){                    str = String.valueOf(request.get("name"));                }                predicateList.add(criteriaBuilder.like(root.get("name"),"%"+str+"%"));                criteriaQuery.where(predicateList.toArray(new Predicate[predicateList.size()]));                return criteriaQuery.getRestriction();            }        });        return DataTransUtil.returnData(users);    }    @Override    public HashMap<String, Object> testQueryOne(HashMap<String, Object> request) {        User user = userRepository.findOne(Long.valueOf(String.valueOf(request.get("id"))));        return DataTransUtil.returnData(user);    }}

工具类：

package com.example.demo.utils;import org.springframework.util.StringUtils;import java.util.HashMap;/** * Created by lean on 2017/9/18. */public class DataTransUtil {    private static Integer defaultCode = 1;    private static String defaultMessage = "succesful";    public static HashMap<String,Object> returnData(Integer code,String message,Object data){        HashMap<String,Object> map = new HashMap<>();        if(null != code){            map.put("code",code);        }else{            map.put("code",defaultCode);        }        if(!StringUtils.isEmpty(message)){            map.put("message",message);        }else{            map.put("message",defaultMessage);        }        map.put("data",data);        return map;    }    public static HashMap<String,Object> returnData(Object data){        return returnData(null,null,data);    }}

Controller层：

package com.example.demo.controller;import com.example.demo.service.TestService;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;import java.util.HashMap;import static org.springframework.web.bind.annotation.RequestMethod.POST;//import static org.springframework.web.bind.annotation.RequestMethod.GET;/** * Created by lean on 2017/9/18. */@RestControllerpublic class InitController {    @Autowired    private TestService testService;    @RequestMapping(value = "/test",method = {POST})    public HashMap<String,Object> initTest(@RequestBody HashMap<String,Object> request){        return testService.testQuery(request);    }//    @RequestMapping(value = "/queryOne",method = {POST})    @PostMapping(value = "queryOne")    public HashMap<String,Object> testQueryOne(@RequestBody HashMap<String,Object> request){        return testService.testQueryOne(request);    }}

具体的JPA和SpringData中的查询就不详细描述了，以后有兴趣再单独写个博客玩玩
运行结果：

注：
这里我使用的web测试工具是火狐的插件restclient，可以模仿http请求来访问服务器，有兴趣的可以自行百度用法