spring boot + spring data jpa

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Spring Data Repository的核心接口是Repository(好像也没什么好惊讶的)。这个接口需要领域类(Domain Class)跟领域类的ID类型作为参数。这个接口主要是让你能知道继承这个类的接口的类型。CrudRepository 供了对被管理的实体类的一些常用CRUD方法。

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2. springboot 整合spring data jpa

默认你已经构建好了spring boot 项目，关于spring boot项目的新建，请参考：
springboot Demo
springboot 整合mybatis

2.1. 首先导入jar 包

springboot 整合spring data jpa 首先要导入依赖的jar包。pom.xml 文件中新增如下依赖：

    <!-- spring-data-jpa -->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
        </dependency>

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.21</version>
</dependency>



    <!--data source  spring data jpa 需要用c3p0 连接池-->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>0.9.5.2</version>
            <exclusions>
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

2.2 配置datasource

新建DBConfig.Java 文件配置数据源。

package com.example.config;

import java.beans.PropertyVetoException;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;

import com.mchange.v2.c3p0.ComboPooledDataSource;

@Configuration
public class DBConfig {
    @Autowired
    private Environment env;

    @Bean(name="dataSource")
    public ComboPooledDataSource dataSource() throws PropertyVetoException {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass(env.getProperty("ms.db.driverClassName"));
        dataSource.setJdbcUrl(env.getProperty("ms.db.url"));
        dataSource.setUser(env.getProperty("ms.db.username"));
        dataSource.setPassword(env.getProperty("ms.db.password"));
        dataSource.setMaxPoolSize(20);
        dataSource.setMinPoolSize(5);
        dataSource.setInitialPoolSize(10);
        dataSource.setMaxIdleTime(300);
        dataSource.setAcquireIncrement(5);
        dataSource.setIdleConnectionTestPeriod(60);

        return dataSource;
    }

}

2.3. 添加数据库连接信息

在配置文件application.properties中添加数据库连接信息如下：

ms.db.driverClassName=com.mysql.jdbc.Driver
ms.db.url=jdbc:mysql://localhost:3306/msm?prepStmtCacheSize=517&cachePrepStmts=true&autoReconnect=true&characterEncoding=utf-8&allowMultiQueries=true
ms.db.username=root
ms.db.password=admin
ms.db.maxActive=500

2.4 配置JpaConfig

新建JpaConfig.java 文件内容如下：

package com.example.config;

import java.util.HashMap;
import java.util.Map;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@Configuration
//此处是你dao文件所在的包名
@EnableJpaRepositories("com.example.*.dao")
@EnableTransactionManagement
public class JpaConfig {

    @Autowired
    private DataSource dataSource;

    @Bean
    public EntityManagerFactory entityManagerFactory() {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        //此处com.example.*.model是你的java bean所在的包名
        factory.setPackagesToScan("com.example.*.model");
        factory.setDataSource(dataSource);

        Map<String, Object> jpaProperties = new HashMap<String, Object>();
        jpaProperties.put("hibernate.ejb.naming_strategy","org.hibernate.cfg.ImprovedNamingStrategy");
        jpaProperties.put("hibernate.jdbc.batch_size",50);

        factory.setJpaPropertyMap(jpaProperties);
        factory.afterPropertiesSet();
        return factory.getObject();
    }

    @Bean
    public PlatformTransactionManager transactionManager() {

        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory());
        return txManager;
    }
}

2.5 新建对应数据库表的实体类。（也就是java bean ）

注意 
@Entity
@Table(name = "sec_user")
标签的使用，@Entity表示这个是一个实体类，@Table(name = "sec_user") 中sec_user 是数据库中对应的表名

@Id
@GeneratedValue 对应ID 
@Column(name = "name") 对应数据库中该列对应的列名，也就是属性名

package com.example.base.model;

import java.util.Date;

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

import com.fasterxml.jackson.annotation.JsonIgnore;

@Entity
@Table(name = "sec_user")
public class User {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    @Column(name = "name")
    private String name;
    @Column(name = "password")
    private String password;
    @Column(name = "username")
    private String username;
    @Column(name = "division_id")
    private Integer divisionId;
    @Column(name = "email")
    private String email;
    @Column(name = "gender")
    private String gender;
    @Column(name = "mobilephone")
    private String mobilephone;
    @Column(name = "telephone")
    private String telephone;
    @Column(name = "user_type")
    private Integer userType;
    @Column(name = "create_by")
    private String createBy;
    @Column(name = "create_time")
    private Date createTime;
    @Column(name = "update_by")
    private String updateBy;
    @Column(name = "update_time")
    private Date updateTime;
    @Column(name = "disabled")
    private Integer disabled;
    @Column(name = "theme")
    private String theme;
    @Column(name = "is_ldap")
    private Integer isLdap;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @JsonIgnore
    public String getPassword() {
        return password;
    }

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

    public String getUsername() {
        return username;
    }

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

    public Integer getDivisionId() {
        return divisionId;
    }

    public void setDivisionId(Integer divisionId) {
        this.divisionId = divisionId;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getMobilephone() {
        return mobilephone;
    }

    public void setMobilephone(String mobilephone) {
        this.mobilephone = mobilephone;
    }

    public String getTelephone() {
        return telephone;
    }

    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }

    public Integer getUserType() {
        return userType;
    }

    public void setUserType(Integer userType) {
        this.userType = userType;
    }

    public String getCreateBy() {
        return createBy;
    }

    public void setCreateBy(String createBy) {
        this.createBy = createBy;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public String getUpdateBy() {
        return updateBy;
    }

    public void setUpdateBy(String updateBy) {
        this.updateBy = updateBy;
    }

    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }

    public Integer getDisabled() {
        return disabled;
    }

    public void setDisabled(Integer disabled) {
        this.disabled = disabled;
    }

    public String getTheme() {
        return theme;
    }

    public void setTheme(String theme) {
        this.theme = theme;
    }

    public Integer getIsLdap() {
        return isLdap;
    }

    public void setIsLdap(Integer isLdap) {
        this.isLdap = isLdap;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
}

2.5 编写spring data jpa 的dao层（重头戏哦）

首先我们先了解一下 spring data jpa 的命名规范，然后再开始编写一个简单的测试例子。
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例子：
新建UserJpaDao类继承 JpaRepository

package com.example.base.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.data.repository.query.Param;

import com.example.base.model.User;

/**
 * The Interface UserJpaDao.
 * @author abel
 */
public interface UserJpaDao extends JpaRepository<User, Long> {

    /**
     * Find by name.
     *
     * @param name the name
     * @return the user
     */
    User findByName(String name);

    /**
     * Find by name and user name.
     * 如果参数名为多个字母组成，请首字母大写。勿使用驼峰命名，jpa不识别驼峰
     * @param name the name
     * @param age the age
     * @return the user
     */
    User findByNameAndAge(String name, Integer age);

    /**
     * Find user.
     * User为@Entity 的名字
     * @param name the name
     * @return the user
     */
    @Query("from User u where u.name=:name")
    User findUser(@Param("name") String name);
}

2.6 service 层的编写（这一步和Spring mvc 已经没有什么差别的了。）

service 代码如下。（此处我就仅仅写了dao的一个方法）

package com.example.base.service;
import com.example.base.model.User;

/**
 * The Interface UserService.
 */
public interface UserService {

    /**
     * Gets the user by name.
     *
     * @param username the user name
     * @return the user by name
     */
    public User getUserByName(String username);
}

实现如下：

package com.example.base.service.Impl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.example.base.dao.UserJpaDao;
import com.example.base.model.User;
import com.example.base.service.UserService;
/**
 * 
 * @ClassName UserServiceImpl
 * @author abel
 * @date 2016年11月10日
 */
@Service
public class UserServiceImpl implements UserService {

    @Autowired
    private UserJpaDao userJpaDao;

    /**
     * 
     * @param UserName
     * @return
     */
    @Override
    public User getUserByName(String username) {
        return userJpaDao.findByName(username);
    }
}

2.7 controller 编写

package com.example.base.controller;

import javax.servlet.http.HttpServletRequest;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
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;

import com.example.base.service.UserService;
import com.example.base.util.CommonUtil;

/**
 * 
 * @ClassName UserController
 * @author abel
 * @date 2016年11月10日
 */
@Controller
@RequestMapping(value = "/users")
public class UserController {

    @Autowired
    private UserService userService;

    /**
     * 通过spring data jpa 调用方法 api :localhost:8099/users/byname?username=xxx
     * 
     * @param request
     * @return
     */
    @RequestMapping(value = "/byname", method = RequestMethod.GET)
    @ResponseBody
    public ResponseEntity<Object> getUser(HttpServletRequest request) {
        Map<String, Object> map = CommonUtil.getParameterMap(request);
        String username = (String) map.get("username");
        return new ResponseEntity<>(userService.getUserByName(username), HttpStatus.OK);
    }
}