springboot第五天---SpringBoot使用spring data jpa

引言： 

在至關長的一段時間內，實現應用程序的數據訪問層一直很麻煩。 必須編寫太多樣板代碼來執行簡單查詢以及執行分頁和審計。 Spring Data JPA旨在經過減小實際須要的工做量來顯著改善數據訪問層的實現。 做爲開發人員，您編寫repository接口，包括自定義查找器方法，Spring將自動提供實現。

Spring Data JPA旨在經過減小實際須要的工做量來顯著改善數據訪問層的實現。 做爲開發人員，您編寫repository接口，包括自定義查找器方法，Spring將自動提供實現。

 

 代碼編寫：

1.依賴配置：

<?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.xhn</groupId>
    <artifactId>springbootdemo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.2.RELEASE</version>
    </parent>

    <!-- 添加spring mvc 依賴-->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

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

        <!--FreeMarker 模板引擎-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</artifactId>
        </dependency>

        <!--整合springboot與mybatis的整合-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

        <!--測試junit-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--redis緩存-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
        </dependency>

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

    </dependencies>
        <!--將mapper下的mapper接口與mapper映射文件放在一個mapper包下所須要的依賴-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.*</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

2.resources配置application.properties：

#DB Configation
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=root

#JPA Configation
spring.jpa.database=MySQL
spring.jpa.generate-ddl=true
spring.jpa.show-sql=true

若是鏈接不上數據庫，那改爲這段配置

#DB Configration
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/你本身的數據庫?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT
spring.datasource.username=root
spring.datasource.password=root

#JAPConfigration
spring.jpa.database=MySQL
spring.jpa.show-sql=true
spring.jpa.generate-ddl=true

也能夠使用19年初剛出的新技術spring data jpa（是爺爺輩，jpa是父輩，Hibernate是孫子輩--->已差很少被淘汰）

 

 

 

3.設置測試controller：

package com.xhn.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

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

@RestController
@RequestMapping("/test")
public class TestController {
    @RequestMapping("/hello")
    public Map sayHell0(){
        Map map=new HashMap();
        map.put("json數據01","我愛java");
        return map;
    }
}

效果圖：

 

 進入正題：

1.建立數據庫並添加數據：

2.建立對應的pojo對象：

package com.xhn.entity;

import javax.persistence.*;

//標記此類爲實體類
@Entity
//標記對應的數據庫中的表
@Table(name = "user")
public class User {
    //設置id爲主鍵 自增
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
   private Integer id;
   private String username;
   private String password;
   private String name;

    public Integer getId() {
        return id;
    }

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

    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;
    }

    public String getName() {
        return name;
    }

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

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

    public User(Integer id, String username, String password, String name) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.name = name;
    }

    public User() {
        super();
    }
}

注意：對應的幾個註解須要格外配置好

 

 

3.建立對應的controller接口：

package com.xhn.controller;

import com.xhn.dao.UserDao;
import com.xhn.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

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

    @Autowired
    private UserDao userDao;

    //查詢出全部數據
    @RequestMapping("/list")
    public List<User> getUserList(){
        return userDao.findAll();
    }
}

4.對應的dao層：

package com.xhn.dao;


import com.xhn.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserDao extends JpaRepository<User,Integer> {

}

代碼測試：

 

 

 

 

 

 本博主對應的json插件爲：JSON-handle_0.5.6.crx，能夠在網上自行百度