Spring Boot的數據訪問 之Spring Boot + jpa的demo
阿新 • • 發佈：2019-05-05
上架 pri pat result over factor ack getname http
1. 快速地創建一個項目，pom中選擇如下
<?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>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.3.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</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>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
2. 新建一個實體，這邊以Book對象為例，主要囊括了書店中書的一些信息
package com.example.demo.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import java.io.Serializable;
@Entity
public class Book implements Serializable {
public static final long seriaVersionUID = 1L;
@Id
@GeneratedValue
private long id;
@Column(nullable=false,unique=true)
private String name;
@Column(nullable=false)
private String author;
@Column(nullable=false)
private String ontime;
@Column(nullable=false)
private int number;
@Column(nullable=false)
private float price;
@Column(nullable=false)
private String createdt;
@Column(nullable=false)
private String updatedt;
@Column(nullable=false)
private String creatuid;
@Column(nullable=false)
private String updateuid;
public long getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public String getOntime() {
return ontime;
}
public void setOntime(String ontime) {
this.ontime = ontime;
}
public int getNumber() {
return number;
}
public void setNumber(int number) {
this.number = number;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
public String getCreatedt() {
return createdt;
}
public void setCreatedt(String createdt) {
this.createdt = createdt;
}
public String getUpdatedt() {
return updatedt;
}
public void setUpdatedt(String updatedt) {
this.updatedt = updatedt;
}
public String getCreatuid() {
return creatuid;
}
public void setCreatuid(String creatuid) {
this.creatuid = creatuid;
}
public String getUpdateuid() {
return updateuid;
}
public void setUpdateuid(String updateuid) {
this.updateuid = updateuid;
}
protected Book(){super();};
public Book(String name, String author, String ontime, int number, float price, String createdt, String updatedt, String creatuid, String updateuid) {
this.name = name;
this.author = author;
this.ontime = ontime;
this.number = number;
this.price = price;
this.createdt = createdt;
this.updatedt = updatedt;
this.creatuid = creatuid;
this.updateuid = updateuid;
}
@Override
public String toString() {
return "Book{" +
"id=" + id +
", name=‘" + name + ‘\‘‘ +
", author=‘" + author + ‘\‘‘ +
", ontime=‘" + ontime + ‘\‘‘ +
", number=" + number +
", price=" + price +
", createdt=‘" + createdt + ‘\‘‘ +
", updatedt=‘" + updatedt + ‘\‘‘ +
", creatuid=‘" + creatuid + ‘\‘‘ +
", updateuid=‘" + updateuid + ‘\‘‘ +
‘}‘;
}
}
3. 新建一個BookRepository接口，且繼承JpaRepository
public interface BookRepository extends JpaRepository<Book, Long> {
}
4. 了解hibernate的ddl-auto四種模式和用途
# 服務端口 server.port=8083 spring.datasource.url=jdbc:mysql://127.0.0.1:3306/spring spring.datasource.username=root spring.datasource.password=root spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver spring.jpa.hibernate.ddl-auto=validate
spring.jpa.hibernate.ddl-auto = 可以是4中Value
create
create-drop
validate
update
Hibernate我們公司的正式項目中基本不用，原因是性能上不是很好，不知道其他公司使用起來如何？
hibernate在多線程下，拼接sql，知道數據庫有問題，卻很難定位到是哪一段sql。後來漸漸棄用。用mybaits了~
5. 添加controller進行新增數據
package com.example.demo.controller;
import com.example.demo.entity.Book;
import com.example.demo.entity.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
public class BookController {
@Autowired
private BookRepository bookRepository;
@RequestMapping("/save")
@ResponseBody
public void save() {
bookRepository.save(new Book("書名11", "作者", "上架時間", 100, 23, "創建時間", "更新時間", "創建uid", "更新uid"));
bookRepository.save(new Book("書名12", "作者", "20001111", 100, 23, "19990111", "19990111", "3", "4"));
bookRepository.save(new Book("西遊記10", "吳承恩", "19991211", 100, 20, "19991111", "19991111", "2", "3"));
} }
項目啟動起來，在瀏覽器中輸入 http://localhost:8083/save，查詢數據庫中，已經新增了三條記錄；
可以順帶測試下ddl-auto的四種值，是否有如同描述一般的作用
6. 再添加查詢方法，並在controller中進行查詢
package com.example.demo.entity;
import org.springframework.data.jpa.repository.JpaRepository;
import java.util.List;
public interface BookRepository extends JpaRepository<Book, Long> {
List<Book> findByAuthor(String author);
}
再在BookRepository 中添加查找方法，根據作者查詢出符合的Book 列表
package com.example.demo.controller;
import com.example.demo.entity.Book;
import com.example.demo.entity.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.List;
@RestController
public class BookController {
@Autowired
private BookRepository bookRepository;
@RequestMapping("/save")
public void save() {
bookRepository.save(new Book("書名11", "作者", "上架時間", 100, 23, "創建時間", "更新時間", "創建uid", "更新uid"));
bookRepository.save(new Book("書名12", "作者", "20001111", 100, 23, "19990111", "19990111", "3", "4"));
bookRepository.save(new Book("西遊記10", "吳承恩", "19991211", 100, 20, "19991111", "19991111", "2", "3"));
}
@RequestMapping("/findByAuthor")
public void findByAuthor() {
List<Book> result = bookRepository.findByAuthor("作者");
System.out.println("一共有多少條呢----" + result.size());
for (Book book : result) {
System.out.println(book);
}
System.out.println("================================");
}
}
保存，啟動新項目，在瀏覽器中輸入http://localhost:8083/findByAuthor，查看控制臺是否打印出Book信息
Spring Boot的數據訪問 之Spring Boot + jpa的demo