SpringBoot JPA学习06

SpringBoot JPA学习

1、结果演示：

2、学习JPA：

+ 1、JPA 全称是 Java Persistence API
+ 2、JPA是java持久化方案
+ 3、Hibernate是其产品之一

3、创建数据库

-- springboottest  简写 sbt
create DATABASE sbt;

4、创建表：Student（id ，name，sex）

USE sbt;
CREATE TABLE student(
	id INT(11) NOT NULL AUTO_INCREMENT,
	name VARCHAR(30),
	sex VARCHAR(2),

	PRIMARY KEY (id)
) DEFAULT CHARSET=UTF8;

5、准备数据：

INSERT INTO student
VALUES ('1', '张三', '男');

INSERT INTO student
VALUES('2', '李四', '男');

INSERT INTO student
VALUES('3', '王妞', '女');

6、基于异常处理的项目进行开发

​ 继续上面的程序开发，有问题去看上一个程序

7、appllication.properties

server.port=8080
#springmvc的前端控制器的prefix和suffix
spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp

#配置数据库链接信息
#我的Mysql是8.0版本跟5.0不同
#sbt 是 我的数据库 springboottest 的简写
#8.0的数据库必须设置时区 serverTimezone = Asia/Shanghai   亚洲上海
spring.datasource.url=jdbc:mysql://localhost:3306/sbt?characterEncoding=utf8&useSSL=false&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.hbm2ddl.auto=update

8、pom.xml

<?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 https://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>2.3.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.zwh</groupId>
    <artifactId>springboot02</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>war</packaging>
    <name>springboot02</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-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- 部署tomcat,排除冲突-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <!--  servlet依賴-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
        </dependency>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>
        <!-- Tomcat 的支持       -->
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
        </dependency>
		<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
		
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional> <!-- 这个需要为 true 热部署才有效 -->
        </dependency>
        <!-- mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.19</version>
        </dependency>
        <!-- jpa-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

        </plugins>
    </build>
</project>

9、实体类：Student

package com.zwh.springboot02.entity;

import javax.persistence.*;

@Entity
@Table(name = "student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private String id;
    @Column(name = "name")
    private String name;
    @Column(name = "sex")
    private String sex;

    public Student() {
    }

    public Student(String id, String name, String sex) {
        this.id = id;
        this.name = name;
        this.sex = sex;
    }

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", sex='" + sex + '\'' +
                '}';
    }
}

出现问题：如图

解决问题：

​ https://blog.youkuaiyun.com/summerif/article/details/105853799

中间出现问题：

解决问题：

当然有的人可能没有第二张图的 Choose Data Source

这个你可以搜一下：Idea 链接 Mysql：

这个是5.x版本：https://www.cnblogs.com/enjoyjava/p/11729714.html

这个是8.x版本： https://www.pianshexicle/71201053530/

区别自己看

加上之后：

然后就会成功了：

10、StudentDao

package com.zwh.springboot02.dao;

import com.zwh.springboot02.entity.Student;
import org.springframework.data.jpa.repository.JpaRepository;
// interface  不是 class
public interface StudentDao extends JpaRepository<Student, Integer> {
}

11、StudentController

package com.zwh.springboot02.controller;

import java.util.List;

import com.zwh.springboot02.entity.Student;
import com.zwh.springboot02.dao.StudentDao;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class StudentController {
    @Autowired
    StudentDao studentDao;

    @RequestMapping("/listStudent")
    public String listStudent(Model model){
        List<Student> students = studentDao.findAll();

        model.addAttribute("students",students);
        return "listStudent";
    }

}

12、studentList.jsp

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%--
  Created by IntelliJ IDEA.
  User: Ctrl_zwh
  Date: 2020/10/16
  Time: 9:41
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>展示学生列表</title>
</head>
<body>
    <table align="center" border="1" cellspacing="0">
        <tr>
            <td>学号</td>
            <td>姓名</td>
            <td>性别</td>
        </tr>
        <c:forEach items="${students}" var="student" varStatus="st">
            <tr>
                <td>${student.id}</td>
                <td>${student.name}</td>
                <td>${student.sex}</td>
            </tr>
        </c:forEach>
    </table>
</body>
</html>

到这可以休息一下。

SpringBoot JPA 进行CRUD和分页操作啦。

1、结果：

2、在上面项目的基础上

3、修改StudentController

package com.zwh.springboot02.controller;

import com.zwh.springboot02.entity.Student;
import com.zwh.springboot02.dao.StudentDao;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;

@Controller
public class StudentController {
    @Autowired
    private StudentDao studentDao;

    @RequestMapping("/listStudent")
    public String listStudent(Model model, @RequestParam(value="start",defaultValue = "0")int start,
                              @RequestParam(value = "size",defaultValue = "5")int size){

        start=start<0?0:start;
        Sort sort = Sort.by(Direction.ASC,"id"); //ASC正序
        Pageable pageable= PageRequest.of(start,size,sort);
        Page<Student> page=studentDao.findAll(pageable);

        model.addAttribute("page",page);
        return "listStudent";
    }


    //增加
    @RequestMapping("/addStudent")
    public String addStudent(Student student){

        studentDao.save(student);

        return "redirect:listStudent";
    }
    @RequestMapping("/toAddStudent")
    public String toAddStudent(Student student){

        return "toAddStudent";
    }
    //删除
    @RequestMapping("/deleteStudent")
    public String deleteStudent(Student student){

        studentDao.delete(student);

        return "redirect:listStudent";
    }
    //修改
    @RequestMapping("/updateStudent")
    public String updateStudent(Student student){
        studentDao.save(student);
        return "redirect:listStudent";
    }
    @RequestMapping("/editStudent")
    public String editStudent(int id,Model model){
        Student student=studentDao.getOne(id);
        model.addAttribute("student",student);
        return "editStudent";
    }
}

4、修改listStudent.jsp实现分页

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>展示学生列表</title>
</head>
<body>

<br><br><br>
    <div align="center">
        <a href="/toAddStudent">增加学生</a>

    </div>
    <table align="center" border="1" cellspacing="0">
        <tr>
            <td>学号</td>
            <td>姓名</td>
            <td>性别</td>
            <td>编辑</td>
            <td>删除</td>
        </tr>

        <%--  分页显示：      --%>

        <c:forEach items="${page.content}" var="student" varStatus="st">
            <tr>
                <td>${student.id}</td>
                <td>${student.name}</td>
                <td>${student.sex}</td>
                <td><a href="/editStudent?id=${student.id}">编辑</a></td>
                <td><a href="/deleteStudent?id=${student.id}">删除</a></td>
            </tr>
        </c:forEach>
        <br/>
    </table>
    <br/>
    <div align="center">
        <a href="?start=0">[首页]</a>
        <a href="?start=${page.number-1}">[上一页]</a>
        <a href="?start=${page.number+1}">[下一页]</a>
        <a href="?start=${page.totalPages-1}">[末页]</a>
    </div>
</body>
</html>

5、toAddStudent.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>增加学生</title>
</head>
<body>
<div align="center">
    <h2>增加学生</h2>
    <form action="/addStudent" method="post">
        <table>
            <tr>
                <td>id</td>
                <td><input type="text" name="id"> <br/></td>
            </tr>
            <tr>
                <td>name</td>
                <td><input type="text" name="name"> <br/></td>
            </tr>
            <tr>
                <td>sex</td>
                <td><input type="text" name="sex"> <br/></td>
            </tr>

        </table>


        <input type="submit" value="提交"> <br>
    </form>
</div>

</body>
</html>

6、editStudent.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
         pageEncoding="UTF-8" isELIgnored="false"%>

    <div align="center">
        <h2>修改学生</h2>
        <form action="/updateStudent" method="post">
            <table>
                <tr>
                    <td>id</td>
                    <td><input type="text" name="id" readonly="true" value="${student.id}"> <br/></td>
                </tr>
                <tr>
                    <td>name</td>
                    <td><input type="text" name="name" value="${student.name}"> <br/></td>
                </tr>
                <tr>
                    <td>sex</td>
                    <td><input type="text" name="sex" value="${student.sex}"> <br/></td>
                </tr>
            </table>
            <input type="submit" value="提交"> <br>
        </form>
    </div>
</div>

8、神奇的Spring Data JPA