springboot之jpa的使用，增删改查及图片上传案例

JPA

1、JPA是什么？

JPA就是Java Persistence API的缩写，是JDK 5.0注解或XML描述对象－关系表的映射关系，并将运行期的实体对象持久化到数据库中。

2、JPA具有什么优势？

a、标准化
JPA 是 JCP 组织发布的 Java EE 标准之一，因此任何声称符合 JPA 标准的框架都遵循同样的架构，提供相同的访问API，这保证了基于JPA开发的企业应用能够经过少量的修改就能够在不同的JPA框架下运行。
b、容器级特性的支持
JPA框架中支持大数据集、事务、并发等容器级事务，这使得 JPA 超越了简单持久化框架的局限，在企业应用发挥更大的作用。
c、简单方便
JPA的主要目标之一就是提供更加简单的编程模型：在JPA框架下创建实体和创建Java 类一样简单，没有任何的约束和限制，只需要使用 javax.persistence.Entity进行注释，JPA的框架和接口也都非常简单，没有太多特别的规则和设计模式的要求，开发者可以很容易的掌握。JPA基于非侵入式原则设计，因此可以很容易的和其它框架或者容器集成。
d、查询能力
JPA的查询语言是面向对象而非面向数据库的，它以面向对象的自然语法构造查询语句，可以看成是Hibernate HQL的等价物。JPA定义了独特的JPQL（Java Persistence Query Language），JPQL是EJB QL的一种扩展，它是针对实体的一种查询语言，操作对象是实体，而不是关系数据库的表，而且能够支持批量更新和修改、JOIN、GROUP BY、HAVING 等通常只有 SQL 才能够提供的高级查询特性，甚至还能够支持子查询。
e、高级特性
JPA 中能够支持面向对象的高级特性，如类之间的继承、多态和类之间的复杂关系，这样的支持能够让开发者最大限度的使用面向对象的模型设计企业应用，而不需要自行处理这些特性在关系数据库的持久化。

代码实战

导入相关pom依赖：

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

在application.yml文件中进行配置：

spring:
  jpa:
    hibernate:
      ddl-auto:update//自动更新
    show-sql:true//在日志中显示SQL语句

jpa.hibernate.ddl-auto是hibernate的配置属性，其主要作用是：自动创建、更新、验证数据库表结构。该参数的几种配置如下：
·create：每次加载hibernate时都会删除上一次的生成的表，然后根据你的model类再重新来生成新表，哪怕两次没有任何改变也要这样执行，这就是导致数据库表数据丢失的一个重要原因。
·create-drop：每次加载hibernate时根据model类生成表，但是sessionFactory一关闭,表就自动删除。
·update：最常用的属性，第一次加载hibernate时根据model类会自动建立起表的结构（前提是先建立好数据库），以后加载hibernate时根据model类自动更新表结构，即使表结构改变了但表中的行仍然存在不会删除以前的行。要注意的是当部署到服务器后，表结构是不会被马上建立起来的，是要等应用第一次运行起来后才会。
·validate：每次加载hibernate时，验证创建数据库表结构，只会和数据库中的表进行比较，不会创建新表，但是会插入新值。

完整pom

<?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>2.2.2.RELEASE</version>

        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.wxm</groupId>
    <artifactId>springboot4</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot4</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <mysql.version>5.1.44</mysql.version>
        <redis.version>2.9.0</redis.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <!--5.其他-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.3</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>${redis.version}</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</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>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <dependencies>
                    <!--使用Mybatis-generator插件不能使用太高版本的mysql驱动 -->
                    <dependency>
                        <groupId>mysql</groupId>
                        <artifactId>mysql-connector-java</artifactId>
                        <version>${mysql.version}</version>
                    </dependency>
                </dependencies>
                <configuration>
                    <overwrite>true</overwrite>
                </configuration>
            </plugin>

        </plugins>
        <resources>
            <!--解决mybatis-generator-maven-plugin运行时没有将XxxMapper.xml文件放入target文件夹的问题-->
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
            <!--解决mybatis-generator-maven-plugin运行时没有将jdbc.properites文件放入target文件夹的问题-->
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>*.properties</include>
                    <include>*.xml</include>
                    <include>*.yml</include>
                </includes>
            </resource>
        </resources>

    </build>

</project>

完整application.yml

server:
  servlet:
    context-path: /
spring:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:2206/test?useUnicode=true&characterEncoding=utf8
    username: root
    password: root
    druid:
      initial-size: 5
      min-idle: 5
      max-active: 20
      max-wait: 60000
      time-between-eviction-runs-millis: 60000
      min-evictable-idle-time-millis: 30000
      validation-query: SELECT 1 FROM DUAL
      test-while-idle: true
      test-on-borrow: true
      test-on-return: false
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      filter:
        stat:
          merge-sql: true
          slow-sql-millis: 5000
      web-stat-filter:
        enabled: true
        url-pattern: /*
        exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"
        session-stat-enable: true
        session-stat-max-count: 100
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        reset-enable: true
        login-username: admin
        login-password: admin
        allow: 127.0.0.1
  thymeleaf:
    cache: false

  # 解决图片上传大小限制问题，也可采取配置类
  servlet:
    multipart:
      max-file-size: 20MB
      max-request-size: 60MB

自动建表相关实体类：

package com.wxm.springboot4.entity.book;

import lombok.Data;

import javax.persistence.*;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-02 21:07
 */
@Entity
@Data
@Table(name="t_springboot_book")
public class Book {
    @Id
    @GeneratedValue
    private Integer bid;

    @Column(length = 100)
    private String bname;

    @Column
    private Float bprice;
}

运行如图后：

数据库自动建表截图，并且会创建一个序列以及t_springboot_book

jpa值增删改查：
BookDao

package com.wxm.springboot4.dao.book;

import com.wxm.springboot4.entity.book.Book;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-02 21:58
 *
 * 只要继承JpaRepository，通常所用的增删查改方法都有
 * 第一个参数：操作的实体类
 * 第二个参数：实体类对应数据表的主键
 */
public interface BookDao extends JpaRepository<Book,Integer> {
}

BookController

package com.wxm.springboot4.controller;

import com.wxm.springboot4.dao.book.BookDao;
import com.wxm.springboot4.entity.book.Book;
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;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-02 21:59
 */
@RestController
@RequestMapping("/book")
public class BookController {
    @Autowired
    private BookDao bookDao;

    @RequestMapping("/add")
    public String add(Book book){

        bookDao.save(book);
        return "success";

    }
    @RequestMapping("/edit")
    public String edit(Book book){
        bookDao.save(book);
        return "success";
    }

    @RequestMapping("/del")
    public String del(Book book){
        bookDao.delete(book);
        return "success";
    }

    @RequestMapping("/getOne")
    public Book getOne(Integer bid){
//        会出现懒加载问题：org.hibernate.LazyInitializationException: could not initialize proxy - no Session
        return bookDao.getOne(bid);
//        return bookDao.findById(bid).get();
    }

    @RequestMapping("/getAll")
    public List<Book> getAll(){
        return bookDao.findAll();
    }
}

效果

查询单个

注意：

会出现此问题
com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.wxm.springboot4.entity.book.Book $HibernateProxy$xtiJQbRE[“hibernateLazyInitializer”])

改成：

        return bookDao.findById(bid).get();

http://localhost/book/getOne?bid=1

查询全部

访问

http://localhost/book/getAll

删除

http://localhost/book/del?bid=1

修改

http://localhost/book/edit?bid=2&bname=小明日记&bprice=999.98

jpa值复杂查询：

dao层

extends JpaRepository<Book,Integer>, JpaSpecificationExecutor< Book>

package com.wxm.springboot4.dao.book;

import com.wxm.springboot4.entity.book.Book;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-02 21:58
 *
 * 只要继承JpaRepository，通常所用的增删查改方法都有
 * 第一个参数：操作的实体类
 * 第二个参数：实体类对应数据表的主键
 */
public interface BookDao extends JpaRepository<Book,Integer>, JpaSpecificationExecutor<Book> {
}

controller层：

    @RequestMapping("/getLike")
    public List<Book> getLike(Book book){
        return bookDao.findAll(new Specification<Book>() {
            @Override
            public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate=criteriaBuilder.conjunction();
                        if(book !=null && book.getBname()!=null&& !"".equals(book.getBname())){
                            predicate.getExpressions().add(criteriaBuilder.like(root.get("bname"),"%"+book.getBname()+"%"));
                        }
                return predicate;
            }
        });
    }

模糊查询：

解决：springboot中实体类上添加@Data标签却无法调用Getter and Setter

Data注解可以却发现此实体类对象调用不到Getter and Setter方法，下面给出具体解决办法：

点击install下载

安装成功后重启Idea后插件就生效了，具体表现如下：

Springboot+bootstrap界面版之增删改查及图片上传

本次案例采取的是spring data jpa和bootstrap3来完成的，并没有使用github提供的 分页插件Pagehelper，pagehelper与SSM配合分页在前面博客已经有所讲解。

pom依赖

<mysql.version>5.1.44</mysql.version>
<version>${mysql.version}</version>

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.10</version>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>
<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-aspects</artifactId>
</dependency>

  thymeleaf:
    cache: false

    # 解决图片上传大小限制问题，也可采取配置类
    servlet:
      multipart:
        max-file-size: 20MB
        max-request-size: 60MB

完整

MyWebAppConfigurer

package com.wxm.springboot4.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

/**
 * 资源映射路径
 */
@Configuration
public class MyWebAppConfigurer extends WebMvcConfigurationSupport {
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");
        registry.addResourceHandler("/uploadImages/**").addResourceLocations("file:E:/temp/");
        super.addResourceHandlers(registry);
    }
}

pom

<?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>2.2.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.wxm</groupId>
    <artifactId>springboot4</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot4</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
        <mysql.version>5.1.44</mysql.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.10</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
        </dependency>

        <!--文件上传-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.1</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

server:
  port: 80
  servlet:
    context-path: /

spring:
  datasource:
    #1.JDBC
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:2206/test?useUnicode=true&characterEncoding=UTF-8&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
    username: root
    password: root
    druid:
      #2.连接池配置
      #初始化连接池的连接数量 大小，最小，最大
      initial-size: 5
      min-idle: 5
      max-active: 20
      #配置获取连接等待超时的时间
      max-wait: 60000
      #配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
      time-between-eviction-runs-millis: 60000
      # 配置一个连接在池中最小生存的时间，单位是毫秒
      min-evictable-idle-time-millis: 30000
      validation-query: SELECT 1 FROM DUAL
      test-while-idle: true
      test-on-borrow: true
      test-on-return: false
      # 是否缓存preparedStatement，也就是PSCache  官方建议MySQL下建议关闭   个人建议如果想用SQL防火墙 建议打开
      pool-prepared-statements: true
      max-pool-prepared-statement-per-connection-size: 20
      # 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
      filter:
        stat:
          merge-sql: true
          slow-sql-millis: 5000
      #3.基础监控配置
      web-stat-filter:
        enabled: true
        url-pattern: /*
        #设置不统计哪些URL
        exclusions: "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*"
        session-stat-enable: true
        session-stat-max-count: 100
      stat-view-servlet:
        enabled: true
        url-pattern: /druid/*
        reset-enable: true
        #设置监控页面的登录名和密码
        login-username: admin
        login-password: admin
        allow: 127.0.0.1
  thymeleaf:
    cache: false

    # 解决图片上传大小限制问题，也可采取配置类
    servlet:
      multipart:
        max-file-size: 20MB
        max-request-size: 60MB
#  freemarker:
#    checkTemplateLocation: false
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: false

Teacher

package com.wxm.springboot4.entity.book;

import lombok.Data;
import lombok.ToString;

import javax.persistence.*;

@Entity
@Data
@Table(name = "t_springboot_teacher")
@ToString
public class Teacher {
    @Id
    @GeneratedValue
    private Integer tid;
    @Column(length = 16)
    private String tname;
    @Column(length = 4)
    private String sex;
    @Column(length = 100)
    private String description;
    @Column(length = 200)
    private String imagePath;

}

TeacherService

package com.wxm.springboot4.service;

import com.github.pagehelper.Page;
import com.wxm.springboot4.entity.book.Teacher;
import com.wxm.springboot4.utils.PageBean;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-03 15:41
 */
public interface TeacherService {

    public Teacher save(Teacher teacher);

    public void deleteById(Integer id);

    public Teacher findById(Integer id);

    public Page<Teacher> listPager(Teacher teacher, PageBean pageBean);
}

TeacherServiceImpl

package com.wxm.springboot4.service;

import com.github.pagehelper.Page;
import com.wxm.springboot4.dao.book.TeacherDao;
import com.wxm.springboot4.entity.book.Teacher;
import com.wxm.springboot4.utils.PageBean;
import com.wxm.springboot4.utils.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.domain.Specification;
import org.springframework.stereotype.Service;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

@Service
public class TeacherServiceImpl implements TeacherService {
    @Autowired
    private TeacherDao teacherDao;
    @Override
    public Teacher save(Teacher teacher) {
        return teacherDao.save(teacher);
    }

    @Override
    public void deleteById(Integer id) {
        teacherDao.deleteById(id);
    }

    @Override
    public Teacher findById(Integer id) {
        return teacherDao.findById(id).get();
    }

    @Override
    public Page<Teacher> listPager(Teacher teacher, PageBean pageBean) {
//        jpa的Pageable分页是从0页码开始
        Pageable pageable = PageRequest.of(pageBean.getPage()-1, pageBean.getRows());
        return (Page<Teacher>) teacherDao.findAll(new Specification<Teacher>() {
            @Override
            public Predicate toPredicate(Root<Teacher> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate=criteriaBuilder.conjunction();
                if(teacher!=null){
                    if((Boolean) StringUtils.isNotBlank(teacher.getTname())){
                        predicate.getExpressions().add(criteriaBuilder.like(root.get("tname"),"%"+teacher.getTname()+"%"));
                    }
                }
                return predicate;
            }
        },pageable);
    }
}

utils

PageBean

package com.wxm.springboot4.utils;

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

/**
 * 分页工具类
 */
public class PageBean {

	private int page = 1;// 页码

	private int rows = 3;// 页大小

	private int total = 0;// 总记录数

	private boolean pagination = true;// 是否分页
	
//	保存上次查询的参数
	private Map<String, String[]> paramMap;
//	保存上次查询的url
	private String url;
	
	public void setRequest(HttpServletRequest request) {
		String page = request.getParameter("page");
		String rows = request.getParameter("offset");
		String pagination = request.getParameter("pagination");
		this.setPage(page);
		this.setRows(rows);
		this.setPagination(pagination);
		this.setUrl(request.getRequestURL().toString());
		this.setParamMap(request.getParameterMap());
	}

	public PageBean() {
		super();
	}

	public Map<String, String[]> getParamMap() {
		return paramMap;
	}

	public void setParamMap(Map<String, String[]> paramMap) {
		this.paramMap = paramMap;
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	public int getPage() {
		return page;
	}

	public void setPage(int page) {
		this.page = page;
	}
	
	public void setPage(String page) {
		if(StringUtils.isNotBlank(page)) {
			this.page = Integer.parseInt(page);
		}
	}

	public int getRows() {
		return rows;
	}

	public void setRows(String rows) {
		if(StringUtils.isNotBlank(rows)) {
			this.rows = Integer.parseInt(rows);
		}
	}

	public int getTotal() {
		return total;
	}

	public void setTotal(int total) {
		this.total = total;
	}

	public void setTotal(String total) {
		if(StringUtils.isNotBlank(total)) {
			this.total = Integer.parseInt(total);
		}
	}

	public boolean isPagination() {
		return pagination;
	}

	public void setPagination(boolean pagination) {
		this.pagination = pagination;
	}
	
	public void setPagination(String pagination) {
		if(StringUtils.isNotBlank(pagination) && "false".equals(pagination)) {
			this.pagination = Boolean.parseBoolean(pagination);
		}
	}
	
	/**
	 * 最大页
	 * @return
	 */
	public int getMaxPage() {
		int max = this.total/this.rows;
		if(this.total % this.rows !=0) {
			max ++ ;
		}
		return max;
	}
	
	/**
	 * 下一页
	 * @return
	 */
	public int getNextPage() {
		int nextPage = this.page + 1;
		if(nextPage > this.getMaxPage()) {
			nextPage = this.getMaxPage();
		}
		return nextPage;
	}
	
	/**
	 * 上一页
	 * @return
	 */
	public int getPreviousPage() {
		int previousPage = this.page -1;
		if(previousPage < 1) {
			previousPage = 1;
		}
		return previousPage;
	}
		

	/**
	 * 获得起始记录的下标
	 * 
	 * @return
	 */
	public int getStartIndex() {
		return (this.page - 1) * this.rows;
	}

	@Override
	public String toString() {
		return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]";
	}
}

PageUtil

package com.wxm.springboot4.utils;

import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

/**
 * html分页条
 */
public class PageUtil {
    public static String createPageCode(PageBean pageBean) {
        StringBuffer sb = new StringBuffer();
        /*
         * 拼接向后台提交数据的form表单
         * 	注意：拼接的form表单中的page参数是变化的，所以不需要保留上一次请求的值
         */
        sb.append("<form id='pageBeanForm' action='"+pageBean.getUrl()+"' method='post'>");
        sb.append("<input type='hidden' name='page'>");
        Map<String, String[]> parameterMap = pageBean.getParamMap();
        if(parameterMap != null && parameterMap.size() > 0) {
            Set<Entry<String, String[]>> entrySet = parameterMap.entrySet();
            for (Map.Entry<String, String[]> entry : entrySet) {
                if(!"page".equals(entry.getKey())) {
                    String[] values = entry.getValue();
                    for (String val : values) {
                        sb.append("<input type='hidden' name='"+entry.getKey()+"' value='"+val+"'>");
                    }
                }
            }
        }
        sb.append("</form>");

        if(pageBean.getTotal()==0){
            return "未查询到数据";
        }else{
            sb.append("<li><a href='javascript:gotoPage(1)'>首页</a></li>");
            if(pageBean.getPage()>1){
                sb.append("<li><a href='javascript:gotoPage("+pageBean.getPreviousPage()+")'>上一页</a></li>");
            }else{
                sb.append("<li class='disabled'><a href='javascript:gotoPage(1)'>上一页</a></li>");
            }
            for(int i=pageBean.getPage()-1;i<=pageBean.getPage()+1;i++){
                if(i<1||i>pageBean.getMaxPage()){
                    continue;
                }
                if(i==pageBean.getPage()){
                    sb.append("<li class='active'><a href='#'>"+i+"</a></li>");
                }else{
                    sb.append("<li><a href='javascript:gotoPage("+i+")'>"+i+"</a></li>");
                }
            }
            if(pageBean.getPage()<pageBean.getMaxPage()){
                sb.append("<li><a href='javascript:gotoPage("+pageBean.getNextPage()+")'>下一页</a></li>");
            }else{
                sb.append("<li class='disabled'><a href='javascript:gotoPage("+pageBean.getMaxPage()+")'>下一页</a></li>");
            }
            sb.append("<li><a href='javascript:gotoPage("+pageBean.getMaxPage()+")'>尾页</a></li>");
        }

        /*
         * 给分页条添加与后台交互的js代码
         */
        sb.append("<script type='text/javascript'>");
        sb.append("		function gotoPage(page) {");
        sb.append("			document.getElementById('pageBeanForm').page.value = page;");
        sb.append("			document.getElementById('pageBeanForm').submit();");
        sb.append("		}");
        sb.append("		function skipPage() {");
        sb.append("			var page = document.getElementById('skipPage').value;");
        sb.append("			if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>"+pageBean.getMaxPage()+"){");
        sb.append("				alert('请输入1~N的数字');");
        sb.append("				return;");
        sb.append("			}");
        sb.append("			gotoPage(page);");
        sb.append("		}");
        sb.append("</script>");
        return sb.toString();
    }
}

StringUtils

package com.wxm.springboot4.utils;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Set;

public class StringUtils {
	// 私有的构造方法，保护此类不能在外部实例化
	private StringUtils() {
	}

	/**
	 * 如果字符串等于null或去空格后等于""，则返回true，否则返回false
	 * 
	 * @param s
	 * @return
	 */
	public static boolean isBlank(String s) {
		boolean b = false;
		if (null == s || s.trim().equals("")) {
			b = true;
		}
		return b;
	}
	
	/**
	 * 如果字符串不等于null或去空格后不等于""，则返回true，否则返回false
	 * 
	 * @param s
	 * @return
	 */
	public static boolean isNotBlank(String s) {
		return !isBlank(s);
	}

	/**
	 * set集合转string
	 * @param hasPerms
	 * @return
	 */
	public static String SetToString(Set hasPerms){
		return  Arrays.toString(hasPerms.toArray()).replaceAll(" ", "").replace("[", "").replace("]", "");
	}

	/**
	 * 转换成模糊查询所需参数
	 * @param before
	 * @return
	 */
	public static String toLikeStr(String before){
		return isBlank(before) ? null : "%"+before+"%";
	}

	/**
	 *	将图片的服务器访问地址转换为真实存放地址
	 * @param imgpath	图片访问地址（http://localhost:8080/uploadImage/2019/01/26/20190126000000.jpg）
	 * @param serverDir	uploadImage
	 * @param realDir	E:/temp/
	 * @return
	 */
	public static String serverPath2realPath(String imgpath, String serverDir, String realDir) {
		imgpath = imgpath.substring(imgpath.indexOf(serverDir));
		return imgpath.replace(serverDir,realDir);
	}

	/**
	 * 过滤掉集合里的空格
	 * @param list
	 * @return
	 */
	public static List<String> filterWhite(List<String> list){
		List<String> resultList=new ArrayList<String>();
		for(String l:list){
			if(isNotBlank(l)){
				resultList.add(l);
			}
		}
		return resultList;
	}

	/**
	 * 从html中提取纯文本
	 * @param strHtml
	 * @return
	 */
	public static String html2Text(String strHtml) {
		String txtcontent = strHtml.replaceAll("</?[^>]+>", ""); //剔出<html>的标签
		txtcontent = txtcontent.replaceAll("<a>\\s*|\t|\r|\n</a>", "");//去除字符串中的空格,回车,换行符,制表符
		return txtcontent;
	}

	public static void main(String[] args) {
	}
}

controller

package com.wxm.springboot4.controller;

import com.wxm.springboot4.entity.book.Teacher;
import com.wxm.springboot4.service.TeacherService;
import com.wxm.springboot4.utils.PageBean;
import com.wxm.springboot4.utils.PageUtil;
import com.wxm.springboot4.utils.StringUtils;
import org.apache.commons.io.FileUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;

/**
 * @author wxm
 * @site www.wxm.com
 * @company xxx公司
 * @create 2020-01-03 16:02
 */
@Controller
@RequestMapping("/teacher")
public class TeacherController {
    @Autowired
    private TeacherService teacherService;

    @RequestMapping("/listPager")
    public ModelAndView list(Teacher teacher, HttpServletRequest request) {
        PageBean pageBean=new PageBean();
        pageBean.setRequest(request);
        ModelAndView modelAndView=new ModelAndView();
        Page<Teacher> teachers=teacherService.listPager(teacher,pageBean);
        modelAndView.addObject("teachers",teachers.getContent());

        modelAndView.addObject("pageCode", PageUtil.createPageCode(pageBean)/*.replaceAll("<","<").replaceAll("&gt:",">")*/);
        modelAndView.setViewName("list");
        return modelAndView;
    }
    @RequestMapping("/toEdit")
    public ModelAndView toEdit(Teacher teacher){
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.setViewName("edit");
        modelAndView.addObject("sexArr",new String[]{"男","女"});
        if(!(teacher.getTid() == null || "".equals(teacher.getTid()))) {
            Teacher t = teacherService.findById(teacher.getTid());
            modelAndView.addObject("teacher", t);
        }
        return modelAndView;
    }

    @RequestMapping("/add")
    public String add(Teacher teacher, MultipartFile image){
        try {
            String diskPath = "E://temp/"+image.getOriginalFilename();
            String serverPath = "/uploadImages/"+image.getOriginalFilename();
            if(StringUtils.isNotBlank(image.getOriginalFilename())){
                FileUtils.copyInputStreamToFile(image.getInputStream(),new File(diskPath));
                teacher.setImagePath(serverPath);
            }
            teacherService.save(teacher);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "redirect:/teacher/listPager";
    }


    @RequestMapping("/edit")
    public String edit(Teacher teacher, MultipartFile image){
        String diskPath = "E://temp/"+image.getOriginalFilename();
        String serverPath = "/uploadImages/"+image.getOriginalFilename();
        if(StringUtils.isNotBlank(image.getOriginalFilename())){
            try {
                FileUtils.copyInputStreamToFile(image.getInputStream(),new File(diskPath));
                teacher.setImagePath(serverPath);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        teacherService.save(teacher);
        return "redirect:/teacher/listPager";
    }

    @RequestMapping("/del/{bid}")
    public String del(@PathVariable(value = "bid") Integer bid){
        teacherService.deleteById(bid);
        return "redirect:/teacher/listPager";
    }
    
}

http://localhost:8080/teacher/listPager

http://localhost:8080/teacher/toEdit?tid=2

已解决：org.thymeleaf.exceptions.TemplateInputException: Error resolving template [list], template might not exist or might not be accessible by any of the configured Template Resolvers

思路：（我这里是缓存也就是第三步的问题->pom依赖问题）
总结如下四步

1 分析:yml配置文件

2 分析:Controller
3 分析:Target/classes
4.pom配置文