springboot对JPA的支持及界面版的增删改查

springboot分页：

配置跟上次博客一样，但后面用到了文件上传和模板，所以还需要导pom依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>

application.yml

 配置文件的大小

# 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

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

在util下

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

/**
 * @author Zhang
 */
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 + "]";
    }
}

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

/**
 * @author Zhang
 * pageTag-->PageBean
 * tld
 * <z:page pageBean="${pageBean}"></z:page>
 * 在HTML里就不可以这么写，c标签也不行
 */
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<Map.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();
    }
}

/**
 * @author Zhang
 */
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);
    }


}

entity层

import lombok.ToString;

import javax.persistence.*;

/**
 * @author Zhang
 */
@Entity
@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;

    public Integer getTid() {
        return tid;
    }

    public void setTid(Integer tid) {
        this.tid = tid;
    }

    public String getTname() {
        return tname;
    }

    public void setTname(String tname) {
        this.tname = tname;
    }

    public String getSex() {
        return sex;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getImagePath() {
        return imagePath;
    }

    public void setImagePath(String imagePath) {
        this.imagePath = imagePath;
    }
}

dao层 

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;

/**
 * @author Zhang
 */
public interface TeacherDao extends JpaRepository<Teacher, Integer>, JpaSpecificationExecutor<Teacher> {
}

service层

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.jpa.domain.Specification;

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

/**
 * @author Zhang
 */
@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
//        pageAspect不仅仅查了数据，还给pagebean设置总记录数pagebean.setTotal();因为这个方法没有给它设置总记录数意味着它的Total是0，所以返回的不是list<Teacher>返回的是Page<Teacher>
//        pageHelper.start("当前页","当页展示记录数");
        Pageable pageable = PageRequest.of(pageBean.getPage()-1, pageBean.getRows());
        return teacherDao.findAll(new Specification<Teacher>() {
            @Override
            public Predicate toPredicate(Root<Teacher> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate = criteriaBuilder.conjunction();
                if(teacher != null){
                    if(StringUtils.isNotBlank(teacher.getTname())){
                        predicate.getExpressions().add(criteriaBuilder.like(root.get("tname"),"%"+teacher.getTname()+"%"));
                    }
                }
                return predicate;
            }
        },pageable);
    }
}

controller层

import org.apache.commons.io.FileUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
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 Zhang
 */
@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());
        pageBean.setTotal(teachers.getTotalElements()+"");
        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 = "http://localhost:8080/springboot/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 = "http://localhost:8080/springboot/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";
    }
}

文件上传

config

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

/**
 * @author Zhang
 */
/**
 * 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);
    }
}

后台部分需要注意的点

1、springboot整合mybatis的时候做一个分页要写一个pageAspect，针对于service下的以pager结尾的类来用GitHub提供的分页插件对它进行分页能够极大的减少我们的代码量
2、jpa不支持GitHub的分页插件，jpa有内置的分页接口pageable,pageable替代了之前的pageAspect
3、GitHub包括很多的一些分页的一些内置的接口都是从第一页开始查数据，jpa的pageable这个分页类是从第0页开始
4、 pageAspect不仅仅查了数据，还给pagebean设置总记录数pagebean.setTotal();因为这个方法没有给它设置总记录数意味着它的Total是0，所以返回的不是list<Teacher>返回的是Page<Teacher>
5、文件上传到服务器可能会遇到需要刷新才能出来，也可能会遇到重启Tomact的时候，图片没有了
解决办法：把服务器与你上传的图片路径分开放入另一个盘，更改Tomcat的conf文件下的server.xml配置（往里面加<Context path="/uploadImage" docBase="E:/temp/">将硬盘中的E:/temp/映射成了网络请求的/uploadImage）如果用IDE的ssm开发，选择具体的你要映射的文件夹，springboot内嵌了一个Tomcat，那么你需要写一个配置类，在配置类里一定要加registry.addResourceHandler("/static/**").addResourceLocations("classpath:/static/");

页面

list.html

<!DOCTYPE html>
<html lang="en">
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>书籍列表</title>
    <script type="text/javascript" th:src="@{/static/js/xxx.js}"></script>
    <link rel="stylesheet" th:href="@{/static/js/bootstrap3/css/bootstrap.min.css}">
    <link rel="stylesheet" th:href="@{/static/js/bootstrap3/css/bootstrap-theme.min.css}">
    <script type="text/javascript" th:src="@{/static/js/bootstrap3/js/jquery-1.11.2.min.js}"></script>
    <script type="text/javascript" th:src="@{/static/js/bootstrap3/js/bootstrap.min.js}"></script>
</head>
<body>
<form th:action="@{/teacher/listPager}" method="post">
    书籍名称： <input type="text" name="tname" />
    <input type="submit" value="提交"/>
</form>
<a th:href="@{/teacher/toEdit}">新增</a>
<table border="1px" width="600px">
    <thead>
    <tr>
        <td>ID</td>
        <td>头像</td>
        <td>姓名</td>
        <td>性别</td>
        <td>简介</td>
        <td>操作</td>
    </tr>
    </thead>
    <tbody>
    <tr th:each="teacher : ${teachers}">
        <td th:text="${teacher.tid}"></td>
        <td><img style="width: 60px;height: 60px;" id="imgshow" th:src="${teacher.imagePath}" th:alt="${teacher.tname}"/></td>
        <!--<td th:text="${teacher.imagePath}"></td>-->
        <td th:text="${teacher.tname}"></td>
        <td th:text="${teacher.sex}"></td>
        <td th:text="${teacher.description}"></td>
        <td>
            <a th:href="@{'/teacher/del/'+${teacher.tid}}">删除</a>
            <a th:href="@{'/teacher/toEdit?tid='+${teacher.tid}}">修改</a>
        </td>
    </tr>
    </tbody>
</table>


<nav>
    <ul class="pagination pagination-sm" th:utext="${pageCode}">
    </ul>

    <!--<ul class="pagination pagination-sm">-->
    <!--<form id='pageBeanForm' action='http://localhost:8080/springboot/teacher/listPager' method='post'><input type='hidden' name='page'></form>-->
    <!--<li><a href='javascript:gotoPage(1)'>首页</a></li>-->
    <!--<li class='disabled'><a href='javascript:gotoPage(1)'>上一页</a></li>-->
    <!--<li class='active'><a href='#'>1</a></li>-->
    <!--<li><a href='javascript:gotoPage(2)'>2</a></li>-->
    <!--<li><a href='javascript:gotoPage(2)'>下一页</a></li>-->
    <!--<li><a href='javascript:gotoPage(4)'>尾页</a></li>-->
    <!--<script type='text/javascript'>	function gotoPage(page) {	document.getElementById('pageBeanForm').page.value = page; document.getElementById('pageBeanForm').submit();	}	function skipPage() {	var page = document.getElementById('skipPage').value;	if(!page || isNaN(page) || parseInt(page)<1 || parseInt(page)>4){ alert('请输入1~N的数字');	return;	}	gotoPage(page);	}</script>-->
    <!--</ul>-->
</nav>
</body>
</html>

edit.html

<!DOCTYPE html>
<html lang="en">
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>用户编辑界面</title>

    <script type="text/javascript">
        function preShow() {

        }
    </script>
</head>
<body>

<form th:action="@{${teacher.tid} ? '/teacher/edit' : '/teacher/add'}" method="post" enctype="multipart/form-data">
    <input type="hidden" name="tid" th:value="${teacher.tid}" />
    <input type="hidden" name="imagePath" th:value="${teacher.imagePath}" />
    <img id="imgshow" src="" alt=""/>
    <input type="file" name="image" onchange="preShow();"></br>
    教员名称： <input type="text" name="tname" th:value="${teacher.tname}" /></br>
    教员描述： <input type="text" name="description" th:value="${teacher.description}" /></br>
    单选回显
    <input type="radio" name="sex"
           th:each ="s:${sexArr}"
           th:value="${s}"
           th:text ="${s}"
           th:attr ="checked=${s == teacher.sex}">

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

</body>
</html>

前台需要注意的点：
1、在jsp获取项目名是pageContext.request.pageContextPath
在jpa获取项目名：<input type="text" th:text="@{/}">
2、拼接方式：
    1、<a th:href="@{'/teacher/del/'+${teacher.tid}}">删除</a>
    2、<a th:href="@{'/teacher/toEdit?tid='+${teacher.tid}}">修改</a>
3、th:utext="${pageCode}"和th:text="${pageCode}"的区别
有u的是指在当前的这个HTML标签去追加HTML字符串
没u的是打印HTML串
4、thymeleaf模板去开发它的三元运算符写法：
<form th:action="@{${teacher.tid} ? '/teacher/edit' : '/teacher/add'}" method="post" enctype="multipart/form-data">意思是tid不为空的话跳修改，如果为空的话跳新增
5、单选框的回显：
单选框如果是男或女他要写两个input标签，写两个input标签的话意味着你要进行遍历，如果你不想遍历的话，那么input标签要写两个，那么值没办法回显到对应按钮里，只能传一个数组，这个数组就是男或女，把数组传到HTML里,之后进行遍历，他teacher.sex是你存到数据库里的值，当你存到数据库的值跟某一个相匹配的话，意味着为选中了你这一项。
6、图片上传默认只能上传1M的图片，设置图片上传大小 
servlet:
    multipart:
      max-file-size: 20MB
      max-request-size:60MB