从.Net到Java学习第十二篇——SpringBoot+JPA提供跨域接口

时间: 2020-09-8｜tag： ｜50次围观｜0 条评论

从.Net到Java学习系列目录

最近又撸了半个月的前端代码，做app离线存储，然后又花了一周去将过去的wcf项目转webapi，java又被落下了，总感觉我特么像斗地主中的癞子牌，变来变去.....

Spring Data JPA 是Spring Data 的一个子项目，它通过提供基于JPA的Repository极大了减少了操作JPA的代码。我觉得它就是一个封装好了的泛型仓储。

点击JpaRepository进去看下它的源码：

@NoRepositoryBeanpublic interface JpaRepository<T, ID extends Serializable> extends PagingAndSortingRepository<T, ID>, QueryByExampleExecutor<T> {    List<T> findAll();    List<T> findAll(Sort var1);    List<T> findAll(Iterable<ID> var1);    <S extends T> List<S> save(Iterable<S> var1);    void flush();    <S extends T> S saveAndFlush(S var1);    void deleteInBatch(Iterable<T> var1);    void deleteAllInBatch();    T getOne(ID var1);    <S extends T> List<S> findAll(Example<S> var1);    <S extends T> List<S> findAll(Example<S> var1, Sort var2);}

关于JPA的详细介绍请移步：spring boot 中使用 jpa以及jpa介绍

有了前面文章的基础之后，下面的操作就信手捏来了，所以就不做过多的解释。

这里用到了mysql数据库，先运行已经准备好mysql脚本，进行数据库初始化。

SET FOREIGN_KEY_CHECKS=0;-- ------------------------------ Table structure for `tb_book`-- ----------------------------DROP TABLE IF EXISTS `tb_book`;CREATE TABLE `tb_book` (  `id` bigint(11) NOT NULL AUTO_INCREMENT,  `bookname` varchar(50) DEFAULT NULL COMMENT '书名',  `price` decimal(10,0) DEFAULT '0' COMMENT '价格',  `author` varchar(30) DEFAULT NULL COMMENT '作者',  `publishdate` date DEFAULT NULL COMMENT '出版日期',  `pagesize` int(11) DEFAULT '0' COMMENT '页数',  PRIMARY KEY (`id`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;-- ------------------------------ Records of tb_book-- ----------------------------INSERT INTO `tb_book` VALUES ('1', 'ASP.NET MVC企业级实战', '89', '邹琼俊', '2017-04-01', '476');INSERT INTO `tb_book` VALUES ('2', 'Java疯狂讲义', '99', '李阳', '2016-05-02', '890');

修改pom.xml文件，添加jpa引用，当然这里用到了mysql数据库，那么还要添加mysql数据库引用

 <!--jpa-->        <dependency>            <groupId>org.springframework.boot</groupId>            <artifactId>spring-boot-starter-data-jpa</artifactId>        </dependency>        <!--集成druid，使用连接池-->        <dependency>            <groupId>com.alibaba</groupId>            <artifactId>druid</artifactId>            <version>1.1.0</version>        </dependency>        <dependency>            <groupId>mysql</groupId>            <artifactId>mysql-connector-java</artifactId>            <scope>runtime</scope>        </dependency>

修改配置文件application.yml，对数据库和jpa进行配置

spring:  profiles:    active: dev  datasource:      name: demo      url: jdbc:mysql://127.0.0.1:3306/demo?&useSSL=false      username: root      password: yujie      # 使用druid数据源      type: com.alibaba.druid.pool.DruidDataSource      driver-class-name: com.mysql.jdbc.Driver      filters: stat      maxActive: 20      initialSize: 1      maxWait: 60000      minIdle: 1      timeBetweenEvictionRunsMillis: 60000      minEvictableIdleTimeMillis: 300000      validationQuery: select 'x'      testWhileIdle: true      testOnBorrow: false      testOnReturn: false      poolPreparedStatements: true      maxOpenPreparedStatements: 20  jpa:    hibernate:      ddl-auto: update    show-sql: true  jackson:    serialization: true

创建实体类Book，创建包model，然后创建类Book，需要注意的是java中没有decimal类型，对，没错，一开始我习惯性的输入decimal，结果果断报错了，然后一查文档，发现要用BigDecimal。

从.Net到Java学习第十二篇——SpringBoot+JPA提供跨域接口插图

package com.yujie.model;import javax.persistence.*;import java.math.BigDecimal;import java.util.Date;@Entity@Table(name = "tb_book")public class Book {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    public long id;    public String bookname;    public BigDecimal price;    public String author;    public Date publishdate;    public int pagesize;    public long getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getBookname() {        return bookname;    }    public void setBookname(String bookname) {        this.bookname = bookname;    }    public BigDecimal getPrice() {        return price;    }    public void setPrice(BigDecimal price) {        this.price = price;    }    public String getAuthor() {        return author;    }    public void setAuthor(String author) {        this.author = author;    }    public Date getPublishdate() {        return publishdate;    }    public void setPublishdate(Date publishdate) {        this.publishdate = publishdate;    }    public int getPagesize() {        return pagesize;    }    public void setPagesize(int pagesize) {        this.pagesize = pagesize;    }    @Override    public String toString() {        return "Book{" +                "id=" + id +                ", bookname='" + bookname + '\'' +                ", price=" + price +                ", author='" + author + '\'' +                ", publishdate=" + publishdate +                ", pagesize=" + pagesize +                '}';    }}

View Code

创建数据库访问接口IBookRepository，这里继承JPA封装的泛型接口JpaRepository

package com.yujie.dao;import com.yujie.model.Book;import org.springframework.data.jpa.repository.JpaRepository;public interface IBookRepository extends JpaRepository<Book,Long> {}

创建控制器BookController，为了让这个控制器直接变成类似.net 中的webapi，我直接在控制器上面添加注解@RestController，这样返回的就是json数据了。

package com.yujie.controller;import com.yujie.dao.IBookRepository;import com.yujie.model.Book;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.*;@RestControllerpublic class BookController {    @Autowired    private IBookRepository repository;    @GetMapping("/book/{id}")    public Book getBookDetail(@PathVariable("id") long id){        return repository.findOne(id);    }}

添加跨域配置类CorsConfig

package com.yujie.filter;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.CorsRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;/** * 解决前端站点(主要为JavaScript发起的Ajax请求)访问的跨域问题 */@Configurationpublic class CorsConfig extends WebMvcConfigurerAdapter {    @Override    public void addCorsMappings(CorsRegistry registry) {        registry.addMapping("/**")                .allowedOrigins("*")    //允许所有前端站点调用                .allowCredentials(true)                .allowedMethods("GET", "POST", "DELETE", "PUT")                .maxAge(1728000);    }}

运行测试

从.Net到Java学习第十二篇——SpringBoot+JPA提供跨域接口插图2

沿用上一篇vue中引用swiper轮播插件来测试 。

1.安装vue-resource

npm install vue-resource --save

2.在main.js中引入vue-resource

// The Vue build version to load with the `import` command// (runtime-only or standalone) has been set in webpack.base.conf with an alias.import Vue from 'vue'import App from './App'import router from './router'import VueResource from 'vue-resource'Vue.config.productionTip = falseVue.use(VueResource)/* eslint-disable no-new */new Vue({  el: '#app',  router,  components: { App },  template: '<App/>',  http:{    root:''  }})

3.修改BookDetail.vue代码：

<template><div class="bookdetail">  <div>书名：<span v-text="bookdata.bookname"></span></div>  <div>作者：<span v-text="bookdata.author"></span></div>  <div>页数：<span v-text="bookdata.pagesize"></span></div>  <div>定价：<span v-text="bookdata.price"></span></div>  <div>出版日期：<span v-text="bookdata.publishdate"></span></div></div></template><script>    export default {      name: "BookDetail",      data(){        return{          id:this.$route.params.id,          bookdata:{bookname:'',author:'',price:0,publishdate:'',pagesize:0}        }      },      created(){        var self=this;        this.$http.get("http://localhost:8083/book/"+this.id).then(res=>{          self.bookdata.bookname=res.body.bookname;          self.bookdata.author=res.body.author;          self.bookdata.price=res.body.price;          self.bookdata.publishdate=res.body.publishdate;          self.bookdata.pagesize=res.body.pagesize;        });      },      props:[      ]    }</script><style scoped>.bookdetail div{text-align: left;}</style>

运行结果：

从.Net到Java学习第十二篇——SpringBoot+JPA提供跨域接口插图3

文章转载于:https://www.cnblogs.com/jiekzou/p/9488520.html

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