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。
创建数据库访问接口IBookRepository，这里继承JPA疯子的泛型接口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
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：
原文出处：https://www.cnblogs.com/jiekzou/p/9488520.html