StringBoot 易上手的java框架
StringBoot是一个几乎不需要配置的Java框架,能够帮助开发者专注于业务逻辑,而不需要关心框架的复杂配置.
1.新建一个SpringBoot项目.
- 打开IDEA,new->project->Spring Intializr(每一步确认JDK版本是否一致)->Web->Spring Web Starter
- 项目创建完成,是一个maven项目,在src/main/java(...)/有一个SpringbootApplication,直接运行该程序,就开启了项目内置的tomcat了.
- 在SpringbootApplication所在目录下新建一个web目录,在其中新建一个控制类.
package com.how2java.springboot.web;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello() {
return "Hello Spring Boot!";
}
}
重写运行,访问/hello就会看到输出的文字了.
2.热部署
- CTRL + SHIFT + A --> 查找make project automatically --> 选中
- CTRL + SHIFT + A --> 查找Registry --> 找到并勾选compiler.automake.allow.when.app.running
- pom.xml下添加依赖
<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>
- application.propertiles下增加
spring.thymeleaf.cache=true
spring.devtools.restart.enabled=true
spring.devtools.restart.additional-paths=src/main/java
之后修改控制类中内容后并ctrl+s保存后,程序会自动重启(需要等待一定时间,约5-6s)
3.配置切换.
在核心配置文件application.propertiles所在目录下新建两个配置文件
application-dev.properties
application-pro.properties
分别代表开发配置和生产配置.通过修改application.propertiles下spring.profiles.active属性=pro或者dev来切换配置.
核心配置文件中的配置在两套配置中都是通用的.
对最终生成的jar文件也可以通过java -jar target/springboot-0.0.1-SNAPSHOT.jar --spring.profiles.active=pro命令使用对应配置
4.JPA
Sun制定了java持久化规范,Hibernate执行了该规范.Springboot内部集成了Hibernate,让用户简单的调用.
- application.properties中增加声明:
spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/how2java?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=admin
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.jpa.properties.hibernate.hbm2ddl.auto=update
- pom.xml添加依赖
<!-- mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.21</version>
</dependency>
<!-- jpa-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
- pojo目录下添加实体类
package com.example.springboot.pojo;
import javax.persistence.*;
@Entity
@Table(name = "category_")
public class Category {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private int id;
@Column(name = "name")
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
- dao目录下添加接口
package com.example.springboot.dao;
import com.example.springboot.pojo.Category;
import org.springframework.data.jpa.repository.JpaRepository;
public interface CategoryDAO extends JpaRepository<Category,Integer> {
}
- web目录下添加控制器
package com.example.springboot.web;
import com.example.springboot.dao.CategoryDAO;
import com.example.springboot.pojo.Category;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import java.util.List;
@Controller
public class CategoryController {
@Autowired
CategoryDAO categoryDAO;
@RequestMapping("/listCategory")
public String listCategory(Model m) throws Exception {
List<Category> cs=categoryDAO.findAll();
m.addAttribute("cs", cs);
return "listCategory";
}
}
- 添加jsp显示
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<table align='center' border='1' cellspacing='0'>
<tr>
<td>id</td>
<td>name</td>
</tr>
<c:forEach items="${cs}" var="c" varStatus="st">
<tr>
<td>${c.id}</td>
<td>${c.name}</td>
</tr>
</c:forEach>
</table>
5. JPA分页,增删改用法
- 为控制器添加映射,redirect表示客户端跳转,RequestMapping表示访问url
@RequestMapping("/addCategory")
public String addCategory(Category c) throws Exception {
categoryDAO.save(c);
return "redirect:listCategory";
}
@RequestMapping("/deleteCategory")
public String deleteCategory(Category c) throws Exception {
categoryDAO.delete(c);
return "redirect:listCategory";
}
@RequestMapping("/updateCategory")
public String updateCategory(Category c) throws Exception {
categoryDAO.save(c);
return "redirect:listCategory";
}
@RequestMapping("/editCategory")
public String editCategory(int id,Model m) throws Exception {
Category c= categoryDAO.getOne(id);
m.addAttribute("c", c);
return "editCategory";
}
@RequestMapping("/listCategory")
public String listCategory(Model m, @RequestParam(value="start",defaultValue = "0")int start,@RequestParam(value="size",defaultValue="5")int size) throws Exception {
start=start<0?0:start;
Sort sort = new Sort(Sort.Direction.DESC,"id");
//2.0版本提示过时
//Pageable pageable = new PageRequest(start,size,sort);
Pageable pageable = PageRequest.of(start,size,sort);
Page<Category> page = categoryDAO.findAll(pageable);
m.addAttribute("page", page);
return "listCategory";
}
@RequestMapping("/editCategory")
public String editCategory(int id,Model m) throws Exception{
Category c = categoryDAO.getOne(id);
m.addAttribute("c",c);
return "editCategory";
}
- jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<div align="center">
</div>
<div style="width:500px;margin:20px auto;text-align: center">
<table align='center' border='1' cellspacing='0'>
<tr>
<td>id</td>
<td>name</td>
<td>编辑</td>
<td>删除</td>
</tr>
<c:forEach items="${page.content}" var="c" varStatus="st">
<tr>
<td>${c.id}</td>
<td>${c.name}</td>
<td><a href="editCategory?id=${c.id}">编辑</a></td>
<td><a href="deleteCategory?id=${c.id}">删除</a></td>
</tr>
</c:forEach>
</table>
<br>
<div>
<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=${page.totalPages-1}">[末 页]</a>
</div>
<br>
<form action="addCategory" method="post">
name: <input name="name"> <br>
<button type="submit">提交</button>
</form>
</div>
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8" isELIgnored="false"%>
<div style="margin:0px auto; width:500px">
<form action="updateCategory" method="post">
name: <input name="name" value="${c.name}"> <br>
<input name="id" type="hidden" value="${c.id}">
<button type="submit">提交</button>
</form>
</div>
6.测试
SpringBoot的测试相当便捷.
- 首先在pom.xml中添加对Springboot测试和junit的依赖
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
</dependency>
- 之后新建一个测试类运行即可
@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class)
public class TestJPA {
@Autowired CategoryDAO dao;
@Test
public void test() {
List<Category> cs= dao.findAll();
for (Category c : cs) {
System.out.println("c.getName():"+ c.getName());
}
}
}
7.JPA条件查询
无需写一条sql语句.JPA规范帮你实现查询,NB!
在DAO接口中添加接口方法.JPA根据方法名通过反射创造相应的SQL语句.
例代码:
public interface CategoryDAO extends JpaRepository<Category,Integer>{
public List<Category> findByName(String name);
public List<Category> findByNameLikeAndIdGreaterThanOrderByNameAsc(String name, int id);
}
调用
List<Category> cs = dao.findByNameLikeAndIdGreaterThanOrderByNameAsc("%是%",16);
for(Category c : cs){
System.out.println(c);
}
8.Restful风格
Restful风格利用不同的method值来区分CRUD.简化url.
@GetMapping("/categories")
public String listCategory(@NotNull Model m, @RequestParam(value = "start", defaultValue = "0") int start, @RequestParam(value = "size", defaultValue = "5") int size) throws Exception {
start = start<0?0:start;
Sort sort = new Sort(Sort.Direction.DESC, "id");
Pageable pageable = new PageRequest(start, size, sort);
Page<Category> page =categoryDAO.findAll(pageable);
m.addAttribute("page", page);
return "listCategory";
}
@PostMapping("/categories")
public String addCategory(Category c) throws Exception {
categoryDAO.save(c);
return "redirect:/categories";
}
@DeleteMapping("/categories/{id}")
public String deleteCategory(Category c) throws Exception {
categoryDAO.delete(c);
return "redirect:/categories";
}
@PutMapping("/categories/{id}")
public String updateCategory(Category c) throws Exception {
categoryDAO.save(c);
return "redirect:/categories";
}
@GetMapping("/categories/{id}")
public String getCategory(@PathVariable("id") int id, @NotNull Model m) throws Exception {
Category c= categoryDAO.getOne(id);
m.addAttribute("c", c);
return "editCategory";
}
9.JSON格式
控制器传递JSON格式数据,需要用直接文本输出注解@RestController.或者@Controller和@ResponseBody,这样就可以直接返回文本传递给前端了.
@GetMapping("category")
public List<Category> listCategory(@RequestParam(value = "start",defaultValue = "0")int start,@RequestParam(value = "size",defaultValue = "5")int size)throws Exception{
start=start<0?0:start;
Sort sort = new Sort(Sort.Direction.DESC,"id");
Pageable pageable = new PageRequest(start,size,sort);
Page<Category> page = categoryDAO.findAll(pageable);
System.out.println(page);
return page.getContent();
}
@GetMapping("/category/{id}")
public Category getCategory(@PathVariable("id")int id)throws Exception{
Category c = categoryDAO.getOne(id);
System.out.println(c);
return c;
}
@PutMapping("/category")
public void addCategoryJson(@RequestBody Category category)throws Exception{
System.out.println("Spring Boot接受浏览器以JSON格式提交的数据: "+category);
}
参考资料:
how2j
posted on 2019-08-15 22:06 Best_Efforts 阅读(771) 评论(0) 编辑 收藏 举报
