Java框架spring Boot学习笔记（三）：Controller的使用

Controller注解介绍

• @Controller：处理http请求
• @RestController： Spirng4之后新加的注解，其实是一个组合注解等同于@ResponseBody和@Controller的组合
• @RequestMapping： 用于配置url映射，期望用户通过url访问方法
• @PathVariable：获取url中的数据
• @RequestParam：使用和@PathVariable差不多，不过以？id=来传递值

@Controller的使用

需要在以前的代码结构基础上修改三个文件

为pom.xml添加一个依赖

1 <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
 </dependency>

右击pom.xml，Reimport一下

新建一个index.html文件，添加一句话

<h1>Hello Spring Boot!</h1>

修改HelloController.java，使用Controller注解，并返回index.html文件

 package com.example.demo;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;

 @Controller
 public class HelloController {

     //自动装配注解
     @Autowired
     private PeopleProperties peopleProperties;

     @RequestMapping(value = "/hello" , method = RequestMethod.GET)
     public String say() {
         return "index";
     }
 }

运行，访问本地8082端口

@RestController的使用

@RestController相当于@ResponseBody和@Controller的组合注解

修改HelloController.java

 package com.example.demo;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.RestController;

 @RestController
 public class HelloController {

     @Autowired
     private PeopleProperties peopleProperties;

     @RequestMapping(value = {"/hello"} , method = RequestMethod.GET)
     public String say() {
         return peopleProperties.getName();
     }
 }

运行，访问本地8082端口

@PathVariable的使用

修改HelloController.java，获取url中的id值显示到页面上

 package com.example.demo;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.ResponseBody;

 @ResponseBody
 @Controller
 public class HelloController {

     @Autowired
     private PeopleProperties peopleProperties;

     @RequestMapping(value = {"/hello/{id}"} , method = RequestMethod.GET)
     public String say(@PathVariable("id") Integer id) {
         return "id: " +id;
     }
 }

运行，url中的id设为2

@RequestParam的使用

修改HelloController.java，用传统的方式?id=value，来获取url中的id值显示到页面上。

 package com.example.demo;

 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.*;

 @ResponseBody
 @Controller
 public class HelloController {

     @Autowired
     private PeopleProperties peopleProperties;

     @RequestMapping(value = {"/hello"} , method = RequestMethod.GET)
     public String say(@RequestParam(value = "id" ,required = false,defaultValue = "0") Integer id) {
         return "id: " +id;
     }
 }

运行