11-SpringBoot——Spring MVC基础-常用注解

Spring MVC基础-常用注解

【博文目录>>>】

【项目源码>>>】

【常用注解】

Spring MVC 常用以下几个注解。

（1） @Controller

@Controller 注解在类上，表明这个类是Spring MVC 的Controller，将其声明为Spring的一个Bean, Dispatcher Servlet 会自动扫描注解了此注解的类并将Web 请求映射到注解了@RequestMapping 的方法上。这里特别指出，在声明普通Bean的时候，使用@Component、@Service 、@Repository 和@Controller 是等等的，因为@Service 、@Repository、@Controller 都组合了@Compoment 元注解；但在Spring MVC 声明控制器Bean 的时候，只能使用@Controller。

（2）@RequestMapping

@RequestMapping 注解是用来映射Web 请求（访问路径和参数）、处理类和方法的。@RequestMapping 可以注解在类或方法上。注解在方法上的@RequestMapping 路径会继承注解在类上的路径，@RequestMapping 支持Serviet 的request 和response 作为参数，也支持对request和response 的媒体类型进行配置。

（3）@Response Body

@ResponseBody 支持将返回值放在response 体内，而不是返回一个页面。我们在很多基于Ajax 的程序的时候，可以以此注解返回数据而不是页面：此注解可放置在返回值前或者方法上。

（4）@RequestBody

@RequestBody 允许request 的参数在request 体中，而不是在直接链接在地址后面。此注解放置在参数前。

（5）@Path Variable

@Path Variable 用来接收路径参数，如/news/001 ，可接收001作为参数，此注解放置在参数前。

（6）@RestController

@RestController 是一个组合注解，组合了@Controller 和＠ResponseBody ，这就意味着当你只开发一个和页面交互数据的控制的时候，需要使用此注解。若没有此注解，要想实现上述功能，则需自己在代码中加@Controller 和@ResponseBody 两个注解。

【代码实现】

package com.example.spring.framework.mvc.annotation.domain;

/**
* Author: 王俊超
* Date: 2017-07-11 22:07
* All Rights Reserved !!!
*/
public class DemoObj {
private Long id;
private String name;

public DemoObj() {
super();
}
public DemoObj(Long id, String name) {
super();
this.id = id;
this.name = name;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

package com.example.spring.framework.mvc.annotation.web;

import com.example.spring.framework.mvc.annotation.domain.DemoObj;
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.ResponseBody;

import javax.servlet.http.HttpServletRequest;

/**
* Author: 王俊超
* Date: 2017-07-11 22:10
* All Rights Reserved !!!
*/
@Controller // 1
@RequestMapping("/anno") //2
public class DemoAnnoController {

@RequestMapping(produces = "text/plain;charset=UTF-8")    // 3
public @ResponseBody
String index(HttpServletRequest request) { // 4
return "url:" + request.getRequestURL() + " can access";
}

@RequestMapping(value = "/pathvar/{str}", produces = "text/plain;charset=UTF-8")// 5
public @ResponseBody
String demoPathVar(@PathVariable String str, //3
HttpServletRequest request) {
return "url:" + request.getRequestURL() + " can access,str: " + str;
}

@RequestMapping(value = "/requestParam", produces = "text/plain;charset=UTF-8") //6
public @ResponseBody
String passRequestParam(Long id,
HttpServletRequest request) {

return "url:" + request.getRequestURL() + " can access,id: " + id;

}

@RequestMapping(value = "/obj", produces = "application/json;charset=UTF-8")//7
@ResponseBody //8
public String passObj(DemoObj obj,
HttpServletRequest request) {

return "url:" + request.getRequestURL()
+ " can access, obj id: " + obj.getId() + " obj name:" + obj.getName();

}

@RequestMapping(value = {"/name1", "/name2"}, produces = "text/plain;charset=UTF-8")//9
public @ResponseBody
String remove(HttpServletRequest request) {

return "url:" + request.getRequestURL() + " can access";
}

}

package com.example.spring.framework.mvc.annotation.web;

import com.example.spring.framework.mvc.annotation.domain.DemoObj;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
* Author: 王俊超
* Date: 2017-07-11 22:12
* All Rights Reserved !!!
*/
@RestController //1
@RequestMapping("/rest")
public class DemoRestController {

@RequestMapping(value = "/getjson",
produces = {"application/json;charset=UTF-8"}) //2
public DemoObj getjson(DemoObj obj) {
return new DemoObj(obj.getId() + 1, obj.getName() + "yy");//3
}

@RequestMapping(value = "/getxml",
produces = {"application/xml;charset=UTF-8"})//4
public DemoObj getxml(DemoObj obj) {
return new DemoObj(obj.getId() + 1, obj.getName() + "yy");
}

}

package com.example.spring.framework.mvc.annotation.web;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

/**
* Author: 王俊超
* Date: 2017-07-11 22:19
* All Rights Reserved !!!
*/
@Configuration
@EnableWebMvc
@ComponentScan("com.example.spring.framework.mvc.annotation.web")
public class MyMvcConfig {
}

package com.example.spring.framework.mvc.annotation.web;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

/**
* Author: 王俊超
* Date: 2017-07-11 21:51
* All Rights Reserved !!!
*/
public class WebInitializer implements WebApplicationInitializer {
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
ctx.register(MyMvcConfig.class);
ctx.setServletContext(servletContext);

ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher",
new DispatcherServlet(ctx));
servlet.addMapping("/");
servlet.setLoadOnStartup(1);
}
}