ssm学习笔记day04

RequestMapping

• 首先添加依赖

• Maven的配置

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测试

在controller创建HelloController，如果只加@RequestMapping，默认跳转到新页面

如果要是加上@ResponseBody就把数据封装在包(JSON)，标签@RestController是前后分离的注解（因为默认用@ResponseBody)

通配符

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精度：'?' > '*' > '**'
例子：
/hell? 可以匹配 /hello 、 /hella 、/hellob，不可以匹配/helloo，因为oo是多个字符
/hell* 可以匹配/hello 、 /hella、/helloo等单层结构，/hello/a不可以
/hello/** 可以匹配所有/hello子层的结构

方法限定method

现在我们限定一个POST方式的Controller

测试需要用到Postman，因为浏览器不能自主Post，然后用Postman发送一个POST

可以看到POST结果返回成功，GET就返回405

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方法类型
在 RequestMethod方法上有八种方法

参数限定params

http://localhost:8080/test02?age=18&username=zhangsan&gender=0正常返回

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测试
http://localhost:8080/test02?age=17&username=zhangsan&gender=0异常，原因是age不为18。
http://localhost:8080/test02?age=18&gender=0异常，原因是不包含username。
http://localhost:8080/test02?age=18&gender=0&username=wangwu正常，顺序不影响结果
http://localhost:8080/test02?age=18&gender=1&username=wangwu异常，原因是gender为1

请求头限定headers

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内容类型限定consumes、produces

MediaType的类型

用json格式返回成功

用text格式返回415异常

produces限定类型，与consumes的区别是一个是消费者、一个是生产者，consumes是客户端到服务端的类型，produces是服务端到客户端的响应类型，即响应报文

请求实战演练

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1.使用普通变量收集参数

/*没有携带自动封装为null,有就自动封装*/@RequestMapping("/handle01")public String test(String username ,String password ,String cellphone ,boolean agreement){System.out.println(username + " " + password + " " + cellphone + " " + agreement);return "ok";}

发送三次请求分别为
第一次：http://localhost:8080/handle01?username=zhangsan&password=123456&cellphone=23142234
第二次：http://localhost:8080/handle01?username=zhangsan&password=123456&cellphone=23142234&agreement=on
第三次：http://localhost:8080/handle01?username=zhangsan&cellphone=23142234

2.使用RequestParam明确收集参数

使用RequestParam明确收集参数默认必须携带，否则报错
ps:不管参数是放到url?后面还是请求体，都能被RequestParam接收

/*使用RequestParam明确收集参数默认必须携带如果不携带就炸了*/@RequestMapping("/handle02")public String handle02(@RequestParam("username") String name ,@RequestParam("password") String pwd ,@RequestParam("cellphone") String phone ,@RequestParam("agreement") boolean ok){System.out.println(name + " " + pwd + " " + phone + " " + ok);return "ok";}

发送http://localhost:8080/handle02?username=zhangsan&password=32451&cellphone=2341234&agreement=on正常
发送http://localhost:8080/handle02?username=zhangsan&password=32451&agreement=on则报错，因为没有携带cellphone信息

@RequestMapping("/handle02")public String handle02(@RequestParam("username") String name ,@RequestParam(value = "password" , defaultValue = "123456") String pwd ,@RequestParam(value = "cellphone" ) String phone ,@RequestParam(value = "agreement" , required = false) boolean ok){System.out.println(name + " " + pwd + " " + phone + " " + ok);return "ok";}

如果属性required=false表示可以不用携带参数、default表示添加默认值，也可以不用携带参数
发送http://localhost:8080/handle02?username=zhangsan&cellphone=2341234&agreement=on返回zhangsan 123456 2341234 true

3.使用Pojo封装所有参数

Person.java

package com.atguigu.springmvc.bean;import lombok.Data;
import lombok.ToString;@Data
@ToString
public class Person {private String username ;private String password ;private String cellphone ;private boolean agreement ;}

    @RequestMapping("/handle03")public String handle03(Person person){System.out.println(person.toString());return "ok";}

4.@RequestHeader

    @RequestMapping("/handle04")public String handle04(@RequestHeader("host") String host){System.out.println(host);return "ok~"+host;}

5.获取Cookie的键值对

用@CookieValue(value = “value”)获取

@RequestMapping("/handle05")public String handle05(@CookieValue("haha") String haha){return "ok" + haha;}

发送一个含有value = haha的cookie的报文

结果正常返回，然后我就好奇如果用@RequestHeader(“Cookie”)会发生什么呢，让我们开始实验

    @RequestMapping("/handle05")public String handle05(@CookieValue("haha") String haha,@RequestHeader("Cookie") String ck){System.out.println(haha + " " + ck);return "ok" + haha + " " + ck;}

结果如下

6.pojo级联封装复杂对象

package com.atguigu.springmvc.bean;import lombok.Data;import java.util.Arrays;@Data
public class Person {private String username ;private String password ;private String cellphone ;private boolean agreement ;private Address address ;private String sex ;private String[] hobby;private String grade;
}
@Data
class Address {private String province;private String city ;private String area;
}

如果遇到以下这种笔记复杂的对象，可以考虑级联（嵌套）封装

ps：由于一直返回地址，不知道什么地方出了问题，然后我就手动Data，即alt + insert快捷键生成，代码如下。

package com.atguigu.springmvc.bean;import lombok.Data;import java.util.Arrays;public class Person {private String username ;private String password ;private String cellphone ;private Boolean agreement ;private Address address ;private String sex ;private String[] hobby;private String grade;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getCellphone() {return cellphone;}public void setCellphone(String cellphone) {this.cellphone = cellphone;}public Boolean getAgreement() {return agreement;}public void setAgreement(Boolean agreement) {this.agreement = agreement;}public Address getAddress() {return address;}public void setAddress(Address address) {this.address = address;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public String[] getHobby() {return hobby;}public void setHobby(String[] hobby) {this.hobby = hobby;}public String getGrade() {return grade;}public void setGrade(String grade) {this.grade = grade;}@Overridepublic String toString() {return "Person{" +"username='" + username + '\'' +", password='" + password + '\'' +", cellphone='" + cellphone + '\'' +", agreement=" + agreement +", address=" + address +", sex='" + sex + '\'' +", hobby=" + Arrays.toString(hobby) +", grade='" + grade + '\'' +'}';}
}class Address {private String province;private String city ;private String area;public String getArea() {return area;}public void setArea(String area) {this.area = area;}public String getCity() {return city;}public void setCity(String city) {this.city = city;}public String getProvince() {return province;}public void setProvince(String province) {this.province = province;}@Overridepublic String toString() {return "Address{" +"area='" + area + '\'' +", province='" + province + '\'' +", city='" + city + '\'' +'}';}
}

结果正常显示

7.@RequestBody接收json字符并转换

首先编写如下代码

    @RequestMapping("/handle07")public String handle07(Person person){System.out.println(person);return "ok";}

用postman发送请求

返回的结果如下

这是因为不使用 @RequestBody 注解，将无法直接接收 JSON 格式的数据，当不使用@RequestsBody的时候，Spring会处理表单数据（form-data/x-www-form-urlencoded）或者url?name=value，即键值对。
现在给它加上一个@RequestBody

    @RequestMapping("/handle07")public String handle07(@RequestBody Person person){System.out.println(person);return "ok";}

8.文件上传

• 文件上传的要求
  method = post , enctype = “multipart/form-data”
• 代码的编写

@RequestMapping("/handle08")public String handle08(Person person,@RequestParam("headerImg") MultipartFile headerImgFile,@RequestParam("lifeImg") MultipartFile[] lifeImgFile) throws IOException {//获取原始路径String originalFilename = headerImgFile.getOriginalFilename();long size = headerImgFile.getSize();InputStream inputStream = headerImgFile.getInputStream();System.out.println(originalFilename + "=>" + size);headerImgFile.transferTo(new File("D:\\javastudy\\img\\" + originalFilename));System.out.println("头像保存结束");if(lifeImgFile.length > 0){for(MultipartFile imgFile : lifeImgFile){imgFile.transferTo(new File("D:\\javastudy\\img\\" + imgFile.getOriginalFilename()));}System.out.println("生活照保存结束");}System.out.println(person);return "ok!!!";}

用MultipartFile的接收文件，MultipartFile的源代码如下

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//package org.springframework.web.multipart;import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import org.springframework.core.io.InputStreamSource;
import org.springframework.core.io.Resource;
import org.springframework.lang.Nullable;
import org.springframework.util.FileCopyUtils;public interface MultipartFile extends InputStreamSource {String getName();@NullableString getOriginalFilename();@NullableString getContentType();boolean isEmpty();long getSize();byte[] getBytes() throws IOException;InputStream getInputStream() throws IOException;default Resource getResource() {return new MultipartFileResource(this);}void transferTo(File dest) throws IOException, IllegalStateException;default void transferTo(Path dest) throws IOException, IllegalStateException {FileCopyUtils.copy(this.getInputStream(), Files.newOutputStream(dest));}
}

Test:



在properties中添加以下两句话可以修改传送文件大小

9.HttpEntity获取整个请求

    @RequestMapping("/handle09")public String handle09(HttpEntity<String> entity){System.out.println("请求头"+entity.getHeaders());System.out.println("请求体"+entity.getBody());return "OK~~~";}

就是Entity是请求头、请求体的总和，用HttpEntity可以获得请求头和请求体。

10.原生api HttpServletRequestRequest、HttpServletResponse

    @RequestMapping("/handle10")public String handle10(HttpServletRequest request, HttpServletResponse response){//原生api，HttpServletRequestRequest和HttpServletResponse 可以参考javawebString username = request.getParameter("username");System.out.println(username);return "OK~~~";}

获取HttpMethod方法

    @RequestMapping("/handle10")public String handle10(HttpServletRequest request, HttpServletResponse response, HttpMethod method){System.out.println(method);//原生api，HttpServletRequestRequest和HttpServletResponse 可以参考javawebString username = request.getParameter("username");System.out.println(username);return "OK~~~";}

小结

响应实战演练

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1.返回json

不加任何注释，默认返回json

package com.atguigu.springmvc.controller;import com.atguigu.springmvc.bean.Person;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class ResponseTestController {@RequestMapping("/resp01")public Person resp01() {Person person = new Person();person.setUsername("zhangsan");person.setPassword("111");person.setCellphone("1234");person.setAgreement(true);person.setSex("男");person.setHobby(new String[]{"足球","篮球"});person.setGrade("三年级");return person;}
}

核心原因：@RestController包含@ReponseBody(返回json对象)

2.文件下载

    @RequestMapping("/download")public ResponseEntity<byte[]> download() throws IOException {FileInputStream inputStream = new FileInputStream("D://javastudy//img//d2d0adc1a979dc30d622b1cb1596875f.png");byte[] bytes = inputStream.readAllBytes();return ResponseEntity.ok().contentType(MediaType.APPLICATION_OCTET_STREAM).contentLength(bytes.length)//文件处理方式.header("Content-Disposition" , "attachment;filename=haha.png").body(bytes);}

首先返回值为一个响应体为字节流的响应体，理由是可以调用响应头的文件类型，然后开始把自己想传输的文件整成一个文件流，然后在ResponseEnitity中配置整个响应的信息。
ps：ResponseEntity.ok()/contentType返回的都是ResponseEntity类，所以顺序先后不影响 ， APPLICATION_OCTET_STREAM是八进制流文件。