Spring Boot之 Controller 接收參數和返回數據總結(包括上傳、下載文件)

 

 

 

 

一、接收參數（postman發送）

1.form表單

@RequestParam("name") String name

會把傳遞過來的Form表單中的name對應到formData方法的name參數上

該注解不能接收json傳參

該注解表示name字段是必須入參的，否則會報錯

@RequestParam(value = "name", required = false) String name

required = false表示必須入參

@RequestParam(value = "name", defaultValue = "admin") String name

defaultValue = "admin"表示當name入參為空的時候給它一個默認值admin

    /**

     * 測試接收form表單、URL的數據。不能接收Json數據

     * */

    @RequestMapping(value = "/test1", method = RequestMethod.POST)

    public String formData(@RequestParam("name") String name , @RequestParam("age") int age){

        String result = "receive name = "+name+" age = "+age;

        System.out.println(result);

        return result;

    }

2.URL

代碼跟1.form表單中的代碼一樣

3.動態接收URL中的數據

@PathVariable將URL中的占位符參數綁定到控制器處理方法的入參

此種情況下，url求情中一定要帶占位符pageNo,pageSize的值，不然訪問失敗

即訪問時一定要用 http://localhost:8088/sid/test2/2/20

如果用 http://localhost:8088/sid/test2 則訪問失敗

    /**

     * 測試動態接收URL中的數據

     * */

    @RequestMapping(value = "/test2/{pageNo}/{pageSize}", method = RequestMethod.POST)

    public String urlData(@PathVariable int pageNo , @PathVariable int pageSize){

        String result = "receive pageNo = "+pageNo+" pageSize = "+pageSize;

        System.out.println(result);

        return result;

    }

 

4.json

@RequestBody 接收Json格式的數據需要加這個注解。該注解不能接收URL、Form表單傳參

    /**

     * 測試接收json數據

     * */

    @RequestMapping(value = "/jsonData", method = RequestMethod.POST)

    public String jsonData(@RequestBody TestModel tm){

        String result = "receive name = "+tm.getName()+" age = "+tm.getAge();

        System.out.println(result);

        return result;

    }

5.@RequestMapping注解詳細介紹

1.處理多個URL

@RestController  

@RequestMapping("/home")  

public class IndexController {  

  

    @RequestMapping(value = {  

        "",  

        "/page",  

        "page*",  

        "view/*,**/msg"  

    })  

    String indexMultipleMapping() {  

        return "Hello from index multiple mapping.";  

    }  

} 

這些 URL 都會由 indexMultipleMapping() 來處理： 

localhost:8080/home

localhost:8080/home/

localhost:8080/home/page

localhost:8080/home/pageabc

localhost:8080/home/view/

localhost:8080/home/view/view

 

2.HTTP的各種方法

如POST方法

@RequestMapping(value = "/test1", method = RequestMethod.POST)

3.produces、consumes 

produces 指定返回的內容類型，僅當request請求頭header中的(Accept)類型中包含該指定類型才返回。結合@ResponseBody使用
---------------------

@Controller
@RequestMapping(value = "/t")
public class TestController {
 
    //方法僅處理request請求中Accept頭中包含了"text/html"的請求
    @ResponseBody
    @RequestMapping(value = "/produces",produces = {"text/html"})
    public String testProduces(String name)
    {
        return "test requestMapping produces attribute! "+name;
    }
}

方法僅處理request請求中Accept頭中包含了"text/html"的請求

比如用postman構建一個Accept=“application/json”的請求，請求會失敗

 

comsumes  指定處理請求的提交內容類型（Content-Type），例如application/json, text/html。結合@RequestBody使用

@Controller
@RequestMapping(value = "/t")
public class TestController {
 
    //方法僅處理request Content-Type為"application/json"類型的請求
    @ResponseBody
    @RequestMapping(value = "/consumes",consumes = {"application/json"})
    public String testConsumes(@RequestBody String name)
    {
        return "test requestMapping consumes attribute! "+name;
    }
}

方法僅處理request Content-Type為"application/json"類型的請求。

如果用postman構建一個Content-Type=“application/x-www-form-urlencoded”的請求，該方法不處理

 

4.headers 

根據請求中的消息頭內容縮小請求映射的范圍

例如：

只處理header中testHeader = sid的請求

    //方法僅處理header中testHeader = sid的請求
    @ResponseBody
    @RequestMapping(value = "/header",headers = {"testHeader = sid"})
    public String testHeader(String name)
    {
        return "test requestMapping headers attribute! "+name;
    }

構建一個header鍾不帶testHeader=sid的請求，會失敗

必須要header中帶testHeader=sid的請求的請求才處理

 

 

 

5.結合params屬性處理請求參數

例如：

請求參數name=sid的時候由getParams方法處理

請求參數name=lee的時候由getParamsDifferent方法處理

@Controller
@RequestMapping(value = "/t")
public class TestController {
 
    @RequestMapping(value = "/params", params = {
            "name=sid"
    })
    @ResponseBody
    public String getParams(@RequestParam("name") String name) {
        return "getParams method do " + name;
    }
    @RequestMapping(value = "/params", params = {
            "name=lee"
    })
    @ResponseBody
    public String getParamsDifferent(@RequestParam("name") String name) {
        return "getParamsDifferent method do  " + name;
    }
}

 

 

二、返回值
@RestController注解，相當於@Controller+@ResponseBody兩個注解的結合，返回json數據不需要在方法前面加@ResponseBody注解了，但使用@RestController這個注解，就不能返回jsp,html頁面，視圖解析器無法解析jsp,html頁面

1.返回靜態html頁面
application.yml
---------------------

server:
  port: 8088
  servlet:
    context-path: /sid
 
spring:
  mvc:
   view:
    prefix: /
    suffix: .html
 
 
 

    /**
     * 返回界面 index.html
     * @Controller修飾的類 直接定義方法返回值為String
     * */
    @RequestMapping(value = "/index")
    public String index(){
 
        return "index";
    }
 
    /**返回界面 index.html
     * @RestController修飾的類  
     * 需要配合視圖解析器    
     * */
    @RequestMapping("/indexmv")
    public ModelAndView indexmv() {
        ModelAndView mv = new ModelAndView("index");
        return mv;
    }

 

2.通過object返回查詢結果

@ResponseBody會把返回值變成json

    /**
     * 直接查詢得到的model類，@ResponseBody會把返回值變成json
     * */
    @RequestMapping(value = "/object", method = RequestMethod.POST)
    @ResponseBody
    public Object object(@RequestParam("name") String name , @RequestParam("age") String age){
 
        TestModel t =getModel( name , age);
        List<TestModel> list =new ArrayList();
        list.add(t);
        return list;
    }

 

3.返回時直接拋出自定義異常

    /**
     * 返回時直接拋出自定義異常
     * */
    @RequestMapping(value = "/list", method = RequestMethod.POST)
    @ResponseBody
    public List<TestModel> list(@RequestParam("name") String name , @RequestParam("age") String age){
        TestModel t =getModel( name , age);
 
        if(t != null){
            throw new MyException("測試拋出自定義異常");
        }
        List<TestModel> list =new ArrayList();
        list.add(t);
        list.add(t);
        return list;
    }

 

4.返回ResponseEntity

兩種不同的創建ResponseEntity的方式

 /**
     * 返回ResponseEntity
     *
     * ResponseEntity的優先級高於@ResponseBody。
     * 在不是ResponseEntity的情況下才去檢查有沒有@ResponseBody注解。
     * 如果響應類型是ResponseEntity可以不寫@ResponseBody注解
     * */
    @RequestMapping(value = "/responseEntity", method = RequestMethod.POST)
    public ResponseEntity<?> responseEntity(@RequestParam("name") String name , @RequestParam("age") String age){
 
        try{
            TestModel t =getModel( name , age);
            if(!t.getAge().equals("27")){
                throw new MyException("年齡錯誤！");
            }
            List<TestModel> list =new ArrayList();
            list.add(t);
            list.add(t);
            HttpHeaders headers = new HttpHeaders();
            //headers.set("Content-type", "application/json;charset=UTF-8");
            headers.add("code", "1");
            headers.add("msg", "success");
            headers.add("error", "");
            return new ResponseEntity<List>(list,headers,HttpStatus.OK);
        }catch (MyException e){
            return ResponseEntity.badRequest()
                    //.header("Content-type", "application/json;charset=UTF-8")
                    .header("code", "0")
                    .header("msg", "")
                    .header("error", e.getMessage())//中文亂碼
                    .build();//build無返回值 body有返回值
        }
    }

--------------------------------------

 

 

5.返回自定義類，其中有code msg error data 而查詢結果在data中

MyResponse.java

package com.sid.springtboot.test.springboottest;
 
public class MyResponse<T> {
    private String code;
    private String msg;
    private String error;
    private T data;
 
    public MyResponse(String code, String msg, String error, T data) {
        this.code = code;
        this.msg = msg;
        this.error = error;
        this.data = data;
    }
 
    public String getCode() {
        return code;
    }
 
    public void setCode(String code) {
        this.code = code;
    }
 
    public String getMsg() {
        return msg;
    }
 
    public void setMsg(String msg) {
        this.msg = msg;
    }
 
    public String getError() {
        return error;
    }
 
    public void setError(String error) {
        this.error = error;
    }
 
    public T getData() {
        return data;
    }
 
    public void setData(T data) {
        this.data = data;
    }
}

MyException.java

package com.sid.springtboot.test.springboottest;
 
public class MyException extends RuntimeException{
 
    private String errorCode;
    private String msg;
 
    public MyException(String message) {
        super(message);
    }
 
    public MyException(String errorCode, String msg) {
        this.errorCode = errorCode;
        this.msg = msg;
    }
 
    public String getErrorCode() {
        return errorCode;
    }
 
    public void setErrorCode(String errorCode) {
        this.errorCode = errorCode;
    }
 
    public String getMsg() {
        return msg;
    }
 
    public void setMsg(String msg) {
        this.msg = msg;
    }
}

controller

 /**
     * 返回自定義類，其中有code msg error data 而查詢結果在data中
     * */
    @RequestMapping(value = "/myResponse", method = RequestMethod.POST)
    @ResponseBody
    public MyResponse<?> myResponse(@RequestParam("name") String name , @RequestParam("age") String age){
        try{
            TestModel t1 =getModel( name , age);
            if(!t1.getAge().equals("27")){
                throw new MyException("年齡錯誤！");
            }
            List<TestModel> list =new ArrayList();
            list.add(t1);
            list.add(t1);
            list.add(t1);
            return new MyResponse<List>("1","success",null,list);
        }catch (MyException e){
            return new MyResponse<>("0",null,e.getMessage(),null);
        }
    }

 

 

 

三、上傳、下載文件

上傳文件

    @PostMapping("/upload")
    @ResponseBody
    public Map<String, String> upload1(@RequestParam("file") MultipartFile file) throws IOException {
        System.out.println("[文件類型] - [{}]"+ file.getContentType());
        System.out.println("[文件名稱] - [{}]"+ file.getOriginalFilename());
        System.out.println("[文件大小] - [{}]"+ file.getSize());
        //保存
        file.transferTo(new File("D:\\gitrep\\springboot\\testFile\\" + file.getOriginalFilename()));
        Map<String, String> result = new HashMap<>(16);
        result.put("contentType", file.getContentType());
        result.put("fileName", file.getOriginalFilename());
        result.put("fileSize", file.getSize() + "");
        return result;
    }

下載文件

1.通過ResponseEntity<InputStreamResource>實現

封裝ResponseEntity，將文件流寫入body中。這里注意一點，就是文件的格式需要根據具體文件的類型來設置，一般默認為application/octet-stream。文件頭中設置緩存，以及文件的名字。文件的名字寫入了，都可以避免出現文件隨機產生名字，而不能識別的問題。
---------------------

@GetMapping("/download")
    public ResponseEntity<InputStreamResource> downloadFile() throws IOException {
        String filePath = "D:\\gitrep\\springboot\\testFile\\" + "api-ms-win-core-console-l1-1-0.dll";
        FileSystemResource file = new FileSystemResource(filePath);
        HttpHeaders headers = new HttpHeaders();
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getFilename()));
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");
 
        return ResponseEntity.ok().headers(headers)
                .contentLength(file.contentLength())
                .contentType(MediaType.parseMediaType("application/octet-stream"))
                .body(new InputStreamResource(file.getInputStream()));
    }

2.用HttpServletResponse

@GetMapping("/download2")
    public String downloadFile2( HttpServletResponse response) throws IOException {
        // 獲取指定目錄下的文件
        String fileName = "D:\\gitrep\\springboot\\testFile\\" + "api-ms-win-core-console-l1-1-0.dll";
        File file = new File(fileName);
        // 如果文件名存在，則進行下載
        if (file.exists()) {
            // 配置文件下載
            response.setHeader("content-type", "application/octet-stream");
            response.setContentType("application/octet-stream");
            // 下載文件能正常顯示中文
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName, "UTF-8"));
 
            // 實現文件下載
            byte[] buffer = new byte[1024];
            FileInputStream fis = null;
            BufferedInputStream bis = null;
            try {
                fis = new FileInputStream(file);
                bis = new BufferedInputStream(fis);
                OutputStream os = response.getOutputStream();
                int i = bis.read(buffer);
                while (i != -1) {
                    os.write(buffer, 0, i);
                    i = bis.read(buffer);
                }
                System.out.println("Download the song successfully!");
            }
            catch (Exception e) {
                System.out.println("Download the song failed!");
            } finally {
                if (bis != null) {
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (fis != null) {
                    try {
                        fis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
        return null;
    }