Enumeration<String> parameterNames = request.getParameterNames();
while (parameterNames.hasMoreElements()) {
    String paraName = parameterNames.nextElement();
    System.out.println(paraName + ": " + request.getParameter(paraName));
}

方法二

Map<String, String[]> map = request.getParameterMap();
Set<Map.Entry<String, String[]>> keSet = map.entrySet();
for (Iterator<Map.Entry<String, String[]>> itr = keSet.iterator(); itr.hasNext(); ) {
    Map.Entry<String, String[]> me = itr.next();
    Object ok = me.getKey();
    Object ov = me.getValue();
    String[] value = new String[1];
    if (ov != null) {
        value = (String[]) ov;
    } else {
        value[0] = ov.toString();
    }
    for (int k = 0; k < value.length; k++) {
        System.out.println(ok + "=" + value[k]);
    }
}

結(jié)論

經(jīng)過測試以上兩個方法可以獲取GET請求的參數(shù)，以及參數(shù)格式為form-data、x-www-form-urlencoded的POST請求，但是json格式參數(shù)（postman中為raw）的參數(shù)不能獲得。

根據(jù)代碼的簡介程度，選擇方法一，明顯更舒服一些。

以上結(jié)論經(jīng)過postman實測.

獲取POST請求json格式的參數(shù)

以上方法已經(jīng)可以獲取大多數(shù)情況下的請求的參數(shù)，但是明顯還不能滿足需求，需要獲取傳入json格式的參數(shù)。

經(jīng)過檢索推薦方法（參看后邊完整方法）

經(jīng)過一番檢索，網(wǎng)上推薦的方法一般都是使用流來進行參數(shù)讀取，即使用getInputStream()和getReader()：

Map<String, Object> params = new HashMap<>();
BufferedReader br = null;
try {
    try {
        br = request.getReader();
    } catch (IOException e) {
        e.printStackTrace();
    }
    String str;
    StringBuilder wholeStr = new StringBuilder();
    while ((str = Objects.requireNonNull(br).readLine()) != null) {
        wholeStr.append(str);
    }
    if (StrUtil.isNotEmpty(wholeStr.toString())) {
        params = JSON.parseObject(wholeStr.toString(), Map.class);
    }
} catch (IOException e) {
    e.printStackTrace();
}
System.out.println(params);

遇到的問題及解決思路

問題1 流不能多次被調(diào)用

但是又會遇到如下問題：

ERROR m.e.handler.GlobalExceptionHandler - getInputStream() has already been called for this request
java.lang.IllegalStateException: getInputStream() has already been called for this request
at org.apache.catalina.connector.Request.getReader(Request.java:1212)
at org.apache.catalina.connector.RequestFacade.getReader(RequestFacade.java:504)

根據(jù)報錯信息分析簡單來說，就是getInputStream()已經(jīng)被調(diào)用了，不能再次調(diào)用?？墒俏铱创a上，我也沒調(diào)用。經(jīng)過一番檢索，原來@RequestBody注解配置后，默認會使用流來讀取數(shù)據(jù)。

具體原因：

默認配置時，getInputStream()和getReader()一起使用會報錯，使用兩遍getInputStream()，第二遍會為空。
當存在@RequestBody等注解時，springMVC已讀取過一遍流，默認單獨使用getInputStream()或getReader()都為空。

實測，不加@RequestBody注解，可以如期獲得請求中的json參數(shù)，但是又不得不加@RequestBody注解。這樣就需要新的思路

解決思路

寫filter繼承HttpServletRequestWrapper，緩存InputStream，覆蓋getInputStream()和getReader()方法，使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());讀取InputStream。

實現(xiàn)方法

1.定義增強類，繼承繼承HttpServletRequestWrapper

將請求體中的流copy一份，覆寫getInputStream()和getReader()方法供外部使用。每次調(diào)用覆寫后的getInputStream()方法都是從復制出來的二進制數(shù)組中進行獲取，這個二進制數(shù)組在對象存在期間一直存在，這樣就實現(xiàn)了流的重復讀取。

public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {
    private byte[] body;
    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        body = HttpHelper.getBodyString(request).getBytes(StandardCharsets.UTF_8);
    }
    @Override
    public BufferedReader getReader() throws IOException {
        return new BufferedReader(new InputStreamReader(getInputStream()));
    }
    @Override
    public ServletInputStream getInputStream() throws IOException {
        final ByteArrayInputStream bais = new ByteArrayInputStream(body);
        return new ServletInputStream() {
            @Override
            public int read() throws IOException {
                return bais.read();
            }
            @Override
            public boolean isFinished() {
                return false;
            }
            @Override
            public boolean isReady() {
                return false;
            }
            @Override
            public void setReadListener(ReadListener readListener) {
            }
        };
    }
    public void setInputStream(byte[] body) {
        this.body = body;
    }
}

2.構(gòu)建過濾器

@Slf4j
@WebFilter(filterName = "RequestWrapperFilter", urlPatterns = "/api/test/test2")
public class RequestWrapperFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException
            , IOException {
        ServletRequest requestWrapper = null;
        if (request instanceof HttpServletRequest) {
            requestWrapper = new BodyReaderHttpServletRequestWrapper((HttpServletRequest) request);
        }
        if (null == requestWrapper) {
            log.error("過濾器包裝request失敗!將返回原來的request");
            chain.doFilter(request, response);
        } else {
            log.info("過濾器包裝request成功");
            chain.doFilter(requestWrapper, response);
        }
    }
    @Override
    public void destroy() {
    }
}

注意事項：

使用@WebFilter注解的urlPatterns屬性，可指定過濾哪一個接口方法。
過濾器類最好不要交由Spring管理，否則每一個接口都會進行過濾（實測）。例如：不要添加@Component注解. 3.編寫工具類方便調(diào)用

/**
 * description:http輔助工具類
 *
 * @author RenShiWei
 * Date: 2021/5/7 22:11
 **/
public class HttpHelper {
    /**
     * description:從request獲取body的json數(shù)據(jù)
     *
     * @param request /
     * @return /
     * @author RenShiWei
     * Date: 2021/5/7 22:44
     */
    public static String getBodyString(ServletRequest request) {
        StringBuilder sb = new StringBuilder();
        ServletInputStream inputStream = null;
        BufferedReader reader = null;
        try {
            inputStream = request.getInputStream();
            reader = new BufferedReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
            String line = "";
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return sb.toString();
    }
    /**
     * description:從request獲取body的json數(shù)據(jù)，并格式化成map形式
     *
     * @param request /
     * @return /
     * @author RenShiWei
     * Date: 2021/5/7 22:44
     */
    @SuppressWarnings("all")
    public static Map<String, Object> getBodyMap(ServletRequest request) {
        Map<String, Object> params = new HashMap<>();
        String bodyString = getBodyString(request);
        if (StrUtil.isNotEmpty(bodyString)) {
            params = JSON.parseObject(bodyString, Map.class);
        }
        return params;
    }
}

4.在SpringBoot啟動類上添加@ServletComponentScan注解

使用

@RestController
@RequestMapping("/api/test")
public class TestController {
    @GetMapping("/test1")
    @AnonymousAccess
    public ResponseEntity<String> test1(HttpServletRequest request) {
        System.out.println("---GET請求 getParameterNames 入?yún)?--");
        try {
            request.setCharacterEncoding("utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        Enumeration<String> parameterNames = request.getParameterNames();
        while (parameterNames.hasMoreElements()) {
            String paraName = parameterNames.nextElement();
            System.out.println(paraName + ": " + request.getParameter(paraName));
        }
        System.out.println("---GET請求 getParameterMap 入?yún)?--");
        Map<String, String[]> map = request.getParameterMap();
        Set<Map.Entry<String, String[]>> keSet = map.entrySet();
        for (Iterator<Map.Entry<String, String[]>> itr = keSet.iterator(); itr.hasNext(); ) {
            Map.Entry<String, String[]> me = itr.next();
            Object ok = me.getKey();
            Object ov = me.getValue();
            String[] value = new String[1];
            if (ov != null) {
                value = (String[]) ov;
            } else {
                value[0] = ov.toString();
            }
            for (int k = 0; k < value.length; k++) {
                System.out.println(ok + "=" + value[k]);
            }
        }
        return ResponseEntity.ok(null);
    }
    @PostMapping("/test2")
    @AnonymousAccess
    public ResponseEntity<String> test2(@RequestBody TestParam testParam, HttpServletRequest request) {
        String body = HttpHelper.getBodyString(request);
        Map<String, Object> bodyMap = HttpHelper.getBodyMap(request);
        System.out.println("body: " + body);
        System.out.println("bodyMap: " + bodyMap);
        return ResponseEntity.ok(null);
    }
}

postman測試

GET請求