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SpringBoot获取request中body的json参数

Duktig丶 人气:0

背景

最近开发项目,因为有第三方调用我们的接口,我们使用SpringBoot以JavaBean的方式接收了我们预期的参数,参数接收也没有什么异常。但是有一些需求问题需要沟通,需要拿到合作第三方传入的所有参数,来进行参数核验。

如何拿到请求的所有参数呢?正常的思路肯定是从request中获取,如果是GET请求,参数在请求路径中拼接;如果是POST请求,参数在request的请求体(body)中。

一番检索,很容易拿到相关代码。但是经过实操,发现并不能如期获取到参数。经过思考,我的接口是POST请求,参数形式是json格式(使用了@RequestBody来修饰参数)。

具体过程参看如下分析

获取请求中的参数(非json格式参数)

获取方法

方法一

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]);
    }
}

结论

经过测试以上两个方法可以获取GET请求的参数,以及参数格式为form-data、x-www-form-urlencoded的POST请求,但是json格式参数(postman中为raw)的参数不能获得

根据代码的简介程度,选择方法一,明显更舒服一些。

以上结论经过postman实测.

获取POST请求json格式的参数

以上方法已经可以获取大多数情况下的请求的参数,但是明显还不能满足需求,需要获取传入json格式的参数。 

经过检索推荐方法(参看后边完整方法)

经过一番检索,网上推荐的方法一般都是使用流来进行参数读取,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);

遇到的问题及解决思路

问题1 流不能多次被调用

但是又会遇到如下问题:

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)

根据报错信息分析简单来说,就是getInputStream()已经被调用了,不能再次调用。可是我看代码上,我也没调用。经过一番检索,原来@RequestBody注解配置后,默认会使用流来读取数据。

具体原因:

实测,不加@RequestBody注解,可以如期获得请求中的json参数,但是又不得不加@RequestBody注解。这样就需要新的思路

解决思路

写filter继承HttpServletRequestWrapper,缓存InputStream,覆盖getInputStream()和getReader()方法,使用ByteArrayInputStream is = new ByteArrayInputStream(body.getBytes());读取InputStream。

实现方法

1.定义增强类,继承继承HttpServletRequestWrapper

将请求体中的流copy一份,覆写getInputStream()和getReader()方法供外部使用。每次调用覆写后的getInputStream()方法都是从复制出来的二进制数组中进行获取,这个二进制数组在对象存在期间一直存在,这样就实现了流的重复读取。

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.构建过滤器

@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("过滤器包装request失败!将返回原来的request");
            chain.doFilter(request, response);
        } else {
            log.info("过滤器包装request成功");
            chain.doFilter(requestWrapper, response);
        }
    }
    @Override
    public void destroy() {
    }
}

注意事项:

/**
 * description:http辅助工具类
 *
 * @author RenShiWei
 * Date: 2021/5/7 22:11
 **/
public class HttpHelper {
    /**
     * description:从request获取body的json数据
     *
     * @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:从request获取body的json数据,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启动类上添加@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请求 getParameterNames 入参---");
        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请求 getParameterMap 入参---");
        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测试

GET请求

POST的JSON格式参数(其他方式结果与GET请求结果一致)

结果

以上为个人经验,希望能给大家一个参考,也希望大家多多支持。

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