解决request.getInputStream()只能读取一次的问题

参考文章：http://dditblog.com/itshare_529.html

代码需要获取入参里面URL后面的参数，还有POST请求里面BODY的数据；

1、直接获取URL后面的数据

直接使用 request.getParameter("appKey"); 就可以完成

2、获取BODY里面的JSON数据

无法直接获取request，直接获取getInputStream()里面入参情况，遍历的时候会提示stream close()的错误；

造成原因：

request在Spring里面已经获取了一次，流只能读一次、 读了就没有了、为了后面的代码还能够取得流；

解决办法：

/**
 * 获取请求Body
 *
 * @param request
 * @return
 */
public static String getBodyString(ServletRequest request) {
    StringBuilder sb = new StringBuilder();
    InputStream inputStream = null;
    BufferedReader reader = null;
    try {
        inputStream = request.getInputStream();
        reader = new BufferedReader(new InputStreamReader(inputStream, Charset.forName("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();
}

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {
            
    // 防止流读取一次后就没有了, 所以需要将流继续写出去
    ServletRequest requestWrapper = new BodyReaderHttpServletRequestWrapper(request);
    String json = HttpHelper.getBodyString(requestWrapper);
            
    System.out.println(json);

    filterChain.doFilter(requestWrapper, response);
}

public class BodyReaderHttpServletRequestWrapper extends HttpServletRequestWrapper {

    private final byte[] body;

    public BodyReaderHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
        super(request);
        body = HttpHelper.getBodyString(request).getBytes(Charset.forName("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) {

            }
        };
    }

}