修改Request与Response中的内容-CFANZ编程社区

需求背景：与客户端通信内容需要加密。客户端将请求参数进行加密，服务端对响应结果进行加密。

那么对于后端而言，最方便的就是在过滤器里面对请求、响应进行统一处理了。这里需要涉及到HttpServletRequestWrapper与HttpServletResponseWrapper。

【1】请求处理

如下所示ParameterRequestWrapper 继承自HttpServletRequestWrapper ，重写获取参数的方法。

/**
 * Created by jianggc at 2022/4/5.
 */
public class ParameterRequestWrapper extends HttpServletRequestWrapper {
    private Map<String , String[]> params = new HashMap<String, String[]>();

    @SuppressWarnings("unchecked")
    public ParameterRequestWrapper(HttpServletRequest request) {
        // 将request交给父类，以便于调用对应方法的时候，将其输出
        super(request);
        //将参数表，赋予给当前的Map以便于持有request中的参数
        this.params.putAll(request.getParameterMap());
    }
    //重载一个构造方法
    public ParameterRequestWrapper(HttpServletRequest request , Map<String , Object> extendParams) {
        this(request);
        addAllParameters(extendParams);//这里将扩展参数写入参数表
    }

    @Override
    public String getParameter(String name) {//重写getParameter，代表参数从当前类中的map获取
        String[]values = params.get(name);
        if(values == null || values.length == 0) {
            return null;
        }
        return values[0];
    }

    @Override
    public Enumeration<String> getParameterNames() {
        return new Vector(params.keySet()).elements();
    }

    @Override
    public String[] getParameterValues(String name) {
        String[] values = params.get(name);
        if (values == null || values.length == 0) {
            return null;
        }
        return values;
    }


    public void addAllParameters(Map<String , Object>otherParams) {//增加多个参数
        for(Map.Entry<String , Object>entry : otherParams.entrySet()) {
            addParameter(entry.getKey() , entry.getValue());
        }
    }

    public void addParameter(String name , Object value) {//增加参数
        if(value != null) {
            if(value instanceof String[]) {
                params.put(name , (String[])value);
            }else if(value instanceof String) {
                params.put(name , new String[] {(String)value});
            }else {
                params.put(name , new String[] {String.valueOf(value)});
            }
        }
    }
}

上面给了入口方法addAllParameters让你可以放入需要的数据。这个操作是在过滤器里面处理的。

由于与客户端协商了参数传递方式为params=encrypt(userName=jane&mobile=13813813800),所以这里我们对params进行处理，回复为springboot喜欢的格式。

/**
 * Created by jianggc at 2022/4/5.
 */
@WebFilter(urlPatterns={"/*"})
public class RequestAesFilter implements Filter {
    private static final Logger logger= LoggerFactory.getLogger(RequestAesFilter.class);
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // 获取request
        HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
        String params = httpServletRequest.getParameter("params");
        Map<String,Object> parmMap= new HashMap<>();
        if(!StringUtils.isEmpty(params)){
            try {
                String decryptBase64 = AesUtils.decryptBase64(params, AesUtils.aesKey);
                String[] split = decryptBase64.split("&");
                for(String entry:split){
                    String[] strings = entry.split("=");
                    parmMap.put(strings[0],strings[1]);
                }
            } catch (Exception e) {
                logger.error(e.getMessage(),e);
            }
        }
        logger.debug("解密后的parmMap：{}",parmMap);
        ParameterRequestWrapper pr = new ParameterRequestWrapper(httpServletRequest, parmMap);
        chain.doFilter(pr, response);

    }
}

【2】响应处理

这里ResponseWrapper继承自HttpServletResponseWrapper提供了写入和读取的方法。

public class ResponseWrapper extends HttpServletResponseWrapper {

    // 真正缓存数据的流
    private ByteArrayOutputStream byteArrayOutputStream = null;
    private ServletOutputStream servletOutputStream = null;
    private PrintWriter writer = null;

    public ResponseWrapper(HttpServletResponse response) {
        super(response);
        // TODO Auto-generated constructor stub
        byteArrayOutputStream = new ByteArrayOutputStream();
        servletOutputStream = new WrapperOutputStream(byteArrayOutputStream);
        writer = new PrintWriter(byteArrayOutputStream);
    }

    /**
     *     当获取字节输出流时，实际获取的是我们自己包装的字节输出流
     */
    public ServletOutputStream getOutputStream() {
        return servletOutputStream;
    }

    /**
     *     当获取字符输出流时，实际获取的是我们自己包装的字符输出流
     */
    public PrintWriter getWriter() {
        return writer;
    }

    public void flushBuffer() throws IOException {
        if (servletOutputStream != null) {
            servletOutputStream.flush();
        }
        if (writer != null) {
            writer.flush();
        }
    }

    public Map<String, String> getHeaders() {
        Map<String, String> headers = new HashMap(0);
        Iterator var3 = this.getHeaderNames().iterator();

        while(var3.hasNext()) {
            String headerName = (String)var3.next();
            headers.put(headerName, this.getHeader(headerName));
        }

        return headers;
    }


    public byte[] getResponseData() throws IOException {
        flushBuffer();
        return byteArrayOutputStream.toByteArray();
    }

    public String getContent() throws IOException {
        flushBuffer();
        return byteArrayOutputStream.toString();
    }
}

class WrapperOutputStream extends ServletOutputStream {

    private ByteArrayOutputStream baos;

    public WrapperOutputStream(ByteArrayOutputStream out) {
        super();
        this.baos = out;
    }

    public boolean isReady() {
        return true;
    }

    public void write(int b) throws IOException {
        this.baos.write(b);
    }

    public void write(byte[] b) throws IOException {
        this.baos.write(b);
    }

    public void write(byte[] b, int off, int len) throws IOException {
        this.baos.write(b, off, len);
    }

    public String getContent() {
        return this.baos.toString();
    }

    public byte[] toByteArray() {
        return this.baos.toByteArray();
    }


    @Override
    public void setWriteListener(WriteListener listener) {

    }
}

同样的思路，我们在过滤器里面对响应结果进行加密。

/**
 * Created by jianggc at 2022/4/5.
 */
@WebFilter(urlPatterns={"/*"})
public class ResponseAesFilter implements Filter {
    private static final Logger logger= LoggerFactory.getLogger(ResponseAesFilter.class);
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        ResponseWrapper responseWrapper = new ResponseWrapper((HttpServletResponse) response);
        HttpServletRequest httpServletRequest= (HttpServletRequest) servletRequest;
        String requestURI = httpServletRequest.getRequestURI();
        chain.doFilter(servletRequest, responseWrapper);
        String wrapperContent = responseWrapper.getContent();
        logger.debug("当前请求requestURI：{}",requestURI);
        logger.debug("当前请求获取的响应数据：{}",wrapperContent);
        if(requestURI.startsWith("/app")){// 只对安卓端进行处理
            try{
                JSONObject parseObject = JSONObject.parseObject(wrapperContent);
                JSONObject dataObj = parseObject.getJSONObject("data");
                if(dataObj!=null&&!dataObj.isEmpty()){
                    String dataObjStr=JsonUtil.replaceAllBlank(dataObj.toJSONString());
                    String encryptBase64 = AesUtils.encryptBase64(dataObjStr, AesUtils.aesKey);
                    logger.debug("加密后的响应data：{}",encryptBase64);
                    parseObject.put("data",JsonUtil.replaceAllBlank(encryptBase64));
                    String decryptBase64 = AesUtils.decryptBase64(encryptBase64, AesUtils.aesKey);
                    logger.debug("解密后的响应data：{}",decryptBase64);
                }
                wrapperContent=parseObject.toJSONString();
                logger.debug("当前安卓请求加密的响应数据：{}",wrapperContent);
            }catch (Exception e){
                logger.error(e.getMessage(),e);
            }
        }
        ServletOutputStream out = response.getOutputStream();
        out.write(wrapperContent.getBytes(Charset.forName("UTF-8")));
        out.flush();
    }
}