Java中HttpServletRequestWrapper的使用与原理详解

<!-- 解析加密的 deviceId 得到 imei 和 sn -->
	<filter>
		<filter-name>deviceIdParseFilter</filter-name>
		<filter-class>com.xxxxxx.DeviceIdParseFilter</filter-class>
		<init-param>
			<param-name>encoding</param-name>
			<param-value>UTF-8</param-value>
		</init-param>
		<init-param>
			<param-name>forceEncoding</param-name>
			<param-value>true</param-value>
		</init-param>
	</filter>
	<filter-mapping>
		<filter-name>deviceIdParseFilter</filter-name>
		<url-pattern>*.do</url-pattern>
	</filter-mapping>

public class DeviceIdParseFilter implements Filter {
    private static final String KEY = "xxxxxxx";
    private static final Logger log = Logger.getLogger(DeviceIdParseFilter.class);
    private static final String[] DEFAULT_RESULT = {"",""};
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        String deviceId = request.getParameter("deviceId");
        if (deviceId != null && deviceId.length() > 0) {
            String[] result = parseDeviceId(deviceId);
            DeviceIdParseRequest req = new DeviceIdParseRequest((HttpServletRequest) request,
                    result[0], result[1]);
            chain.doFilter(req, response);
        } else {
            chain.doFilter(request, response);
        }
    }
    /**
     * 
     * 从 deviceId 里解析出 imei 和 sn
     * 
     * imei = result[0]
     * sn   = result[1]
     * 
     * 
     * @param deviceId
     * @return
     */
    private static final String[] parseDeviceId(String deviceId) {
        try {
            String src = Rc4Util.decrypt(deviceId, KEY);
            if (src.indexOf('_') >= 0) {
                return src.split("_");
            }
        } catch (Exception e) {
            log.error(e, e);
        }
        return DEFAULT_RESULT;
    }
    @Override
    public void destroy() {
    }
}

public class DeviceIdParseRequest extends HttpServletRequestWrapper {
    private String imei;
    private String sn;
    /**
     * @param request
     */
    public DeviceIdParseRequest(HttpServletRequest request) {
        super(request);
        this.imei = "";
        this.sn = "";
    }
    /**
     * @param request
     * @param imei
     * @param sn
     */
    public DeviceIdParseRequest(HttpServletRequest request, String imei, String sn) {
        super(request);
        this.imei = imei;
        this.sn = sn;
    }
    @Override
    public String getParameter(String name) {
        if ("imei".equals(name)) {
            return imei;
        } else if ("sn".equals(name)) {
            return sn;
        } else {
            return super.getParameter(name);
        }
    }
    @Override
    public String[] getParameterValues(String name) {
        if ("imei".equals(name)) {
            return new String[] { imei };
        } else if ("sn".equals(name)) {
            return new String[] { sn };
        } else {
            return super.getParameterValues(name);
        }
    }
}

@Controller
@RequestMapping("/api/")
public class TestController {


    @ResponseBody
    @RequestMapping("test.do")
    public Result test(String deviceId, String imei, String sn) {
        Map<String, String> map = new HashMap<>();
        map.put("deviceId", deviceId);
        map.put("imei", imei);
        map.put("sn", sn);
        return new Result(map);
    }


}

http://xxxxx.in.xxxxx.com/api/test.do?reqno=123456&imei=imei&sn=1001&model=mx6&os=flyme6&ver=1.0.0&locale=en_US

{
	"code": "200",
	"message": "",
	"redirect": "",
	"value": {
		"sn": "1001",
		"imei": "imei",
		"deviceId": null
	}
}

http://xxxxxxx.com/api/test.do?reqno=123456&sn=1001&model=mx6&os=flyme6&ver=1.0.0&locale=en_US&deviceId=7cfbf5cbd70bcf1c006d7d0aa77688518444497a2b45683ea41ce690e92d6d38

{

	"code": "200",
	"message": "",
	"redirect": "",
	"value": {
		"sn": "111",
		"imei": "org.testng.annotations.Test;",
		"deviceId": "7cfbf5cbd70bcf1c006d7d0aa77688518444497a2b45683ea41ce690e92d6d38"
	}
}