springboot HandlerIntercepter拦截器修改request body数据的操作

springboot HandlerIntercepter-修改request body数据的操作

实际工作中学习技术是最快、最深刻的。当然，自身的持续学习意识是必须的

技术栈版本：

spring boot 2.0.2

遇到事儿了

近来做业务需求，前端同学fe将userId和userName放到request header中了。

后端api接口要想使用userId和userName，每个接口都要从header中获取。

试想一下，如果你有十个接口，那么每个接口都要写一遍

Object.setUserId(request.getHeader("userId"))

正如下面代码段

@RestController

@Validated

@RequestMAPPing("/template")

public class TemplateController {

// 一个feign client

@Autowired

TemplateClient templateClient

@PostMapping(value = "/create", produces = MediaType.APPLICATION_jsON_VALUE)

public ResultVO create(@RequestBody @Valid TemplateParam param, HttpServletRequest request) {

// 每个接口都要写一遍setXXX()方法

param.setUserId(request.getHeader("userId"));

param.setUserName(request.getHeader("userName"));

return templateClient.createTemplate(param).toResultVO();

}

}

@Data

public class TemplateParam{

private Long templateId;

private Long userId;

private String userName;

}

解决办法

大家都知道的两大利器，

tomcat的Filter和spring的Intercepter(具体为HandlerIntercepter)

实现原理

具体方法为定义一个Filter实现类和一个HandlerIntercepter的实现类。再定义一个HttpServletRequest实现类，其作用分别为

Filter实现类：UserInfoFilter

创建一个入口，在这个入口中定义一个机会：将我们自定义的CustomHttpServletRequestWrapper代替HttpServletRequest随着请求传递下去

HttpServletRequest实现类：customHttpServletRequestWrapper

因为HttpServletRequest对象的body数据只能get，不能set，即不能再次赋值。

而我们的需求是需要给HttpServletRequest赋值，所以需要定义一个HttpServletRequest实现类：customHttpServletRequestWrapper，这个实现类可以被赋值来满足我们的需求。

HandlerIntercepter的实现类：CustomInterceptor

拦截请求，获取接口方法相关信息(方法名，参数，返回值等)。从而实现统一的给request body动态赋值

实现思路如上所述，具体的实现代码如下

代码实现

声明基础bean: UserInfoParam

UserInfoParam：定义了包含userId,userName的实体bean,要想将用户信息注入进入，需要入参对象XXXParam继承UserInfoParam，-中只处理@Requestbody中实现了UserInfoParam类的bean。

如上文controller中create方法的入参：TemplateParam，继承UserInfoParam

@Data

public class TemplateParam extends UserInfoParam{

private Long templateId;

// private Long userId;

// private String userName;

}

@Data

public class UserInfoParam {

// 用户id

private Long userId;

// 用户名称

private String userName;

}

定义Filter实现类: UserInfoFilter

@Slf4j

public class UserInfoFilter implements Filter {

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {

CustomHttpServletRequestWrapper customHttpServletRequestWrapper = null;

try {

HttpServletRequest req = (HttpServletRequest)request;

customHttpServletRequestWrapper = new CustomHttpServletRequestWrapper(req);

}catch (Exception e){

log.warn("customHttpServletRequestWrapper Error:", e);

}

chain.doFilter((Objects.isNull(customHttpServletRequestWrapper) ? request : customHttpServletRequestWrapper), response);

}

}

HttpServletRequest实现类：CustomHttpServletRequestWrapper

public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {

// 保存request body的数据

private String body;

// 解析request的inputStream(即body)数据，转成字符串

public CustomHttpServletRequestWrapper(HttpServletRequest request) {

super(request);

StringBuilder stringBuilder = new StringBuilder();

BufferedReader bufferedReader = null;

InputStream inputStream = null;

try {

inputStream = request.getInputStream();

if (inputStream != null) {

bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

char[] charBuffer = new char[128];

int bytesRead = -1;

while ((bytesRead = bufferedReader.read(charBuffer)) > 0) {

stringBuilder.append(charBuffer, 0, bytesRead);

}

} else {

stringBuilder.append("");

}

} catch (IOException ex) {

} finally {

if (inputStream != null) {

try {

inputStream.close();

}

catch (IOException e) {

e.printStackTrace();

}

}

if (bufferedReader != null) {

try {

bufferedReader.close();

}

catch (IOException e) {

e.printStackTrace();

}

}

}

body = stringBuilder.toString();

}

@Override

public ServletInputStream getInputStream() throws IOException {

final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(body.getBytes());

ServletInputStream servletInputStream = new ServletInputStream() {

@Override

public boolean isFinished() {

return false;

}

@Override

public boolean isReady() {

return false;

}

@Override

public void setReadListener(ReadListener readListener) {

}

@Override

public int read() throws IOException {

return byteArrayInputStream.read();

}

};

return servletInputStream;

}

@Override

public BufferedReader getReader() throws IOException {

return new BufferedReader(new InputStreamReader(this.getInputStream()));

}

public String getBody() {

return this.body;

}

// 赋值给body字段

public void setBody(String body) {

this.body = body;

}

}

HandlerIntercepter的实现类：CustomInterceptor

@Slf4j

public class CustomInterceptor implements HandlerInterceptor {

@Override

public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)

throws Exception {

if (!(handler instanceof HandlerMethod)) {

return true;

}

HandlerMethod handlerMethod = (HandlerMethod)handler;

pushUserInfo2Body(request, handlerMethod);

return true;

}

private void pushUserInfo2Body(HttpServletRequest request, HandlerMethod handlerMethod) {

try{

String userId = request.getHeader("userId");

String userName = request.getHeader("userName");

MethodParameter[] methodParameters = handlerMethod.getMethodParameters();

if(ArrayUtils.isEmpty(methodParameters)) {

return;

}

for (MethodParameter methodParameter : methodParameters) {

Class clazz = methodParameter.getParameterType();

if(ClassUtils.isAssignable(UserInfoParam.class, clazz)){

if(request instanceof CustomHttpServletRequestWrapper){

CustomHttpServletRequestWrapper requestWrapper = (CustomHttpServletRequestWrapper)request;

String body = requestWrapper.getBody();

JSONObject param = JSONObject.parseObject(body);

param.put("userId", userId);

param.put("userName", Objects.isNull(userName) ? null : URLDecoder.decode(userName, "UTF-8"));

requestWrapper.setBody(JSON.toJSONString(param));

}

}

}

}catch (Exception e){

log.warn("fill userInfo to request body Error ", e);

}

}

定义Configuration class，增加-和过滤器的配置

WebMvcConfigurer子类：CustomWebMvcConfigurer

@Configuration

public class CustomWebMvcConfigurer implements WebMvcConfigurer {

@Override

public void addInterceptors(InterceptorRegistry registry) {

CustomInterceptor customInterceptor= new CustomInterceptor();

registry.addInterceptor(customInterceptor);

}

@Bean

public FilterRegistrationBean servletRegistrationBean() {

UserInfoFilter userInfoFilter = new UserInfoFilter();

FilterRegistrationBean bean = new FilterRegistrationBean<>();

bean.setFilter(userInfoFilter);

bean.setName("userInfoFilter");

bean.addUrlPatterns("/*");

bean.setOrder(Ordered.LOWEST_PRECEDENCE);

return bean;

}

}

到此，实现功能的代码撸完了。启动spring boot App，就可以curl访问restful接口了

http访问

curl -X POST \

http://localhost:8080/template/create

-H 'Content-Type: application/json'

-H 'username: tiankong天空'

-H 'userId: 11'

-d '{

"templateId": 1000}

效果

可以看到TemplateController.create(…)打出的信息，userId和username的值正是header中传的值

toDo

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