SpringBoot 过滤器更改 Request body ，并实现数据解密
客户端、服务端网络通信，为了安全，会对报文数据进行加解密操作。
在SpringBoot项目中，最好使用参考AOP思想，加解密与Controller业务逻辑解耦，互不影响。
以解密为例：需要在request请求到达Controller之前进行拦截，获取请求body中的密文并对其进行解密，然后把解密后的明文重新设置到request的body上。
拦截器、过滤器、Controller之间的关系
如图所示，在Request对象进入Controller之前，可使用Filter过滤器和Interceptor拦截器进行拦截。
过滤器、拦截器主要差异：
1、过滤器来自于 Servlet；而拦截器来自于 Spring 框架；
2、触发时机不同：请求的执行顺序是：请求进入容器 > 进入过滤器 > 进入 Servlet > 进入拦截器 > 执行控制器（Controller）
3、过滤器是基于方法回调实现的；拦截器是基于动态代理（底层是反射）实现的；
4、过滤器是 Servlet 规范中定义的，所以过滤器要依赖 Servlet 容器，它只能用在 Web 项目中；拦截器是 Spring 中的一个组件，因此拦截器既可以用在 Web 项目中，同时还可以用在 Application 或 Swing 程序中；
5、过滤器通常是用来实现通用功能过滤的，比如：敏感词过滤、字符集编码设置、响应数据压缩等功能；拦截器更接近业务系统，所以拦截器主要用来实现项目中的业务判断的，比如：登录判断、权限判断、日志记录等业务；
对于我们当前应用场景来说，区别就是过滤器更适用于修改request body。
具体实现分析
修改请求，会有两个问题：
1、请求体的输入流被读取，它就不能再被其他组件读取，因为输入流只能被标记、重置，并且在读取后会被消耗。
2、HttpServletRequest对象的body数据只能get，不能set，不能再次赋值。而咱们的需求是需要给HttpServletRequest body解密并重新赋值。
基于以上两个问题，咱们需要定义一个HttpServletRequest实现类，增加赋值方法，来满足我们的需求。
CustomHttpServletRequestWrapper.java
import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;
/**
* 自定义HttpServletRequestWrapper
* qxc
* 20240622
*/
public class CustomHttpServletRequestWrapper extends HttpServletRequestWrapper {
private String body;
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;
}
public void setBody(String body) {
this.body = body;
}
}
接下来，继续写Filter类，用于拦截请求，解析body, 解密报文，替换请求body数据。
RequestWrapperFilter.java
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.Objects;
/**
* 自定义Filter
* qxc
* 20240622
*/
@Slf4j
public class RequestWrapperFilter 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);
preHandle(customHttpServletRequestWrapper);
} catch (Exception e) {
log.warn("customHttpServletRequestWrapper Error:", e);
}
chain.doFilter((Objects.isNull(customHttpServletRequestWrapper) ? request : customHttpServletRequestWrapper), response);
}
public void preHandle(CustomHttpServletRequestWrapper request) throws Exception {
//仅当请求方法为POST时修改请求体
if (!request.getMethod().equalsIgnoreCase("POST")) {
return;
}
//读取原始请求体
StringBuilder originalBody = new StringBuilder();
String line;
try (BufferedReader reader = new BufferedReader(new InputStreamReader(request.getInputStream()))) {
while ((line = reader.readLine()) != null) {
originalBody.append(line);
}
}
String bodyText = originalBody.toString();
//json字符串转成map集合
Map<String, String> map = getMap(bodyText);
//获取解密参数，解密数据
if (map != null && map.containsKey("time") && map.containsKey("data")) {
String time = map.get("time");
String key = "基于时间戳等参数生成密钥、此处请换成自己的密钥";
String data = map.get("data");
//解密数据
String decryptedData = Cipher.decrypt(key, data);
//为请求对象重新设置body
request.setBody(decryptedData);
}
}
private Map<String, String> getMap(String text) {
ObjectMapper objectMapper = new ObjectMapper();
try {
// 将JSON字符串转换为Map
Map<String, String> map = objectMapper.readValue(text, Map.class);
return map;
} catch (IOException e) {
e.printStackTrace();
return null;
}
}
}
AES加解密算法封装
Cipher.java
import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.util.Base64;
import javax.crypto.spec.SecretKeySpec;
/**
* 自定义AES加解密算法类
* qxc
* 20240622
*/
public class Cipher {
public static String encrypt(String key, String text){
try {
SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("AES");
cipher.init(javax.crypto.Cipher.ENCRYPT_MODE, secretKeySpec);
byte[] encryptedBytes = cipher.doFinal(text.getBytes("UTF-8"));
String cipherText = base64Encode(encryptedBytes);
return cipherText;
}catch (Exception ex){
ex.printStackTrace();
return "";
}
}
public static String decrypt(String key, String cipherText) {
try {
SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");
javax.crypto.Cipher cipher = javax.crypto.Cipher.getInstance("AES");
cipher.init(javax.crypto.Cipher.DECRYPT_MODE, secretKeySpec);
byte[] decryptedBytes = cipher.doFinal(base64Decode(cipherText));
return new String(decryptedBytes, StandardCharsets.UTF_8);
}catch (Exception ex){
ex.printStackTrace();
return "";
}
}
public static String getMd5(String input) {
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(input.getBytes());
byte[] digest = md.digest();
BigInteger bigInt = new BigInteger(1, digest);
String md5Hex = bigInt.toString(16);
while (md5Hex.length() < 32) {
md5Hex = "0" + md5Hex;
}
return md5Hex;
} catch (Exception e) {
e.printStackTrace();
return "";
}
}
public static String base64Encode(byte[] bytes) {
if (bytes != null && bytes.length > 0) {
return Base64.getEncoder().encodeToString(bytes);
}
return "";
}
public static byte[] base64Decode(String base64Str) {
if (base64Str != null && base64Str.length() > 0) {
return Base64.getDecoder().decode(base64Str);
}
return new byte[]{};
}
}
最后，需要在WebMvcConfigurer中配置并使用RequestWrapperFilter
import com.qxc.server.encryption.RequestWrapperFilter;
import com.qxc.server.jwt.JwtInterceptor;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.core.Ordered;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
@SpringBootApplication
public class ServerApplication implements WebMvcConfigurer {
public static void main(String[] args) {
SpringApplication.run(ServerApplication.class, args);
}
@Bean
public FilterRegistrationBean servletRegistrationBean() {
RequestWrapperFilter userInfoFilter = new RequestWrapperFilter();
FilterRegistrationBean<RequestWrapperFilter> bean = new FilterRegistrationBean<>();
bean.setFilter(userInfoFilter);
bean.setName("requestFilter");
bean.addUrlPatterns("/*");
bean.setOrder(Ordered.LOWEST_PRECEDENCE);
return bean;
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
}
}
这样，就实现了请求报文的解密、数据替换，而且对Controller逻辑没有影响。
