一、案例演示
说明：如下案例通过springboot的方式演示Filter是如何使用的，以获取Controller中的请求参数为切入点进行演示
1.1、前置准备工作
1.1.1、pom
<dependencies>
<!-- spring-boot -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<scope>runtime</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.76</version>
</dependency>
</dependencies>1.1.2、UserDTO
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/4 18:32
* @Description:
*/
@Data
@AllArgsConstructor
@NoArgsConstructor
@Accessors(chain = true)
public class UserDTO implements Serializable {
/**
* 用户名
*/
private String username;
/**
* 密码
*/
private String password;
}1.1.3、StreamUtil
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/5 1:15
* @Description:
*/
public class StreamUtil {
public static String getBody(HttpServletRequest 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 e) {
e.printStackTrace();
} finally {
if (inputStream != null) {
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return stringBuilder.toString();
}
public static ServletInputStream getServletInputStream(byte[] byteArr) {
final ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArr);
return 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();
}
};
}
}1.1.4、MyHttpServletRequestWrapper
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/4 20:50
* @Description:
*/
@Getter
@Setter
public class MyHttpServletRequestWrapper extends HttpServletRequestWrapper {
/**
* 用于保存读取到的body中的数据
*/
private String body;
public MyHttpServletRequestWrapper(HttpServletRequest request) throws IOException {
super(request);
this.body = StreamUtil.getBody(request);
}
@Override
public ServletInputStream getInputStream() throws IOException {
return StreamUtil.getServletInputStream(this.body.getBytes(Charset.forName("UTF-8")));
}
@Override
public BufferedReader getReader() throws IOException {
return new BufferedReader(new InputStreamReader(this.getInputStream()));
}
}1.1.5、LoginService
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/4 23:49
* @Description:
*/
@Service
public class LoginService {
}二、创建过滤器
参考：
（1）https://blog.csdn.net/bzu_mei/article/details/126644963
（2）https://blog.csdn.net/worilb/article/details/1296169562.1、方式一：@WebFilter + @ServletComponentScan
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/4 23:46
* @Description:
* @WebFilter(urlPatterns = "/login"):标识在类上，表明这个类是一个过滤器类，当访问 /login 接口时先执行此处的doFilter（执行业务逻辑），
* 当执行chain.doFilter(wrapper, servletResponse);时，才会真正执行Controller层的代码逻辑
*/
@WebFilter
@Slf4j
public class LoginFilter implements Filter {
// 实现方法处理逻辑
}/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/4 23:43
* @Description:
*
* @ServletComponentScan的作用：将标识了@WebServlet、@WebFilter、@WebListener注解标注的类注入到IOC容器中
*/
@ServletComponentScan
@SpringBootApplication
public class SpringbootFilterApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootFilterApplication.class, args);
}
}2.2、方式二：FilterRegistrationBean
/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/5 1:53
* @Description:
*
*/
@Slf4j
public class AuthorityFilter implements Filter {
// 业务逻辑代码
}/**
* @Author : 一叶浮萍归大海
* @Date: 2023/11/5 1:59
* @Description:
*
* 注意事项：
* 此处也可以不写此配置，不写的话，AuthorityFilter由于加了@Component注解，也会被Spring容器管理，但是@Component注解没有路径过滤规则，
* 即会将所有请求都过滤，配置的意义主要就是为了过滤某一类的请求，如下的配置是只有访问以 /privilege/* 打头的请求才会过滤，访问其他的则不过滤
*/
@Configuration
public class MyFilterConfig {
@Bean
public FilterRegistrationBean registrationBean() {
FilterRegistrationBean registrationBean = new FilterRegistrationBean();
registrationBean.setFilter(new AuthorityFilter());
registrationBean.setName("authorityFilter");
registrationBean.addUrlPatterns("/privilege/*");
registrationBean.setOrder(1);
return registrationBean;
}
}三、使用过滤器（案例）
3.1、获取Controller层@RequestBody中的对象参数
3.1.1、LoginController#login()
@PostMapping("/login")
public String login(@RequestBody UserDTO param) {
log.info("LoginController login param : {}", param);
return "OK";
}3.1.2、LoginFilter#doFilter()
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
log.info("==================== LoginFilter doFilter ====================");
log.info("bean loginService exist result : {} 存在", loginService == null ? "不" : "");
HttpServletRequest request = (HttpServletRequest) servletRequest;
MyHttpServletRequestWrapper wrapper = new MyHttpServletRequestWrapper(request);
String jsonParam = wrapper.getBody();
log.info("jsonParam:{}", jsonParam);
chain.doFilter(wrapper, servletResponse);
}3.1.3、测试
3.2、获取Controller层普通的对象参数
3.2.1、LoginController#login2()
@PostMapping("/login2")
public String login2(UserDTO param) {
log.info("LoginController login2 param : {}", param);
return "OK";
}3.2.2、LoginFilter#doFilter()
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
log.info("==================== LoginFilter doFilter ====================");
log.info("bean loginService exist result : {} 存在", loginService == null ? "不" : "");
HttpServletRequest request = (HttpServletRequest) servletRequest;
Map<String, String[]> parameterMap = request.getParameterMap();
Map<String, Object> requestMap = new HashMap<>();
for (String key : parameterMap.keySet()) {
String[] values = parameterMap.get(key);
requestMap.put(key,values[0]);
}
log.info("requestMap:{}",requestMap);
chain.doFilter(servletRequest, servletResponse);
}3.2.3、测试#form-data
3.2.4、测试#x-www-form-urlencoded
3.3、获取Controller层字符串参数
3.3.1、LoginController#login3()
@GetMapping("/login3")
public String login3(String username, String password) {
log.info("LoginController login3 username:{},password:{}", username, password);
return "OK";
}3.3.2、LoginFilter#doFilter()
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) throws IOException, ServletException {
log.info("==================== LoginFilter doFilter ====================");
log.info("bean loginService exist result : {} 存在", loginService == null ? "不" : "");
HttpServletRequest request = (HttpServletRequest) servletRequest;
String username = request.getParameter("username");
String password = request.getParameter("password");
Map<String, Object> paramMap = new HashMap<>(2);
paramMap.put("username", username);
paramMap.put("password", password);
log.info("paramMap:{}", paramMap);
chain.doFilter(servletRequest, servletResponse);
}3.3.3、测试
