系列六、过滤器（二）#案例演示

过滤器（二）#案例演示"/>

系列六、过滤器（二）#案例演示

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() {@Overridepublic boolean isFinished() {return false;}@Overridepublic boolean isReady() {return false;}@Overridepublic void setReadListener(ReadListener readListener) {}@Overridepublic 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);}@Overridepublic ServletInputStream getInputStream() throws IOException {return StreamUtil.getServletInputStream(this.body.getBytes(Charset.forName("UTF-8")));}@Overridepublic 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）
（2）

2.1、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 {@Beanpublic 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