springboot扫描自定义的servlet和filter代码详解

/**
 * Created by xiaxuan on 16/11/1.
 */
@WebFilter(urlPatterns = "/*",filterName="CharacterEncodeFilter",
    initParams={
        @WebInitParam(name="encoding",value="UTF-8"),
        @WebInitParam(name = "forceEncoding", value = "true")
    })
@Singleton
public class CharacterEncodingFilter implements Filter {
  private String encoding = "UTF-8";
  private boolean forceEncoding = true;
  @Override
  public void init(FilterConfig filterConfig) throws ServletException {
    this.encoding = filterConfig.getInitParameter("encoding");
    String force = filterConfig.getInitParameter("forceEncoding");
    this.forceEncoding = (force == null) || Boolean.valueOf(force);
  }
  @Override
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    if (this.forceEncoding || request.getCharacterEncoding() == null) {
      request.setCharacterEncoding(this.encoding);
      response.setCharacterEncoding(this.encoding);
    }
    chain.doFilter(request, response);
  }
  @Override
  public void destroy() {
  }
  public void setEncoding(String encoding) {
    this.encoding = encoding;
  }
  public void setForceEncoding(boolean forceEncoding) {
    this.forceEncoding = forceEncoding;
  }
}

@SpringBootApplication
@ServletComponentScan
@ComponentScan
public class SpringBootWebApplication {
  public static void main(String[] args) {
    SpringApplication.run(SpringBootWebApplication.class, args);
  }
}

/**
 * Enables scanning for Servlet components ({@link WebFilter filters}, {@link WebServlet
 * servlets}, and {@link WebListener listeners}). Scanning is only performed when using an
 * embedded Servlet container.
 * <p>
 * Typically, one of {@code value}, {@code basePackages}, or {@code basePackageClasses}
 * should be specified to control the packages to be scanned for components. In their
 * absence, scanning will be performed from the package of the class with the annotation.
 *
 * @author Andy Wilkinson
 * @since 1.3.0
 * @see WebServlet
 * @see WebFilter
 * @see WebListener
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(ServletComponentScanRegistrar.class)
public @interface ServletComponentScan {
  /**
   * Alias for the {@link #basePackages()} attribute. Allows for more concise annotation
   * declarations e.g.: {@code @ServletComponentScan("org.my.pkg")} instead of
   * {@code @ServletComponentScan(basePackages="org.my.pkg")}.
   * @return the base packages to scan
   */
  @AliasFor("basePackages")
  String[] value() default {};
  /**
   * Base packages to scan for annotated servlet components. {@link #value()} is an
   * alias for (and mutually exclusive with) this attribute.
   * <p>
   * Use {@link #basePackageClasses()} for a type-safe alternative to String-based
   * package names.
   * @return the base packages to scan
   */
  @AliasFor("value")
  String[] basePackages() default {};
  /**
   * Type-safe alternative to {@link #basePackages()} for specifying the packages to
   * scan for annotated servlet components. The package of each class specified will be
   * scanned.
   * @return classes from the base packages to scan
   */
  Class<?>[] basePackageClasses() default {};
}

@ServletComponentScan(value = "cn.com")