這幾天使用spring boot編寫公司一個應(yīng)用，在編寫了一個filter，用于指定編碼的filter，如下：
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/** * Created by xiaxuan on 16/11/1. */@WebFilter(urlPatterns = "/*",filterName="CharacterEncodeFilter", initParams={ @WebInitParam(name="encoding",value="UTF-8"), @WebInitParam(name = "forceEncoding", value = "true") })@Singletonpublic 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; }} |
但是在實際使用的時候，卻是完全沒有起作用，后來查看了一下springboot的官方文檔，filter和servlet、listener之類的需要單獨(dú)進(jìn)行注冊才能使用，但是spring boot里面提供了一個注解來替代，為@ServletComponentScan，這個注解直接加在對應(yīng)的Application啟動類上即可，如下：
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@SpringBootApplication@ServletComponentScan@ComponentScanpublic class SpringBootWebApplication { public static void main(String[] args) { SpringApplication.run(SpringBootWebApplication.class, args); }} |
這樣編寫完之后，如果對應(yīng)的filter是在自己當(dāng)前模塊下的某個package中的時候是可以起作用的，但是如果本身項目中有多個模塊的時候，如果filter在一個類似與core下的package中，這樣注解加上去并沒有多大用處，最后會發(fā)現(xiàn)這個filter仍然沒有起作用。
我自己編寫的應(yīng)用有兩個，最開始的做法是把filter從core包中拆出來，然后在兩個模塊中各自添加一個，但是這樣未免有些代碼冗余，并且實現(xiàn)方式并不優(yōu)雅，然后我查看了下@ServletComponentScan的源碼，里面確實是有更好的解決方法。
@ServletComponentScan的源碼如下：
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/** * 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 {};} |
這里有一個value()屬性，上面的注解默認(rèn)為basePackage,那么在掃描的時候就只掃描當(dāng)前模塊下面的包，其他不掃描，如果要連同其他模塊一起掃描的話，給這個屬性加上值即可，如下：
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@ServletComponentScan(value = "cn.com") |
如上，自定義的filter和servlet就可以正常起作用。
總結(jié)
以上就是本文關(guān)于springboot掃描自定義的servlet和filter代碼詳解的全部內(nèi)容，希望對大家有所幫助。有什么問題可以隨時留言，小編會及時回復(fù)大家。同時希望朋友們對服務(wù)器之家網(wǎng)站多多支持！
原文鏈接：http://blog.csdn.net/u012734441/article/details/53389351
