struts2注解默认action和url的映射

前言

struts2配置action类访问路径的时候，可以采用@Action(value="")这样的注解，当然也可以不配置这个注解。假如不配置的时候，默认的路径是怎么样的呢？

struts2-convention-plugin-2.2.3.jar

用idea打开struts2-convention-plugin-2.2.3.jar的源码，如果是其他ide的，请反编译或者下载这个jar的源码查看。

打开org.apache.struts2.convention.SEOActionNameBuilder类，类注释如下：

<span style="font-size:18px;">/**
 * <p>
 * This class converts the class name into a SEO friendly name by recognizing
 * camel casing and inserting dashes. This also converts everything to
 * lower case if desired. And this will also strip off the word <b>Action</b>
 * from the class name.
 * </p>
 */</span>

根据类注释，可以大概知道一些情况。意思就是奖类名转化为对于SEO来说友好的名称，通过识别驼峰法命名和插入连接号（“-”），如果需要的话，还会将所有单词转化为小写，并去掉类名当中的“Action“。

源码分析

<span style="font-size:18px;">private static final Logger LOG = LoggerFactory.getLogger(SEOActionNameBuilder.class);
    private String actionSuffix = "Action";
    private boolean lowerCase;
    private String separator;

    @Inject
    public SEOActionNameBuilder(@Inject(value="struts.convention.action.name.lowercase") String lowerCase,
            @Inject(value="struts.convention.action.name.separator") String separator) {
        this.lowerCase = Boolean.parseBoolean(lowerCase);
        this.separator = separator;
    }

    /**
     * @param   actionSuffix (Optional) Classes that end with these value will be mapped as actions
     *          (defaults to "Action")
     */
    @Inject(value = "struts.convention.action.suffix", required = false)
    public void setActionSuffix(String actionSuffix) {
        if (StringUtils.isNotBlank(actionSuffix)) {
            this.actionSuffix = actionSuffix;
        }
    }</span>

1、后缀可以用struts.convention.action.suffix配置；

2、是否小写和分隔符可以用struts.convention.action.name.lowercase和struts.convention.action.name.separator配置。

3、默认值可以查看struts-plugin.xml配置文件。

<span style="font-size:18px;">public String build(String className) {
        String actionName = className;
        
        if (actionName.equals(actionSuffix))
            throw new IllegalStateException("The action name cannot be the same as the action suffix [" + actionSuffix + "]");

        // Truncate Action suffix if found
        if (actionName.endsWith(actionSuffix)) {
            actionName = actionName.substring(0, actionName.length() - actionSuffix.length());
        }

        // Convert to underscores
        char[] ca = actionName.toCharArray();
        StringBuilder build = new StringBuilder("" + ca[0]);
        boolean lower = true;
        for (int i = 1; i < ca.length; i++) {
            char c = ca[i];
            if (Character.isUpperCase(c) && lower) {
                build.append(separator);
                lower = false;
            } else if (!Character.isUpperCase(c)) {
                lower = true;
            }

            build.append(c);
        }

        actionName = build.toString();
        if (lowerCase) {
            actionName = actionName.toLowerCase();
        }

        if (LOG.isTraceEnabled()) {
            LOG.trace("Changed action name from [#0] to [#1]", className, actionName);
        }

        return actionName;
    }</span>

2、加入类名称是以后缀结尾的，则会去掉后缀字符串；

3、遇到大写字母，会在大写字母前面加入分隔符；

4、根据是否小写配置，决定是否讲所有字符串小写。

例子

AbcdEfg------------------------>abcd-efg

ABcdEfg------------------------>a-bcd-efg