SpringMVC源码-----ThemeResolver

本是古典何须时尚 2022-05-15 06:41 182阅读 0赞

## ThemeResolver ##

public interface ThemeResolver {
        String resolveThemeName(HttpServletRequest var1);
    
        void setThemeName(HttpServletRequest var1, @Nullable HttpServletResponse var2, @Nullable String var3);
    }

结构如下所示：

![70][]

它的继承结构图和LocaleResolver非常相似，不过接口相比少，也更简单。

## 1. AbstractThemeResolver  ##

它提供了默认的Theme - --“theme”

public abstract class AbstractThemeResolver implements ThemeResolver {
        public static final String ORIGINAL_DEFAULT_THEME_NAME = "theme";
        private String defaultThemeName = "theme";
    
        public AbstractThemeResolver() {
        }
    
        public void setDefaultThemeName(String defaultThemeName) {
            this.defaultThemeName = defaultThemeName;
        }
    
        public String getDefaultThemeName() {
            return this.defaultThemeName;
        }
    }

### 2.FixedThemeResolver  ###

他提供固定的主题名，不能修改，源码如下所示：

public class FixedThemeResolver extends AbstractThemeResolver {
        public FixedThemeResolver() {
        }
    
        public String resolveThemeName(HttpServletRequest request) {
            return this.getDefaultThemeName();
        }
    
        public void setThemeName(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable String themeName) {
            throw new UnsupportedOperationException("Cannot change theme - use a different theme resolution strategy");
        }
    }

### 3.SessionThemeResolver  ###

这个是从session中获取，并且支持修改。

public class SessionThemeResolver extends AbstractThemeResolver {
        public static final String THEME_SESSION_ATTRIBUTE_NAME = SessionThemeResolver.class.getName() + ".THEME";
    
        public SessionThemeResolver() {
        }
    
        public String resolveThemeName(HttpServletRequest request) {
            String themeName = (String)WebUtils.getSessionAttribute(request, THEME_SESSION_ATTRIBUTE_NAME);
            return themeName != null ? themeName : this.getDefaultThemeName();
        }
    
        public void setThemeName(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable String themeName) {
            WebUtils.setSessionAttribute(request, THEME_SESSION_ATTRIBUTE_NAME, StringUtils.hasText(themeName) ? themeName : null);
        }
    }

### 4.CookieThemeResolver  ###

这个将主题保存到Cookie中，它为了处理Cookie方法继承了CookieGennerator，所以没有继承AbstractThemeResolver。但是也实现了默认的主题的。

public class CookieThemeResolver extends CookieGenerator implements ThemeResolver {
        public static final String ORIGINAL_DEFAULT_THEME_NAME = "theme";
        public static final String THEME_REQUEST_ATTRIBUTE_NAME = CookieThemeResolver.class.getName() + ".THEME";
        public static final String DEFAULT_COOKIE_NAME = CookieThemeResolver.class.getName() + ".THEME";
        private String defaultThemeName = "theme";
    
        public CookieThemeResolver() {
            this.setCookieName(DEFAULT_COOKIE_NAME);
        }
    
        public void setDefaultThemeName(String defaultThemeName) {
            this.defaultThemeName = defaultThemeName;
        }
    
        public String getDefaultThemeName() {
            return this.defaultThemeName;
        }
    
        public String resolveThemeName(HttpServletRequest request) {
            //从request获取thememName
            String themeName = (String)request.getAttribute(THEME_REQUEST_ATTRIBUTE_NAME);
            if (themeName != null) {
                return themeName;
            } else {
                //从cookie中获取
                String cookieName = this.getCookieName();
                if (cookieName != null) {
                    Cookie cookie = WebUtils.getCookie(request, cookieName);
                    if (cookie != null) {
                        String value = cookie.getValue();
                        if (StringUtils.hasText(value)) {
                            themeName = value;
                        }
                    }
                }
                //如果没有这是用默认值
                if (themeName == null) {
                    themeName = this.getDefaultThemeName();
                }
                //将获取到的theme设置到request中
                request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, themeName);
                return themeName;
            }
        }
    
        public void setThemeName(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable String themeName) {
            Assert.notNull(response, "HttpServletResponse is required for CookieThemeResolver");
            if (StringUtils.hasText(themeName)) {
                request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, themeName);
                this.addCookie(response, themeName);
            } else {
                request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, this.getDefaultThemeName());
                this.removeCookie(response);
            }
    
        }
    }

[70]: /images/20220515/2d85207473c24d28a0f0c8c7caf9a85c.png