springMVC源碼解析--ViewResolverComposite視圖解析器集合（二）

上一篇部落格​​ springMVC源碼分析--ViewResolver視圖解析器（一）​​中我們介紹了一些springMVC提供的很多視圖解析器ViewResolver，在開發的一套springMVC系統中是可以使用多個視圖的，當然就需要配置多個視圖解析器了，ViewResolverComposite簡單來說就是使用簡單的List來儲存你配置使用的視圖解析器。

ViewResolverComposite中定義了兩個變量：

（1）private final List<ViewResolver> viewResolvers = new ArrayList<ViewResolver>();用來存儲所有的視圖解析器

（2）private int order 用來配置視圖解析器的使用順序。

public class ViewResolverComposite implements ViewResolver, Ordered, InitializingBean,
    ApplicationContextAware, ServletContextAware {

  //用來存儲所有的視圖解析器
  private final List<ViewResolver> viewResolvers = new ArrayList<ViewResolver>();
  //設定視圖解析器的執行順序
  private int order = Ordered.LOWEST_PRECEDENCE;

  
  //設定視圖解析器
  public void setViewResolvers(List<ViewResolver> viewResolvers) {
    this.viewResolvers.clear();
    if (!CollectionUtils.isEmpty(viewResolvers)) {
      this.viewResolvers.addAll(viewResolvers);
    }
  }

  //擷取所有的視圖解析器
  public List<ViewResolver> getViewResolvers() {
    return Collections.unmodifiableList(this.viewResolvers);
  }
  
  //設定執行順序
  public void setOrder(int order) {
    this.order = order;
  }

  @Override
  public int getOrder() {
    return this.order;
  }
  
  @Override
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    for (ViewResolver viewResolver : this.viewResolvers) {
      if (viewResolver instanceof ApplicationContextAware) {
        ((ApplicationContextAware)viewResolver).setApplicationContext(applicationContext);
      }
    }
  }

  @Override
  public void setServletContext(ServletContext servletContext) {
    for (ViewResolver viewResolver : this.viewResolvers) {
      if (viewResolver instanceof ServletContextAware) {
        ((ServletContextAware)viewResolver).setServletContext(servletContext);
      }
    }
  }
  //初始化視圖解析器
  @Override
  public void afterPropertiesSet() throws Exception {
    for (ViewResolver viewResolver : this.viewResolvers) {
      if (viewResolver instanceof InitializingBean) {
        ((InitializingBean) viewResolver).afterPropertiesSet();
      }
    }
  }
  //生成View對象
  @Override
  public View resolveViewName(String viewName, Locale locale) throws Exception {
    for (ViewResolver viewResolver : this.viewResolvers) {
      View view = viewResolver.resolveViewName(viewName, locale);
      if (view != null) {
        return view;
      }
    }
    return null;
  }

}