springMVC源码解析--ViewResolverComposite视图解析器集合（二）

上一篇博客​​ springMVC源码分析--ViewResolver视图解析器（一）​​中我们介绍了一些springMVC提供的很多视图解析器ViewResolver，在开发的一套springMVC系统中是可以使用多个视图的，当然就需要配置多个视图解析器了，ViewResolverComposite简单来说就是使用简单的List来保存你配置使用的视图解析器。

ViewResolverComposite中定义了两个变量：

（1）private final List<ViewResolver> viewResolvers = new ArrayList<ViewResolver>();用来存储所有的视图解析器

（2）private int order 用来配置视图解析器的使用顺序。

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

  //用来存储所有的视图解析器
  private final List<ViewResolver> viewResolvers = new ArrayList<ViewResolver>();
  //设置视图解析器的执行顺序
  private int order = Ordered.LOWEST_PRECEDENCE;

  
  //设置视图解析器
  public void setViewResolvers(List<ViewResolver> viewResolvers) {
    this.viewResolvers.clear();
    if (!CollectionUtils.isEmpty(viewResolvers)) {
      this.viewResolvers.addAll(viewResolvers);
    }
  }

  //获取所有的视图解析器
  public List<ViewResolver> getViewResolvers() {
    return Collections.unmodifiableList(this.viewResolvers);
  }
  
  //设置执行顺序
  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);
      }
    }
  }
  //初始化视图解析器
  @Override
  public void afterPropertiesSet() throws Exception {
    for (ViewResolver viewResolver : this.viewResolvers) {
      if (viewResolver instanceof InitializingBean) {
        ((InitializingBean) viewResolver).afterPropertiesSet();
      }
    }
  }
  //生成View对象
  @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;
  }

}