Volley框架的基本解读

Posted 2022-11-30 zero-27

这是Volley框架解析的最后一栏，Response类的源码总共不到100行，我就直接全部贴出来了：

public class Response<T> 

    /** Callback interface for delivering parsed responses. */
    public interface Listener<T> 
        /** Called when a response is received. */
        public void onResponse(T response);
    

    /** Callback interface for delivering error responses. */
    public interface ErrorListener 
        /**
         * Callback method that an error has been occurred with the
         * provided error code and optional user-readable message.
         */
        public void onErrorResponse(VolleyError error);
    

    /** 
     * Returns a successful response containing the parsed result. 
     * 
     * 成功
     */
    public static <T> Response<T> success(T result, Cache.Entry cacheEntry) 
        return new Response<T>(result, cacheEntry);
    

    /**
     * Returns a failed response containing the given error code and an optional
     * localized message displayed to the user.
     * 
     * 失败
     */
    public static <T> Response<T> error(VolleyError error) 
        return new Response<T>(error);
    

    /** Parsed response, or null in the case of error. 返回数据，错误的情况下为空*/
    public final T result;

    /** Cache metadata for this response, or null in the case of error. 缓存数据，错误的情况下为空*/
    public final Cache.Entry cacheEntry;

    /** Detailed error information if <code>errorCode != OK</code>. 错误error*/
    public final VolleyError error;

    /** True if this response was a soft-expired one and a second one MAY be coming.命中过期缓存标志*/
    public boolean intermediate = false;

    /**
     * Returns whether this response is considered successful.
     * 
     * 是否成功
     */
    public boolean isSuccess() 
        return error == null;
    


    private Response(T result, Cache.Entry cacheEntry) 
        this.result = result;
        this.cacheEntry = cacheEntry;
        this.error = null;
    

    private Response(VolleyError error) 
        this.result = null;
        this.cacheEntry = null;
        this.error = error;
    

这里有一些我们非常熟悉的东西，比如Listener.onResponse成功回调，ErrorListener.onErrorResponse失败回调，框架内部用于通知的方法，success与error等等，关于这两个方法的如何工作，我们已经在前面说的很清楚了，如果还不明白的同学可以回头看看。

至此整篇Volley框架的解析全部结束，可能有同学会认为最后的Request与Response解析的太过肤浅，虽然它们是Volley中十分重要的两个类，但连接它们的主线在前面我们就已经说完了，这里只是对它们进行补充，单说方法却没有一根线能贯通全局，理解起来就会十分抽象，这也是我一开始不说它们的原因。

愿大家能在这篇博客中收获一二！

最后附上Volley的源码，供大家学习参考，点击下载