Volley源码学习2--Error类

Volley

网络请求错误返回

VolleyError

package com.android.volley;

/** Exception style class encapsulating Volley errors */
@SuppressWarnings("serial")
public class VolleyError extends Exception {
    public final NetworkResponse networkResponse;
    private long networkTimeMs;

    public VolleyError() {
        networkResponse = null;
    }

    public VolleyError(NetworkResponse response) {
        networkResponse = response;
    }

    public VolleyError(String exceptionMessage) {
        super(exceptionMessage);
        networkResponse = null;
    }

    public VolleyError(String exceptionMessage, Throwable reason) {
        super(exceptionMessage, reason);
        networkResponse = null;
    }

    public VolleyError(Throwable cause) {
        super(cause);
        networkResponse = null;
    }

    /* package */ void setNetworkTimeMs(long networkTimeMs) {
        this.networkTimeMs = networkTimeMs;
    }

    public long getNetworkTimeMs() {
        return networkTimeMs;
    }
}

可以看到Volley这个类,写了5个平时可能用到的错误返回的构造方法。源码很清除，具体就不解释了。但是我搜索这个类被引用的地方的时候，发现很多类都引用了这个类，volley就47个java文件，有这么多类竟然引用到VolleyError,说明Volley设计的非常的简洁，而且严谨，一个不多一个不少，都充分的去利用每个类的价值，应该是极高的构架师来构架的volley这个项目。（试想平时我们自己写的一个接口或者抽象类，写的有这样的简单吗？而且被很多的类（不同的类型的类）引用）。

服务器错误类 ServerError，ServerError.class继承自VolleyError.class

package com.android.volley;
/** Indicates that the server responded with an error response. */
@SuppressWarnings("serial")
public class ServerError extends VolleyError {
    public ServerError(NetworkResponse networkResponse) {
        super(networkResponse);
    }
    public ServerError() {
        super();
    }
}

解析错误类 ParseError

package com.android.volley;

/** Indicates that the server's response could not be parsed. */
@SuppressWarnings("serial")
public class ParseError extends VolleyError {
    public ParseError() {}

    public ParseError(NetworkResponse networkResponse) {
        super(networkResponse);
    }

    public ParseError(Throwable cause) {
        super(cause);
    }
}

网络错误类 NetworkError

package com.android.volley;

/** Indicates that there was a network error when performing a Volley request. */
@SuppressWarnings("serial")
public class NetworkError extends VolleyError {
    public NetworkError() {
        super();
    }

    public NetworkError(Throwable cause) {
        super(cause);
    }

    public NetworkError(NetworkResponse networkResponse) {
        super(networkResponse);
    }
}

AuthFailureError 认证失败类

package com.android.volley;

import android.content.Intent;

/** Error indicating that there was an authentication failure when performing a Request. */
@SuppressWarnings("serial")
public class AuthFailureError extends VolleyError {
    /** An intent that can be used to resolve this exception. (Brings up the password dialog.) */
    private Intent mResolutionIntent;

    public AuthFailureError() {}

    public AuthFailureError(Intent intent) {
        mResolutionIntent = intent;
    }

    public AuthFailureError(NetworkResponse response) {
        super(response);
    }

    public AuthFailureError(String message) {
        super(message);
    }

    public AuthFailureError(String message, Exception reason) {
        super(message, reason);
    }

    public Intent getResolutionIntent() {
        return mResolutionIntent;
    }

    @Override
    public String getMessage() {
        if (mResolutionIntent != null) {
            return "User needs to (re)enter credentials.";
        }
        return super.getMessage();
    }
}

时间错误类

package com.android.volley;

/** Indicates that the connection or the socket timed out. */
@SuppressWarnings("serial")
public class TimeoutError extends VolleyError {}

….还有一个子类没有列出
我在想为什么VolleyError 和子类没有用接口了，而是用类来表示
我看了下子类被用到的地方，发现基本上都是可以new Object（）即用到了实例，这个平时开发中需要去学习的。

对于VolleyError:

Java中接口不能被实例化的，可以继承接口（不能继承类）。

显示不满足VolleyError需求。