前言

App開發(fā)過(guò)程中，會(huì)涉及到很多三方支持組件的使用，比如網(wǎng)絡(luò)框架，在重度依賴某框架的情況下，一旦發(fā)生不得不進(jìn)行的替換，所帶來(lái)的工作量將是巨大的，而如果前期對(duì)第三方的使用進(jìn)行了代理控制，我們所做的工作將會(huì)大量減輕

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定義

代理模式（Proxy）：為其他對(duì)象提供一種代理以控制對(duì)這個(gè)對(duì)象的訪問(wèn)

簡(jiǎn)單說(shuō)明

在使用該設(shè)計(jì)模式過(guò)程中，主要涉及三個(gè)對(duì)象：調(diào)用方，支持方，代理支持方。以網(wǎng)絡(luò)框架為例，App作為調(diào)用方需要網(wǎng)絡(luò)請(qǐng)求，三方框架作為支持方提供請(qǐng)求功能，如果不使用代理支持方的話，app將調(diào)用具體的某一請(qǐng)求框架（如okhttp等），代碼深度耦合，改動(dòng)多處或難以替換。而通過(guò)代理支持方來(lái)開發(fā)時(shí)，則只要在替換時(shí)，進(jìn)行對(duì)行的第三方框架進(jìn)行適配預(yù)置的規(guī)則便可快速實(shí)現(xiàn)需求。

快速切換網(wǎng)絡(luò)框架設(shè)計(jì)

1. 通用規(guī)則設(shè)計(jì)

/**
 * Created by SJ on 2020/3/18.
 */
public interface IHttpProcessor {

    void post(String url, Map<String,Object> params,ICallback callback);

    void get(String url, Map<String,Object> params,ICallback callback);
    //....
}

/**
 * Created by SJ on 2020/3/18.
 * 頂層回調(diào)接口
 * 隔離層接口回調(diào)
 */
public interface ICallback {

    /**
     * 三方框架 返回都可以是String
     * @param results
     */
    void onSuccess(String results);

    void onFailure(HttpError httpError);

}

2. 具體的代理對(duì)象

/**
 * Created by SJ on 2020/3/18.
 * 具體的操作代理對(duì)象
 */
public class HttpHelper implements IHttpProcessor {

    private static HttpHelper httpHelper = new HttpHelper();

    private HttpHelper() {
    }
    // 被代理的對(duì)象
    private static IHttpProcessor httpProcessor = null;

    public static void init(IHttpProcessor processor){
        httpProcessor = processor;
    }

    public static HttpHelper getHttpHelper() {
        return httpHelper;
    }

    @Override
    public void post(String url, Map<String, Object> params, ICallback callback) {
        String finalUrl = appendParams(url, params);
        httpProcessor.post(finalUrl, params, callback);
    }

    @Override
    public void get(String url, Map<String, Object> params, ICallback callback) {
        httpProcessor.get(url, params, callback);
    }


    public static String appendParams(String url,Map<String, Object> params){
        if (params == null||params.isEmpty()) {
            return url;
        }
        StringBuilder urlBuilder = new StringBuilder(url);
        if (urlBuilder.indexOf("?")<=0) {
            urlBuilder.append("?");
        }else {
            if (!urlBuilder.toString().endsWith("?")) {
                urlBuilder.append("&");
            }
        }
        for (Map.Entry<String, Object> entry : params.entrySet()) {
            urlBuilder.append("&"+entry.getKey())
                    .append("=")
                    .append(encode(entry.getValue().toString()));
        }
        return urlBuilder.toString();
    }

    private static String encode(String string) {
        try {
            return URLEncoder.encode(string,"utf-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            throw new RuntimeException();
        }
    }

}

3. 對(duì)通用規(guī)則適配的三方框架

/**
 * Created by SJ on 2020/3/18.
 * 被代理的訪問(wèn)框架
 */
public class ProxyXutils implements IHttpProcessor{


    public ProxyXutils() {
        x.Ext.init(MyApplication.getInstance());
    }

    @Override
    public void post(String url, Map<String, Object> params, final ICallback callback) {
        x.http().post(new RequestParams(url), new Callback.CommonCallback<String>() {
            @Override
            public void onSuccess(String result) {
                callback.onSuccess(result);
            }

            @Override
            public void onError(Throwable ex, boolean isOnCallback) {

            }

            @Override
            public void onCancelled(CancelledException cex) {

            }

            @Override
            public void onFinished() {

            }
        });
    }

    @Override
    public void get(String url, Map<String, Object> params, final ICallback callback) {
        x.http().get(new RequestParams(url), new Callback.CommonCallback<String>() {
            @Override
            public void onSuccess(String result) {
                callback.onSuccess(result);
            }

            @Override
            public void onError(Throwable ex, boolean isOnCallback) {

            }

            @Override
            public void onCancelled(CancelledException cex) {

            }

            @Override
            public void onFinished() {

            }
        });
    }
}

4. 調(diào)用方的使用及切換

 HttpHelper.init(new ProxyVolley(ProxyDesignActivity.this));
 //HttpHelper.init(new ProxyXutils());
 //HttpHelper.init(new ProxyOkhttp());
 HttpHelper.getHttpHelper().get(imageUrl, null, new HttpCallback<TestBean>() {
            @Override
            protected void onSuccess(TestBean testBean) {
                showImageView(testBean);
            }
        });

作者：Shimmer_
鏈接：http://www.itdecent.cn/p/34061da40fcf

進(jìn)程管理與大家日常開發(fā)息息相關(guān)，也是在Android系統(tǒng)中是個(gè)舉足輕重的模塊。相信通過(guò)本系列的兩篇文章，大家已經(jīng)對(duì)進(jìn)程啟動(dòng)期間涉及到fork、對(duì)進(jìn)程的優(yōu)先級(jí)管理涉及到adj、對(duì)進(jìn)程的調(diào)度這些概念已經(jīng)有了更加深入的理解了。