RxJava zip操作符在Android中的实际使用场景

（转载）http://blog.csdn.net/johnny901114/article/details/51614927

zip操作符概述

官方文档描述：

Returns an Observable that emits the results of a specified combiner function applied to combinations of two items emitted, 
in sequence, by two other Observables.

流程图： 

简单来说zip操作符就是合并多个数据流， 
然后发送(Emit)最终合并的数据。

zip操作符实际案例

需求描述：

<code class="hljs  has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">在很多app种都会有图片上传的功能，比如商品的评价，客户端允许用户拍照上传(可能多张)，把图片上传到又拍云(现在很多中小型公司都是用又拍云作为图片服务器)，然后获取图片的url，再把图片的信息（图片url，图片大小）发送给图片。</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

主要逻辑：

1,先把所有的图片上传到又拍云（比如3张图片）

2,获取图片的url路径，图片大小等

3,最后把数据全部提交给服务器

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;">        //需要上传的图片        Picture[] ps = xxx<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>        Observable<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.zip</span>(                Observable<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.from</span>(ps),                getUpYunAddress(ps<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.length</span>),//获取上传的url                new Func2<Picture, UpYunAddress, Picture>() {                    @Override                    public Picture <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(Picture picture, UpYunAddress upYunAddress) {                        //如果该图片已经上传则不应该上传                        if (TextUtils<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.isEmpty</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getSource</span>())) {                            try {                                //使用又拍云提供的工具类，上传图片                                String path = UpYunUtil<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.uploadImage</span>(upYunAddress, picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getLocalUrl</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                                //获取最终的url                                String finalUrl = upYunAddress<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getPrefix</span>() + path<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                                picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setSource</span>(finalUrl)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            } catch (Exception e) {                                e<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.printStackTrace</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            }                        }                        return picture<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                    }                })                <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.subscribeOn</span>(Schedulers<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.io</span>())                <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.observeOn</span>(AndroidSchedulers<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.mainThread</span>())                //上传成功后获取图片大小                <span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.flatMap</span>(new Func1<Picture, Observable<Picture>>() {                    @Override                    public Observable<Picture> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">call</span>(Picture picture) {                        if (TextUtils<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.isEmpty</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getHeight</span>()) || TextUtils<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.isEmpty</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getWidth</span>())) {                            BitmapFactory<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.Options</span> options<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            if (!TextUtils<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.isEmpty</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getLocalUrl</span>())) {                                options = ImageUtil<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getBitmapOptions</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getLocalUrl</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                                picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setLocalUrl</span>(null)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            } else {                                options = ImageUtil<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getBitmapOptions</span>(picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getSource</span>())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            }                            picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setWidth</span>(String<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.valueOf</span>(options<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.outWidth</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                            picture<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setHeight</span>(String<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.valueOf</span>(options<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.outHeight</span>))<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                        }                        return Observable<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.just</span>(picture)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                    }                })<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>                //最后处理最终的数据。</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li></ul>

代码的注释非常详细，我就不再赘述了！

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对于复杂的业务，使用RxJava来解决，感觉行云流水般，再也不用各种复杂的嵌套了。 :D）