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<a class="post-title-link" href="/cato.github.io/2018/06/05/文件下载笔记/" itemprop="url">服务器实现文件下载</a></h1>
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<h1 id="服务器文件下载"><a href="#服务器文件下载" class="headerlink" title="服务器文件下载"></a>服务器文件下载</h1><h2 id="需要的-jar-包"><a href="#需要的-jar-包" class="headerlink" title="需要的 jar 包"></a>需要的 jar 包</h2><ul>
<li>commons-fileupload</li>
<li>commons-io</li>
</ul>
<h2 id="文件下载-API"><a href="#文件下载-API" class="headerlink" title="文件下载 API"></a>文件下载 API</h2><h3 id="使用超链接的方式实现文件的下载"><a href="#使用超链接的方式实现文件的下载" class="headerlink" title="使用超链接的方式实现文件的下载"></a>使用超链接的方式实现文件的下载</h3><figure class="highlight html"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="tag"><<span class="name">a</span> <span class="attr">href</span>=<span class="string">"文件的路径"</span>></span>文件名<span class="tag"></<span class="name">a</span>></span></span><br></pre></td></tr></table></figure>
<h3 id="手动编码实现文件的下载"><a href="#手动编码实现文件的下载" class="headerlink" title="手动编码实现文件的下载"></a>手动编码实现文件的下载</h3><ul>
<li>设置两个头和一个流<ul>
<li>Content-Type: 文件的 MIME 类型</li>
<li>Content-Disposition：浏览器支持该格式的文件，提示下载</li>
<li>设置代表该文件的输入流：输入流是固定 <code>response.getOutputStream()</code></li>
</ul>
</li>
</ul>
<h2 id="附"><a href="#附" class="headerlink" title="附"></a>附</h2><p>遍历一个目录内的所有内容</p>
<p>使用树的遍历：广度优先遍历</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br></pre></td><td class="code"><pre><span class="line"> <span class="comment">/*</span></span><br><span class="line"><span class="comment"> * 1. 创建队列</span></span><br><span class="line"><span class="comment"> * 2. 创建根目录</span></span><br><span class="line"><span class="comment"> * 3. 添加根目录进队列</span></span><br><span class="line"><span class="comment"></span></span><br><span class="line"><span class="comment"> * while 循环遍历目录过程：</span></span><br><span class="line"><span class="comment"></span></span><br><span class="line"><span class="comment"> * 循环判断条件：判断队列是否为空</span></span><br><span class="line"><span class="comment"> * 循环体：</span></span><br><span class="line"><span class="comment"> * 1. 队列出列一个元素</span></span><br><span class="line"><span class="comment"> * 2. 获取它里面的所有 File 对象(listFiles()),循环遍历 File[]</span></span><br><span class="line"><span class="comment"> * 3. 判断该元素是否叶子节点（使用 isFile() 方法）</span></span><br><span class="line"><span class="comment"> * 4. 返回 true 则为叶子节点，使用 HTML 标签显示该文件链接提供下载</span></span><br><span class="line"><span class="comment"> * 5. 返回 false 则为目录，添加进队列</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"></span><br><span class="line">Queue<File> queue = <span class="keyword">new</span> LinkedList<File>();</span><br><span class="line">File root = <span class="keyword">new</span> File(<span class="string">"C:\\Users\\cato\\Desktop\\Resource"</span>);</span><br><span class="line">queue.offer(root);</span><br><span class="line"><span class="keyword">while</span> (!queue.isEmpty()) {</span><br><span class="line"> File file = queue.poll();</span><br><span class="line"> File[] files = file.listFiles();</span><br><span class="line"> <span class="keyword">for</span> (File son : files) {</span><br><span class="line"> <span class="keyword">if</span> (son.isFile()) {</span><br><span class="line"> %></span><br><span class="line"> <h4><a href="${ pageContext.request.contextPath }/DownloadServlet?filename=<%= son.getCanonicalPath() %>"><%= son.getName() %></a> </h4></span><br><span class="line"> <%</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> queue.offer(son);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
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<h1 id="服务器文件上传"><a href="#服务器文件上传" class="headerlink" title="服务器文件上传"></a>服务器文件上传</h1><h2 id="需要的-jar-包"><a href="#需要的-jar-包" class="headerlink" title="需要的 jar 包"></a>需要的 jar 包</h2><ul>
<li>commons-fileupload</li>
<li>commons-io</li>
</ul>
<h2 id="文件上传-API"><a href="#文件上传-API" class="headerlink" title="文件上传 API"></a>文件上传 API</h2><h3 id="DiskFileItemFactor-磁盘文件项工厂类"><a href="#DiskFileItemFactor-磁盘文件项工厂类" class="headerlink" title="DiskFileItemFactor: 磁盘文件项工厂类"></a>DiskFileItemFactor: 磁盘文件项工厂类</h3><p><em>Initial</em></p>
<ul>
<li><code>DiskFileItemFactory()</code></li>
<li><code>DiskFileItemFactory(int sizeThreshold,File repostory)</code><ul>
<li>sizeThreshold: 设置文件上传的缓冲区大小，默认值未 10 KB</li>
<li>respository: 设置文件上传过程中产生临时文件存放的路径</li>
</ul>
</li>
</ul>
<p><em>Method</em></p>
<ul>
<li><code>setSizeThreshold()</code>: 设置缓冲区大小</li>
<li><code>setRepository</code>: 设置临时文件存放的路径</li>
</ul>
<p><em>Usage</em></p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 1.创建磁盘文件项工厂</span></span><br><span class="line">DiskFileItemFactory disFileItemFactory = <span class="keyword">new</span> DiskFileItemFactory();</span><br><span class="line"><span class="comment">// 1.1 设置缓冲区的大小</span></span><br><span class="line">diskFileItemFactory.setSizeThreshold(<span class="number">3</span> * <span class="number">1024</span> * <span class="number">1024</span>); <span class="comment">// 设置缓冲区的大小未 3M</span></span><br><span class="line"><span class="comment">// 1.2 设置临时文件存放的路径</span></span><br><span class="line"><span class="comment">// 创建新的临时文件存放的路径的 String 对象</span></span><br><span class="line">String tempPath = getServletContext().getRealPath(<span class="string">"/temp"</span>);</span><br><span class="line">diskFileItemFactory.setRepository(<span class="keyword">new</span> File(tempPath));</span><br></pre></td></tr></table></figure>
<h3 id="ServletFileUpload-核心解析类"><a href="#ServletFileUpload-核心解析类" class="headerlink" title="ServletFileUpload: 核心解析类"></a>ServletFileUpload: 核心解析类</h3><p><em>Initial</em></p>
<ul>
<li><code>ServletFileUpload</code></li>
<li><code>ServletFileUpload(FileItemFactory fileItemFactory)</code></li>
</ul>
<p><em>Method</em></p>
<ul>
<li><p><code>(static boolean) isMultipartContent(HttpServletRequest request)</code>: 判断表单的 enctype 属性是否正确</p>
</li>
<li><p><code>(List) parseRequest(HttpServletRequest request)</code>: 解析 Request 对象，返回一个 List 集合（每个部分的对象 FileItem）</p>
</li>
<li><p><code>setFileSizeMax(long fileSizeMax)</code>: 设置单个文件的大小</p>
</li>
<li><p><code>setSizeMax(long sizeMax)</code>: 设置上传的文件的总大小</p>
</li>
<li><p><code>setHeaderEncoding(String encoding)</code>: 中文文件名上传的乱码的问题</p>
</li>
<li><p><code>setProgressListener(ProgressListener pListener)</code>: 设置监听文件上传的进度</p>
</li>
</ul>
<h3 id="FileItem-文件项"><a href="#FileItem-文件项" class="headerlink" title="FileItem 文件项"></a>FileItem 文件项</h3><p><em>Usage</em></p>
<ul>
<li><p>普通项 </p>
<ul>
<li><p><code>(boolean) isFormField()</code>: 判断表单项是普通项还是文件上传项。如果为 true 代表是普通项</p>
</li>
<li><p><code>(String) getFieldName()</code>: 获得普通项的名称</p>
</li>
<li><p><code>(String) getString()</code></p>
</li>
<li><p><code>(String) getString(String encoding)</code>: 获得普通项的值</p>
</li>
</ul>
</li>
<li><p>文件上传项</p>
<ul>
<li><p><code>(String) getName()</code>: 获取上传的文件的文件名</p>
</li>
<li><p><code>(InputStream) getInputStream()</code>: 获取文件上传的输入流</p>
</li>
<li><p><code>(long) getSize()</code>: 获取上传的文件大小</p>
</li>
<li><p><code>delete()</code>: 删除文件上传过程中的临时文件</p>
</li>
</ul>
</li>
</ul>
<p>代码示例</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">protected</span> <span class="keyword">void</span> <span class="title">doGet</span><span class="params">(HttpServletRequest request, HttpServletResponse response)</span> <span class="keyword">throws</span> ServletException, IOException </span>{</span><br><span class="line"> <span class="keyword">try</span> {</span><br><span class="line"> <span class="comment">// 判断表单的enctype属性：</span></span><br><span class="line"> <span class="keyword">boolean</span> flag = ServletFileUpload.isMultipartContent(request);</span><br><span class="line"> <span class="keyword">if</span> (!flag) {</span><br><span class="line"> <span class="comment">// enctype属性不是multipart/form-data</span></span><br><span class="line"> request.setAttribute(<span class="string">"msg"</span>, <span class="string">"表单的格式不正确！"</span>);</span><br><span class="line"> request.getRequestDispatcher(<span class="string">"/jsp/upload.jsp"</span>).forward(request, response);</span><br><span class="line"> <span class="keyword">return</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">// 1.创建磁盘文件项工厂</span></span><br><span class="line"> DiskFileItemFactory diskFileItemFactory = <span class="keyword">new</span> DiskFileItemFactory();</span><br><span class="line"> <span class="comment">// 下列按需设置</span></span><br><span class="line"> <span class="comment">// 1.1设置缓冲区的大小：</span></span><br><span class="line"> diskFileItemFactory.setSizeThreshold(<span class="number">3</span> * <span class="number">1024</span> * <span class="number">1024</span>);<span class="comment">// 设置缓冲区的大小为3M</span></span><br><span class="line"> <span class="comment">// 1.2设置临时文件存放的路径:</span></span><br><span class="line"> <span class="comment">// 获得临时文件存放的路径：</span></span><br><span class="line"> String tempPath = getServletContext().getRealPath(<span class="string">"/temp"</span>);</span><br><span class="line"> diskFileItemFactory.setRepository(<span class="keyword">new</span> File(tempPath));</span><br><span class="line"> <span class="comment">// 2.创建一个核心的解析类</span></span><br><span class="line"> ServletFileUpload fileUpload = <span class="keyword">new</span> ServletFileUpload(diskFileItemFactory);</span><br><span class="line"> <span class="comment">// 设置文件上传的文件的大小：</span></span><br><span class="line"> <span class="comment">//fileUpload.setSizeMax(5*1024*1024);</span></span><br><span class="line"> <span class="comment">// 3.利用核心类解析Request，解析后会得到多个部分。返回一个List集合。List集合装的是每个部分的内容（FileItem文件项）。</span></span><br><span class="line"> List<FileItem> list = fileUpload.parseRequest(request);</span><br><span class="line"> <span class="comment">// 4.遍历List集合，会得到代表每个部分的文件项的对象。根据文件项判断是否是文件上传项。</span></span><br><span class="line"> <span class="keyword">for</span> (FileItem fileItem : list) {</span><br><span class="line"> <span class="comment">// 判断这个文件项是否是普通项还是文件上传项。</span></span><br><span class="line"> <span class="keyword">if</span> (fileItem.isFormField()) {</span><br><span class="line"> <span class="comment">// 普通项:</span></span><br><span class="line"> <span class="comment">// 接收普通项的值:(接收值不能再使用request.getParameter())</span></span><br><span class="line"> String name = fileItem.getFieldName();<span class="comment">// 获得普通项的名称</span></span><br><span class="line"> <span class="comment">// 获得普通项的值</span></span><br><span class="line"> String value = fileItem.getString(<span class="string">"UTF-8"</span>);</span><br><span class="line"> System.out.println(name+<span class="string">" "</span>+value);</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="comment">// 文件上传项:</span></span><br><span class="line"> <span class="comment">// 获得文件上传项的文件的名称:</span></span><br><span class="line"> String filename = fileItem.getName();</span><br><span class="line"> <span class="comment">// System.out.println("文件名:"+filename);</span></span><br><span class="line"> <span class="keyword">int</span> idx = filename.lastIndexOf(<span class="string">"\\"</span>);</span><br><span class="line"> <span class="keyword">if</span> (idx != -<span class="number">1</span>) {</span><br><span class="line"> <span class="comment">// 使用老版本浏览器：</span></span><br><span class="line"> filename = filename.substring(idx+<span class="number">1</span>);</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">// 得到唯一文件名:</span></span><br><span class="line"> String uuidFilename = UploadUtils.getUuidFilename(filename);</span><br><span class="line"> <span class="comment">// 获得文件上传的文件的数据:</span></span><br><span class="line"> InputStream is = fileItem.getInputStream();</span><br><span class="line"> <span class="comment">// 获得文件上传的路径：磁盘绝对路径。</span></span><br><span class="line"> String realPath = getServletContext().getRealPath(<span class="string">"/upload"</span>);</span><br><span class="line"> <span class="comment">// 进行目录分离:</span></span><br><span class="line"> String path = UploadUtils.getRealPath(uuidFilename);</span><br><span class="line"> String newPath = realPath + path;</span><br><span class="line"> File file = <span class="keyword">new</span> File(newPath);</span><br><span class="line"> <span class="keyword">if</span> (!file.exists()) {</span><br><span class="line"> file.mkdirs();</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">// 创建一个输出流，写入到设置的路径中。</span></span><br><span class="line"> OutputStream os = <span class="keyword">new</span> FileOutputStream(newPath+<span class="string">"/"</span>+uuidFilename);</span><br><span class="line"> <span class="comment">// 两个流对接:</span></span><br><span class="line"> <span class="keyword">int</span> len = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">byte</span>[] b = <span class="keyword">new</span> <span class="keyword">byte</span>[<span class="number">1024</span>];</span><br><span class="line"> <span class="keyword">while</span> ((len = is.read(b)) != -<span class="number">1</span>) {</span><br><span class="line"> os.write(b, <span class="number">0</span>, len);</span><br><span class="line"> }</span><br><span class="line"> is.close();</span><br><span class="line"> os.close();</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">// 删除临时文件</span></span><br><span class="line"> fileItem.delete();</span><br><span class="line"> }</span><br><span class="line"> } <span class="keyword">catch</span> (Exception e) {</span><br><span class="line"> e.printStackTrace();</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<h2 id="附"><a href="#附" class="headerlink" title="附"></a>附</h2><h3 id="文件上传兼容浏览器问题"><a href="#文件上传兼容浏览器问题" class="headerlink" title="文件上传兼容浏览器问题"></a>文件上传兼容浏览器问题</h3><p>如果使用 IE 老版本的浏览器会出现一个文件名称获取时带有路径的情况：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">//正确的文件名：aa.txt</span></span><br><span class="line"><span class="comment">//获取到错误的文件名：C:\Users\cato\Desktop\aa.txt</span></span><br></pre></td></tr></table></figure>
<p>解决：</p>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">int</span> idx = fileName.lastIndexOf(<span class="string">"\\"</span>);</span><br><span class="line"><span class="keyword">if</span> (idx != -<span class="number">1</span>) {</span><br><span class="line"> <span class="comment">//使用老版本 IE 浏览器：</span></span><br><span class="line"> fileName = fileName.substring(idx + <span class="number">1</span>);</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<h3 id="文件上传同一个目录下文件同名问题与同一目录下存放文件过多的问题"><a href="#文件上传同一个目录下文件同名问题与同一目录下存放文件过多的问题" class="headerlink" title="文件上传同一个目录下文件同名问题与同一目录下存放文件过多的问题"></a>文件上传同一个目录下文件同名问题与同一目录下存放文件过多的问题</h3><ul>
<li>在同一个目录下同名文件会出现后上传的覆盖掉先上传的文件，使用唯一文件名解决：</li>
</ul>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 通过 UUID 获取随机的唯一标识</span></span><br><span class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">static</span> String <span class="title">getUniqueFileName</span><span class="params">(String fileName)</span> </span>{</span><br><span class="line"> <span class="keyword">int</span> idx = fileName.lastIndexOf(<span class="string">"."</span>);</span><br><span class="line"> String extetions = fileName.substring(idx);</span><br><span class="line"> <span class="keyword">return</span> UUID.randomUUID().toString().replace(<span class="string">"-"</span>, <span class="string">""</span>) + extetions;</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
<ul>
<li><p>同一目录下存放文件过多，打开时卡顿且不便管理<br> <em>解决方法：</em></p>
<ul>
<li>按时间分离：月、周、天、毫秒等</li>
<li>按用户分离：user id</li>
<li>按个数分离：一个目录放3000个文件</li>
<li>按目录分离算法：以某种特定算法分离</li>
</ul>
<p> <em>目录分离算法简述：</em></p>
<ul>
<li>创建一个唯一文件名</li>
<li>获取上面文件名的 hashCode 值：int 类型（32 位）</li>
<li>让 hashCode 的值 & 0xf：得出来的值作为一级目录的名字</li>
<li>让hashCode 右移 4 位( >>> 4 )</li>
<li>让 hashCode 的值 & 0xf：得出来的值作为二级目录的名字</li>
<li>…(以此类推到想要的层级数)</li>
</ul>
</li>
</ul>
<figure class="highlight java"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">public</span> <span class="keyword">static</span> String <span class="title">getPath</span><span class="params">(String uniqueFileName, <span class="keyword">int</span> count)</span> </span>{</span><br><span class="line"> StringBuilder stringBuilder = <span class="keyword">new</span> StringBuilder();</span><br><span class="line"> <span class="keyword">int</span> code = uniqueFileName.hashCode();</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">int</span> i = <span class="number">0</span>; i < count; i++) {</span><br><span class="line"> <span class="keyword">int</span> directoryName = code & <span class="number">0xf</span>;</span><br><span class="line"> stringBuilder += (<span class="string">"/"</span> + directoryName);</span><br><span class="line"> code = code >>> <span class="number">4</span>;</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure>
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<h2 id="ImagePickerHelper"><a href="#ImagePickerHelper" class="headerlink" title="ImagePickerHelper"></a>ImagePickerHelper</h2><p>一个封装了获取 iOS 系统相机/相册的流程组件，内置权限验证，避免未验证权限导致 Crash，刚好也是学习如何制作自己的 Cocoapods 库，附上传成功后的截图😋：</p>
<p><img src="https://github.com/Cato-chuk/cato.github.io/blob/master/images/searchicon.png" alt="screenshot01"></p>
<h3 id="项目地址"><a href="#项目地址" class="headerlink" title="项目地址"></a>项目地址</h3><p><a href="https://github.com/Cato-chuk/ImagePickerHelper" target="_blank" rel="noopener">https://github.com/Cato-chuk/ImagePickerHelper</a></p>
<h3 id="Usage"><a href="#Usage" class="headerlink" title="Usage"></a>Usage</h3><ul>
<li>在项目的 Profile 文件添加 <code>pod ImagePickerHelper</code></li>
<li>Terminal.app 进入项目根路径执行 <code>pod install</code></li>
<li>在需要调用系统相册/相机的 Controller 里 <code>import ImagePickerHelper</code></li>
<li>使用 <code>ImagePickerHelper.sharedInstance</code> 单例对象来调用方法</li>
</ul>
<h3 id="Method"><a href="#Method" class="headerlink" title="Method"></a>Method</h3><p>定义 Closure 别名</p>
<figure class="highlight swift"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">public</span> <span class="keyword">typealias</span> <span class="type">VoidBlock</span> = () -> <span class="type">Void</span></span><br><span class="line"><span class="keyword">public</span> <span class="keyword">typealias</span> <span class="type">ImageBlock</span> = (<span class="number">_</span> image: <span class="type">UIImage</span>) -> <span class="type">Void</span></span><br></pre></td></tr></table></figure>
<ul>
<li>使用 ActionSheet（从底部升上） 显示 相机/照片 选项</li>
</ul>
<figure class="highlight swift"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/// - Parameters:</span></span><br><span class="line"><span class="comment">/// - title: ActionSheet 显示的标题</span></span><br><span class="line"><span class="comment">/// - message: ActionSheet 显示的信息</span></span><br><span class="line"><span class="comment">/// - controller: 当前需要显示 ActionSheet 的 Controller</span></span><br><span class="line"><span class="comment">/// - completion: 选择照片完成后执行的 Closure</span></span><br><span class="line"><span class="keyword">public</span> <span class="function"><span class="keyword">func</span> <span class="title">showObtainPhotoOptionSheet</span><span class="params">(withTipsTitle title: String, message: String, controller: UIViewController, completion: @escaping ImageBlock)</span></span></span><br></pre></td></tr></table></figure>
<ul>
<li>直接打开系统的相册选择器</li>
</ul>
<figure class="highlight swift"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/// - Parameters:</span></span><br><span class="line"><span class="comment">/// - controller: 负责 present UIImagePickerController(.photoLibrary) 的 Controller</span></span><br><span class="line"><span class="comment">/// - completion: 选择照片完成后执行的 Closure</span></span><br><span class="line"><span class="keyword">public</span> <span class="function"><span class="keyword">func</span> <span class="title">showPhotoLibrary</span><span class="params">(byController controller: UIViewController, completion: @escaping ImageBlock)</span></span></span><br></pre></td></tr></table></figure>
<ul>
<li>直接打开相机</li>
</ul>
<figure class="highlight swift"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/// - Parameters:</span></span><br><span class="line"><span class="comment">/// - controller: 负责 present UIImagePickerController(.camera) 的 Controller</span></span><br><span class="line"><span class="comment">/// - completion: 选择照片完成后执行的 Closure</span></span><br><span class="line"><span class="keyword">public</span> <span class="function"><span class="keyword">func</span> <span class="title">showCamera</span><span class="params">(byController controller: UIViewController, completion: @escaping ImageBlock)</span></span></span><br></pre></td></tr></table></figure>
<ul>
<li><p>系统相册权限验证</p>
<ul>
<li>参数 <code>callSystemImagePicker</code> 默认为 true（调用系统相册选择器），若设为 false 则需要在 authorizedBlock 里提供自定义相册选择器的嗲用</li>
<li>验证结果：notDetermined：将会请求相册权限</li>
<li>验证结果：authorized：直接打开相册</li>
<li>验证结果：其他（即未获得权限）：未默认行为，但会执行 deniedBlock，可通过传入 deniedBlock 做想要的操作</li>
</ul>
<figure class="highlight swift"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/// - Parameters:</span></span><br><span class="line"><span class="comment">/// - callSystemImagePicker: 是否使用系统的相册图库来选择图片</span></span><br><span class="line"><span class="comment">/// - authorizedBlock: 权限验证成功后执行的 Closure</span></span><br><span class="line"><span class="comment">/// - deniedBlock: 权限被拒绝后执行的 Closure</span></span><br><span class="line"><span class="keyword">public</span> <span class="function"><span class="keyword">func</span> <span class="title">photoAlbumPermissions</span><span class="params">(callSystemImagePicker: Bool = <span class="literal">true</span>, authorizedBlock: @escaping VoidBlock = {}, deniedBlock: @escaping VoidBlock = {})</span></span></span><br></pre></td></tr></table></figure>
</li>
</ul>
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