Site updated: 2018-06-05 00:48:33

Author: geekhoon

2017/04/06/JavaWeb-09-HttpServletRequest/index.html

@@ -93,7 +93,7 @@
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 <meta name="twitter:title" content="HttpServletRequest">
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@@ -406,6 +406,13 @@ <h4 id="8-dao"><a href="#8-dao" class="headerlink" title="8.dao"></a>8.dao</h4><
 <h4 id="9-utils"><a href="#9-utils" class="headerlink" title="9.utils"></a>9.utils</h4><figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">package</span> com.geekhoon.utils;</div><div class="line"></div><div class="line"><span class="keyword">import</span> java.sql.Connection;</div><div class="line"><span class="keyword">import</span> java.sql.SQLException;</div><div class="line"></div><div class="line"><span class="keyword">import</span> javax.sql.DataSource;</div><div class="line"></div><div class="line"><span class="keyword">import</span> com.mchange.v2.c3p0.ComboPooledDataSource;</div><div class="line"></div><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">C3P0Utils</span> </span>&#123;</div><div class="line">	<span class="keyword">private</span> <span class="keyword">static</span> DataSource ds = <span class="keyword">new</span> ComboPooledDataSource();</div><div class="line">	</div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">static</span> DataSource <span class="title">getDs</span><span class="params">()</span></span>&#123;</div><div class="line">		<span class="keyword">return</span> ds;</div><div class="line">	&#125;</div><div class="line">	</div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">static</span> Connection <span class="title">getConnection</span><span class="params">()</span> <span class="keyword">throws</span> SQLException</span>&#123;</div><div class="line">		<span class="keyword">return</span> ds.getConnection();</div><div class="line">	&#125;</div><div class="line">	</div><div class="line">&#125;</div></pre></td></tr></table></figure>
 <figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div><div class="line">10</div><div class="line">11</div><div class="line">12</div><div class="line">13</div><div class="line">14</div><div class="line">15</div><div class="line">16</div><div class="line">17</div><div class="line">18</div><div class="line">19</div><div class="line">20</div><div class="line">21</div><div class="line">22</div><div class="line">23</div><div class="line">24</div><div class="line">25</div><div class="line">26</div><div class="line">27</div><div class="line">28</div><div class="line">29</div><div class="line">30</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">package</span> com.geekhoon.utils;</div><div class="line"></div><div class="line"><span class="keyword">import</span> java.lang.reflect.InvocationTargetException;</div><div class="line"><span class="keyword">import</span> java.util.Date;</div><div class="line"><span class="keyword">import</span> java.util.Map;</div><div class="line"></div><div class="line"><span class="keyword">import</span> org.apache.commons.beanutils.BeanUtils;</div><div class="line"><span class="keyword">import</span> org.apache.commons.beanutils.ConvertUtils;</div><div class="line"><span class="keyword">import</span> org.apache.commons.beanutils.converters.DateConverter;</div><div class="line"></div><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">MyBeanUtils</span> </span>&#123;</div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">static</span> <span class="keyword">void</span> <span class="title">populate</span><span class="params">(Object obj,Map map)</span></span>&#123;</div><div class="line">		<span class="comment">//设置并注册一个时间转换器</span></div><div class="line">		DateConverter dc = <span class="keyword">new</span> DateConverter();</div><div class="line">		<span class="comment">//设置当前转换的字符串的格式</span></div><div class="line">		dc.setPattern(<span class="string">"yyyy-MM-dd"</span>);</div><div class="line">		<span class="comment">//注册该转换器</span></div><div class="line">		ConvertUtils.register(dc, Date.class);</div><div class="line">		<span class="comment">//2、使用BeanUtils 为 JavaBean 对象赋值</span></div><div class="line">		<span class="keyword">try</span> &#123;</div><div class="line">			BeanUtils.populate(obj, map);</div><div class="line">		&#125; <span class="keyword">catch</span> (IllegalAccessException e) &#123;</div><div class="line">			<span class="comment">// TODO Auto-generated catch block</span></div><div class="line">			e.printStackTrace();</div><div class="line">		&#125; <span class="keyword">catch</span> (InvocationTargetException e) &#123;</div><div class="line">			<span class="comment">// TODO Auto-generated catch block</span></div><div class="line">			e.printStackTrace();</div><div class="line">		&#125;</div><div class="line">	&#125;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
 <figure class="highlight java"><table><tr><td class="gutter"><pre><div class="line">1</div><div class="line">2</div><div class="line">3</div><div class="line">4</div><div class="line">5</div><div class="line">6</div><div class="line">7</div><div class="line">8</div><div class="line">9</div></pre></td><td class="code"><pre><div class="line"><span class="keyword">package</span> com.geekhoon.utils;</div><div class="line"></div><div class="line"><span class="keyword">import</span> java.util.UUID;</div><div class="line"></div><div class="line"><span class="keyword">public</span> <span class="class"><span class="keyword">class</span> <span class="title">UUIDUtils</span> </span>&#123;</div><div class="line">	<span class="function"><span class="keyword">public</span> <span class="keyword">static</span> String <span class="title">getId</span><span class="params">()</span></span>&#123;</div><div class="line">		<span class="keyword">return</span> UUID.randomUUID().toString().replace(<span class="string">"-"</span>, <span class="string">""</span>);</div><div class="line">	&#125;</div><div class="line">&#125;</div></pre></td></tr></table></figure>
+<h2 id="补充重要内容"><a href="#补充重要内容" class="headerlink" title="补充重要内容"></a>补充重要内容</h2><h3 id="域对象"><a href="#域对象" class="headerlink" title="域对象"></a>域对象</h3><p>注意两个重要的域对象：<strong>ServletContext和Request</strong><br>ServletContext：Web项目启动后，创建唯一的ServletContext对象，存取的数据为所有的Servlet所共享。<br>Request：Request存取的数据只在当前请求中有效。</p>
+<p>存取的方法都是setAttribute和getAttribute。</p>
+<h3 id="请求转发和重定向举例"><a href="#请求转发和重定向举例" class="headerlink" title="请求转发和重定向举例"></a>请求转发和重定向举例</h3><p>请求重定向相当于是重新发送了一次请求，而请求转发是一次请求；<br><strong>请求重定向</strong>：就好比我们找一个A广告公司给设计名片，A明确告诉我们他们不会设计，就让我们找B公司，结果B公司给我设计好了，所以我们会对外宣称是B公司给我们设计的名片，（所以我们就相当于发送了两次次请求，URL地址栏里就从A变成了B公司）</p>
+<p><strong>请求转发</strong>：同样去找A公司给设计名片，A公司虽然不能设计但是他们接下了我们的活，把这项任务外包（转发）给B公司，最终我们会把钱给A公司，也就会对外宣称是A公司给我们设计的名片这就是请求重定向（所以我们就相当于只对A发送了一次请求，URL地址栏里依然是A公司）。</p>
+<h3 id="请求转发和重定向如何选择"><a href="#请求转发和重定向如何选择" class="headerlink" title="请求转发和重定向如何选择"></a>请求转发和重定向如何选择</h3><p>1.涉及到数据传递，使用请求转发，否则重定向<br>2.对数据进行修改、删除、添加操作的时候，应该用重定向，如果采用请求转发，那么操作前后的地址栏不发生改变，仍然是修改的Servlet，如果此时再对当前页面刷新的话，就会重新发送一次请求对数据进行修改，这也就是有的人在刷新一次页面就增加一条数据的原因。</p>
+<h3 id="使用重定向如何传递参数"><a href="#使用重定向如何传递参数" class="headerlink" title="使用重定向如何传递参数"></a>使用重定向如何传递参数</h3><p>1.可以选择session，但要在第二个文件中删除<br>2.可以在请求的url中带上参数，如”add.html?id=1”</p>
+
 
     </div>
 
@@ -662,7 +669,7 @@ <h4 id="9-utils"><a href="#9-utils" class="headerlink" title="9.utils"></a>9.uti
 
 
 
-              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#概述"><span class="nav-number">1.</span> <span class="nav-text">概述</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#使用"><span class="nav-number">2.</span> <span class="nav-text">使用</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#作用范围"><span class="nav-number">3.</span> <span class="nav-text">作用范围</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#请求处理"><span class="nav-number">4.</span> <span class="nav-text">请求处理</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#请求转发"><span class="nav-number">4.1.</span> <span class="nav-text">请求转发</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#重定向"><span class="nav-number">4.2.</span> <span class="nav-text">重定向</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#原理图"><span class="nav-number">4.3.</span> <span class="nav-text">原理图</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#区别"><span class="nav-number">4.4.</span> <span class="nav-text">区别</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#路径问题-—–"><span class="nav-number">5.</span> <span class="nav-text">路径问题 ## —–</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#BeanUtils-——–反射"><span class="nav-number">6.</span> <span class="nav-text">BeanUtils ## ——–反射</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#使用-1"><span class="nav-number">6.1.</span> <span class="nav-text">使用</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#代码"><span class="nav-number">6.2.</span> <span class="nav-text">代码</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#案例"><span class="nav-number">7.</span> <span class="nav-text">案例</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#需求"><span class="nav-number">7.1.</span> <span class="nav-text">需求</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#实现步骤"><span class="nav-number">7.2.</span> <span class="nav-text">实现步骤</span></a><ol class="nav-child"><li class="nav-item nav-level-4"><a class="nav-link" href="#1-导入jar包及配置文件"><span class="nav-number">7.2.1.</span> <span class="nav-text">1.导入jar包及配置文件</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#2-创建数据库-表"><span class="nav-number">7.2.2.</span> <span class="nav-text">2.创建数据库,表</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#3-注册界面"><span class="nav-number">7.2.3.</span> <span class="nav-text">3.注册界面</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#4-构建代码结构"><span class="nav-number">7.2.4.</span> <span class="nav-text">4.构建代码结构</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#5-domain"><span class="nav-number">7.2.5.</span> <span class="nav-text">5.domain</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#6-servlet"><span class="nav-number">7.2.6.</span> <span class="nav-text">6.servlet</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#7-service"><span class="nav-number">7.2.7.</span> <span class="nav-text">7.service</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#8-dao"><span class="nav-number">7.2.8.</span> <span class="nav-text">8.dao</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#9-utils"><span class="nav-number">7.2.9.</span> <span class="nav-text">9.utils</span></a></li></ol></li></ol></li></ol></div>
+              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-2"><a class="nav-link" href="#概述"><span class="nav-number">1.</span> <span class="nav-text">概述</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#使用"><span class="nav-number">2.</span> <span class="nav-text">使用</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#作用范围"><span class="nav-number">3.</span> <span class="nav-text">作用范围</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#请求处理"><span class="nav-number">4.</span> <span class="nav-text">请求处理</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#请求转发"><span class="nav-number">4.1.</span> <span class="nav-text">请求转发</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#重定向"><span class="nav-number">4.2.</span> <span class="nav-text">重定向</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#原理图"><span class="nav-number">4.3.</span> <span class="nav-text">原理图</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#区别"><span class="nav-number">4.4.</span> <span class="nav-text">区别</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#路径问题-—–"><span class="nav-number">5.</span> <span class="nav-text">路径问题 ## —–</span></a></li><li class="nav-item nav-level-2"><a class="nav-link" href="#BeanUtils-——–反射"><span class="nav-number">6.</span> <span class="nav-text">BeanUtils ## ——–反射</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#使用-1"><span class="nav-number">6.1.</span> <span class="nav-text">使用</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#代码"><span class="nav-number">6.2.</span> <span class="nav-text">代码</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#案例"><span class="nav-number">7.</span> <span class="nav-text">案例</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#需求"><span class="nav-number">7.1.</span> <span class="nav-text">需求</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#实现步骤"><span class="nav-number">7.2.</span> <span class="nav-text">实现步骤</span></a><ol class="nav-child"><li class="nav-item nav-level-4"><a class="nav-link" href="#1-导入jar包及配置文件"><span class="nav-number">7.2.1.</span> <span class="nav-text">1.导入jar包及配置文件</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#2-创建数据库-表"><span class="nav-number">7.2.2.</span> <span class="nav-text">2.创建数据库,表</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#3-注册界面"><span class="nav-number">7.2.3.</span> <span class="nav-text">3.注册界面</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#4-构建代码结构"><span class="nav-number">7.2.4.</span> <span class="nav-text">4.构建代码结构</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#5-domain"><span class="nav-number">7.2.5.</span> <span class="nav-text">5.domain</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#6-servlet"><span class="nav-number">7.2.6.</span> <span class="nav-text">6.servlet</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#7-service"><span class="nav-number">7.2.7.</span> <span class="nav-text">7.service</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#8-dao"><span class="nav-number">7.2.8.</span> <span class="nav-text">8.dao</span></a></li><li class="nav-item nav-level-4"><a class="nav-link" href="#9-utils"><span class="nav-number">7.2.9.</span> <span class="nav-text">9.utils</span></a></li></ol></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#补充重要内容"><span class="nav-number">8.</span> <span class="nav-text">补充重要内容</span></a><ol class="nav-child"><li class="nav-item nav-level-3"><a class="nav-link" href="#域对象"><span class="nav-number">8.1.</span> <span class="nav-text">域对象</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#请求转发和重定向举例"><span class="nav-number">8.2.</span> <span class="nav-text">请求转发和重定向举例</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#请求转发和重定向如何选择"><span class="nav-number">8.3.</span> <span class="nav-text">请求转发和重定向如何选择</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#使用重定向如何传递参数"><span class="nav-number">8.4.</span> <span class="nav-text">使用重定向如何传递参数</span></a></li></ol></li></ol></div>
 
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