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通常我们生成序列号的时候喜欢把时间作为序列号的一种，但时间序列号的长度为15，这样导致我们的序列号就非常长导致
1，存放时占用空间大,
2，查询时效率慢
我们是不是可以把时间序列号变短呢？
我们知道：
根据ascII编码表，我们可以看出
<table class="gen" border="1" cellspacing="0" cellpadding="0"> |
<tr>
<td class="field" colspan="2">ASCII 码</td>
<td class="field" rowspan="2">字符</td>
<td class="bk">?</td>
<td class="field" colspan="2">ASCII 码</td>
<td class="field" rowspan="2">字符</td>
<td class="bk">?</td>
<td class="field" colspan="2">ASCII 码</td>
<td class="field" rowspan="2">字符</td>
<td class="bk">?</td>
<td class="field" colspan="2">ASCII 码</td>
<td class="field" rowspan="2">字符</td>
</tr>
<tr>
<td class="field">十进位</td>
<td class="field">十六进位</td>
<td class="bk">?</td>
<td class="field">十进位</td>
<td class="field">十六进位</td>
<td class="bk">?</td>
<td class="field">十进位</td>
<td class="field">十六进位</td>
<td class="bk">?</td>
<td class="field">十进位</td>
<td class="field">十六进位</td>
</tr>
<tr>
<td class="cellgen">032</td>
<td class="cellgen">20</td>
<td class="cellgen">?</td>
<td class="bk">?</td>
<td class="cellgen">056</td>
<td class="cellgen">38</td>
<td class="cellgen">8</td>
<td class="bk">?</td>
<td class="cellgen">080</td>
<td class="cellgen">50</td>
<td class="cellgen">P</td>
<td class="bk">?</td>
<td class="cellgen">104</td>
<td class="cellgen">68</td>
<td class="cellgen">h</td>
</tr>
<tr>
<td class="cellgen">033</td>
<td class="cellgen">21</td>
<td class="cellgen">!</td>
<td class="bk">?</td>
<td class="cellgen">057</td>
<td class="cellgen">39</td>
<td class="cellgen">9</td>
<td class="bk">?</td>
<td class="cellgen">081</td>
<td class="cellgen">51</td>
<td class="cellgen">Q</td>
<td class="bk">?</td>
<td class="cellgen">105</td>
<td class="cellgen">69</td>
<td class="cellgen">i</td>
</tr>
<tr>
<td class="cellgen">034</td>
<td class="cellgen">22</td>
<td class="cellgen">"</td>
<td class="bk">?</td>
<td class="cellgen">058</td>
<td class="cellgen">3A</td>
<td class="cellgen">:</td>
<td class="bk">?</td>
<td class="cellgen">082</td>
<td class="cellgen">52</td>
<td class="cellgen">R</td>
<td class="bk">?</td>
<td class="cellgen">106</td>
<td class="cellgen">6A</td>
<td class="cellgen">j</td>
</tr>
<tr>
<td class="cellgen">035</td>
<td class="cellgen">23</td>
<td class="cellgen">#</td>
<td class="bk">?</td>
<td class="cellgen">059</td>
<td class="cellgen">3B</td>
<td class="cellgen">;</td>
<td class="bk">?</td>
<td class="cellgen">083</td>
<td class="cellgen">53</td>
<td class="cellgen">S</td>
<td class="bk">?</td>
<td class="cellgen">107</td>
<td class="cellgen">6B</td>
<td class="cellgen">k</td>
</tr>
<tr>
<td class="cellgen">036</td>
<td class="cellgen">24</td>
<td class="cellgen">$</td>
<td class="bk">?</td>
<td class="cellgen">060</td>
<td class="cellgen">3C</td>
<td class="cellgen"><</td>
<td class="bk">?</td>
<td class="cellgen">084</td>
<td class="cellgen">54</td>
<td class="cellgen">T</td>
<td class="bk">?</td>
<td class="cellgen">108</td>
<td class="cellgen">6C</td>
<td class="cellgen">l</td>
</tr>
<tr>
<td class="cellgen">037</td>
<td class="cellgen">25</td>
<td class="cellgen">%</td>
<td class="bk">?</td>
<td class="cellgen">061</td>
<td class="cellgen">3D</td>
<td class="cellgen">=</td>
<td class="bk">?</td>
<td class="cellgen">085</td>
<td class="cellgen">55</td>
<td class="cellgen">U</td>
<td class="bk">?</td>
<td class="cellgen">109</td>
<td class="cellgen">6D</td>
<td class="cellgen">m</td>
</tr>
<tr>
<td class="cellgen">038</td>
<td class="cellgen">26</td>
<td class="cellgen">&</td>
<td class="bk">?</td>
<td class="cellgen">062</td>
<td class="cellgen">3E</td>
<td class="cellgen">></td>
<td class="bk">?</td>
<td class="cellgen">086</td>
<td class="cellgen">56</td>
<td class="cellgen">V</td>
<td class="bk">?</td>
<td class="cellgen">110</td>
<td class="cellgen">6E</td>
<td class="cellgen">n</td>
</tr>
<tr>
<td class="cellgen">039</td>
<td class="cellgen">27</td>
<td class="cellgen">'</td>
<td class="bk">?</td>
<td class="cellgen">063</td>
<td class="cellgen">3F</td>
<td class="cellgen">?</td>
<td class="bk">?</td>
<td class="cellgen">087</td>
<td class="cellgen">57</td>
<td class="cellgen">W</td>
<td class="bk">?</td>
<td class="cellgen">111</td>
<td class="cellgen">6F</td>
<td class="cellgen">o</td>
</tr>
<tr>
<td class="cellgen">040</td>
<td class="cellgen">28</td>
<td class="cellgen">(</td>
<td class="bk">?</td>
<td class="cellgen">064</td>
<td class="cellgen">40</td>
<td class="cellgen">@</td>
<td class="bk">?</td>
<td class="cellgen">088</td>
<td class="cellgen">58</td>
<td class="cellgen">X</td>
<td class="bk">?</td>
<td class="cellgen">112</td>
<td class="cellgen">70</td>
<td class="cellgen">p</td>
</tr>
<tr>
<td class="cellgen">041</td>
<td class="cellgen">29</td>
<td class="cellgen">)</td>
<td class="bk">?</td>
<td class="cellgen">065</td>
<td class="cellgen">41</td>
<td class="cellgen">A</td>
<td class="bk">?</td>
<td class="cellgen">089</td>
<td class="cellgen">59</td>
<td class="cellgen">Y</td>
<td class="bk">?</td>
<td class="cellgen">113</td>
<td class="cellgen">71</td>
<td class="cellgen">q</td>
</tr>
<tr>
<td class="cellgen">042</td>
<td class="cellgen">2A</td>
<td class="cellgen">*</td>
<td class="bk">?</td>
<td class="cellgen">066</td>
<td class="cellgen">42</td>
<td class="cellgen">B</td>
<td class="bk">?</td>
<td class="cellgen">090</td>
<td class="cellgen">5A</td>
<td class="cellgen">Z</td>
<td class="bk">?</td>
<td class="cellgen">114</td>
<td class="cellgen">72</td>
<td class="cellgen">r</td>
</tr>
<tr>
<td class="cellgen">043</td>
<td class="cellgen">2B</td>
<td class="cellgen">+</td>
<td class="bk">?</td>
<td class="cellgen">067</td>
<td class="cellgen">43</td>
<td class="cellgen">C</td>
<td class="bk">?</td>
<td class="cellgen">091</td>
<td class="cellgen">5B</td>
<td class="cellgen">[</td>
<td class="bk">?</td>
<td class="cellgen">115</td>
<td class="cellgen">73</td>
<td class="cellgen">s</td>
</tr>
<tr>
<td class="cellgen">044</td>
<td class="cellgen">2C</td>
<td class="cellgen">,</td>
<td class="bk">?</td>
<td class="cellgen">068</td>
<td class="cellgen">44</td>
<td class="cellgen">D</td>
<td class="bk">?</td>
<td class="cellgen">092</td>
<td class="cellgen">5C</td>
<td class="cellgen">&;/td>
<td class="bk">?</td>
<td class="cellgen">116</td>
<td class="cellgen">74</td>
<td class="cellgen">t</td>
</tr>
<tr>
<td class="cellgen">045</td>
<td class="cellgen">2D</td>
<td class="cellgen">-</td>
<td class="bk">?</td>
<td class="cellgen">069</td>
<td class="cellgen">45</td>
<td class="cellgen">E</td>
<td class="bk">?</td>
<td class="cellgen">093</td>
<td class="cellgen">5D</td>
<td class="cellgen">]</td>
<td class="bk">?</td>
<td class="cellgen">117</td>
<td class="cellgen">75</td>
<td class="cellgen">u</td>
</tr>
<tr>
<td class="cellgen">046</td>
<td class="cellgen">2E</td>
<td class="cellgen">.</td>
<td class="bk">?</td>
<td class="cellgen">070</td>
<td class="cellgen">46</td>
<td class="cellgen">F</td>
<td class="bk">?</td>
<td class="cellgen">094</td>
<td class="cellgen">5E</td>
<td class="cellgen">^</td>
<td class="bk">?</td>
<td class="cellgen">118</td>
<td class="cellgen">76</td>
<td class="cellgen">v</td>
</tr>
<tr>
<td class="cellgen">047</td>
<td class="cellgen">2F</td>
<td class="cellgen">/</td>
<td class="bk">?</td>
<td class="cellgen">071</td>
<td class="cellgen">47</td>
<td class="cellgen">G</td>
<td class="bk">?</td>
<td class="cellgen">095</td>
<td class="cellgen">5F</td>
<td class="cellgen">_</td>
<td class="bk">?</td>
<td class="cellgen">119</td>
<td class="cellgen">77</td>
<td class="cellgen">w</td>
</tr>
<tr>
<td class="cellgen">048</td>
<td class="cellgen">30</td>
<td class="cellgen">0</td>
<td class="bk">?</td>
<td class="cellgen">072</td>
<td class="cellgen">48</td>
<td class="cellgen">H</td>
<td class="bk">?</td>
<td class="cellgen">096</td>
<td class="cellgen">60</td>
<td class="cellgen">`</td>
<td class="bk">?</td>
<td class="cellgen">120</td>
<td class="cellgen">78</td>
<td class="cellgen">x</td>
</tr>
<tr>
<td class="cellgen">049</td>
<td class="cellgen">31</td>
<td class="cellgen">1</td>
<td class="bk">?</td>
<td class="cellgen">073</td>
<td class="cellgen">49</td>
<td class="cellgen">I</td>
<td class="bk">?</td>
<td class="cellgen">097</td>
<td class="cellgen">61</td>
<td class="cellgen">a</td>
<td class="bk">?</td>
<td class="cellgen">121</td>
<td class="cellgen">79</td>
<td class="cellgen">y</td>
</tr>
<tr>
<td class="cellgen">050</td>
<td class="cellgen">32</td>
<td class="cellgen">2</td>
<td class="bk">?</td>
<td class="cellgen">074</td>
<td class="cellgen">4A</td>
<td class="cellgen">J</td>
<td class="bk">?</td>
<td class="cellgen">098</td>
<td class="cellgen">62</td>
<td class="cellgen">b</td>
<td class="bk">?</td>
<td class="cellgen">122</td>
<td class="cellgen">7A</td>
<td class="cellgen">z</td>
</tr>
<tr>
<td class="cellgen">051</td>
<td class="cellgen">33</td>
<td class="cellgen">3</td>
<td class="bk">?</td>
<td class="cellgen">075</td>
<td class="cellgen">4B</td>
<td class="cellgen">K</td>
<td class="bk">?</td>
<td class="cellgen">099</td>
<td class="cellgen">63</td>
<td class="cellgen">c</td>
<td class="bk">?</td>
<td class="cellgen">123</td>
<td class="cellgen">7B</td>
<td class="cellgen">{</td>
</tr>
<tr>
<td class="cellgen">052</td>
<td class="cellgen">34</td>
<td class="cellgen">4</td>
<td class="bk">?</td>
<td class="cellgen">076</td>
<td class="cellgen">4C</td>
<td class="cellgen">L</td>
<td class="bk">?</td>
<td class="cellgen">100</td>
<td class="cellgen">64</td>
<td class="cellgen">d</td>
<td class="bk">?</td>
<td class="cellgen">124</td>
<td class="cellgen">7C</td>
<td class="cellgen">|</td>
</tr>
<tr>
<td class="cellgen">053</td>
<td class="cellgen">35</td>
<td class="cellgen">5</td>
<td class="bk">?</td>
<td class="cellgen">077</td>
<td class="cellgen">4D</td>
<td class="cellgen">M</td>
<td class="bk">?</td>
<td class="cellgen">101</td>
<td class="cellgen">65</td>
<td class="cellgen">e</td>
<td class="bk">?</td>
<td class="cellgen">125</td>
<td class="cellgen">7D</td>
<td class="cellgen">}</td>
</tr>
<tr>
<td class="cellgen">054</td>
<td class="cellgen">36</td>
<td class="cellgen">6</td>
<td class="bk">?</td>
<td class="cellgen">078</td>
<td class="cellgen">4E</td>
<td class="cellgen">N</td>
<td class="bk">?</td>
<td class="cellgen">102</td>
<td class="cellgen">66</td>
<td class="cellgen">f</td>
<td class="bk">?</td>
<td class="cellgen">126</td>
<td class="cellgen">7E</td>
<td class="cellgen">~</td>
</tr>
<tr>
<td class="cellgen">055</td>
<td class="cellgen">37</td>
<td class="cellgen">7</td>
<td class="bk">?</td>
<td class="cellgen">079</td>
<td class="cellgen">4F</td>
<td class="cellgen">O</td>
<td class="bk">?</td>
<td class="cellgen">103</td>
<td class="cellgen">67</td>
<td class="cellgen">g</td>
<td class="bk">?</td>
<td class="cellgen">127</td>
<td class="cellgen">7F</td>
<td class="cellgen">DEL</td>
</tr>
小写字符a(97) 使用不同存储时的编码长度
二进制：01100001
八进制：141
十进制:97
十六进制:61
可以看出，随着进制的增高，字符的长度也会越来越短，如果我们拿我们常用的0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ这个62个字符作为编码，那么62进制就可以表示了。
再进行编码前，我搜了一下git，上面已经有代码实现了（），我就不再实现一遍了，代码如下：
1.编码，将long型转换为62进制字符串
String.
*
* String.
String encodeBase10( (b10 < 0 IllegalArgumentException("b10 must be nonnegative"= "" (b10 > 0= characters.charAt(() (b10 % 62)) +/= 62}</span></pre>
2.解码，逆过程
String returning a long.
*
* String to decode.
* long.
* String contains characters not
* specified in the constructor.
( (! IllegalArgumentException("Invalid character(s) in string: " + ret = 0= count = 1 (+= characters.indexOf(character) **= 62
测试用例：
=== System.out.println(time);
System.out.println(encoder.decodeBase62(timeStr));
}</span></pre>
console输出结果如下：
613534552694770
613534552694770
长度由15位变为9位，减少了40%的长度，当前查询效率也得到相应的提升了。
是不是蛮有趣的？
（编辑：李大同）
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