Android Base64 编码/解码 · Android学习笔记

### Base64编码说明 Base64编码要求把3个8位字节（3*8=24）转化为4个6位的字节（4*6=24），之后在6位的前面补两个0，形成8位一个字节的形式。如果剩下的字符不足3个字节，则用0填充，输出字符使用'='，因此编码后输出的文本末尾可能会出现1或2个'='。为了保证所输出的编码位可读字符，Base64制定了一个编码表，以便进行统一转换。编码表的大小为2^6=64，这也是Base64名称的由来。 ### Base64编码表 <table class="mtable " style="border-collapse:collapse; border-spacing:0px; font-size:12px; border-top-width:1px; border-top-style:solid; border-top-color:rgb(198,222,240); border-left-width:1px; border-left-style:solid; border-left-color:rgb(198,222,240); margin:5px 0px; color:rgb(0,0,0); font-family:tahoma,helvetica,arial,'5b8b4f53',sans-serif; line-height:18px; text-align:center"><tbody><tr><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">码值</th><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">字符</th><td rowspan="18" style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)"> </td><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">码值</th><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">字符</th><td rowspan="18" style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)"> </td><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">码值</th><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">字符</th><td rowspan="18" style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)"> </td><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">码值</th><th scope="col" style="margin:0px; padding:2px 4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240); background-color:rgb(237,247,255)">字符</th></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">0</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">A</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">16</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">Q</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">32</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">g</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">48</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">w</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">1</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">B</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">17</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">R</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">33</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">h</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">49</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">x</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">2</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">C</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">18</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">S</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">34</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">i</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">50</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">y</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">3</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">D</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">19</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">T</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">35</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">j</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">51</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">z</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">4</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">E</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">20</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">U</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">36</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">k</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">52</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">0</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">5</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">F</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">21</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">V</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">37</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">l</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">53</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">1</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">6</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">G</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">22</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">W</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">38</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">m</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">54</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">2</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">7</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">H</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">23</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">X</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">39</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">n</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">55</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">3</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">8</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">I</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">24</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">Y</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">40</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">o</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">56</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">4</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">9</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">J</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">25</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">Z</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">41</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">p</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">57</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">5</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">10</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">K</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">26</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">a</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">42</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">q</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">58</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">6</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">11</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">L</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">27</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">b</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">43</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">r</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">59</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">7</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">12</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">M</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">28</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">c</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">44</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">s</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">60</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">8</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">13</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">N</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">29</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">d</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">45</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">t</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">61</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">9</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">14</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">O</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">30</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">e</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">46</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">u</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">62</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">+</td></tr><tr><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">15</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">P</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">31</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">f</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">47</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">v</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">63</td><td style="margin:0px; padding:4px; border-bottom-width:1px; border-bottom-style:solid; border-bottom-color:rgb(198,222,240); border-right-width:1px; border-right-style:solid; border-right-color:rgb(198,222,240)">/ </td></tr></tbody></table> **用法：** ~~~ String token = "hello world"; // 编码前 String base64Token = Base64.encodeToString(token.getBytes(), Base64.DEFAULT);// 编码后 byte[] m = Base64.decode(base64Token,Base64.DEFAULT);// 解码后 ~~~ 其中第二个参数： Base64.flag - CRLF 这个参数看起来比较眼熟，它就是Win风格的换行符，意思就是使用CR LF这一对作为一行的结尾而不是Unix风格的LF - DEFAULT 这个参数是默认，使用默认的方法来加密 - NO_PADDING 这个参数是略去加密字符串最后的”=” - NO_WRAP 这个参数意思是略去所有的换行符（设置后CRLF就没用了） - URL_SAFE 这个参数意思是加密时不使用对URL和文件名有特殊意义的字符来作为加密字符，具体就是以-和_取代+和/