Android Base64 編碼/解碼 · Android學習筆記

### Base64編碼說明 Base64編碼要求把3個8位字節（3*8=24）轉化為4個6位的字節（4*6=24），之后在6位的前面補兩個0，形成8位一個字節的形式。如果剩下的字符不足3個字節，則用0填充，輸出字符使用'='，因此編碼后輸出的文本末尾可能會出現1或2個'='。為了保證所輸出的編碼位可讀字符，Base64制定了一個編碼表，以便進行統一轉換。編碼表的大小為2^6=64，這也是Base64名稱的由來。 ### Base64編碼表 <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)">碼值</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)">碼值</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)">碼值</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)">碼值</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"; // 編碼前 String ?base64Token = Base64.encodeToString(token.getBytes(), Base64.DEFAULT);// ?編碼后 byte[] m = Base64.decode(base64Token,Base64.DEFAULT);// 解碼后 ~~~ 其中第二個參數： Base64.flag - CRLF?這個參數看起來比較眼熟，它就是Win風格的換行符，意思就是使用CR LF這一對作為一行的結尾而不是Unix風格的LF - DEFAULT?這個參數是默認，使用默認的方法來加密 - NO_PADDING?這個參數是略去加密字符串最后的”=” - NO_WRAP?這個參數意思是略去所有的換行符（設置后CRLF就沒用了） - URL_SAFE?這個參數意思是加密時不使用對URL和文件名有特殊意義的字符來作為加密字符，具體就是以-和_取代+和/