base64.html

解析RSS工具源码

<a name="99" href="#99">99</a>                      pad =1;
<a name="100" href="#100">100</a>                 }
<a name="101" href="#101">101</a>             }
<a name="102" href="#102">102</a>             <strong>else</strong> {
<a name="103" href="#103">103</a>                 pad =2;
<a name="104" href="#104">104</a>             }
<a name="105" href="#105">105</a> 
<a name="106" href="#106">106</a>             e1 = ALPHASET[(d1&amp;I6O2)>>2];
<a name="107" href="#107">107</a>             e2 = ALPHASET[(d1&amp;O6I2)&lt;&lt;4 | (d2&amp;I4O4)>>4];
<a name="108" href="#108">108</a>             e3 = ALPHASET[(d2&amp;O4I4)&lt;&lt;2 | (d3&amp;I2O6)>>6];
<a name="109" href="#109">109</a>             e4 = ALPHASET[(d3&amp;O2I6)];
<a name="110" href="#110">110</a> 
<a name="111" href="#111">111</a>             eData[eIndex++] = (byte)e1;
<a name="112" href="#112">112</a>             eData[eIndex++] = (byte)e2;
<a name="113" href="#113">113</a>             eData[eIndex++] = (pad&lt;2) ?(byte)e3 : (byte)'=';
<a name="114" href="#114">114</a>             eData[eIndex++] = (pad&lt;1) ?(byte)e4 : (byte)'=';
<a name="115" href="#115">115</a> 
<a name="116" href="#116">116</a>         }
<a name="117" href="#117">117</a>         <strong>return</strong> eData;
<a name="118" href="#118">118</a>     }
<a name="119" href="#119">119</a> 
<a name="120" href="#120">120</a>     <strong>private</strong> <strong>final</strong> <strong>static</strong> <strong>int</strong>[] CODES = <strong>new</strong> <strong>int</strong>[256];
<a name="121" href="#121">121</a> 
<a name="122" href="#122">122</a>     <strong>static</strong> {
<a name="123" href="#123">123</a>         <strong>for</strong> (<strong>int</strong> i=0;i&lt;CODES.length;i++) {
<a name="124" href="#124">124</a>             CODES[i] = 64;
<a name="125" href="#125">125</a>         }
<a name="126" href="#126">126</a>         <strong>for</strong> (<strong>int</strong> i=0;i&lt;ALPHASET.length;i++) {
<a name="127" href="#127">127</a>             CODES[ALPHASET[i]] = i;
<a name="128" href="#128">128</a>         }
<a name="129" href="#129">129</a>     }
<a name="130" href="#130">130</a> 
<a name="131" href="#131">131</a>     <em>/**<em>*</em></em>
<a name="132" href="#132">132</a> <em>     * Dencodes a com.sun.syndication.io.impl.Base64 byte array.</em>
<a name="133" href="#133">133</a> <em>     * &lt;p></em>
<a name="134" href="#134">134</a> <em>     * @param eData byte array to decode.</em>
<a name="135" href="#135">135</a> <em>     * @return decoded byte array.</em>
<a name="136" href="#136">136</a> <em>     * @throws java.lang.IllegalArgumentException thrown if the given byte array was not valid com.sun.syndication.io.impl.Base64 encoding.</em>
<a name="137" href="#137">137</a> <em>     *</em>
<a name="138" href="#138">138</a> <em>     */</em>
<a name="139" href="#139">139</a>     <strong>public</strong> <strong>static</strong> byte[] decode(byte[] eData) {
<a name="140" href="#140">140</a>         <strong>if</strong> (eData==<strong>null</strong>) {
<a name="141" href="#141">141</a>             <strong>throw</strong> <strong>new</strong> IllegalArgumentException(<span class="string">"Cannot decode null"</span>);
<a name="142" href="#142">142</a>         }
<a name="143" href="#143">143</a>         byte[] cleanEData = (byte[]) eData.clone();
<a name="144" href="#144">144</a>         <strong>int</strong> cleanELength = 0;
<a name="145" href="#145">145</a>         <strong>for</strong> (<strong>int</strong> i=0;i&lt;eData.length;i++) {
<a name="146" href="#146">146</a>             <strong>if</strong> (eData[i]&lt;256 &amp;&amp; CODES[eData[i]]&lt;64) {
<a name="147" href="#147">147</a>                 cleanEData[cleanELength++] = eData[i];
<a name="148" href="#148">148</a>             }
<a name="149" href="#149">149</a>         }
<a name="150" href="#150">150</a> 
<a name="151" href="#151">151</a>         <strong>int</strong> dLength = (cleanELength/4)*3;
<a name="152" href="#152">152</a>         <strong>switch</strong> (cleanELength%4) {
<a name="153" href="#153">153</a>             <strong>case</strong> 3:
<a name="154" href="#154">154</a>                 dLength += 2;
<a name="155" href="#155">155</a>                 <strong>break</strong>;
<a name="156" href="#156">156</a>             <strong>case</strong> 2:
<a name="157" href="#157">157</a>                 dLength++;
<a name="158" href="#158">158</a>                 <strong>break</strong>;
<a name="159" href="#159">159</a>         }
<a name="160" href="#160">160</a> 
<a name="161" href="#161">161</a>         byte[] dData = <strong>new</strong> byte[dLength];
<a name="162" href="#162">162</a>         <strong>int</strong> dIndex = 0;
<a name="163" href="#163">163</a>         <strong>for</strong> (<strong>int</strong> i=0;i&lt;cleanELength;i+=4) {
<a name="164" href="#164">164</a>             <strong>if</strong> ((i+3)>cleanELength) {
<a name="165" href="#165">165</a>                 <strong>throw</strong> <strong>new</strong> IllegalArgumentException(<span class="string">"byte array is not a valid com.sun.syndication.io.impl.Base64 encoding"</span>);
<a name="166" href="#166">166</a>             }
<a name="167" href="#167">167</a>             <strong>int</strong> e1 = CODES[cleanEData[i]];
<a name="168" href="#168">168</a>             <strong>int</strong> e2 = CODES[cleanEData[i+1]];
<a name="169" href="#169">169</a>             <strong>int</strong> e3 = CODES[cleanEData[i+2]];
<a name="170" href="#170">170</a>             <strong>int</strong> e4 = CODES[cleanEData[i+3]];
<a name="171" href="#171">171</a>             dData[dIndex++] = (byte) ((e1&lt;&lt;2)|(e2>>4));
<a name="172" href="#172">172</a>             <strong>if</strong> (dIndex&lt;dData.length) {
<a name="173" href="#173">173</a>                 dData[dIndex++] = (byte) ((e2&lt;&lt;4) | (e3>>2));
<a name="174" href="#174">174</a>             }
<a name="175" href="#175">175</a>             <strong>if</strong> (dIndex&lt;dData.length) {
<a name="176" href="#176">176</a>                 dData[dIndex++] = (byte) ((e3&lt;&lt;6) | (e4));
<a name="177" href="#177">177</a>             }
<a name="178" href="#178">178</a>         }
<a name="179" href="#179">179</a>         <strong>return</strong> dData;
<a name="180" href="#180">180</a>     }
<a name="181" href="#181">181</a> 
<a name="182" href="#182">182</a>     <strong>public</strong> <strong>static</strong> <strong>void</strong> main(String[] args) throws Exception {
<a name="183" href="#183">183</a>         String s =
<a name="184" href="#184">184</a>                 <span class="string">"\nPGRpdiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMTk5OS94aHRtbCI+V2UncmUgcHJvcG9zaW5nIDxhIGhy\n"</span>+
<a name="185" href="#185">185</a> <span class="string">"ZWY9Imh0dHA6Ly93d3cuZ29vZ2xlLmNvbS9jb3Jwb3JhdGUvc29mdHdhcmVfcHJpbmNpcGxlcy5odG1sIj5z\n"</span>+
<a name="186" href="#186">186</a> <span class="string">"b21lIGd1aWRlbGluZXMgPC9hPnRvIGhlbHAgY3VyYiB0aGUgcHJvYmxlbSBvZiBJbnRlcm5ldCBzb2Z0d2Fy\n"</span>+
<a name="187" href="#187">187</a> <span class="string">"ZSB0aGF0IGluc3RhbGxzIGl0c2VsZiB3aXRob3V0IHRlbGxpbmcgeW91LCBvciBiZWhhdmVzIGJhZGx5IG9u\n"</span>+
<a name="188" href="#188">188</a> <span class="string">"Y2UgaXQgZ2V0cyBvbiB5b3VyIGNvbXB1dGVyLiBXZSd2ZSBiZWVuIGhlYXJpbmcgYSBsb3Qgb2YgY29tcGxh\n"</span>+
<a name="189" href="#189">189</a> <span class="string">"aW50cyBhYm91dCB0aGlzIGxhdGVseSBhbmQgaXQgc2VlbXMgdG8gYmUgZ2V0dGluZyB3b3JzZS4gV2UgdGhp\n"</span>+
<a name="190" href="#190">190</a> <span class="string">"bmsgaXQncyBpbXBvcnRhbnQgdGhhdCB5b3UgcmV0YWluIGNvbnRyb2wgb2YgeW91ciBjb21wdXRlciBhbmQg\n"</span>+
<a name="191" href="#191">191</a> <span class="string">"dGhhdCB0aGVyZSBiZSBzb21lIGNsZWFyIHN0YW5kYXJkcyBpbiBvdXIgaW5kdXN0cnkuIExldCB1cyBrbm93\n"</span>+
<a name="192" href="#192">192</a> <span class="string">"IGlmIHlvdSB0aGluayB0aGVzZSBndWlkZWxpbmVzIGFyZSB1c2VmdWwgb3IgaWYgeW91IGhhdmUgc3VnZ2Vz\n"</span>+
<a name="193" href="#193">193</a> <span class="string">"dGlvbnMgdG8gaW1wcm92ZSB0aGVtLgo8YnIgLz4KPGJyIC8+Sm9uYXRoYW4gUm9zZW5iZXJnCjxiciAvPgo8\n"</span>+
<a name="194" href="#194">194</a> <span class="string">"L2Rpdj4K\n"</span>;
<a name="195" href="#195">195</a> 
<a name="196" href="#196">196</a>         System.out.println(decode(s));
<a name="197" href="#197">197</a>     }
<a name="198" href="#198">198</a> }
<a name="199" href="#199">199</a> 
</pre>
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