cumulativeprotocoldecoder.html

MINA+API 关于MINA的API

<a name="105" href="#105">105</a> <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">abstract</strong> <strong class="jxr_keyword">class</strong> <a href="../../../../../org/apache/mina/filter/codec/CumulativeProtocolDecoder.html">CumulativeProtocolDecoder</a> <strong class="jxr_keyword">extends</strong> <a href="../../../../../org/apache/mina/filter/codec/ProtocolDecoderAdapter.html">ProtocolDecoderAdapter</a> {
<a name="106" href="#106">106</a> 
<a name="107" href="#107">107</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">final</strong> <a href="../../../../../org/apache/mina/common/AttributeKey.html">AttributeKey</a> BUFFER = <strong class="jxr_keyword">new</strong> <a href="../../../../../org/apache/mina/common/AttributeKey.html">AttributeKey</a>(getClass(), <span class="jxr_string">"buffer"</span>);
<a name="108" href="#108">108</a> 
<a name="109" href="#109">109</a>     <em class="jxr_javadoccomment">/**</em>
<a name="110" href="#110">110</a> <em class="jxr_javadoccomment">     * Creates a new instance.</em>
<a name="111" href="#111">111</a> <em class="jxr_javadoccomment">     */</em>
<a name="112" href="#112">112</a>     <strong class="jxr_keyword">protected</strong> <a href="../../../../../org/apache/mina/filter/codec/CumulativeProtocolDecoder.html">CumulativeProtocolDecoder</a>() {
<a name="113" href="#113">113</a>     }
<a name="114" href="#114">114</a> 
<a name="115" href="#115">115</a>     <em class="jxr_javadoccomment">/**</em>
<a name="116" href="#116">116</a> <em class="jxr_javadoccomment">     * Cumulates content of &lt;tt&gt;in&lt;/tt&gt; into internal buffer and forwards</em>
<a name="117" href="#117">117</a> <em class="jxr_javadoccomment">     * decoding request to {@link #doDecode(IoSession, IoBuffer, ProtocolDecoderOutput)}.</em>
<a name="118" href="#118">118</a> <em class="jxr_javadoccomment">     * &lt;tt&gt;doDecode()&lt;/tt&gt; is invoked repeatedly until it returns &lt;tt&gt;false&lt;/tt&gt;</em>
<a name="119" href="#119">119</a> <em class="jxr_javadoccomment">     * and the cumulative buffer is compacted after decoding ends.</em>
<a name="120" href="#120">120</a> <em class="jxr_javadoccomment">     *</em>
<a name="121" href="#121">121</a> <em class="jxr_javadoccomment">     * @throws IllegalStateException if your &lt;tt&gt;doDecode()&lt;/tt&gt; returned</em>
<a name="122" href="#122">122</a> <em class="jxr_javadoccomment">     *                               &lt;tt&gt;true&lt;/tt&gt; not consuming the cumulative buffer.</em>
<a name="123" href="#123">123</a> <em class="jxr_javadoccomment">     */</em>
<a name="124" href="#124">124</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> decode(<a href="../../../../../org/apache/mina/common/IoSession.html">IoSession</a> session, <a href="../../../../../org/apache/mina/common/IoBuffer.html">IoBuffer</a> in,
<a name="125" href="#125">125</a>             <a href="../../../../../org/apache/mina/filter/codec/ProtocolDecoderOutput.html">ProtocolDecoderOutput</a> out) <strong class="jxr_keyword">throws</strong> Exception {
<a name="126" href="#126">126</a>         <strong class="jxr_keyword">if</strong> (!session.getTransportMetadata().hasFragmentation()) {
<a name="127" href="#127">127</a>             doDecode(session, in, out);
<a name="128" href="#128">128</a>             <strong class="jxr_keyword">return</strong>;
<a name="129" href="#129">129</a>         }
<a name="130" href="#130">130</a> 
<a name="131" href="#131">131</a>         <strong class="jxr_keyword">boolean</strong> usingSessionBuffer = <strong class="jxr_keyword">true</strong>;
<a name="132" href="#132">132</a>         <a href="../../../../../org/apache/mina/common/IoBuffer.html">IoBuffer</a> buf = (IoBuffer) session.getAttribute(BUFFER);
<a name="133" href="#133">133</a>         <em class="jxr_comment">// If we have a session buffer, append data to that; otherwise</em>
<a name="134" href="#134">134</a>         <em class="jxr_comment">// use the buffer read from the network directly.</em>
<a name="135" href="#135">135</a>         <strong class="jxr_keyword">if</strong> (buf != <strong class="jxr_keyword">null</strong>) {
<a name="136" href="#136">136</a>             buf.put(in);
<a name="137" href="#137">137</a>             buf.flip();
<a name="138" href="#138">138</a>         } <strong class="jxr_keyword">else</strong> {
<a name="139" href="#139">139</a>             buf = in;
<a name="140" href="#140">140</a>             usingSessionBuffer = false;
<a name="141" href="#141">141</a>         }
<a name="142" href="#142">142</a> 
<a name="143" href="#143">143</a>         <strong class="jxr_keyword">for</strong> (;;) {
<a name="144" href="#144">144</a>             <strong class="jxr_keyword">int</strong> oldPos = buf.position();
<a name="145" href="#145">145</a>             <strong class="jxr_keyword">boolean</strong> decoded = doDecode(session, buf, out);
<a name="146" href="#146">146</a>             <strong class="jxr_keyword">if</strong> (decoded) {
<a name="147" href="#147">147</a>                 <strong class="jxr_keyword">if</strong> (buf.position() == oldPos) {
<a name="148" href="#148">148</a>                     <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> IllegalStateException(
<a name="149" href="#149">149</a>                             <span class="jxr_string">"doDecode() can't return true when buffer is not consumed."</span>);
<a name="150" href="#150">150</a>                 }
<a name="151" href="#151">151</a> 
<a name="152" href="#152">152</a>                 <strong class="jxr_keyword">if</strong> (!buf.hasRemaining()) {
<a name="153" href="#153">153</a>                     <strong class="jxr_keyword">break</strong>;
<a name="154" href="#154">154</a>                 }
<a name="155" href="#155">155</a>             } <strong class="jxr_keyword">else</strong> {
<a name="156" href="#156">156</a>                 <strong class="jxr_keyword">break</strong>;
<a name="157" href="#157">157</a>             }
<a name="158" href="#158">158</a>         }
<a name="159" href="#159">159</a> 
<a name="160" href="#160">160</a>         <em class="jxr_comment">// if there is any data left that cannot be decoded, we store</em>
<a name="161" href="#161">161</a>         <em class="jxr_comment">// it in a buffer in the session and next time this decoder is</em>
<a name="162" href="#162">162</a>         <em class="jxr_comment">// invoked the session buffer gets appended to</em>
<a name="163" href="#163">163</a>         <strong class="jxr_keyword">if</strong> (buf.hasRemaining()) {
<a name="164" href="#164">164</a>             <strong class="jxr_keyword">if</strong> (usingSessionBuffer) {
<a name="165" href="#165">165</a>                 buf.compact();
<a name="166" href="#166">166</a>             } <strong class="jxr_keyword">else</strong> {
<a name="167" href="#167">167</a>                 storeRemainingInSession(buf, session);
<a name="168" href="#168">168</a>             }
<a name="169" href="#169">169</a>         } <strong class="jxr_keyword">else</strong> {
<a name="170" href="#170">170</a>             <strong class="jxr_keyword">if</strong> (usingSessionBuffer) {
<a name="171" href="#171">171</a>                 removeSessionBuffer(session);
<a name="172" href="#172">172</a>             }
<a name="173" href="#173">173</a>         }
<a name="174" href="#174">174</a>     }
<a name="175" href="#175">175</a> 
<a name="176" href="#176">176</a>     <em class="jxr_javadoccomment">/**</em>
<a name="177" href="#177">177</a> <em class="jxr_javadoccomment">     * Implement this method to consume the specified cumulative buffer and</em>
<a name="178" href="#178">178</a> <em class="jxr_javadoccomment">     * decode its content into message(s).</em>
<a name="179" href="#179">179</a> <em class="jxr_javadoccomment">     *</em>
<a name="180" href="#180">180</a> <em class="jxr_javadoccomment">     * @param in the cumulative buffer</em>
<a name="181" href="#181">181</a> <em class="jxr_javadoccomment">     * @return &lt;tt&gt;true&lt;/tt&gt; if and only if there's more to decode in the buffer</em>
<a name="182" href="#182">182</a> <em class="jxr_javadoccomment">     *         and you want to have &lt;tt&gt;doDecode&lt;/tt&gt; method invoked again.</em>
<a name="183" href="#183">183</a> <em class="jxr_javadoccomment">     *         Return &lt;tt&gt;false&lt;/tt&gt; if remaining data is not enough to decode,</em>
<a name="184" href="#184">184</a> <em class="jxr_javadoccomment">     *         then this method will be invoked again when more data is cumulated.</em>
<a name="185" href="#185">185</a> <em class="jxr_javadoccomment">     * @throws Exception if cannot decode &lt;tt&gt;in&lt;/tt&gt;.</em>
<a name="186" href="#186">186</a> <em class="jxr_javadoccomment">     */</em>
<a name="187" href="#187">187</a>     <strong class="jxr_keyword">protected</strong> <strong class="jxr_keyword">abstract</strong> <strong class="jxr_keyword">boolean</strong> doDecode(<a href="../../../../../org/apache/mina/common/IoSession.html">IoSession</a> session, <a href="../../../../../org/apache/mina/common/IoBuffer.html">IoBuffer</a> in,
<a name="188" href="#188">188</a>             <a href="../../../../../org/apache/mina/filter/codec/ProtocolDecoderOutput.html">ProtocolDecoderOutput</a> out) <strong class="jxr_keyword">throws</strong> Exception;
<a name="189" href="#189">189</a> 
<a name="190" href="#190">190</a>     <em class="jxr_javadoccomment">/**</em>
<a name="191" href="#191">191</a> <em class="jxr_javadoccomment">     * Releases the cumulative buffer used by the specified &lt;tt&gt;session&lt;/tt&gt;.</em>
<a name="192" href="#192">192</a> <em class="jxr_javadoccomment">     * Please don't forget to call &lt;tt&gt;super.dispose( session )&lt;/tt&gt; when</em>
<a name="193" href="#193">193</a> <em class="jxr_javadoccomment">     * you override this method.</em>
<a name="194" href="#194">194</a> <em class="jxr_javadoccomment">     */</em>
<a name="195" href="#195">195</a>     @Override
<a name="196" href="#196">196</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> dispose(<a href="../../../../../org/apache/mina/common/IoSession.html">IoSession</a> session) <strong class="jxr_keyword">throws</strong> Exception {
<a name="197" href="#197">197</a>         removeSessionBuffer(session);
<a name="198" href="#198">198</a>     }
<a name="199" href="#199">199</a> 
<a name="200" href="#200">200</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">void</strong> removeSessionBuffer(<a href="../../../../../org/apache/mina/common/IoSession.html">IoSession</a> session) {
<a name="201" href="#201">201</a>         session.removeAttribute(BUFFER);
<a name="202" href="#202">202</a>     }
<a name="203" href="#203">203</a> 
<a name="204" href="#204">204</a>     <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">void</strong> storeRemainingInSession(<a href="../../../../../org/apache/mina/common/IoBuffer.html">IoBuffer</a> buf, <a href="../../../../../org/apache/mina/common/IoSession.html">IoSession</a> session) {
<a name="205" href="#205">205</a>         <strong class="jxr_keyword">final</strong> <a href="../../../../../org/apache/mina/common/IoBuffer.html">IoBuffer</a> remainingBuf = <strong class="jxr_keyword">new</strong> <a href="../../../../../org/apache/mina/common/UnderivableBuffer.html">UnderivableBuffer</a>(
<a name="206" href="#206">206</a>                 IoBuffer.allocate(buf.capacity()).setAutoExpand(<strong class="jxr_keyword">true</strong>));
<a name="207" href="#207">207</a>         
<a name="208" href="#208">208</a>         remainingBuf.order(buf.order());
<a name="209" href="#209">209</a>         remainingBuf.put(buf);
<a name="210" href="#210">210</a>         
<a name="211" href="#211">211</a>         session.setAttribute(BUFFER, remainingBuf);
<a name="212" href="#212">212</a>     }
<a name="213" href="#213">213</a> }
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