limitedinputstream.html

java 的上传功能很强大的实施上述事实上说是

<a name="76" href="#76">76</a>  <em class="jxr_javadoccomment">     * Reads the next byte of data from this input stream. The value</em>
<a name="77" href="#77">77</a>  <em class="jxr_javadoccomment">     * byte is returned as an &lt;code&gt;int&lt;/code&gt; in the range</em>
<a name="78" href="#78">78</a>  <em class="jxr_javadoccomment">     * &lt;code&gt;0&lt;/code&gt; to &lt;code&gt;255&lt;/code&gt;. If no byte is available</em>
<a name="79" href="#79">79</a>  <em class="jxr_javadoccomment">     * because the end of the stream has been reached, the value</em>
<a name="80" href="#80">80</a>  <em class="jxr_javadoccomment">     * &lt;code&gt;-1&lt;/code&gt; is returned. This method blocks until input data</em>
<a name="81" href="#81">81</a>  <em class="jxr_javadoccomment">     * is available, the end of the stream is detected, or an exception</em>
<a name="82" href="#82">82</a>  <em class="jxr_javadoccomment">     * is thrown.</em>
<a name="83" href="#83">83</a>  <em class="jxr_javadoccomment">     * &lt;p&gt;</em>
<a name="84" href="#84">84</a>  <em class="jxr_javadoccomment">     * This method</em>
<a name="85" href="#85">85</a>  <em class="jxr_javadoccomment">     * simply performs &lt;code&gt;in.read()&lt;/code&gt; and returns the result.</em>
<a name="86" href="#86">86</a>  <em class="jxr_javadoccomment">     *</em>
<a name="87" href="#87">87</a>  <em class="jxr_javadoccomment">     * @return     the next byte of data, or &lt;code&gt;-1&lt;/code&gt; if the end of the</em>
<a name="88" href="#88">88</a>  <em class="jxr_javadoccomment">     *             stream is reached.</em>
<a name="89" href="#89">89</a>  <em class="jxr_javadoccomment">     * @exception  IOException  if an I/O error occurs.</em>
<a name="90" href="#90">90</a>  <em class="jxr_javadoccomment">     * @see        java.io.FilterInputStream#in</em>
<a name="91" href="#91">91</a>  <em class="jxr_javadoccomment">     */</em>
<a name="92" href="#92">92</a>      <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">int</strong> read() <strong class="jxr_keyword">throws</strong> IOException {
<a name="93" href="#93">93</a>          <strong class="jxr_keyword">int</strong> res = <strong class="jxr_keyword">super</strong>.read();
<a name="94" href="#94">94</a>          <strong class="jxr_keyword">if</strong> (res != -1) {
<a name="95" href="#95">95</a>              count++;
<a name="96" href="#96">96</a>              checkLimit();
<a name="97" href="#97">97</a>          }
<a name="98" href="#98">98</a>          <strong class="jxr_keyword">return</strong> res;
<a name="99" href="#99">99</a>      }
<a name="100" href="#100">100</a> 
<a name="101" href="#101">101</a>     <em class="jxr_javadoccomment">/**</em>
<a name="102" href="#102">102</a> <em class="jxr_javadoccomment">     * Reads up to &lt;code&gt;len&lt;/code&gt; bytes of data from this input stream</em>
<a name="103" href="#103">103</a> <em class="jxr_javadoccomment">     * into an array of bytes. If &lt;code&gt;len&lt;/code&gt; is not zero, the method</em>
<a name="104" href="#104">104</a> <em class="jxr_javadoccomment">     * blocks until some input is available; otherwise, no</em>
<a name="105" href="#105">105</a> <em class="jxr_javadoccomment">     * bytes are read and &lt;code&gt;0&lt;/code&gt; is returned.</em>
<a name="106" href="#106">106</a> <em class="jxr_javadoccomment">     * &lt;p&gt;</em>
<a name="107" href="#107">107</a> <em class="jxr_javadoccomment">     * This method simply performs &lt;code&gt;in.read(b, off, len)&lt;/code&gt;</em>
<a name="108" href="#108">108</a> <em class="jxr_javadoccomment">     * and returns the result.</em>
<a name="109" href="#109">109</a> <em class="jxr_javadoccomment">     *</em>
<a name="110" href="#110">110</a> <em class="jxr_javadoccomment">     * @param      b     the buffer into which the data is read.</em>
<a name="111" href="#111">111</a> <em class="jxr_javadoccomment">     * @param      off   The start offset in the destination array</em>
<a name="112" href="#112">112</a> <em class="jxr_javadoccomment">     *                   &lt;code&gt;b&lt;/code&gt;.</em>
<a name="113" href="#113">113</a> <em class="jxr_javadoccomment">     * @param      len   the maximum number of bytes read.</em>
<a name="114" href="#114">114</a> <em class="jxr_javadoccomment">     * @return     the total number of bytes read into the buffer, or</em>
<a name="115" href="#115">115</a> <em class="jxr_javadoccomment">     *             &lt;code&gt;-1&lt;/code&gt; if there is no more data because the end of</em>
<a name="116" href="#116">116</a> <em class="jxr_javadoccomment">     *             the stream has been reached.</em>
<a name="117" href="#117">117</a> <em class="jxr_javadoccomment">     * @exception  NullPointerException If &lt;code&gt;b&lt;/code&gt; is &lt;code&gt;null&lt;/code&gt;.</em>
<a name="118" href="#118">118</a> <em class="jxr_javadoccomment">     * @exception  IndexOutOfBoundsException If &lt;code&gt;off&lt;/code&gt; is negative,</em>
<a name="119" href="#119">119</a> <em class="jxr_javadoccomment">     * &lt;code&gt;len&lt;/code&gt; is negative, or &lt;code&gt;len&lt;/code&gt; is greater than</em>
<a name="120" href="#120">120</a> <em class="jxr_javadoccomment">     * &lt;code&gt;b.length - off&lt;/code&gt;</em>
<a name="121" href="#121">121</a> <em class="jxr_javadoccomment">     * @exception  IOException  if an I/O error occurs.</em>
<a name="122" href="#122">122</a> <em class="jxr_javadoccomment">     * @see        java.io.FilterInputStream#in</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">int</strong> read(byte[] b, <strong class="jxr_keyword">int</strong> off, <strong class="jxr_keyword">int</strong> len) <strong class="jxr_keyword">throws</strong> IOException {
<a name="125" href="#125">125</a>         <strong class="jxr_keyword">int</strong> res = <strong class="jxr_keyword">super</strong>.read(b, off, len);
<a name="126" href="#126">126</a>         <strong class="jxr_keyword">if</strong> (res &gt; 0) {
<a name="127" href="#127">127</a>             count += res;
<a name="128" href="#128">128</a>             checkLimit();
<a name="129" href="#129">129</a>         }
<a name="130" href="#130">130</a>         <strong class="jxr_keyword">return</strong> res;
<a name="131" href="#131">131</a>     }
<a name="132" href="#132">132</a> 
<a name="133" href="#133">133</a>     <em class="jxr_javadoccomment">/**</em>
<a name="134" href="#134">134</a> <em class="jxr_javadoccomment">     * Returns, whether this stream is already closed.</em>
<a name="135" href="#135">135</a> <em class="jxr_javadoccomment">     * @return True, if the stream is closed, otherwise false.</em>
<a name="136" href="#136">136</a> <em class="jxr_javadoccomment">     * @throws IOException An I/O error occurred.</em>
<a name="137" href="#137">137</a> <em class="jxr_javadoccomment">     */</em>
<a name="138" href="#138">138</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">boolean</strong> isClosed() <strong class="jxr_keyword">throws</strong> IOException {
<a name="139" href="#139">139</a>         <strong class="jxr_keyword">return</strong> closed;
<a name="140" href="#140">140</a>     }
<a name="141" href="#141">141</a> 
<a name="142" href="#142">142</a>     <em class="jxr_javadoccomment">/**</em>
<a name="143" href="#143">143</a> <em class="jxr_javadoccomment">     * Closes this input stream and releases any system resources</em>
<a name="144" href="#144">144</a> <em class="jxr_javadoccomment">     * associated with the stream.</em>
<a name="145" href="#145">145</a> <em class="jxr_javadoccomment">     * This</em>
<a name="146" href="#146">146</a> <em class="jxr_javadoccomment">     * method simply performs &lt;code&gt;in.close()&lt;/code&gt;.</em>
<a name="147" href="#147">147</a> <em class="jxr_javadoccomment">     *</em>
<a name="148" href="#148">148</a> <em class="jxr_javadoccomment">     * @exception  IOException  if an I/O error occurs.</em>
<a name="149" href="#149">149</a> <em class="jxr_javadoccomment">     * @see        java.io.FilterInputStream#in</em>
<a name="150" href="#150">150</a> <em class="jxr_javadoccomment">     */</em>
<a name="151" href="#151">151</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">void</strong> close() <strong class="jxr_keyword">throws</strong> IOException {
<a name="152" href="#152">152</a>         closed = <strong class="jxr_keyword">true</strong>;
<a name="153" href="#153">153</a>         <strong class="jxr_keyword">super</strong>.close();
<a name="154" href="#154">154</a>     }
<a name="155" href="#155">155</a> }
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