📄 0034.htm
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lang=EN-US>GET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是从服务器上请求数据，</SPAN><SPAN
lang=EN-US>POST</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">是发送数据到服务器。事实上，</SPAN><SPAN
lang=EN-US>GET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法是把数据参数队列（</SPAN><EM><SPAN
lang=EN-US>query string</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">）</SPAN></EM><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">加到一个</SPAN><SPAN
lang=EN-US>URL</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">上，值和表单是一一对应的。比如说，</SPAN><SPAN
lang=EN-US>name=John</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。在队列里，值和表单用一个</SPAN> &</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">符号分开，空格用</SPAN> +</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">号替换，特殊的符号转换成十六进制的代码。因为这一队列在</SPAN><SPAN
lang=EN-US>URL</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">里边，这样队列的参数就能看得到，可以被记录下来，或更改。通常</SPAN><SPAN
lang=EN-US>GET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法还限制字符的大小。事实上</SPAN><SPAN
lang=EN-US>POST</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法可以没有时间限制的传递数据到服务器，用户在浏览器端是看不到这一过程的，所以</SPAN><SPAN
lang=EN-US>POST</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法比较适合用于发送一个保密的（比如信用卡号）或者比较大量的数据到服务器。</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">写</SPAN><SPAN
lang=EN-US>Bean</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如果</SPAN><SPAN
lang=EN-US>JSP</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序用到了</SPAN><SPAN
lang=EN-US>Bean</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，你就得按照</SPAN><SPAN
lang=EN-US>JavaBeans API</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的说明设计你的</SPAN><SPAN
lang=EN-US>Bean</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">记住下面两个关键部分。</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如果</SPAN><SPAN
lang=EN-US>JSP</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序里用</SPAN> <jsp:getProperty></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">标签，那你就得在</SPAN><SPAN
lang=EN-US>Bean</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">里边配合的</SPAN><SPAN
lang=EN-US>GET</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法。</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">如果</SPAN><SPAN
lang=EN-US>JSP</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序进而用</SPAN> <jsp:setProperty></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">标签，那你就得在</SPAN><SPAN
lang=EN-US>Bean</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">里边配合的</SPAN><SPAN
lang=EN-US>Set</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法。</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">设置参数到</SPAN><SPAN
lang=EN-US>Bean</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">或者从里边取参数将在以后的部分详细介绍。</SPAN></P>
<P class=MsoNormal><SPAN lang=EN-US> <O:P> </O:P></SPAN></P>
<H4>传数据到<SPAN lang=EN-US>Bean</SPAN></H4>
<P><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">把<SPAN
lang=EN-US>HTML表单的数据传到Bean里需要两个工作：<O:P> </O:P></SPAN></SPAN></P>
<P
style="MARGIN-LEFT: 36pt; TEXT-INDENT: -18pt; mso-list: l6 level1 lfo7; tab-stops: list 36.0pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Symbol; FONT-SIZE: 10pt; mso-bidi-font-size: 12.0pt">·<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">用<SPAN
lang=EN-US><jsp:useBean>标签创建或者定位到Bean<O:P>
</O:P></SPAN></SPAN></P>
<P
style="MARGIN-LEFT: 36pt; TEXT-INDENT: -18pt; mso-list: l6 level1 lfo7; tab-stops: list 36.0pt"><SPAN
lang=EN-US
style="FONT-FAMILY: Symbol; FONT-SIZE: 10pt; mso-bidi-font-size: 12.0pt">·<SPAN
style="FONT: 7pt 'Times New Roman'">
</SPAN></SPAN><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">在<SPAN
lang=EN-US>Bean里面用<jsp:serProperty>设置属性值<O:P>
</O:P></SPAN></SPAN></P>
<P><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">第一步用<SPAN
lang=EN-US><jsp:useBean>标签创建或者定位到Bean一定要用在<jsp:setProperty>之前，<jsp:useBean>首先按照你指定的名字查找Bean，如果没找到，会给你指定一个。允许在一个JSP文件中创建一个Bean，然后再另一个文件中调用，这就给了Bean一个很广泛的运行空间。<O:P>
</O:P></SPAN></SPAN></P>
<P><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">第二步在<SPAN
lang=EN-US>Bean里面用<jsp:setProperty>设置属性值。最简单的方法是把值定义成与表单名相配合。举个例子，如果你把表单名定义成“username”那么，你就在Bean里定义属性“username”然后用方法getUsername和setUsername。<O:P>
</O:P></SPAN></SPAN></P>
<P><SPAN
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt">当然也可以定义成不同的名字，只要你不认为麻烦。谁让你记忆力好呢！
<SPAN lang=EN-US><O:P></O:P></SPAN></SPAN></P>
<H4><SPAN lang=EN-US>Request对象</SPAN><SPAN lang=EN-US
style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 12.0pt"><O:P>
</O:P></SPAN></H4>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">用户输入的数据用来存放在</SPAN><SPAN
lang=EN-US>Request</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对象里，用</SPAN><SPAN
lang=EN-US>javax.servlet.HttpServletRequest</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来执行（你也可以用其他不同的工具来执行，但他们其实都是</SPAN><SPAN
lang=EN-US>javax.servlet.HttpServletRequest</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的子集）</SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">你也可以直接用</SPAN><SPAN
lang=EN-US>scriptlet</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">来直接访问</SPAN><SPAN
lang=EN-US>Request</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对象。</SPAN><SPAN
lang=EN-US>Scriptlet</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">将在下一讲里边详细的讨论，现在你只需要知道他是用脚本语言写的一段放在</SPAN> <% </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN> %> </SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">之间的代码就足够了。在</SPAN><SPAN
lang=EN-US>JSP 1.0</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">中，你必须用</SPAN><SPAN
lang=EN-US>JavaTM</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">程序语言作为你的脚本语言。</SPAN> <BR></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">你经常会用到如下方法处理</SPAN><SPAN
lang=EN-US>Request</SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">对象：</SPAN></P>
<TABLE border=1 cellPadding=0 cellSpacing=0
style="BORDER-BOTTOM: medium none; BORDER-COLLAPSE: collapse; BORDER-LEFT: medium none; BORDER-RIGHT: medium none; BORDER-TOP: medium none; mso-padding-alt: 0cm 5.4pt 0cm 5.4pt; mso-border-alt: solid windowtext .5pt"
width=600>
<TBODY>
<TR>
<TD align=middle
style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: windowtext 0.5pt solid; BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm"
vAlign=top width=140>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">方法</SPAN></P></TD>
<TD align=middle
style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; mso-border-left-alt: solid windowtext .5pt"
vAlign=top width=211>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">说明</SPAN></P></TD>
<TD align=middle
style="BORDER-BOTTOM: windowtext 0.5pt solid; BORDER-LEFT: medium none; BORDER-RIGHT: windowtext 0.5pt solid; BORDER-TOP: windowtext 0.5pt solid; PADDING-BOTTOM: 0cm; PADDING-LEFT: 5.4pt; PADDING-RIGHT: 5.4pt; PADDING-TOP: 0cm; mso-border-left-alt: solid windowtext .5pt"
vAlign=top width=203>
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