📄 jdk1.5学习之rowset（一）.htm
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<P id=hijpqktrcajgvvbgip>o]业络9教中V无6]垠$络.C1管</P>而且他是无连接的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">RowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">的其他</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个实现的父接口，也就是说其他</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">3</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">个接口都直接或者间接继承了它。从名字我们可以知道，它的原理就是读入数据保存在缓存进行相应的操作。</SPAN></FONT>
<P></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US><FONT face="Times New Roman"><SPAN style="mso-spacerun: yes">
</SPAN><SPAN style="mso-tab-count: 1">
</SPAN></FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">创建接口对象除了上面的两种创建方式，还有一个方法，就是在构造方法里面传递一个</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">SyncProvider</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。之前我说过无连接的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">RowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">都是基于流读写的，那么这里所说的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">SyncProvider</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">就是提供了特定的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Reader</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Writer</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">。</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">jdk1.5</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">文档的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Sample Coder</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">有这样的实现：</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT
face="Times New Roman"><FONT size=3><SPAN
style="mso-tab-count: 1"> </SPAN>String
provider= “com.fred.providers.HighAvailabilityProvider”</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><SPAN lang=EN-US><FONT
face="Times New Roman"><FONT size=3><SPAN style="mso-spacerun: yes">
</SPAN><SPAN style="mso-tab-count: 1"> </SPAN>CachedRowSet
crs=new CachedRowSetImpl(provider);</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">这样我们就为</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">RowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">设置了特定的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Reader</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">和</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Writer</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，但是这是需要第三方的包支持的。而我们使用无参的构造方法创建的对象是使用了默认的</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">SyncProvider</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">，当然一般来说这对于我们就已经足够了。创建了对象之后就可以使用和</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">JdbcRowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一样的方法来进行就结果集的增删改操作了，但是唯一不同的就是在更新了结果集之后必须调用</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Writer</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">将缓存中的数据写入数据库，而其方法就是</SPAN><SPAN
lang=EN-US><FONT
face="Times New Roman">crs.acceptChages();</FONT></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
lang=EN-US><FONT face="Times New Roman"><SPAN
style="mso-tab-count: 1">
</SPAN>CachedRowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">提供的最令人兴奋的功能就是分页功能。以前程序员很头疼的问题就是怎么处理数据分页而不影响性能，
<DIV id=iwrlqoaghckev>MvmF+业y育:U&Tk</DIV>现在有了</SPAN><SPAN lang=EN-US><FONT
face="Times New Roman">CachedRowSet</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">一切都变得那么简单，请看下面的代码：</SPAN></FONT>
<P></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman" size=3>CachedRowSet
crs=new CaehedRowSetImpl();</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.setUrl(“jdbc:mydql://localhost:3306/test”);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.setUsername(“root”);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.setPassword(“”);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.setCommand(“select * from table<CHMETCNV w:st="on" tcsc="0"
numbertype="1" negative="False" hasspace="False" sourcevalue="1"
unitname="”">1”</CHMETCNV>);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.setPageSize(5);</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>crs.execute();</FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"
size=3>while(crs.nextPage()) </FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"><FONT size=3><SPAN
style="mso-tab-count: 1">
</SPAN>while(crs.next()) </FONT></FONT></SPAN></P>
<P class=MsoNormal
style="MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 21.75pt; TEXT-ALIGN: left; mso-layout-grid-align: none"
align=left><SPAN lang=EN-US><FONT face="Times New Roman"><FONT size=3><SPAN
style="mso-tab-count: 2">
</SPAN>System.out.println(crs.getInt(“id”+”\t\t”+crs.getString(“name”));</FONT></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">我们在</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">crs.execute()</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">之前设置每页的数据行数，那么</SPAN><SPAN
lang=EN-US><FONT face="Times New Roman">Reader</FONT></SPAN><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">读取数据的时候就只读指定的行数的数据，这样我们就避免了一次读取所有数据再进行分页操作。是不是很简单呢？</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'"></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0cm 0cm 0pt"><FONT size=3><SPAN
style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">
to be continued....</SPAN></FONT></P></SPAN></SPAN>
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