freemarker中顯示某對象使用${name}.
但如果name爲null。如果需要判斷對象是否爲空:
<#if name??>
……
</#if>
當然也可以通過設置默認值${name!''}來避免對象爲空的錯誤。如果name爲空,就以默認值(“!”後的字符)顯示。
user,name都有可能爲空,那麼可以寫成${(user.name)!''},表示user或者name爲null,都顯示爲空。
判斷爲空
<#if (user.name)??>
……
</#if>
List insNoticeDtoList=JSONObject.parseObject(strInsNotices,List.class); //json字符串轉List
JSONObject jsobj=(JSONObject)JSONObject.toJSON(map); //map 轉爲json對象。再將json轉字符串。
String tt=jsobj.toJSONString();
//requst 參數轉MAP
Gson json = new Gson();
Map<String,String> mapData2 = json.fromJson(request.getParameter("data"), new TypeToken<Map<String,String>>(){}.getType());
//讀取文件亂碼
bufferedreader = new BufferedReader(new FileReader(filename));
//改寫,指定編碼格式
BufferedReader br=new BufferedReader(new InputStreamReader(new FileInputStream(fileName),"UTF-8"));
//輸出文件編碼
File outFile = new File(targetFile);
Writer out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outFile),"UTF-8"));
解決TOMCAT內存溢出
set JAVA_OPTS=%JAVA_OPTS% %LOGGING_MANAGER% -Xms512m -Xmx1024m -XX:MaxNewSize=256m -XX:PermSize=64M -XX:MaxPermSize=256m
線程快速簡單寫法
new Thread(new TestThread()).start();
內部類:
class TestThread implements Runnable{
@Override
public void run(){
}
}
sql語句
insert into NEED_RESEND values (sys_guid(),'10',
to_timestamp('2015-05-20 11:17:25.287','yyyy-MM-dd HH24:MI:ss.ff'),
to_timestamp('2015-05-20 11:17:25.287','yyyy-MM-dd HH24:MI:ss.ff'),'6','第三次補數失敗!');
Mybatis傳多個參數(三種解決方案)
1、PublicUserselectUser(Stringname,String area);
<selectid="selectUser"resultMap="BaseResultMap">
select * fromuser_user_t whereuser_name = #{0}anduser_area=#{1}
</select>
2、PublicUserselectUser(Map paramMap);
resultMap="BaseResultMap">
select * fromuser_user_t whereuser_name = #{userName,jdbcType=VARCHAR}anduser_area=#{userArea,jdbcType=VARCHAR}
</select>
3、PublicUserselectUser(@param(“userName”)Stringname,@param(“userArea”)String area);
<selectid=" selectUser"resultMap="BaseResultMap">
select * fromuser_user_t whereuser_name = #{userName,jdbcType=VARCHAR}anduser_area=#{userArea,jdbcType=VARCHAR}
</select>
mybatis 返回結果
1、自定義的Bean Map對象, resultMap要預先定義
<select id="getResourcesInfoPage" parameterType="Map" resultMap="ExtResultMap" >
2、sql 返回的字段名Map對象
<select id="getResourcesInfoPage" parameterType="Map" resultType="Map" >
spring 方法自定義跳轉
@RequestMapping(value = "/getWordXmlJsp")
public @ResponseBody
void getWordXmlJsp(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
String url="/fileupload/template-xuqiu-format3.xml";
RequestDispatcher rd = request.getServletContext().getRequestDispatcher(url);
request.getServletContext().setAttribute("name", "788");
rd.forward(request, response);
}
<!-- 登錄攔截器 3.0用這種方式 -->
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
<property name="interceptors">
<list>
<ref bean="loginInterceptor"/> <!--這是你自定義的攔截器 -->
</list>
</property>
</bean>
<bean id="loginInterceptor" class="com.xpoplarsoft.interceptor.LoginInterceptor"/>
清理word插件緩存
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Bin>mage -cc
//拖動圖標的位置偏移
mxUtils.makeDraggable(a,this.editor.graph,b,c,-c.width,-c.height);
<add as="Start" template="start" style="symbol;image=images/symbols/event.png" icon="images/start_2.png" pressedIcon="images/arrow_2.png"><![CDATA[
//在鼠標單擊時執行的函數
function (editor, cell, evt, targetCell)
{
var pt = mxUtils.convertPoint(editor.graph.container, mxEvent.getClientX(evt),mxEvent.getClientY(evt));
return editor.addVertex(targetCell, cell, pt.x-(cell.geometry.width/2), pt.y-(cell.geometry.height/2));
}
]]></add>
廣播IP地址:想要參與組播的所有機器可以“加入”這個地址,任意一臺機器只要向該地址發送信息,那麼該信息就會自動廣播給所有“加入”到該地址的機器上,也就是說這個神祕的廣播IP地址彷彿是一個虛擬的服務器,它履行着我們之前TCP羣聊的服務器的功能
byte data[] = new byte[65535];
DatagramPacket packet = new DatagramPacket(data, data.length);
multicastSocket.receive(packet);
int dataLen = packet.getLength();
byte[] dataBuf = new byte[dataLen];
System.arraycopy(data, 0, dataBuf, 0, dataLen);
電腦自動重啓是什麼原因,電腦自動重啓什麼解決
https://jingyan.baidu.com/article/ab69b2706d5a182ca6189f4c.html