Action和jsp的開發(fā)其實(shí)就是對(duì)Struts標(biāo)簽的運(yùn)用.掌握標(biāo)簽的熟練程度決定了開發(fā)效率.初學(xué)者往往對(duì)某個(gè)數(shù)據(jù)表示或數(shù)據(jù)獲取,束手無策.一個(gè)簡單的問題浪費(fèi)一兩天時(shí)間也就不足為怪了.導(dǎo)致整個(gè)開發(fā)進(jìn)度延后.外面的struts書籍介紹標(biāo)簽和數(shù)據(jù)傳輸原理都比較簡單,下面我對(duì)標(biāo)簽技術(shù)和數(shù)據(jù)傳輸原理,進(jìn)行全方位多角度的剖析.希望對(duì)各位有所幫助.以此為模版,將大大提高開發(fā)效率.以sample為機(jī)能名稱.
①畫面上有一text框,顯現(xiàn)內(nèi)容為某一數(shù)據(jù)表中的某一字段.那我們?cè)撊绾卧O(shè)置和得到此數(shù)據(jù)呢?
SampleJsp:
??<html:text?name?=?"sampleForm"?property="name"?/>
SampleForm.java:?//?form文件名必須和jsp中標(biāo)簽的name對(duì)應(yīng)
??String?name;?//?必須和jsp中該項(xiàng)目的property一樣
??public?String?getName()?{?return?name;?}
??public?void?setName(String?name)?{?this.name?=?name;}
變量和方法名,不可以順意.變量abcd,那方法名就是setAbcd和getAbcd.注意大小寫.
jsp中的項(xiàng)目必然全部在form里面有所表示,當(dāng)然反過來,form里的項(xiàng)目在jsp中不一定全部表示(可能有輔助動(dòng)作的對(duì)象或驗(yàn)證)
SampleAction.java?
??public?ActionForward?start(ActionMapping?mapping,
??ActionForm?argForm,?HttpServletRequest?req,?HttpServletResponse?res)
??throws?Exception?{
????????SampleForm?form?=?(SampleForm)?argForm;
????????String?name?=?………………other?codes?for?get?name?from?db
????????//?set?name
????????form.setName(name);
????????//?now?text?will?show?the?name
??}
public?ActionForward?save(ActionMapping?mapping,
??ActionForm?argForm,?HttpServletRequest?req,?HttpServletResponse?res)
????????throws?Exception?{
????????SampleForm?form?=?(SampleForm)?argForm;
????????//?get?name
????????String?name?=?form.getName();
????????………………other?codes?for?save?name
??}
jsp和form對(duì)應(yīng),action操作form,form其實(shí)起了傳輸數(shù)據(jù)的作用.這就是struts標(biāo)簽的核心原理.得到數(shù)據(jù)和設(shè)置數(shù)據(jù)沒問題了,剩下的工作也就得心應(yīng)手了.
②再看一個(gè)處理標(biāo)簽的方法.畫面上是一個(gè)明細(xì)一覽表示(表).表示的是數(shù)據(jù)表user的相關(guān)數(shù)據(jù)(id,name).
SampleJsp:?
??<logic:present?name="sampleForm"?property="userList"?>
????<logic:iterate?id="user"?name="?sampleForm?"?property="userList">
??????<tr>
????????<td><bean:write?name="user"?property="id"?/></td>
????????<td><bean:write?name="user"?property="name"?/></td>
??????</tr>
????</logic:iterate>?
??</logic:present>
logic:present是邏輯判斷,sampleForm中userList為空(無數(shù)據(jù)或null),下面的東東不顯示.
logic:iterate是邏輯循環(huán),userList有幾條數(shù)據(jù),就循環(huán)幾次.
<bean:write?name="user"?property="id"?/>是lable標(biāo)簽,顯示user這個(gè)對(duì)象(entity)的id屬性.或者說顯示數(shù)據(jù)表user中的一條記錄中的id這個(gè)列.
User.java(就是entity,因?yàn)楹蜆I(yè)務(wù)密切,高達(dá)不開發(fā),切記切記不可順意修改.遇到設(shè)計(jì)有問題,QA日本)
????String?id;
????public?String?getId()?{?return?id;?}
????public?void?setId(String?id)?{?this.id?=?id;?}
????String?name;
????public?String?getName?()?{?return?name;?}
????public?void?setName?(String?name)?{?this.name?=?name;?}
看到這,是否覺得面熟啊,好象和FORM一樣,但有點(diǎn)不一樣,不一樣在哪里,看下去后,自己感悟吧.
SampleForm.java:?
????List?userList;
????public?List?getUserList?()?{?return?userList;?}
????public?void?setUserList?(List?userList)?{?this.userList?=?userList;?}
form只要這些,那你會(huì)問,id和name,struts如何能得到呢?你不是說過jsp必須和form一樣對(duì)應(yīng)嗎?不錯(cuò),一一對(duì)應(yīng)是肯定的.?UserList信息已經(jīng)包含了一切,還需要定義id和name嗎?至于struts如何得到數(shù)據(jù),那就看下面的action是如何處理的吧.
SampleAction.java?
public?ActionForward?start(ActionMapping?mapping,
??ActionForm?argForm,?HttpServletRequest?req,?HttpServletResponse?res)
????????throws?Exception?{
????????SampleForm?form?=?(SampleForm)?argForm;
????????ArrayList?userList?=?new?ArrayList();
????????User?user?=?new?User();
????????user.setId(1);
????????user.setName(“name1”);
????????userList.add(user);
????????User?user?=?new?User();
????????user.setId(2);
????????user.setName(“name2”);?
????????userList.add(user);
????????
????????//?set?userList
????????form.setUserList(userList);
????????//?now?table?will?show
??}
一切搞定.是不是很簡單,但估計(jì)你還是有點(diǎn)暈.你還是想問我,id和name到底是如何設(shè)置的?
Action設(shè)置了userList就夠了,它包含夠多的信息了.?struts看見了你設(shè)置了userList.它就知道了這個(gè)list里面都user(entity),useruser(entity)里面不是有很多get,set方法嗎?
再看下下面的東東.
<logic:iterate?id="user"?name="?sampleForm?"?property="userList">
<bean:write?name="user"?property="id"?/>
id=”user”,和name="user"?對(duì)應(yīng)了,明白啥意思嗎?.就象循環(huán)指明索引一樣.?property="id"就是要顯示的這個(gè)索引對(duì)應(yīng)的內(nèi)容.Struts就是這樣來認(rèn)id和name的.
③接下來,看一個(gè)加強(qiáng)版的table例子,在顯示的明細(xì)一覽,每一行前面加一個(gè)radio框,讓用戶選擇哪個(gè)user.進(jìn)行刪除操作.
SampleJsp:?
??<logic:present?name="sampleForm"?property="userList"?>
??<logic:iterate?id="user"?name="?sampleForm?"?property="userList">
??<tr>
????<td>
??<html:radio?name="sampleForm"?property="selectedUserId"?value="<%=((jp.co.mhcb.obs.persis.entity.User)pageContext.getAttribute("user?")).getId().toString()?%>"?/>
???</td>
???<td><bean:write?name="user"?property="id"?/></td>
???<td><bean:write?name="user"?property="name"?/></td>
??</tr>
</logic:iterate>?
</logic:present>
sampleForm.java:
????String?selectedUserId;?
????public?String?getSelectedUserId?()?{?return?selectedUserId;?}
????public?void?setSelectedUserId(String?selectedUserId)?{
????????this.selectedUserId?=?selectedUserId;
????}
SampleAction.java?
public?ActionForward?delete(ActionMapping?mapping,
??ActionForm?argForm,?HttpServletRequest?req,?HttpServletResponse?res)
????????throws?Exception?{
????????SampleForm?form?=?(SampleForm)?argForm;
????????String?selectedUserId?=?form.getSelectedUserId();
????????//?get?user?by?selected?id
????????User?user?=?getUser(selectedUserId);
????????//?delete?user
????????}
radio框.?propertys值對(duì)應(yīng)form里的對(duì)象.value值是該行radio對(duì)應(yīng)的user中的id(數(shù)據(jù)表中user的id是主鍵),那么當(dāng)用戶選中任何一個(gè)radio,struts通過form得到propertys值,就可以得到選中哪個(gè)user了,然后進(jìn)行相應(yīng)操作.
設(shè)置哪個(gè)user被選中,一是通過用戶選擇,沒的說.二,通過程序控制,如果進(jìn)入初期畫面,我要讓user.id?=?‘3’的radio被選中,只要在初期Action中form.selectedUserId(“3”);一切搞定,就一句話,進(jìn)入初期畫面時(shí),?user.id?=?‘3’的radio被選中了.
注意以下標(biāo)簽
<html:radio?name="sampleForm"?property="selectedUserId"?value="<%=?((jp.co.mhcb.obs.persis.entity.User)pageContext.getAttribute("user?")).getId().toString()?%>"?/>
下面發(fā)揮想象一下以下標(biāo)簽啥意思?
<html:radio?name="sampleForm"?property="selectedUserId"?value="<%=?((jp.co.mhcb.obs.persis.entity.User)pageContext.getAttribute("user?")).getObject1().getObject1().getObject2()…………getObjectN().getId().toString()?%>"?/>
能看出來什么?
User包含object1,object2包含object3,….objectN-1包含objectN,objectN有id屬性.
看出來了嗎?靈活運(yùn)用,想象一下,各個(gè)entity和form,action該如何寫?
④接著介紹一下,checkbox是使用.畫面有一排checkbox,如何設(shè)置和得到數(shù)據(jù)呢?先看一個(gè)簡單點(diǎn)的.?
?<html:checkbox?name="?sampleForm"?property="chechbox1"?value="true"?/>
?<html:checkbox?name="?sampleForm"?property="chechbox2"?value="false"?/>
?<html:checkbox?name="?sampleForm"?property="chechbox3"?value="true"?/>
第二個(gè)框未選中,其他選中.form里面對(duì)應(yīng)三個(gè)String?chechbox1,chechbox2,?chechbox3;下面來個(gè)復(fù)雜點(diǎn)的,多選擇對(duì)話框multibox
SampleJsp中：
<logic:iterate?name?=?"sampleForm"?id="user"?property="userList">
??<html:multibox?property="selectedUsers">
????<bean:write?name="user"?property="id"/>?
??</html:multibox>
??<bean:write?name="user"?property="name"/>?
</logic:iterate>
SampleForm中:
????private?String?userList[]?=?new?String[0];?
????public?String[]?getUserList?()?{?return?userList;}
????public?void?setUserList(String[]userList)?{this.userList?=?userList;}
????private?String?selectedUsers[]?=?new?String[0];
????public?String[]?getSelectedUsers?()?{return?selectedUsers;}
????public?void?setSelectedUsers?(String[]selectedUsers)?{this.selectedUsers?=?selectedUsers;}
如果我們?cè)诔跗跁r(shí)在action里對(duì)bean賦值：
userList?=?{?User(”1”,”name1”),?User(”2”,?”name2”),?User(”3”,”name3”)?}
selectedUsers?=?{“1”，”3”}
那畫面選中第一第三個(gè)選擇框.
用戶修改選擇框,選擇了第二,第三個(gè),那么在action里取bean的值
String?selectedItems[]?=?new?String[list.getSize()];
selectedItems?=?form.getSelectedItems();
for?(?int?i?=?0?;?i?<?selectedItems.length?;?++i?){
??LOGGER.debug(?"selected?"?+?i?+?":?"?+?selectedItems[i]);
}
Selected?0?:?2?
Selected?1?:?3
selectedUsers?=?{“2”，”3”}
⑤畫面上有一user表,每條數(shù)據(jù)前面有個(gè)button,對(duì)應(yīng)一條記錄,如何確定選中那條數(shù)據(jù)呢??
SampleJsp:
<logic:iterate?id="user"?indexId="buttonIndex"?name="sampleForm"?property="userList">
<tr>
<td>
<html:submit?property="button"?indexed='false'?>
<bean:message?key="label.button.selectUser"/>
</td>
<td><bean:write?name="user"?property="id"?/></td>
<td><bean:write?name="user"?property="name"?/></td>
</tr>
<html:hidden?name="sampleForm"?property="selectUserIndex"?value='<%=?""?+?buttonIndex?%>'/>
</logic:iterate>
SampleAction.java
???int?index?=?Integer.parseInt(form.getSelectUserIndex());
???通過一個(gè)隱藏變量,得到選中第幾條數(shù)據(jù),然后就能做相應(yīng)處理.
⑥上面都是通過form和jsp傳輸數(shù)據(jù)的.還有session也能讓jsp顯示數(shù)據(jù).但如果我做為設(shè)計(jì)者,是不提倡這樣做的.為什么就不說了.但日本以前的設(shè)計(jì)很可能會(huì)用到session和jsp傳數(shù)據(jù).那我就有必要講一下如何用了?做為高達(dá)的設(shè)計(jì)者還是盡量不要用session和jsp溝通.
有個(gè)下拉列表框,里面顯示所有用戶名稱.用session傳數(shù)據(jù).
SampleJsp:
<%pageContext.setAttribute("userList",(List)?(FwThreadContext
????????????????.getAttribute("AllUser")));
%>
<html:select?property="selectedUser">?
??<html:options?collection="userList"?property="id"?labelProperty="name"?/>
</html:select>
SampleForm.java:
????String?selectedUser;
Form里只要一個(gè)selectedUser,表示選擇的user.?下拉列表框用session表示.
在action等地方設(shè)置了session的內(nèi)容,那下拉列表框就能顯示內(nèi)容了.這里session名為AllUser,?labelProperty="name"是下拉列表框顯示的東東,?property="id"是下拉列表框每條數(shù)據(jù)隱藏的東東.通過property="selectedUser"里得到選中那條數(shù)據(jù)
<html:text?name="sampleForm"?property="name"?
value="<%=?(FwThreadContext.getAttribute("UserName")).toString()?%>"?/>
這里很簡單就是把session名為UserName設(shè)置到Text框中.得的時(shí)候還是通過form中的name得到.
標(biāo)簽寶典:
1,lable
<bean:write?name="sampleForm"?property="name"?/>
2,text
<html:text?name="sampleForm?"?property="name"?/>
3,button
<html:submit?property="button">
<bean:message?key="label.button.save"?/>
</html:submit>
<html:button?property="button"?onclick="javascript:openCalendar(date);">
<bean:message?key="label.button.date"?/>
</html:button>
4,select?
<html:select?property="selectedUser">?
??<html:options?name="sampleForm"?collection="userList"?property="id"?labelProperty="name"?/>
</html:select>
5,checkbox,multibox
??<html:checkbox?name="sampleForm"?property="chechbox1"?value="true"?/>
??
??<logic:iterate?name?=?"sampleForm"?id="user"?property="userList">
????<html:multibox?property="selectedUsers">
?????<bean:write?name="user"?property="id"/>?
????</html:multibox>
????<bean:write?name="user"?property="name"/>?
??</logic:iterate>
6,?循環(huán)邏輯
<logic:present?name="sampleForm"?property="userList"?>
<logic:iterate?id="user"?name="?sampleForm?"?property="userList">
<tr>
??<td>
??<html:radio?name="sampleForm"?property="selectedUserId"?value="<%=?((jp.co.mhcb.obs.persis.entity.User)pageContext.getAttribute("user?")).getId().toString()?%>"?/>
??</td>
??<td><bean:write?name="user"?property="id"?/></td>
??<td><bean:write?name="user"?property="name"?/></td>
</tr>
</logic:iterate>?
</logic:present>
7,if邏輯
<logic:equal?name="?sampleForm?"?property="showAllFlg"?value="true"?>
??<html:submit?property="button">
????<bean:message?key="label.button.all"/>
??</html:submit>
</logic:equal>
<logic:equal?name="?sampleForm?"?property="?showAllFlg?"?value="false"?>
??<html:submit?property="button">
????<bean:message?key="label.button.noall"/>
??</html:submit>
</logic:equal>??