文章目录
select标签
思路：首先思考select标签所需要的属性，取数据的集合是必须的(item)，还有显示的数据和上传的数据(TextVal和TextKey)，还有设置默认选择的数据(SelectedVal)，还有我们头标签的显示和上次数据(headerVal和headerKey),下面我们是以一个学生类的id和name来当作我们的传值数据和显示数据，所以我们就是以它的属性名id和name来取值的
SelectTag助手类
/**
* 1、值的传递 id、name
* 2、数据源 items
* 3、展示列与数据存储列与实体类的对应关系 textKey textVal
* 4、数据回显 selectedVal
* 5、可能下拉框有默认值(头标签) headerTextKey headerTextVal
*
*
* @author 86135
*
*/
public class SelectTag extends BodyTagSupport{
private String id;
private String name;
private List<Object> items=new ArrayList<>();
private String textKey; //id=textKey
private String textVal;
private String selectedVal;
private String headerTextKey;
private String headerTextVal;
@Override
public int doStartTag() throws JspException {
JspWriter out = pageContext.getOut();
try {
try {
out.print(toHTML());
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (SecurityException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
}
return SKIP_BODY;
}
private String toHTML() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
StringBuffer sb=new StringBuffer();
sb.append("<select id='"+id+"' name='"+name+"'>");//初始select
//判断头标签不能为空
if(!(headerTextKey==null||"".equals(headerTextVal)||headerTextVal==null||"".equals(headerTextVal))) {
sb.append("<option selected value='"+headerTextKey+"'>"+headerTextVal+"</option>");
}
String value;
String html;
for (Object obj : items) {
//利用反射获取类对象的属性，也就是我们下拉框的显示值和数据值
Field textKeyField = obj.getClass().getDeclaredField(textKey);
textKeyField.setAccessible(true);
value=(String)textKeyField.get(obj);
Field textValField = obj.getClass().getDeclaredField(textVal);
textValField.setAccessible(true);
html=(String)textValField.get(obj);
//设置回显，设置的值和你下拉框的值相同就默认选中
if(value.equals(selectedVal)) {
sb.append("<option selected value='"+value+"'>"+html+"</option>");
}
else {
sb.append("<option value='"+value+"'>"+html+"</option>");
}
}
return sb.toString();
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Object> getItems() {
return items;
}
public void setItems(List<Object> items) {
this.items = items;
}
public String getTextKey() {
return textKey;
}
public void setTextKey(String textKey) {
this.textKey = textKey;
}
public String getTextVal() {
return textVal;
}
public void setTextVal(String textVal) {
this.textVal = textVal;
}
public String getSelectedVal() {
return selectedVal;
}
public void setSelectedVal(String selectedVal) {
this.selectedVal = selectedVal;
}
public String getHeaderTextKey() {
return headerTextKey;
}
public void setHeaderTextKey(String headerTextKey) {
this.headerTextKey = headerTextKey;
}
public String getHeaderTextVal() {
return headerTextVal;
}
public void setHeaderTextVal(String headerTextVal) {
this.headerTextVal = headerTextVal;
}
public SelectTag() {
super();
}
}
最后再jsp页面输入验证代码就可以用了(是再引入了taglib的前提下)
<%
List ls=new ArrayList();
ls.add(new Student("001","aaaa"));
ls.add(new Student("002","bbbb"));
ls.add(new Student("003","cccc"));
List ls1=new ArrayList();
ls1.add("001");
ls1.add("002");
request.setAttribute("ls", ls);
%>
<z:select headerTextKey="-1" headerTextVal="---请选择---" textVal="name" items="${ls}" textKey="id"></z:select>
结果为成功显示数据
checkbox标签
一样，首先我们来分析它需要的属性，取数据的集合，显示值和传入值，它与select标签不同的是它的回显数据需要是一个集合，因为它可能选中的标签不只一个，所以是一个集合。
配置描述文件
<tag>
<name>checkbox</name>
<tag-class>com.xy.taglib.CheckboxTag</tag-class>
<body-content>JSP</body-content>
<attribute>
<name>textKey</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>textVal</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>item</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
<attribute>
<name>checkedVal</name>
<required>false</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag>
CheckeboxTag助手类
public class CheckboxTag extends BodyTagSupport {
private String textKey;//传入值
private String textVal;//显示值
private List<Object> checkedVal=new ArrayList<>();//回显数据集合
private List<Object> item=new ArrayList<>();//数据集合
public List<Object> getItem() {
return item;
}
public void setItem(List<Object> item) {
this.item = item;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getTextKey() {
return textKey;
}
public List<Object> getCheckedVal() {
return checkedVal;
}
public void setCheckedVal(List<Object> checkedVal) {
this.checkedVal = checkedVal;
}
public void setTextKey(String textKey) {
this.textKey = textKey;
}
public String getTextVal() {
return textVal;
}
public void setTextVal(String textVal) {
this.textVal = textVal;
}
public CheckboxTag() {
super();
}
public CheckboxTag(String textKey, String textVal, List<Object> checkedVal, List<Object> item) {
super();
this.textKey = textKey;
this.textVal = textVal;
this.checkedVal = checkedVal;
this.item = item;
}
@Override
public int doStartTag() throws JspException {
JspWriter out = pageContext.getOut();
try {
out.print(toHTML());
} catch (IOException e) {
e.printStackTrace();
} catch (NoSuchFieldException e) {
e.printStackTrace();
} catch (SecurityException e) {
e.printStackTrace();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
}
return super.doStartTag();
}
private String toHTML() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException {
StringBuffer sb=new StringBuffer();
String value;
String html;
for (Object obj : item) {
//一样利用放射取属性值
Field textKeyfield = obj.getClass().getDeclaredField(textKey);
textKeyfield.setAccessible(true);
value=(String)textKeyfield.get(obj);
Field textValfield = obj.getClass().getDeclaredField(textVal);
textValfield.setAccessible(true);
html=(String)textValfield.get(obj);
if(checkedVal.contains(value)) {//判断回显集合里是否包含这个value，包含就设置选择
sb.append("<input checked type='checkbox' value='"+value+"' />"+html+"");
}
else {
sb.append("<input type='checkbox' value='"+value+"' />"+html+"");
}
}
return sb.toString();
}
}
代码验证复选框标签是否正确
<%
List ls=new ArrayList();
ls.add(new Student("001","aaaa"));
ls.add(new Student("002","bbbb"));
ls.add(new Student("003","cccc"));
List ls1=new ArrayList();
ls1.add("001");
ls1.add("002");
request.setAttribute("ls", ls);
request.setAttribute("ls1", ls1);
%>
<z:checkbox textVal="name" checkedVal="${ls1}" item="${ls}" textKey="id"></z:checkbox>
结果可知，ls1集合中的数据全部选中了
数据字典应用
使用的下拉框，只要定义使用那个字典就会将这个字典可用的内容显示出来
显示字典时只要定义那个字典和属性值就可以显示出字典的显示值,和我们的out标签的效果是一样的
下面我们用下拉框的一个案例来说明，用3个助手类来好理解
OptionTag
public class OptionsTag extends BodyTagSupport {
public int doStartTag() throws JspException {
return EVAL_BODY_INCLUDE;
}
@Override
public int doEndTag() throws JspException {
try {
StringBuffer results = new StringBuffer("");
if ("SEX".equals(collection)) {//数据当然可以从数据遍历
results.append("<option value=\"0\" selected=\"selected\">请选择</option>");
results.append("<option value=\"1\">男</option>");
results.append("<option value=\"2\">女</option>");
}
pageContext.getOut().write(results.toString());
} catch (IOException ex) {
throw new JspTagException("错误");
}
return EVAL_PAGE;
}
// collection只是传递一个标识，具体下拉值内容是从数据库取还是从请求中得到为不同具体实现
protected String collection;
public String getCollection() {
return collection;
}
public void setCollection(String collection) {
this.collection = collection;
}
}
SelectTag
public int doStartTag() throws JspException {
try {
StringBuffer results = new StringBuffer("<select");
if(name != null){
results.append(" name=\"");
results.append(name);
results.append("\"");
}
if(style != null){
results.append(" style=\"");
results.append(style);
results.append("\"");
}
results.append(">");
pageContext.getOut().write(results.toString());
} catch (IOException ex) {
throw new JspTagException("错误");
}
return EVAL_BODY_INCLUDE;
}
@Override
public int doEndTag() throws JspException {
try {
StringBuffer results = new StringBuffer("");
// 因为下拉中包含下拉内容，所以只能在遇到结束标签时才能写select结束
results.append("</select>");
pageContext.getOut().write(results.toString());
} catch (IOException ex) {
throw new JspTagException("错误");
}
return EVAL_PAGE;
}
// 样式
protected String style;
// 名字
protected String name;
public String getStyle() {
return style;
}
public void setStyle(String style) {
this.style = style;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
SelectDisplay
public int doStartTag() throws JspException {
try {
StringBuffer results = new StringBuffer("");
pageContext.getOut().write(results.toString());
} catch (IOException ex) {
throw new JspTagException("错误");
}
return EVAL_BODY_INCLUDE;
}
@Override
public int doEndTag() throws JspException {
try {
StringBuffer results = new StringBuffer("");
if ("SEX".equals(collection)) {
results.append("<span>");
results.append("<input type=\"");
results.append("hidden\" name=\"");
results.append(getName());
results.append("\"");
results.append(" value=\"");
results.append(getValue());
results.append("\">");
if ("1".equals(getValue())) {
results.append("男");
} else if ("2".equals(getValue())) {
results.append("女");
} else {
results.append("请选择");
}
results.append("</span>");
}
pageContext.getOut().write(results.toString());
} catch (IOException ex) {
throw new JspTagException("错误");
}
return EVAL_PAGE;
}
// collection只是传递一个标识，具体下拉值内容是从数据库取还是从请求中得到为不同具体实现
protected String collection;
// 传递的值
protected String value;
// 该属性的名称
protected String name;
public String getCollection() {
return collection;
}
public void setCollection(String collection) {
this.collection = collection;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
tld文件就不写了，根据属性去配置就好了,这是jsp代码验证，我这里value值为1，也就是男，如果数据显示为了男那就是对了
请选择：
<x:select name="sex" style="width:100px">
<x:options collection="SEX"></x:options>
</x:select>
显示性别：
<x:selectDisplay collection="SEX" value="1" name="sex"></x:selectDisplay>
结果为：显示性别为男，我如果改为2，显示性别就为女了
