开发标签开发标签开发迭代标签源代码
• 开发<c:if>标签
package com.hbsi.web.tag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class IfTag extends SimpleTagSupport {
private boolean test;
public void setTest(boolean test) {
this.test = test;
}
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
if(test){
//处理标签体
JspFragment jf=this.getJspBody();
jf.invoke(null);
}
}
}
• 开发<c:if><c:else>标签
package com.hbsi.web.tag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class ChooseTag extends SimpleTagSupport {
private boolean flag=false;
public boolean isFlag() {
return flag;
}
public void setFlag(boolean flag) {
this.flag = flag;
}
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
//对标签体处理
JspFragment jf=this.getJspBody();
jf.invoke(null);
}
}
package com.hbsi.web.tag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class OtherwiseTag extends SimpleTagSupport {
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
ChooseTag parent=(ChooseTag) this.getParent();
if(!parent.isFlag()){
this.getJspBody().invoke(null);
parent.setFlag(true);
}
}
}
package com.hbsi.web.tag;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;
public class WhenTag extends SimpleTagSupport {
private boolean test;
public void setTest(boolean test) {
this.test = test;
}
@Override
public void doTag() throws JspException, IOException {
// TODO Auto-generated method stub
//获取父标签对象
ChooseTag parent=(ChooseTag)this.getParent();
if(test&&!parent.isFlag()){
//处理标签体
this.getJspBody().invoke(null);
//有分支执行过设为真
parent.setFlag(true);
}
}
}
• 开发迭代标签
• package com.hbsi.web.tag;
•
• import java.io.IOException;
• import java.lang.reflect.Array;
• import java.util.ArrayList;
• import java.util.Arrays;
• import java.util.Collection;
• import java.util.Iterator;
• import java.util.List;
• import java.util.Map;
•
• import javax.servlet.jsp.JspException;
• import javax.servlet.jsp.tagext.SimpleTagSupport;
•
• public class ForeachTag extends SimpleTagSupport {
• private Object items;
• private String var;
• public void setItems(Object items) {
• this.items = items;
• }
• public void setVar(String var) {
• this.var = var;
• }
• @Override
• public void doTag() throws JspException, IOException {
• // TODO Auto-generated method stub
• //得到集合对象
• //List list=(List) items;
• //Iterator it=list.iterator();
• Collection collection=null;
• if(items instanceof Map){
• Map map=(Map)items;
• //两列的集合转换成单列
• collection=map.entrySet();
• }else if(items instanceof Collection){
• collection=(Collection) items;
• }
• // else if(items instanceof Object[]){
• //
• // Object[] objs=(Object[]) items;
• // //倒换到一个一个集合中
• // collection=Arrays.asList(objs);
• //
• // }
• //应用反射机制
• else if(items.getClass().isArray()){
• collection=new ArrayList();
• int length=Array.getLength(items);
• for(int i=0;i<length;i++){
• collection.add(Array.get(items, i));
• }
•
• }
• Iterator it=collection.iterator();
• while(it.hasNext()){
• Object obj=it.next();//迭代出来的一个元素
• this.getJspContext().setAttribute(var, obj);
• this.getJspBody().invoke(null);
•
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•
•
• }
• }
• }