开发<c:if>标签开发<c:if><c:else>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);

•

•

•

•

•

•

•

•

• }

• }

• }