jsp标签（二）

jsp标签（out，if，set，select，forEach）
一、自定义标签源码
1、导包

2、有些改变的out，if，set自定义标签

out标签：

package com.tang.tag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class OutTag extends BodyTagSupport {
	
	private static final long serialVersionUID = 1L;
		private Object value;		

		public OutTag() {
			super();
		}

		public Object getValue() {
			return value;
		}

		public void setValue(Object value) {
			this.value = value;
		}

		@Override
		public int doStartTag() throws JspException {
			JspWriter out = pageContext.getOut();
			try {
				out.println(value==null?"":value);
			} catch (Exception e) {
				// TODO Auto-generated catch block
				throw new RuntimeException(e);
			}
			return super.doStartTag();
		}		
		
}

if标签：

package com.tang.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class IfTag extends BodyTagSupport {
	
	private Boolean test;

	public IfTag() {
		super();
	}

	public Boolean getTest() {
		return test;
	}

	public void setTest(Boolean test) {
		this.test = test;
	}

	@Override
	public int doStartTag() throws JspException {
		if(test) {
			return EVAL_BODY_INCLUDE;
		}
		return SKIP_BODY;
	}	

}

set标签：

package com.tang.tag;

import java.util.List;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

import com.tang.dao.DeptDao;
import com.tang.entity.Dept;

public class SetTag extends BodyTagSupport {
	
	private String value;//保存数据库的key
	private DeptDao deptDao = new DeptDao();
	
	public SetTag() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	public String getValue() {
		return value;
	}
	public void setValue(String value) {
		this.value = value;
	}
	public DeptDao getDeptDao() {
		return deptDao;
	}
	public void setDeptDao(DeptDao deptDao) {
		this.deptDao = deptDao;
	}

	@Override
	public int doStartTag() throws JspException {
		List list = deptDao.list();
		pageContext.setAttribute(value, list);
		return super.doStartTag();
	}

}

set标签中用到的entity包，dao包
entity包：

package com.tang.entity;

import java.io.Serializable;

public class Dept implements Serializable {

	private static final long serialVersionUID = 1L;
	
	private Integer DeptId;
	
	private String DeptName;
	
	public Dept() {
		super();
	}
	
	public Dept(Integer deptId, String deptName) {
		super();
		DeptId = deptId;
		DeptName = deptName;
	}

	public Integer getDeptId() {
		return DeptId;
	}

	public void setDeptId(Integer deptId) {
		DeptId = deptId;
	}

	public String getDeptName() {
		return DeptName;
	}

	public void setDeptName(String deptName) {
		DeptName = deptName;
	}

	@Override
	public String toString() {
		return "Dept [DeptId=" + DeptId + ", DeptName=" + DeptName + "]";
	}
}

dao包：

package com.tang.dao;

import java.util.ArrayList;
import java.util.List;

import com.tang.entity.Dept;

public class DeptDao {
	
	public List list(){
		//访问数据库
		List list = new ArrayList();
		list.add(new Dept(1, "教质部"));
		list.add(new Dept(2, "教学部"));
		list.add(new Dept(3, "财务部"));
		list.add(new Dept(4, "就业部"));
		return list;
	}

}

forEach标签：

package com.tang.tag;

import java.util.Iterator;
import java.util.List;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;

public class ForEachTag extends BodyTagSupport {
	
	private List