JSP自定义标签（二）

其他 2019-06-14 13:31:39 阅读次数: 0

文章目录

1、set标签与out标签

set助手类

package com.zyp.jsp02;

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

public class SetTag extends BodyTagSupport{

	private static final long serialVersionUID = 1L;

	private String var;
	private Object value;
	public String getVar() {
		return var;
	}
	public void setVar(String var) {
		this.var = var;
	}
	public Object getValue() {
		return value;
	}
	public void setValue(Object value) {
		this.value = value;
	}
	
	@Override
	public int doStartTag() throws JspException {
		pageContext.setAttribute(var, value);//将值存入pageContext
		return SKIP_BODY;
	}
}

配置set属性文件

<tag>
    <name>set</name>
    <tag-class>com.zyp.jsp02.SetTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <name>var</name>
        <required>false</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
        <name>value</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>

out的助手类

package com.zyp.jsp02;

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 = 8655118409172739205L;
	
	private Object value;

	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.print(value);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return SKIP_BODY;
	}
	
}

out配置文件

<tag>
    <name>out</name>
    <tag-class>com.zyp.jsp02.OutTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <name>value</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>

set\out测试结果

<z:set var="name" value="hello"></z:set>
<z:out value="${name }"></z:out>

结果是hello。

2、if标签

IF助手类【if只有test一个属性值】

	private boolean test;

	public boolean isTest() {
		return test;
	}
	public void setTest(boolean test) {
		this.test = test;
	}
	@Override
	public int doStartTag() throws JspException {
		//如果test为true，则进入doAfterBody方法，如果为false，则直接进入doEndTag方法
		return test?EVAL_BODY_INCLUDE:SKIP_BODY;
	}

IF配置属性文件

<tag>
    <name>if</name>
    <tag-class>com.zyp.jsp02.IfTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
        <name>text</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>

IF测试结果

<z:if text="true">aaa</z:if>
<z:if text="false">bbb</z:if>

输出结果是aaa出来，bbb则不会出来。

3、foreach标签

foreach助手类，虽然set，get的方法没有截取到，但并受不影响。

package com.zyp.jsp02;

import java.util.ArrayList;
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 static final long serialVersionUID = 1L;

	private String var;
	private List<Object> items=new ArrayList<>();
	public String getVar() {
		return var;
	}
	public void setVar(String var) {
		this.var = var;
	}
	public List<Object> getItems() {
		return items;
	}
	public void setItems(List<Object> items) {
		this.items = items;
	}
	public int doStartTag() throws JspException {
		if(items.size()==0) {
			return SKIP_BODY;
		}
		else {
			Iterator<Object> it = items.iterator();
			pageContext.setAttribute(var, it.next());
			pageContext.setAttribute("it", it);
			return EVAL_BODY_INCLUDE;
		}
	}
	
	@Override
	public int doAfterBody() throws JspException {
		Iterator<Object> it = (Iterator<Object>) pageContext.getAttribute("it");
		if(it.hasNext()) {
			pageContext.setAttribute(var, it.next());
			pageContext.setAttribute("it", it);
			return EVAL_BODY_AGAIN;
		}
		return EVAL_PAGE;
	}
}

配置Foreach属性文件

 <tag>
    <name>foreach</name>
    <tag-class>com.zyp.jsp02.ForeachTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
    	<name>var</name>
        <required>true</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>items</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
  </tag>

Foreach测试结果

<%
	List li=new ArrayList();
	li.add(new Student("1","a"));
	li.add(new Student("2","b"));
	li.add(new Student("3","c"));
	request.setAttribute("stus", li);
%>

<s:foreach items="${stus }" var="stu">
	${stu.id }:${stu.name }<br>
</s:foreach>

输出结果：		  1,a
				  2,b
				  3,c

4、select标签

select助手类

package com.zyp.jsp02;

import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

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

import org.apache.commons.beanutils.PropertyUtils;

public class SelectTag extends BodyTagSupport {

	private static final long serialVersionUID = 1L;

	private String id;
	private String name;
	private List<Object> items=new ArrayList<>();
	private String textKey;
	private String textVal;
	private String selectedVal;
	private String headerTextKey;
	private String headerTextVal;
	
	@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();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		} catch (NoSuchMethodException e) {
			e.printStackTrace();
		}
		return super.doStartTag();
	}
	
	private String toHTML() throws NoSuchFieldException, SecurityException, IllegalArgumentException, IllegalAccessException, InvocationTargetException, NoSuchMethodException {
		StringBuffer sb=new StringBuffer();
		sb.append("<select id='"+id+"' name='"+name+"'>");
		
		if(!(headerTextKey==null||"".equals(headerTextKey)||headerTextVal==null||"".equals(headerTextVal)))
			sb.append("<option selected value='"+headerTextKey+"'>"+headerTextVal+"</option>");
		}
		
		String value;
		String html;
		
		for (Object obj: items) {
//			第一种方式 反射
//			Field textKeyField = obj.getClass().getDeclaredField(textKey);
//			textKeyField.setAccessible(true);
//			value=(String) textKeyField.get(obj);
			
//			第二种方式 导jar包
			value=(String) PropertyUtils.getProperty(obj, textKey);
			html=(String) PropertyUtils.getProperty(obj, textVal);
			
			if(value.equals(selectedVal)) {
				sb.append("<option selected value='"+value+"'>"+html+"</option>");
			}
			sb.append("<option value='"+value+"'>"+html+"</option>");
		}
		sb.append("</select>");
		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;
	}

	
}

配置Select属性文件

<tag>
    <name>select</name>
    <tag-class>com.zyp.jsp02.SelectTag</tag-class>
    <body-content>JSP</body-content>
    <attribute>
    	<name>id</name>
        <required>false</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>name</name>
        <required>false</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>items</name>
        <required>true</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
    	<name>textKey</name>
        <required>true</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>textVal</name>
        <required>true</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>selectedVal</name>
        <required>false</required>
        <rtexprvalue>true</rtexprvalue>
    </attribute>
    <attribute>
    	<name>headerTextKey</name>
        <required>false</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
    <attribute>
    	<name>headerTextVal</name>
        <required>false</required>
        <rtexprvalue>false</rtexprvalue>
    </attribute>
  </tag>

Select测试结果

<%
	List li=new ArrayList();
	li.add(new Student("1","a"));
	li.add(new Student("2","b"));
	li.add(new Student("3","c"));
	request.setAttribute("stus", li);
%>

<s:select headerTextKey="-1" headerTextVal="请选择" textVal="name" items="${stus }" selectedVal="2" textKey="id"></s:select>

如果不想要选中的值就可以不要selectedVal的属性，如果没有默认选中值的时候就可以不要headerTextKey和headerTextVal这两个属性就可以了。

5、checkbox标签

    <tag>
    <name>checkbox</name>
    <tag-class>com.zyp.jsp02.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>

Checkebox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) {
		//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();
	}
}

Checkebox测试结果

<%
	List ls=new ArrayList();
	ls.add(new Student("1","aaa"));
	ls.add(new Student("2","bbb"));
	ls.add(new Student("3","ccc"));
	List ls1=new ArrayList();
	ls1.add("1");
	ls1.add("2");
	request.setAttribute("ls", ls);
	request.setAttribute("ls1", ls1);
	
%>
	
	<z:checkbox textVal="name" checkedVal="${ls1}" item="${ls}" textKey="id"></z:checkbox>

输出结果是aaa和bbb选中，ccc没有选中。

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