java jsp自定义标签-白红宇

java jsp自定义标签

阅读量：4915 次

发布时间：2019-06-11

本文共 15334 字，大约阅读时间需要 51 分钟。

1、web.xml配置

1 
      2 
     
       6     
      
       test_Servlet
       7      
      
        8         
       
         9             
        
         kongxh_tag
        10             
        
         /WEB-INF/mytag.tld
        11         
       12     
      13     
      14     
      
       15         
       
        index.jsp
       16     
      17

2、tld的编写

1 
       2 
      
        5     
       
        1.0
        6     
       
        2.0
        7     
       
        firsttags
        8     
       
         9         
        
         IterTag
        10         
        
         test_servlet_package.tag.IterTag
        11         
        
         jsp
        12         
        
         13             
         
          scope
         14             
         
          true
         15             
         
          true
         16         
        17         
        
         18             
         
          id
         19             
         
          true
         20             
         
          true
         21         
        22         
        
         23             
         
          name
         24             
         
          true
         25             
         
          true
         26         
        27     
       28     
       
        29         
        
         MyBodyTag
        30         
        
         test_servlet_package.tag.MyBodyTag
        31         
        
         test_servlet_package.tag.MyTagExtraInfo
        32         
        
         jsp
        33         
        
         34             
         
          scope
         35             
         
          true
         36             
         
          true
         37         
        38         
        
         39             
         
          id
         40             
         
          true
         41             
         
          true
         42         
        43         
        
         44             
         
          name
         45             
         
          true
         46             
         
          true
         47         
        48     
       49     
       
        50         
        
         MySimpleTag
        51         
        
         test_servlet_package.tag.MySimpleTag
        52         
        
         empty
        53         
        
         54             
         
          format
         55             
         
          true
         56             
         
          true
         57         
        58     
       59     
       
        60         
        
         MySimpleTagForIter
        61         
        
         test_servlet_package.tag.MySimpleTagForIter
        62         
        
         scriptless
        63         
        
         64             
         
          scope
         65             
         
          true
         66             
         
          true
         67         
        68         
        
         69             
         
          id
         70             
         
          true
         71             
         
          true
         72         
        73         
        
         74             
         
          name
         75             
         
          true
         76             
         
          true
         77         
        78     
       79     
       
        80         
        
         DynamicAttributesTag
        81         
        
         test_servlet_package.tag.DynamicAttributesTag
        82         
        
         empty
        83         
        
         true
        84     
       85

View Code

3、Tag的编写

IterTag：循环标签

1 package test_servlet_package.tag; 2 import java.util.Iterator; 3 import java.util.List; 4 import javax.servlet.jsp.JspException; 5 import javax.servlet.jsp.PageContext; 6 import javax.servlet.jsp.tagext.TagSupport; 7 public class IterTag extends TagSupport { 8     /** 9      * jsp 1.2 之前 的 做法 10      */11     private static final long serialVersionUID = 1L;12     //接受属性名称13     private String name;14     //接受查找范围15     private String scope;16     private String id;17     private Iterator
       iter = null;18     @Override19     public int doStartTag() throws JspException {20         Object value = null;21         //是否是page范围22         if ("page".equals(this.scope)) {23             value = super.pageContext24                     .getAttribute(name, PageContext.PAGE_SCOPE);25         } else if ("request".equals(this.scope)) {26             //是否是request范围27             value = super.pageContext.getAttribute(name,28                     PageContext.REQUEST_SCOPE);29         } else if ("session".equals(this.scope)) {30             //是否是session范围31             value = super.pageContext.getAttribute(name,32                     PageContext.SESSION_SCOPE);33         } else {34             //是否是application范围35             value = super.pageContext.getAttribute(name,36                     PageContext.APPLICATION_SCOPE);37         }38         //如果没有查到属性39         if (value !=null && value instanceof List
      ) {40             this.iter = ((List
      )value).iterator();41             if(iter.hasNext()){42                 super.pageContext.setAttribute(this.id,iter.next());43                 //找到属性，执行标签题内容44                 return TagSupport.EVAL_BODY_INCLUDE;45             }else{46                 //找到属性，执行标签题内容47                 return TagSupport.SKIP_BODY;48             }49         }else{50             //不执行标签体内容51             return TagSupport.SKIP_BODY;52         }53     }54     public String getName() {55         return name;56     }57 58     @Override59     public int doAfterBody() throws JspException {60         if(iter.hasNext()){61             super.pageContext.setAttribute(this.id,iter.next());62             return TagSupport.EVAL_BODY_AGAIN; //反复执行63         }else{64             return TagSupport.SKIP_BODY;65         }66     }67     @Override68     public int doEndTag() throws JspException {69         return super.doEndTag();70     }71     public void setName(String name) {72         this.name = name;73     }74     public String getScope() {75         return scope;76     }77     public void setScope(String scope) {78         this.scope = scope;79     }80     public String getId() {81         return id;82     }83     public void setId(String id) {84         this.id = id;85     }86 }

View Code

MyBodyTag

1 package test_servlet_package.tag; 2 import java.io.IOException; 3 import java.util.Iterator; 4 import java.util.List; 5 import javax.servlet.jsp.JspException; 6 import javax.servlet.jsp.PageContext; 7 import javax.servlet.jsp.tagext.BodyTagSupport; 8 public class MyBodyTag extends BodyTagSupport{ 9     private static final long serialVersionUID = 1L;10     private String name; //接受属性名称11     private String scope; //接受查找范围12     private String id;13     private Iterator
       iter = null;14     @Override15     public int doStartTag() throws JspException {16         Object value = null;17         if ("page".equals(this.scope)) {18             value = super.pageContext.getAttribute(name, PageContext.PAGE_SCOPE); //是否是page范围19         } else if ("request".equals(this.scope)) {    20             value = super.pageContext.getAttribute(name,PageContext.REQUEST_SCOPE); //是否是request范围21         } else if ("session".equals(this.scope)) {22             value = super.pageContext.getAttribute(name,PageContext.SESSION_SCOPE); //是否是session范围23         } else {24             value = super.pageContext.getAttribute(name,PageContext.APPLICATION_SCOPE); //是否是application范围25         }26         if (value !=null && value instanceof List
      ) { //如果没有查到属性27             this.iter = ((List
      )value).iterator();28             if(iter.hasNext()){29                 super.pageContext.setAttribute(this.id,iter.next());30                 return BodyTagSupport.EVAL_BODY_BUFFERED; //找到属性，执行标签题内容31             }else{32                 return BodyTagSupport.SKIP_BODY; //找到属性，执行标签题内容33             }34         }else{35             return BodyTagSupport.SKIP_BODY; //不执行标签体内容36         }37     }38     @Override39     public int doAfterBody() throws JspException {40         if(iter.hasNext()){41             super.pageContext.setAttribute(this.id,iter.next());42             return BodyTagSupport.EVAL_BODY_AGAIN; //反复执行43         }else{44             return BodyTagSupport.SKIP_BODY;45         }46     }47     @Override48     public int doEndTag() throws JspException { //这个 方法 不执行 则 没有 输出 49         if(super.bodyContent != null){50             try {51                 super.bodyContent.writeOut(super.getPreviousOut());52             } catch (IOException e) {53                 e.printStackTrace();54             }55         }56         return BodyTagSupport.EVAL_PAGE;57     }58     public String getName() {59         return name;60     }61     public void setName(String name) {62         this.name = name;63     }64     public String getScope() {65         return scope;66     }67     public void setScope(String scope) {68         this.scope = scope;69     }70     public String getId() {71         return id;72     }73     public void setId(String id) {74         this.id = id;75     }76 }

View Code

1 package test_servlet_package.tag; 2 import javax.servlet.jsp.tagext.TagData; 3 import javax.servlet.jsp.tagext.TagExtraInfo; 4 import javax.servlet.jsp.tagext.VariableInfo; 5 public class MyTagExtraInfo extends TagExtraInfo{ 6     @Override 7     public VariableInfo[] getVariableInfo(TagData data) { 8         // TODO Auto-generated method stub 9         return new  VariableInfo[]{ new VariableInfo(data.getId(),"java.lang.String",true,VariableInfo.NESTED)};10     }11 }

View Code

MySimpleTag

1 package test_servlet_package.tag; 2 import java.io.IOException; 3 import java.text.SimpleDateFormat; 4 import java.util.Date; 5 import javax.servlet.jsp.JspException; 6 import javax.servlet.jsp.tagext.SimpleTagSupport; 7 public class MySimpleTag extends SimpleTagSupport{ 8     //jsp 2.0 之后 的 出现  为了 简化 开发  9     private String format;10     @Override11     public void doTag() throws JspException, IOException {12         SimpleDateFormat sdf = new SimpleDateFormat(this.format);13         this.getJspContext().getOut().write(sdf.format(new Date()));14     }15     public String getFormat() {16         return format;17     }18     public void setFormat(String format) {19         this.format = format;20     }21 }

View Code

MySimpleTagForIter

1 package test_servlet_package.tag; 2 import java.io.IOException; 3 import java.io.StringWriter; 4 import java.util.Iterator; 5 import java.util.List; 6 import javax.servlet.jsp.JspException; 7 import javax.servlet.jsp.PageContext; 8 import javax.servlet.jsp.tagext.JspFragment; 9 import javax.servlet.jsp.tagext.SimpleTagSupport;10 public class MySimpleTagForIter extends SimpleTagSupport{11     //jsp 2.0 之后 的 出现  为了 简化 开发 12     private String name; //接受属性名称13     private String scope; //接受查找范围14     private String id;15     @Override16     public void doTag() throws JspException, IOException {17         Object value = null;18         if ("page".equals(this.scope)) {19             value = super.getJspContext().getAttribute(name, PageContext.PAGE_SCOPE); //是否是page范围20         } else if ("request".equals(this.scope)) {21             value = super.getJspContext().getAttribute(name,PageContext.REQUEST_SCOPE);//是否是request范围22         } else if ("session".equals(this.scope)) {23             value = super.getJspContext().getAttribute(name,PageContext.SESSION_SCOPE); //是否是session范围24         } else {25             value = super.getJspContext().getAttribute(name,PageContext.APPLICATION_SCOPE); //是否是application范围26         }27         if(value !=null && value instanceof List
      ){28             Iterator iter = ((List
      )value).iterator();29             while(iter.hasNext()){30                 super.getJspContext().setAttribute(this.id,iter.next());31                 //PageContext pageContext = (PageContext) super.getJspBody().getJspContext();32                 //super.getJspBody().invoke(pageContext.getOut());33                 //super.getJspBody().invoke(null);//输出到相应里去 ，如果 是 个 流 文件 ，这会输出 到 文件 里去 ，，，34                 JspFragment jf = this.getJspBody();35                 StringWriter sw = new StringWriter();36                 jf.invoke(sw);37                 String s = sw.toString();38                 s = "zczx";39                 this.getJspContext().getOut().write(s); 40             }41         }42     }43     public String getName() {44         return name;45     }46     public void setName(String name) {47         this.name = name;48     }49     public String getScope() {50         return scope;51     }52     public void setScope(String scope) {53         this.scope = scope;54     }55     public String getId() {56         return id;57     }58     public void setId(String id) {59         this.id = id;60     }61 }

View Code

DynamicAttributesTag

1 package test_servlet_package.tag; 2 import java.io.IOException; 3 import java.util.HashMap; 4 import java.util.Iterator; 5 import java.util.Map; 6 import javax.servlet.jsp.JspException; 7 import javax.servlet.jsp.tagext.DynamicAttributes; 8 import javax.servlet.jsp.tagext.SimpleTagSupport; 9 10 public class DynamicAttributesTag extends SimpleTagSupport implements DynamicAttributes {11     // jsp 2.0 之后 的 出现 为了 简化 开发12     private Map
      
        map = new HashMap
       
        ();13     @Override14     public void doTag() throws JspException, IOException {15         Float num = 0.0f;16         Iterator
        
         
          > iter = map.entrySet().iterator();17         while (iter.hasNext()) {18             Map.Entry
          
            val = iter.next();19             num += val.getValue();20         }21         this.getJspContext().getOut().write(num + "");22     }23 24     @Override25     public void setDynamicAttribute(String arg0, String arg1, Object arg2) throws JspException {26         map.put(arg1, Float.parseFloat(arg2.toString()));27     }28 }

View Code

测试

1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 2 <%@ page import="java.util.*"%> 3 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> 4 <%@ taglib prefix="x" uri="http://java.sun.com/jsp/jstl/xml"%> 5 <%@ taglib prefix="fmt" uri="http://java.sun.com/jsp/jstl/fmt"%> 6 <%@ taglib prefix="sql" uri="http://java.sun.com/jsp/jstl/sql"%> 7 <%@ taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions"%> 8 <%@ taglib uri="kongxh_tag" prefix="mytag"%> 9 10 11     index.jsp12 13 14         <%15             List
      
        all = new ArrayList
       
        ();16             all.add("test 1,");17             all.add("test 2,");18             all.add("test 3,");19             request.setAttribute("all", all);20         %>21 22     
        
         23         ${url}24     
        25     
        
26     ----------------------27     
        
         28         ${url}\ <%=url.length()%>29     
        30     
        
31     ----------------------32     
        33     
        
34     ----------------------35     
        
         36         ${url}37     
        38     
        
39     ----------------------40     
        41     
        
42     ----------------------43     
        44 45