java jsp自定义标签
1、web.xml配置
1 <?xml version="1.0" encoding="UTF-8"?> 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xmlns="http://java.sun.com/xml/ns/javaee" 4 xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 5 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"> 6 <display-name>test_Servlet</display-name> 7 <jsp-config> 8 <taglib> 9 <taglib-uri>kongxh_tag</taglib-uri> 10 <taglib-location>/WEB-INF/mytag.tld</taglib-location> 11 </taglib> 12 </jsp-config> 13 <!-- 配置欢迎界面 --> 14 <welcome-file-list> 15 <welcome-file>index.jsp</welcome-file> 16 </welcome-file-list> 17 </web-app>
2、tld的编写
1 <?xml version="1.0" encoding="UTF-8" ?> 2 <taglib xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 3 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee web-jsptaglibrary_2_0.xsd" 4 version="2.0"> 5 <tlib-version>1.0</tlib-version> 6 <jsp-version>2.0</jsp-version> 7 <short-name>firsttags</short-name> 8 <tag> 9 <name>IterTag</name> 10 <tag-class>test_servlet_package.tag.IterTag</tag-class> 11 <body-content>jsp</body-content> 12 <attribute> 13 <name>scope</name> 14 <required>true</required> 15 <rtexprvalue>true</rtexprvalue> 16 </attribute> 17 <attribute> 18 <name>id</name> 19 <required>true</required> 20 <rtexprvalue>true</rtexprvalue> 21 </attribute> 22 <attribute> 23 <name>name</name> 24 <required>true</required> 25 <rtexprvalue>true</rtexprvalue> 26 </attribute> 27 </tag> 28 <tag> 29 <name>MyBodyTag</name> 30 <tag-class>test_servlet_package.tag.MyBodyTag</tag-class> 31 <tei-class>test_servlet_package.tag.MyTagExtraInfo</tei-class> 32 <body-content>jsp</body-content> 33 <attribute> 34 <name>scope</name> 35 <required>true</required> 36 <rtexprvalue>true</rtexprvalue> 37 </attribute> 38 <attribute> 39 <name>id</name> 40 <required>true</required> 41 <rtexprvalue>true</rtexprvalue> 42 </attribute> 43 <attribute> 44 <name>name</name> 45 <required>true</required> 46 <rtexprvalue>true</rtexprvalue> 47 </attribute> 48 </tag> 49 <tag> 50 <name>MySimpleTag</name> 51 <tag-class>test_servlet_package.tag.MySimpleTag</tag-class> 52 <body-content>empty</body-content> 53 <attribute> 54 <name>format</name> 55 <required>true</required> 56 <rtexprvalue>true</rtexprvalue> 57 </attribute> 58 </tag> 59 <tag> 60 <name>MySimpleTagForIter</name> 61 <tag-class>test_servlet_package.tag.MySimpleTagForIter</tag-class> 62 <body-content>scriptless</body-content> 63 <attribute> 64 <name>scope</name> 65 <required>true</required> 66 <rtexprvalue>true</rtexprvalue> 67 </attribute> 68 <attribute> 69 <name>id</name> 70 <required>true</required> 71 <rtexprvalue>true</rtexprvalue> 72 </attribute> 73 <attribute> 74 <name>name</name> 75 <required>true</required> 76 <rtexprvalue>true</rtexprvalue> 77 </attribute> 78 </tag> 79 <tag> 80 <name>DynamicAttributesTag</name> 81 <tag-class>test_servlet_package.tag.DynamicAttributesTag</tag-class> 82 <body-content>empty</body-content> 83 <dynamic-attributes>true</dynamic-attributes> 84 </tag> 85 </taglib>
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 @Override 19 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.pageContext 24 .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 @Override 59 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 @Override 68 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 }
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 @Override 15 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 @Override 39 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 @Override 48 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 }
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 }
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 @Override 11 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 }
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 @Override 16 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 }
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<String, Float> map = new HashMap<String, Float>(); 13 @Override 14 public void doTag() throws JspException, IOException { 15 Float num = 0.0f; 16 Iterator<Map.Entry<String, Float>> iter = map.entrySet().iterator(); 17 while (iter.hasNext()) { 18 Map.Entry<String, Float> val = iter.next(); 19 num += val.getValue(); 20 } 21 this.getJspContext().getOut().write(num + ""); 22 } 23 24 @Override 25 public void setDynamicAttribute(String arg0, String arg1, Object arg2) throws JspException { 26 map.put(arg1, Float.parseFloat(arg2.toString())); 27 } 28 }
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 <html> 10 <head> 11 <title>index.jsp</title> 12 </head> 13 <body> 14 <% 15 List<String> all = new ArrayList<String>(); 16 all.add("test 1,"); 17 all.add("test 2,"); 18 all.add("test 3,"); 19 request.setAttribute("all", all); 20 %> 21 22 <mytag:IterTag name="all" scope="request" id="url"> 23 ${url} 24 </mytag:IterTag> 25 <br/> 26 ---------------------- 27 <mytag:MyBodyTag name="all" scope="request" id="url"> 28 ${url}\ <%=url.length()%> 29 </mytag:MyBodyTag> 30 <br/> 31 ---------------------- 32 <mytag:MySimpleTag format="yyyy-mm-dd" /> 33 <br/> 34 ---------------------- 35 <mytag:MySimpleTagForIter name="all" scope="request" id="url"> 36 ${url} 37 </mytag:MySimpleTagForIter> 38 <br/> 39 ---------------------- 40 <mytag:DynamicAttributesTag ab="3.4" gh="9.0" /> 41 <br/> 42 ---------------------- 43 <c:out value="Hello world"></c:out> 44 </body> 45 </html>
总结：复习和记录一下之前用到一个知识点。
