一，tag類
1.1 TagMy标簽類，格式化目前日期并輸出
package com.dkt.tag;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
public class TagMy extends TagSupport{
private String format;
public int doStartTag() {
SimpleDateFormat simpleDateFormat = new SimpleDateFormat(format);
String nowdate = simpleDateFormat.format(new Date());
JspWriter out = pageContext.getOut();
try {
out.print("Hello 世界！！");
out.print(nowdate);
} catch (IOException e) {
e.printStackTrace();
}
return super.SKIP_BODY;
}
public int doAfterBody() throws JspException {
return super.doAfterBody();
}
public int doEndTag() throws JspException {
return super.doEndTag();
}
public String getFormat() {
return format;
}
public void setFormat(String format) {
this.format = format;
}
}
1.2 ForTag 标簽類，自定義标簽，循環輸出
package com.dkt.tag;
import javax.servlet.jsp.tagext.TagSupport;
public class FroTag extends TagSupport{
private int start;
private int end;
private String var;
public int doStartTag(){
System.out.println("doStartTag()"+start);
if(start<=end){
pageContext.setAttribute(var, start);
start++;
return super.EVAL_BODY_INCLUDE;
}else {
return super.SKIP_BODY;
}
//執行doAfterBody()
}
public int doAfterBody() {
if(start<=end){
pageContext.setAttribute(var, start);
start++;
System.out.println("doAfterBody()"+start);
return super.EVAL_BODY_AGAIN;
}else {
return super.SKIP_BODY;
}
}
public int doEndTag(){
System.out.println("doEndTag()"+start);
return super.EVAL_PAGE;
}
public int getStart() {
return start;
}
public void setStart(int start) {
this.start = start;
}
public int getEnd() {
return end;
}
public void setEnd(int end) {
this.end = end;
}
public String getVar() {
return var;
}
public void setVar(String var) {
this.var = var;
}
}
1.3 IteratorTag标簽類，疊代集合，全部循環輸出顯示在頁面
package com.dkt.tag;
import java.util.ArrayList;
import java.util.Iterator;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class IteratorTag extends TagSupport{
private String scope;
private String var;
private ArrayList list = null;
Iterator it = null;
public int doStartTag() {
it = list.iterator();
return super.EVAL_BODY_INCLUDE;
}
public int doAfterBody() {
if (it.hasNext()) {
Object next = it.next();
pageContext.setAttribute(var, next);
return super.EVAL_BODY_AGAIN;
}else {
return super.SKIP_BODY;
}
}
public int doEndTag() throws JspException {
return super.doEndTag();
}
public String getScope() {
return scope;
}
public void setScope(String scope) {
this.scope = scope;
}
public String getVar() {
return var;
}
public void setVar(String var) {
this.var = var;
}
public ArrayList getList() {
return list;
}
public void setList(ArrayList list) {
this.list = list;
}
}
1.4 QueryTag 标簽類，根據表名，查詢資料庫，并由表格輸出到頁面
package com.dkt.tag;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
import com.dkt.util.DButil;
public class QueryTag extends TagSupport{
private String tableName;
public int doStartTag() {
DButil dButil = new DButil();
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
conn = dButil.createConn();
String sql = "select * from "+tableName;
try {
ps = conn.prepareStatement(sql);
ResultSetMetaData rsmd = ps.getMetaData();//得到表結構
rs = ps.executeQuery();
JspWriter out = pageContext.getOut();
out.print("
for (int i = 0; i < rsmd.getColumnCount(); i++) {//字段數量
out.print("
"+rsmd.getColumnName(i+1)+"");//字段名字
}
out.print("
");
while(rs.next()){
out.print("
");
for (int i = 0; i < rsmd.getColumnCount(); i++) {
out.print("
"+rs.getObject(i+1)+"");
}
out.print("
");
}
out.print("
");
} catch (SQLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return super.SKIP_BODY;
}
public int doAfterBody() throws JspException {
return super.doAfterBody();
}
public int doEndTag() throws JspException {
return super.doEndTag();
}
public String getTableName() {
return tableName;
}
public void setTableName(String tableName) {
this.tableName = tableName;
}
}
二，hellotag.tld
檔案 hellotag.tld 放在WEB-INF目錄下，與web.xml同級
/p>
"http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd">
1.0
1.2
hello
hello
hello
com.dkt.tag.TagMy
empty
format
true
true
formy
com.dkt.tag.FroTag
jsp
start
true
true
end
true
true
var
true
true
iteratormy
com.dkt.tag.IteratorTag
jsp
list
true
true
scope
true
true
var
true
true
query
com.dkt.tag.QueryTag
empty
tableName
true
true
三，jsp
index.jsp 開啟伺服器，直接通路項目下的index.jsp頁面即可顯示自定義标簽
在jsp頁面導入自定義标簽
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
My JSP 'index.jsp' starting page
formy:
${item1 }----
iterator：
ArrayList list = new ArrayList();
list.add(new UserInfo(0,"小白","123456","",""));
list.add(new UserInfo(1,"小白111","353456","",""));
list.add(new UserInfo(2,"小白222","532456","",""));
list.add(new UserInfo(3,"小白333","532356","",""));
list.add(new UserInfo(4,"小白444","123536","",""));
request.setAttribute("list",list);
%>
${item2.name}+++${item2.password }
四，web.xml
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
index.jsp