An introduction to the Unified Modeling Language

2018-03-20

The most useful, standard UML diagrams are: use case diagram, class diagram, sequence diagram, statechart diagram, activity diagram, component diagram, and deployment diagram.

Use-case diagram

A use case illustrates a unit of functionality provided by the system. The main purpose of the use-case diagram is to help development teams visualize the functional requirements of a system, including the relationship of “actors” (human beings who will interact with the system) to essential processes, as well as the relationships among different use cases. Use-case diagrams generally show groups of use cases — either all use cases for the complete system, or a breakout of a particular group of use cases with related functionality (e.g., all security administration-related use cases). To show a use case on a use-case diagram, you draw an oval in the middle of the diagram and put the name of the use case in the center of, or below, the oval. To draw an actor (indicating a system user) on a use-case diagram, you draw a stick person to the left or right of your diagram (and just in case you’re wondering, some people draw prettier stick people than others). Use simple lines to depict relationships between actors and use cases, as shown in Figure 1.

A use-case diagram is typically used to communicate the high-level functions of the system and the system’s scope. By looking at our use-case diagram in Figure 1, you can easily tell the functions that our example system provides. This system lets the band manager view a sales statistics report and the Billboard 200 report for the band’s CDs. It also lets the record manager view a sales statistics report and the Billboard 200 report for a particular CD. The diagram also tells us that our system delivers Billboard reports from an external system called Billboard Reporting Service.

In addition, the absence of use cases in this diagram shows what the system doesn’t do. For example, it does not provide a way for a band manager to listen to songs from the different albums on the Billboard 200 — i.e., we see no reference to a use case called Listen to Songs from Billboard 200. This absence is not a trivial matter. With clear and simple use-case descriptions provided on such a diagram, a project sponsor can easily see if needed functionality is present or not present in the system.
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Entity Relationship Modeling Examples

2018-03-20

This section explains the requirements for our three example databases—music, university, and flight—and shows you their Entity Relationship diagrams:

The music database is designed to store details of a music collection, including the albums in the collection, the artists who made them, the tracks on the albums, and when each track was last played.
The university database captures the details of students, courses, and grades for a university.
The flight database stores an airline timetable of flight routes, times, and the plane types.
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SSM 类别删除

2018-03-14

用于删除的超链

1	<a deleteLink="true" href="admin_category_delete?id=${c.id}"><span class=" glyphicon glyphicon-trash"></span></a>

删除前的确认操作

$(function(){
	$("a").click(function(){
		var deleteLink = $(this).attr("deleteLink");
		console.log(deleteLink);
		if("true"==deleteLink){
			var confirmDelete = confirm("确认要删除");
			if(confirmDelete)
				return true;
			return false;
			
		}
	});
})

增加删除sql语句

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.how2java.tmall.mapper.CategoryMapper">
    <select id="list" resultType="Category">
        select * from   category         order by id desc
        <if test="start!=null and count!=null">
            limit #{start},#{count}
        </if>
    </select>
    <select id="total" resultType="int">
        select count(*) from category
    </select>
    <insert id="add"  keyProperty="id"  useGeneratedKeys="true" parameterType="Category" >
        insert into category ( name ) values (#{name})
    </insert>
    <delete id="delete">
        delete from category where id= #{id}
    </delete>
</mapper>

CategoryController

映射路径admin_category_delete
提供参数接受id注入
提供session参数，用于后续定位文件位置
通过categoryService删除数据
通过session获取ControllerContext然后获取分类图片位置，接着删除分类图片
客户端跳转到 admin_category_list

@RequestMapping("admin_category_delete")
  public String delete(int id,HttpSession session) throws IOException {
      categoryService.delete(id);
      File  imageFolder= new File(session.getServletContext().getRealPath("img/category"));
      File file = new File(imageFolder,id+".jpg");
      file.delete();
      return "redirect:/admin_category_list";
  }

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SSM 类别编辑

2018-01-23

用于编辑的超链

1	<a href="admin_category_edit?id=${c.id}"><span class="glyphicon glyphicon-edit"></span></a>

增加通过id获取Category对象的sql语句

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
<mapper namespace="com.how2java.tmall.mapper.CategoryMapper">
    <select id="list" resultType="Category">
        select * from   category         order by id desc
        <if test="start!=null and count!=null">
            limit #{start},#{count}
        </if>
 
    </select>
    <select id="total" resultType="int">
        select count(*) from category
    </select>
    <insert id="add"  keyProperty="id"  useGeneratedKeys="true" parameterType="Category" >
        insert into category ( name ) values (#{name})
    </insert>
    <delete id="delete">
        delete from category where id= #{id}
    </delete>
 
    <select id="get" resultType="Category">
        select * from category  where id= #{id}
    </select>
</mapper>

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MYBATIS basic operation

2018-01-23

MyBatis is an open source, lightweight, persistence framework. It automates the mapping between SQL databases and objects in Java. The mappings are decoupled from the application logic by packaging the SQL statements in XML configuration files.

configure the details of the database

<?xml version = "1.0" encoding = "UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
		
   <environments default = "development">
      <environment id = "development">
         <transactionManager type = "JDBC"/> 
			
         <dataSource type = "POOLED">
            <property name = "driver" value = "com.mysql.jdbc.Driver"/>
            <property name = "url" value = "jdbc:mysql://localhost:3306/details"/>
            <property name = "username" value = "root"/>
            <property name = "password" value = "password"/>
         </dataSource>   
         
      </environment>
   </environments>
	
   <mappers>
      <mapper resource = "mybatis/Student.xml"/>
   </mappers>
   
</configuration>

The POJO class

public class Student {
   private int id;
   private String name;
   private String branch;
   private int percentage;
   private int phone;
   private String email;
   
   //Setters and getters   
}

Mapped Statements

Mapped SQL statements are resided within the element named . This element contains an attribute called ‘namespace’:

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2
3

<mapper namespace = "Student">
   //mapped statements and result maps
<mapper>

id is unique identifier used to identify the insert statement. On the other hand, parametertype is the class name or the alias of the parameter that will be passed into the statement:

<insert id = "insert" parameterType = "Student">
   INSERT INTO STUDENT1 (NAME, BRANCH, PERCENTAGE, PHONE, EMAIL ) 
   VALUES (#{name}, #{branch}, #{percentage}, #{phone}, #{email});    
</insert>
<update id = "update" parameterType = "Student">
   UPDATE STUDENT SET EMAIL = #{email}, NAME = #{name}, BRANCH = #{branch}, PERCENTAGE = #{percentage}, PHONE = #{phone} WHERE ID = #{id};
</update>
<delete id = "deleteById" parameterType = "int">
   DELETE from STUDENT WHERE ID = #{id};
</delete>

invoke the ‘insert’ mapped query:

//Assume session is an SqlSession object.  
session.insert("Student.insert", student);
session.update("Student.update",student);
session.delete("Student.deleteById", 18);

resultMaps

maps the results of the select queries to the Student class

<resultMap id = "result" type = "Student">
   <result property = "id" column = "ID"/>
   <result property = "name" column = "NAME"/>
   <result property = "branch" column = "BRANCH"/>
   <result property = "percentage" column = "PERCENTAGE"/>
   <result property = "phone" column = "PHONE"/>
   <result property = "email" column = "EMAIL"/>
</resultMap>
<select id = "getAll" resultMap = "result">
   SELECT * FROM STUDENT; 
</select>
<select id = "getById" parameterType = "int" resultMap = "result">
   SELECT * FROM STUDENT WHERE ID = #{id};
</select>

The method returns the data of the selected record in the form of List:

1	List<Student> list = session.selectList("Student.getAll");

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MYBATIS Dynamic SQL

2018-01-23

MYBATIS Dynamic SQL

Dynamic SQL is a very powerful feature of MyBatis. It enables to build queries based on the scenario dynamically.

if
choose (when, otherwise)
trim (where, set)
foreach
The if Statement
This statement provides an optional text search type of functionality.

<select id = "getRecByName_Id" parameterType = "Student" resultType = "Student">
   SELECT * FROM STUDENT		 
   <if test = "name != null">
      WHERE name LIKE #{name}
   </if>
   <if test = "id != null">
      AND id LIKE #{id}
   </if> 
</select>

The choose, when, and otherwise Statements

a choose element, which is similar to Java’s switch statement.

<select id = "getName_Id_phone" parameterType = "Student" resultType = "Student">
   SELECT * FROM STUDENT
	
   <where>
      <if test = "id != null">
         id = #{id}
      </if>
      <if test = "name != null">
         AND name LIKE #{name}
      </if>
   </where>
		
</select>

The foreach Statement

foreach element allows you to specify a collection and declare item and index variables that can be used inside the body of the element

<select id = "selectPostIn" resultType = "domain.blog.Post">
   SELECT *
   FROM POST P
   WHERE ID in
	
   <foreach item = "item" index = "index" collection = "list"
      open = "(" separator = "," close = ")">
      #{item}
   </foreach>
	
</select>

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SSM 类别增加

2018-01-23

页面中的增加分类部分

<div class="panel panel-warning addDiv">
     <div class="panel-heading">新增分类</div>
     <div class="panel-body">
         <form method="post" id="addForm" action="admin_category_add" enctype="multipart/form-data">
             <table class="addTable">
                 <tr>
                     <td>分类名称</td>
                     <td><input  id="name" name="name" type="text" class="form-control"></td>
                 </tr>
                 <tr>
                     <td>分类圖片</td>
                     <td>
                         <input id="categoryPic" accept="image/*" type="file" name="image" />
                     </td>
                 </tr>
                 <tr class="submitTR">
                     <td colspan="2" align="center">
                         <button type="submit" class="btn btn-success">提 交</button>
                     </td>
                 </tr>
             </table>
         </form>
     </div>

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商城框架搭建

2018-01-23

实体类，声明了id和name,以及对应的setter,getter

public class Category {
    private Integer id;
 
    private String name;
 
    public Integer getId() {
        return id;
    }
 
    public void setId(Integer id) {
        this.id = id;
    }
 
    public String getName() {
        return name;
    }
 
    public void setName(String name) {
        this.name = name == null ? null : name.trim();
    }
}

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Java工具类

2018-01-17

日期工具类

字符串与日期的转换：

import java.text.SimpleDateFormat;
import java.util.Date;
public class DateUtil {
    //日期转字符
	public static String formatDate(Date date,String format){
		String result="";
		SimpleDateFormat sdf=new SimpleDateFormat(format);
		if(date!=null){
			result=sdf.format(date);
		}
		return result;
	}
	
	//字符转日期
	public static Date formatString(String str,String format) throws Exception{
		if(StringUtil.isEmpty(str)){
			return null;
		}
		SimpleDateFormat sdf=new SimpleDateFormat(format);
		return sdf.parse(str);
	}
	//获取当前时间
	public static String getCurrentDateStr()throws Exception{
		Date date=new Date();
		SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMddhhmmss");
		return sdf.format(date);
	}
}

数据库连接工具类

public class DbUtil {
	//获得连接
	public Connection getCon() throws Exception{
		Class.forName(PropertiesUtil.getValue("jdbcName"));
		Connection con=DriverManager.getConnection(PropertiesUtil.getValue("dbUrl"), PropertiesUtil.getValue("dbUserName"), PropertiesUtil.getValue("dbPassword"));
		return con;
	}
	//关闭连接
	public void closeCon(Connection con)throws Exception{
		if(con!=null){
			con.close();
		}
	}
	
	
}

加密工具类

public class MD5Util {
	public static String EncoderPwdByMd5(String str) throws NoSuchAlgorithmException, UnsupportedEncodingException{
		MessageDigest md5=MessageDigest.getInstance("MD5");
		BASE64Encoder base64en=new BASE64Encoder();
		return base64en.encode(md5.digest(str.getBytes("utf-8")));
	}
}

读取配置文件

public class PropertiesUtil {
	public static String getValue(String key){
		Properties prop=new Properties();
		InputStream in=new PropertiesUtil().getClass().getResourceAsStream("/setting.properties");
		try {
			prop.load(in);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return (String)prop.get(key);
	}
}

字符串工具类

public class StringUtil {
	    public static boolean isEmpty(String str){
		if(str==null || "".equals(str.trim())){
			return true;
		}else{
			return false;
		}
	}
	
		public static boolean isNotEmpty(String str){
		if(str!=null && !"".equals(str.trim())){
			return true;
		}else{
			return false;
		}
	}
	
	    public static String formatLike(String str){
		if(isNotEmpty(str)){
			return "%"+str+"%";
		}else{
			return null;
		}
	}
}

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Mysql select statement

2018-01-17

select statement可以从表或视图中查询数据

syntax of the SELECT statement:

SELECT 
    column_1, column_2, ...
FROM
    table_1
[INNER | LEFT |RIGHT] JOIN table_2 ON conditions
WHERE
    conditions
GROUP BY column_1
HAVING group_conditions
ORDER BY column_1
LIMIT offset, length;

SELECT statement examples：

SELECT
lastname,firstname,jobtype 
FROM
employees;

1	SELECT * FROM employees;

MySQL DISTINCT clause

SELECT DISTINCT
    columns
FROM
    table_name
WHERE
    where_conditions;

MySQL DISTINCT example:

SELECT DISTINCT
lastname 
FROM
employees
ORDER BY lastname;

If a column has NULL values and you use the DISTINCT clause for that column, MySQL keeps one NULL value and eliminates the other.
use the DISTINCT clause with more than one column. In this case, MySQL uses the combination of all columns to determine the uniqueness of the row in the result set.

SELECT DISTINCT
    state, city
FROM
    customers
WHERE
    state IS NOT NULL
ORDER BY state , city;

use the GROUP BY clause in the SELECT statement without using aggregate functions, the GROUP BY clause behaves like the DISTINCT clause.

SELECT
  state
FROM
  customers
GROUP BY
  state;

use the DISTINCT clause with an aggregate function e.g., SUM, AVG, and COUNT, to remove duplicate rows before MySQL applies the aggregate function to the result set.

SELECT 
    COUNT(DISTINCT state)
FROM
    customers
WHERE
    country = 'USA';

use the DISTINCT clause with the LIMIT clause, MySQL stops searching immediately when it finds the number of unique rows specified in the LIMIT clause

SELECT DISTINCT
    state
FROM
    customers
WHERE
    state IS NOT NULL
LIMIT 5;

WHERE clause

use WHERE clause to specify exact rows to select based on particular filter express or condition

SELECT 
    lastname,firstname,jobtype
FROM
    employees
WHERE
    jobtype='Sales Rep' AND officeCode = 1;

the comparison operators that can use to form filtering expressions in the WHERE clause.

Operator	Description
=	Equal to. You can use it with almost any data types.
<> or !=	Not equal to.
<	Less than. You typically use it with numeric and date/time data types.
>	Greater than.
<=	Less than or equal to
>=	Greater than or equal to

Note:

some useful operators that you can use in the WHERE clause to form complex conditions:BETWEEN,LIKE,IN,IS NULL.
The WHERE clause is used not only with the SELECT statement but also other SQL statements to filter rows such as DELETE and UPDATE.
ORDER BY clause
use the ORDER BY clause to sort the result set

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SELECT column1, column2,...
FROM tbl
ORDER BY column1 [ASC|DESC], column2 [ASC|DESC],...

ORDER BY sort by an expression example:

SELECT
 ordernumber,
 orderlinenumber,
 quantityOrdered * priceEach AS subtotal
FROM
 orderdetails
ORDER BY
 ordernumber,
 orderLineNumber,
 subtotal;

ORDER BY with customer sort order:
define custom sort order use FIELD() function

SELECT 
    orderNumber, status
FROM
    orders
ORDER BY FIELD(status,
        'In Process',
        'On Hold',
        'Cancelled',
        'Resolved',
        'Disputed',
        'Shipped');

Natural Sorting with ORDER BY Clause:


SELECT 
    item_no
FROM
    items
ORDER BY CAST(item_no AS UNSIGNED) , item_no;

the LENGTH function returns the length of a string

SELECT 
    item_no
FROM
    items
ORDER BY LENGTH(item_no) , item_no;

use the parentheses statement returns the customers who locate in the USA or France and have credit limit greater than 10000:

SELECT 
    customername, country, creditLimit
FROM
    customers
WHERE
    (country = 'USA' OR country = 'France')
        AND creditlimit > 100000;

IN Operator

The IN operator allows you to determine if a specified value matches any one of a list or a subquery:

SELECT 
    column1,column2,...
FROM
    table_name
WHERE 
 (expr|column_1) IN ('value1','value2',...);

find out the offices that locate in the U.S. and France:

SELECT 
    officeCode, city, phone, country
FROM
    offices
WHERE
    country IN ('USA' , 'France');

get offices that do not locate in USA and France, you use NOT IN in the WHERE clause:

SELECT 
    officeCode, city, phone
FROM
    offices
WHERE
    country NOT IN ('USA' , 'France');

MySQL IN with subquery:

SELECT 
    orderNumber, customerNumber, status, shippedDate
FROM
    orders
WHERE
    orderNumber IN (SELECT 
            orderNumber
        FROM
            orderDetails
        GROUP BY orderNumber
        HAVING SUM(quantityOrdered * priceEach) > 60000);

BETWEEN Operator

use the BETWEEN operator in the WHERE clause of the SELECT, INSERT, UPDATE, and DELETE statements:

1	expr [NOT] BETWEEN begin_expr AND end_expr;

find products whose buy prices are within the ranges of $90 and $100:

SELECT 
    productCode, productName, buyPrice
FROM
    products
WHERE
    buyPrice BETWEEN 90 AND 100;

get the orders whose required dates are from 01/01/2003 to 01/31/2003:

SELECT orderNumber,
         requiredDate,
         status
FROM orders
WHERE requireddate
    BETWEEN CAST('2003-01-01' AS DATE)
        AND CAST('2003-01-31' AS DATE);

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Use-case diagram

用于删除的超链

删除前的确认操作

增加删除sql语句

CategoryController

用于编辑的超链

增加通过id获取Category对象的sql语句

configure the details of the database

The POJO class

Mapped Statements

resultMaps

MYBATIS Dynamic SQL

The if Statement

The choose, when, and otherwise Statements

The foreach Statement

页面中的增加分类部分

实体类，声明了id和name,以及对应的setter,getter

日期工具类

数据库连接工具类

加密工具类

读取配置文件

字符串工具类

select statement可以从表或视图中查询数据

MySQL DISTINCT clause

WHERE clause

ORDER BY clause

IN Operator

BETWEEN Operator