模拟Hibernate动态生成SQL语句
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这里有一个xml配置文件，也就是Hibernate框架中会用到的POJO和数据库的映射文件
1
<?
xml version="1.0" encoding="utf-8"
?>
2
<!
DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
3
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"
>
4
<!--
5
Mapping file autogenerated by MyEclipse Persistence Tools
6
-->
7
<
hibernate-mapping
>
8
<
class
name
="hp.pojo.Member"
table
="member"
catalog
="hedb"
>
9
<
id
name
="mid"
type
="java.lang.String"
>
10
<
column
name
="mid"
length
="50"
/>
11
<
generator
class
="assigned"
></
generator
>
12
</
id
>
13
<
property
name
="name"
type
="java.lang.String"
>
14
<
column
name
="name"
length
="50"
/>
15
</
property
>
16
<
property
name
="age"
type
="java.lang.Integer"
>
17
<
column
name
="age"
/>
18
</
property
>
19
<
property
name
="salary"
type
="java.lang.Double"
>
20
<
column
name
="salary"
precision
="22"
scale
="0"
/>
21
</
property
>
22
<
property
name
="birthday"
type
="java.util.Date"
>
23
<
column
name
="birthday"
length
="0"
/>
24
</
property
>
25
<
property
name
="note"
type
="java.lang.String"
>
26
<
column
name
="note"
length
="65535"
/>
27
</
property
>
28
</
class
>
29
</
hibernate-mapping
>
POJO类如下:
1
package
hp.pojo;
2
3
import
java.util.Date;
4
5
/**
6
* Member entity.
@author
MyEclipse Persistence Tools
7
*/
8
9 @SuppressWarnings("serial")
10publicclass Member implements java.io.Serializable
11{
12 13// Fields 14 15private String mid;
16private String name;
17private Integer age;
18private Double salary;
19private Date birthday;
20private String note;
21 22// Constructors 23 24/** default constructor */ 25public Member()
26 {
27 }
28 29/** minimal constructor */ 30public Member(String mid)
31 {
32this.mid = mid;
33 }
34 35/** full constructor */ 36public Member(String mid, String name, Integer age, Double salary, Date birthday, String note)
37 {
38this.mid = mid;
39this.name = name;
40this.age = age;
41this.salary = salary;
42this.birthday = birthday;
43this.note = note;
44 }
45 46// Property accessors 47 48public String getMid()
49 {
50returnthis.mid;
51 }
52 53publicvoid setMid(String mid)
54 {
55this.mid = mid;
56 }
57 58public String getName()
59 {
60returnthis.name;
61 }
62 63publicvoid setName(String name)
64 {
65this.name = name;
66 }
67 68public Integer getAge()
69 {
70returnthis.age;
71 }
72 73publicvoid setAge(Integer age)
74 {
75this.age = age;
76 }
77 78public Double getSalary()
79 {
80returnthis.salary;
81 }
82 83publicvoid setSalary(Double salary)
84 {
85this.salary = salary;
86 }
87 88public Date getBirthday()
89 {
90returnthis.birthday;
91 }
92 93publicvoid setBirthday(Date birthday)
94 {
95this.birthday = birthday;
96 }
97 98public String getNote()
99 {
100returnthis.note;
101 }
102103publicvoid setNote(String note)
104 {
105this.note = note;
106 }
107108 }
下面代码演示了利用反射以及XML解析，动态生成SQL语句，并且利用JDBC技术执行SQL语句的过程：
1
package
hp.test;
2
3
import
java.io.File;
4
import
java.lang.reflect.Field;
5
import
java.lang.reflect.Method;
6
import
java.sql.Connection;
7
import
java.sql.DriverManager;
8
import
java.util.ArrayList;
9
import
java.util.Date;
10
import
java.util.List;
11
12
13
14
15
16
import
org.dom4j.Document;
17
import
org.dom4j.Element;
18
import
org.dom4j.io.SAXReader;
19
20
import
com.mysql.jdbc.PreparedStatement;
21
22
public
class
MyHibernate
23
{
24
private
class
Column
25
{
26
private
String name;
27
private
String length;
28
}
29
30
private
class
Generator
31
{
32
private
String type;
33
}
34
35
private
class
Id
36
{
37
private
String name;
38
private
String type;
39
40
private
Column column;
41
private
Generator generator;
42
}
43
private
class
Property
44
{
45
private
String name;
46
private
String type;
47
private
Column column;
48
}
49
50
private
class
Class
51
{
52
private
String name;
53
private
String table;
54
private
String catalog;
55
56
private
Id id;
57
private List<Property> allProperties;
58 }
59privateclass KeyValuePair
60 {
61private String type;
62private Object value;
63 64private KeyValuePair(String type,Object value)
65 {
66this.type = type;
67this.value = value;
68 }
69 }
70 71private String configPath ;
72private Object obj = null;
73private Document document;
74private Class voClass ;
75private String sql;
76private List<KeyValuePair> allValues;
77 78 79public MyHibernate(String configPath)
80 {
81this.configPath = configPath;
82 }
83 84publicint save(Object obj) throws Exception
85 {
86this.obj = obj;
87this.load();
88this.format();
89this.generateSql();
90returnthis.saveToDb();
91 }
92 93publicvoid load() throws Exception
94 {
95 SAXReader saxReader = new SAXReader();
96this.document = saxReader.read(new File(this.configPath));
97 }
98publicvoid format() throws Exception
99 {
100 Class _class = new Class();
101 org.dom4j.Element root = this.document.getRootElement();
102 Element classElement = root.element("class");
103 _class.name = classElement.attributeValue("name");
104 _class.table = classElement.attributeValue("table");
105 _class.catalog = classElement.attributeValue("catalog");
106107 Element idElement = classElement.element("id");
108 _class.id = new Id();
109 _class.id.name = idElement.attributeValue("name");
110 _class.id.type = idElement.attributeValue("type");
111112 Element columnElementInId = idElement.element("column");
113 _class.id.column = new Column();
114 _class.id.column.name = columnElementInId.attributeValue("name");
115 _class.id.column.length = columnElementInId.attributeValue("length");
116117 Element generatorElement = idElement.element("generator");
118 _class.id.generator = new Generator();
119 _class.id.generator.type = generatorElement.attributeValue("class");
120121 List<Property> allProperties = new ArrayList<MyHibernate.Property>();
122 _class.allProperties = allProperties;
123124 List<Element> allPropertiesElements = classElement.elements("property");
125for(Element item : allPropertiesElements)
126 {
127 Property property = new Property();
128 property.name = item.attributeValue("name");
129 property.type = item.attributeValue("type");
130131 Element columnElement = item.element("column");
132 property.column = new Column();
133 property.column.name = columnElement.attributeValue("name");
134 property.column.length = columnElement.attributeValue("length");
135 allProperties.add(property);
136//System.out.println("name: " + property.name);137 }
138this.voClass = _class;
139 }
140141publicvoid generateSql() throws Exception
142 {
143this.allValues = new ArrayList<MyHibernate.KeyValuePair>();
144 StringBuffer columns = new StringBuffer();
145 StringBuffer values = new StringBuffer();
146 StringBuffer sql = new StringBuffer(" INSERT INTO ");
147 sql.append(this.voClass.table).append("( ");
148149if("assigned".equals(this.voClass.id.generator.type))
150 {
151//需要用户提供主键列152 columns.append(this.voClass.id.column.name).append(",");
153 values.append("?,");
154155 Field field = this.obj.getClass().getDeclaredField(this.voClass.id.name);
156 field.setAccessible(true);
157this.allValues.add(new KeyValuePair(this.voClass.id.type, field.get(this.obj)));
158 }
159160for(Property property : this.voClass.allProperties)
161 {
162 columns.append(property.column.name).append(",");
163 values.append("?,");
164165 Field field = this.obj.getClass().getDeclaredField(property.name);
166 field.setAccessible(true);
167this.allValues.add(new KeyValuePair(property.type, field.get(this.obj)));
168 }
169170 columns.delete(columns.length()-1, columns.length());
171 values.delete(values.length()-1, columns.length());
172173 sql.append(columns.toString()).append(") VALUES (");
174 sql.append(values.toString()).append(")");
175this.sql = sql.toString();
176 System.out.println(this.sql);
177 }
178179publicint saveToDb() throws Exception
180 {
181 java.lang.Class.forName("org.gjt.mm.mysql.Driver");
182 Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hedb", "root", "admin");
183 java.sql.PreparedStatement ps = conn.prepareStatement(this.sql);
184185for(int i = 0; i < this.allValues.size(); i++)
186 {
187//System.out.println("***type:" + this.allValues.get(i).type);188if(String.class.getName().toString().equals(this.allValues.get(i).type))
189 {
190 ps.setString(i+1, (String)this.allValues.get(i).value);
191 }
192elseif(Integer.class.getName().toString().equals(this.allValues.get(i).type))
193 {
194 ps.setInt(i+1, (Integer)this.allValues.get(i).value);
195 }elseif(Double.class.getName().toString().equals(this.allValues.get(i).type))
196 {
197 ps.setDouble(i+1, (Double)this.allValues.get(i).value);
198 }elseif(Date.class.getName().toString().equals(this.allValues.get(i).type))
199 {
200 ps.setDate(i+1, new java.sql.Date(((Date)this.allValues.get(i).value).getTime()));
201 }
202203//System.out.println("设置第" + (i+1) + "个值("+this.allValues.get(i).type+","+this.allValues.get(i).value+")");204 }
205return ps.executeUpdate();
206207 }
208 }
测试代码：
1
package
hp.test;
2
3
import
java.util.Date;
4
5
import
org.hibernate.Session;
6
import
org.hibernate.SessionFactory;
7
8
import
hp.pojo.Member;
9
import
hp.utils.HibernateHelper;
10
11
public
class
Main
12
{
13
14
public
static
void
main(String[] args)
15
{
16 Member vo = new Member();
17 vo.setMid("admin4");
18 vo.setAge(24);
19 vo.setBirthday(new Date());
20 vo.setName("sheldon4");
21 vo.setNote("a good person4");
22 vo.setSalary(44444.44);
2324try25 {
26 MyHibernate mh = new MyHibernate("C:\\D\\code\\resource\\mapping.xml");
27int count = mh.save(vo);
28 System.out.println("成功插入" + count + "行数据");
29 }
30catch(Exception e)
31 {
32 e.printStackTrace();
3334 }
35 System.out.println("main done//~");
36 }
3738 }
原文：http://www.cnblogs.com/kuillldan/p/6266344.html
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