java中select的用法_mybaties中select用法，以及常用增删改查

查询语句是使用 MyBatis 时最常用的元素之一

select元素配置细节如下

属性

描述

取值

默认

在这个模式下唯一的标识符，可被其它语句引用

parameterType

传给此语句的参数的完整类名或别名

resultType

语句返回值类型的整类名或别名。注意，如果是集合，那么这里填写的是集合的项的整类名或别名，而不是集合本身的类名。(resultType 与resultMap 不能并用)

resultMap

引用的外部resultMap 名。结果集映射是MyBatis 中最强大的特性。许多复杂的映射都可以轻松解决。(resultType 与resultMap 不能并用)

flushCache

如果设为true，则会在每次语句调用的时候就会清空缓存。select 语句默认设为false

true|false

false

useCache

如果设为true，则语句的结果集将被缓存。select 语句默认设为false true|false false

timeout 设置驱动器在抛出异常前等待回应的最长时间，默认为不设值，由驱动器自己决定

true|false

false

timeout

设置驱动器在抛出异常前等待回应的最长时间，默认为不设值，由驱动器自己决定

正整数

未设置

fetchSize

设置一个值后，驱动器会在结果集数目达到此数值后，激发返回，默认为不设值，由驱动器自己决定

正整数

驱动器决定

statementType

statement，preparedstatement，callablestatement。

预准备语句、可调用语句

STATEMENT

PREPARED

CALLABLE

PREPARED

resultSetType

forward_only，scroll_sensitive，scroll_insensitive

只转发，滚动敏感，不区分大小写的滚动

FORWARD_ONLY

SCROLL_SENSITIVE

SCROLL_INSENSITIVE

驱动器决定

例子：

1 <?xml version="1.0" encoding="UTF-8"?>

2 /p>

4 "http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">

7 keyProperty="classId">

8 INSERT INTO users(username,PASSWORD)9 VALUES(#{username},#{password});10

12 resultMap="adminResultMap">

13 SELECT *FROM t_admin;14

下面是常用的增删查改方法：

1)configuration.xml ， MyBatis主配置文件

1 <?xml version="1.0" encoding="UTF-8"?>

2 /p>

3 "http://mybatis.org/dtd/mybatis-3-config.dtd">

2)jdbc.properties

1 driver=com.mysql.jdbc.Driver2 url=jdbc:mysql://localhost:3306/keith

3 username=keith4 password=keith

3)log4j.properties

1 log4j.rootLogger=DEBUG,CONSOLE,FILEOUT2 log4j.addivity.org.apache=true

4 # CONSOLE5 log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender6 log4j.appender.Threshold=DEBUG7 log4j.appender.CONSOLE.Target=System.out8 log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout9 #log4j.appender.CONSOLE.layout.ConversionPattern=[framework] %d - %c -%-4r [%t] %-5p %c %x - %m%n10 log4j.appender.CONSOLE.layout.ConversionPattern=[%-5p] %d{yyyy-MM-dd HH\:mm\:ss} \:%m%n11

12 #13 # FILEOUT14 log4j.appender.FILEOUT=org.apache.log4j.RollingFileAppender15 log4j.appender.FILEOUT.File=${catalina.home}\\file.log16 log4j.appender.fileout.MaxFileSize=100000KB17 # default is true，append to the file; if false, the replace the log file whenever restart system18 log4j.appender.FILEOUT.Append=true

19 #RollingFileAppender没有DatePattern这个属性20 log4j.appender.FILEOUT.layout=org.apache.log4j.PatternLayout21 #log4j.appender.CONSOLE.layout.ConversionPattern=[framework] %d - %c -%-4r [%t] %-5p %c %x - %m%n22 log4j.appender.FILEOUT.layout.ConversionPattern=[%-5p]_%d{yyyy-MM-dd HH:mm:ss} :%m%n

4)User .java

1 packagecom.mybatis.model;2

3 importjava.io.Serializable;4

5 @SuppressWarnings("serial")6 public class User implementsSerializable {7

8 private intid;9 privateString userName;10 privateString password;11

12 publicUser(){13 }14

15 public intgetId() {16 returnid;17 }18 public void setId(intid) {19 this.id =id;20 }21 publicString getUserName() {22 returnuserName;23 }24 public voidsetUserName(String userName) {25 this.userName =userName;26 }27 publicString getPassword() {28 returnpassword;29 }30 public voidsetPassword(String password) {31 this.password =password;32 }33

34 }

5)UserSqlMap.xml

1 <?xml version="1.0" encoding="UTF-8"?>

2 /p>

4 "http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">

17 userName,password18

22 INSERT INTO USER() VALUES(#{userName},#{password})23

26 UPDATE USER SET userName=#{userName} ,password=#{password} WHERE id=#{id}27

30 DELETE FROM USER WHERE id=#{id}31

34 SELECT *FROM USER35

39 SELECT *FROM USER LIMIT #{pageNow},#{pageSize}40

43 SELECT * FROM USER WHERE id=#{id}44

47 SELECT count(*) FROM USER48

51 SELECT * FROM USER WHERE userName=#{userName}52

6)SessionFactoryUtil.java MyBatis工具类，用于创建SqlSessionFactory

1 packagecom.mybatis.sessionfactory;2

3 importjava.io.IOException;4 importjava.io.Reader;5

6 importorg.apache.ibatis.io.Resources;7 importorg.apache.ibatis.session.SqlSession;8 importorg.apache.ibatis.session.SqlSessionFactory;9 importorg.apache.ibatis.session.SqlSessionFactoryBuilder;10

11 public classSessionFactoryUtil {12

13 private static final String RESOURCE = "Configuration.xml";14 private static SqlSessionFactory sqlSessionFactory = null;15 private static ThreadLocal threadLocal = new ThreadLocal();16

17 static{18 Reader reader = null;19 try{20 reader =Resources.getResourceAsReader(RESOURCE);21 } catch(IOException e) {22 throw new RuntimeException("Get resource error:"+RESOURCE, e);23 }24

25 sqlSessionFactory = newSqlSessionFactoryBuilder().build(reader);26 }27

28 /**

29 * Function : 获得SqlSessionFactory30 */

31 public staticSqlSessionFactory getSqlSessionFactory(){32 returnsqlSessionFactory;33 }34

35 /**

36 * Function : 重新创建SqlSessionFactory37 */

38 public static voidrebuildSqlSessionFactory(){39 Reader reader = null;40 try{41 reader =Resources.getResourceAsReader(RESOURCE);42 } catch(IOException e) {43 throw new RuntimeException("Get resource error:"+RESOURCE, e);44 }45

46 sqlSessionFactory = newSqlSessionFactoryBuilder().build(reader);47 }48

49 /**

50 * Function : 获取sqlSession51 */

52 public staticSqlSession getSession(){53 SqlSession session =threadLocal.get();54

55 if(session!=null){56 if(sqlSessionFactory == null){57 getSqlSessionFactory();58 }59 //如果sqlSessionFactory不为空则获取sqlSession，否则返回null

60 session = (sqlSessionFactory!=null) ? sqlSessionFactory.openSession(): null;61 }62

63 returnsession;64 }65

66 /**

67 * Function : 关闭sqlSession68 */

69 public static voidcloseSession(){70 SqlSession session =threadLocal.get();71 threadLocal.set(null);72 if(session!=null){73 session.close();74 }75 }76 }

7)UserDao interface

1 packagecom.mybatis.dao;2

3 importjava.util.List;4

5 importcom.mybatis.model.User;6

7 public interfaceUserDao {8

9 public User load(intid);10 public voidadd(User user);11 public voidupdate(User user);12 public void delete(intid);13 publicUser findByName(String userName);14 public ListqueryAllUser();15 public List list(int pageNow,intpageSize);16 public intgetAllCount();17

18 }

8)UserDaoImpl

1 packagecom.mybatis.dao.implment;2

3 importjava.util.HashMap;4 importjava.util.List;5 importjava.util.Map;6

7 importorg.apache.ibatis.session.SqlSession;8

9 importcom.mybatis.dao.UserDao;10 importcom.mybatis.model.User;11 importcom.mybatis.sessionfactory.SessionFactoryUtil;12

14 public class UserDaoImpl implementsUserDao {15

16 public User load(intid){17 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();18 User user = (User) session.selectOne("com.mybatis.model.User.selectById_user", id);19 session.close();20 returnuser;21 }22

23 public voidadd(User user) {24 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();25 session.insert("com.mybatis.model.User.inser_user", user);26 session.commit();27 session.close();28 }29

30 public voidupdate(User user){31 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();32 session.update("com.mybatis.model.User.update_user", user);33 session.commit();34 session.close();35 }36

37 public void delete(intid){38 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();39 session.delete("com.mybatis.model.User.delete_user", id);40 session.close();41 }42

43 publicUser findByName(String userName){44 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();45 User user = (User)session.selectOne("com.mybatis.model.User.selectByName_user", userName);46 session.close();47 returnuser;48 }49

50 @SuppressWarnings("unchecked")51 public ListqueryAllUser() {52 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();53 List list = session.selectList("com.mybatis.model.User.selectAll_user");54 session.close();55 returnlist;56 }57

58 @SuppressWarnings("unchecked")59 public List list(int pageNow , intpageSize){60 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();61 Map params = new HashMap();62 params.put("pageNow", pageNow);63 params.put("pageSize", pageSize);64 List list = session.selectList("com.mybatis.model.User.selectList_user", params);65 session.close();66 returnlist;67 }68

69 public intgetAllCount(){70 SqlSession session =SessionFactoryUtil.getSqlSessionFactory().openSession();71 int count = (Integer) session.selectOne("com.mybatis.model.User.selectCount_user");72 session.close();73 returncount;74 }75

76 }

9)测试类：

1 packagecom.mybatis.dao.implment;2

3 importjava.util.List;4

5 importorg.junit.Test;6

7 importcom.mybatis.dao.UserDao;8 importcom.mybatis.model.User;9

10 public classUserDaoTest {11

12 private UserDao userDao = newUserDaoImpl();13

14 @Test15 public voidtestLoad(){16 User u = userDao.load(1);17 if(u!=null){18 System.out.println("UserId:"+u.getId()+" UserName:"+u.getUserName()+" Password:"+u.getPassword());19 }20 else{21 System.out.println("id不存在！！");22 }23 }24

25 @Test26 public voidtestAdd(){27 User user = newUser();28 user.setUserName("admin5");29 user.setPassword("123456");30 userDao.add(user);31 }32

33 @Test34 public voidtestUpdate(){35 User user = newUser();36 user.setId(2);37 user.setUserName("manager");38 user.setPassword("123456");39 userDao.update(user);40 }41

42 @Test43 public voidtestQueryAllUser(){44 List list =userDao.queryAllUser();45 if(list!=null&list.size()>0){46 for(User u:list){47 System.out.println("UserId:"+u.getId()+" UserName:"+u.getUserName()+" Password:"+u.getPassword());48 }49 }50 }51

52 @Test53 public voidtestFindByName(){54 User u = userDao.findByName("admin");55 if(u!=null){56 System.out.println("UserId:"+u.getId()+" UserName:"+u.getUserName()+" Password:"+u.getPassword());57 }58 else{59 System.out.println("用户名不存在！！");60 }61 }62

63 @Test64 public voidtestList(){65 List list = userDao.list(1, 4);66 if(list!=null&list.size()>0){67 for(User u:list){68 System.out.println("UserId:"+u.getId()+" UserName:"+u.getUserName()+" Password:"+u.getPassword());69 }70 }71 }72

73 @Test74 public voidtestGetAllCount(){75 System.out.println("All Count : "+userDao.getAllCount());76 }77

78 @Test79 public voidtestDelete(){80 userDao.delete(3);81 }82

83 }

10)执行testFindByName()：