注解：
- 注解是用于描述代码的代码。例如：@Test（用于描述方法进行junit测试），@Override(用于描述方法的重写),@Param（用于描述属性的名称）
- 注解的使用风格：@xxx（属性），使用前必须进行导包
- 使用注解一般用于简化配置文件，但是注解有时候也不是很友好(有时候反而更麻烦)，例如动态sql
- 关于注解的属性
属性的设定方式是：属性名=属性值
- 关于属性的类型
- 基本类型和String，可以直接使用双引号的形式
- 数组类型，name={值1，值2，......}如果数组元素只有一个，可以省略大括号。
- 对象类型，name=@对象名（属性）
- 如果属性是该注解的默认注解，而且该注解只配置这一个属性，key将属性名省略。
mybatis注解之CURD代码如下
1 package com.bjsxt.mapper; 2 3 import java.util.List; 4 5 import org.apache.ibatis.annotations.Delete; 6 import org.apache.ibatis.annotations.Insert; 7 import org.apache.ibatis.annotations.Select; 8 import org.apache.ibatis.annotations.Update; 9 10 import com.bjsxt.pojo.Student; 11 12 public interface StudentMapper { 13 14 @Select("select * from t_student") 15 List<Student> selAll(); 16 17 @Insert("insert into t_student values (default, #{name}, #{age}, #{gender}, #{cid})") 18 int insStu(Student student); 19 20 @Update("update t_student set age=#{1} where id=#{0}") 21 int updStu(int id, int age); 22 23 @Delete("delete from t_student where id=#{0}") 24 int delStu(int id); 25 }
1 package com.bjsxt.pojo; 2 3 import java.io.Serializable; 4 5 public class Student implements Serializable { 6 7 private int id; 8 private String name; 9 private int age; 10 private String gender; 11 private int cid; 12 13 public Student() { 14 super(); 15 } 16 17 public int getId() { 18 return id; 19 } 20 21 public void setId(int id) { 22 this.id = id; 23 } 24 25 public String getName() { 26 return name; 27 } 28 29 public void setName(String name) { 30 this.name = name; 31 } 32 33 public int getAge() { 34 return age; 35 } 36 37 public void setAge(int age) { 38 this.age = age; 39 } 40 41 public String getGender() { 42 return gender; 43 } 44 45 public void setGender(String gender) { 46 this.gender = gender; 47 } 48 49 public int getCid() { 50 return cid; 51 } 52 53 public void setCid(int cid) { 54 this.cid = cid; 55 } 56 57 @Override 58 public int hashCode() { 59 final int prime = 31; 60 int result = 1; 61 result = prime * result + age; 62 result = prime * result + cid; 63 result = prime * result + ((gender == null) ? 0 : gender.hashCode()); 64 result = prime * result + id; 65 result = prime * result + ((name == null) ? 0 : name.hashCode()); 66 return result; 67 } 68 69 @Override 70 public boolean equals(Object obj) { 71 if (this == obj) 72 return true; 73 if (obj == null) 74 return false; 75 if (getClass() != obj.getClass()) 76 return false; 77 Student other = (Student) obj; 78 if (age != other.age) 79 return false; 80 if (cid != other.cid) 81 return false; 82 if (gender == null) { 83 if (other.gender != null) 84 return false; 85 } else if (!gender.equals(other.gender)) 86 return false; 87 if (id != other.id) 88 return false; 89 if (name == null) { 90 if (other.name != null) 91 return false; 92 } else if (!name.equals(other.name)) 93 return false; 94 return true; 95 } 96 97 @Override 98 public String toString() { 99 return "Student [id=" + id + ", name=" + name + ", age=" + age + ", gender=" + gender + ", cid=" + cid + "]"; 100 } 101 }
1 package com.bjsxt.test; 2 3 import java.util.List; 4 5 import org.apache.ibatis.session.SqlSession; 6 import org.junit.Test; 7 8 import com.bjsxt.mapper.StudentMapper; 9 import com.bjsxt.pojo.Student; 10 import com.bjsxt.util.MyBatisUtil; 11 12 public class TestStu { 13 14 @Test 15 public void testSel() { 16 SqlSession session = MyBatisUtil.getSession(); 17 18 StudentMapper mapper = session.getMapper(StudentMapper.class); 19 20 List<Student> list = mapper.selAll(); 21 for (Student student : list) { 22 System.out.println(student); 23 } 24 25 session.close(); 26 } 27 @Test 28 public void testIns() { 29 SqlSession session = MyBatisUtil.getSession(); 30 31 StudentMapper mapper = session.getMapper(StudentMapper.class); 32 33 Student student = new Student(); 34 student.setName("小王"); 35 student.setAge(20); 36 student.setGender("女"); 37 student.setCid(2); 38 39 int num = mapper.insStu(student); 40 if(num > 0) { 41 System.out.println("ok"); 42 session.commit(); 43 } else { 44 session.rollback(); 45 } 46 47 session.close(); 48 } 49 @Test 50 public void testUpd() { 51 SqlSession session = MyBatisUtil.getSession(); 52 53 StudentMapper mapper = session.getMapper(StudentMapper.class); 54 55 int num = mapper.updStu(6, 30); 56 if(num > 0) { 57 System.out.println("ok"); 58 session.commit(); 59 } else { 60 session.rollback(); 61 } 62 63 session.close(); 64 } 65 @Test 66 public void testDel() { 67 SqlSession session = MyBatisUtil.getSession(); 68 69 StudentMapper mapper = session.getMapper(StudentMapper.class); 70 71 int num = mapper.delStu(6); 72 if(num > 0) { 73 System.out.println("ok"); 74 session.commit(); 75 } else { 76 session.rollback(); 77 } 78 79 session.close(); 80 } 81 }
1 package com.bjsxt.util; 2 3 import java.io.IOException; 4 import java.io.InputStream; 5 6 import org.apache.ibatis.io.Resources; 7 import org.apache.ibatis.session.SqlSession; 8 import org.apache.ibatis.session.SqlSessionFactory; 9 import org.apache.ibatis.session.SqlSessionFactoryBuilder; 10 11 public class MyBatisUtil { 12 13 private static SqlSessionFactory factory = null; 14 15 static { 16 try { 17 InputStream is = Resources.getResourceAsStream("mybatis-cfg.xml"); 18 factory = new SqlSessionFactoryBuilder().build(is); 19 } catch (IOException e) { 20 e.printStackTrace(); 21 } 22 } 23 24 public static SqlSession getSession() { 25 SqlSession session = null; 26 if (factory != null) { 27 // true表示开启自动提交 28 // session = factory.openSession(true); 29 session = factory.openSession(); 30 } 31 return session; 32 } 33 }
1 jdbc.driver=com.mysql.jdbc.Driver 2 jdbc.url=jdbc:mysql://localhost:3306/java505 3 jdbc.username=root 4 jdbc.password=root
1 # Set root category priority to INFO and its only appender to CONSOLE. 2 log4j.rootCategory=ERROR, CONSOLE 3 # log4j.rootCategory=DEBUG, CONSOLE, LOGFILE 4 5 # 单独设置SQL语句的输出级别为DEBUG级别 6 log4j.logger.com.bjsxt.mapper=DEBUG 7 8 # CONSOLE is set to be a ConsoleAppender using a PatternLayout. 9 log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender 10 log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout 11 log4j.appender.CONSOLE.layout.ConversionPattern=- %m%n 12 13 # LOGFILE is set to be a File appender using a PatternLayout. 14 log4j.appender.LOGFILE=org.apache.log4j.FileAppender 15 log4j.appender.LOGFILE.File=d:/test.log 16 log4j.appender.LOGFILE.Append=true 17 log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout 18 log4j.appender.LOGFILE.layout.ConversionPattern=- %m %l%n
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE configuration 3 PUBLIC "-//mybatis.org//DTD Config 3.0//EN" 4 "http://mybatis.org/dtd/mybatis-3-config.dtd"> 5 <configuration> 6 <!-- properties加载外部文件 --> 7 <properties resource="db.properties" /> 8 <!-- settings标签 --> 9 <settings> 10 <!-- 设置MyBatis使用log4j日志支持 --> 11 <setting name="logImpl" value="LOG4J"/> 12 </settings> 13 <!-- typeAliases给类型起别名 --> 14 <typeAliases> 15 <package name="com.bjsxt.pojo" /> 16 </typeAliases> 17 <environments default="dev"> 18 <environment id="dev"> 19 <transactionManager type="JDBC" /> 20 <dataSource type="POOLED"> 21 <property name="driver" value="${jdbc.driver}"/> 22 <property name="url" value="${jdbc.url}"/> 23 <property name="username" value="${jdbc.username}"/> 24 <property name="password" value="${jdbc.password}"/> 25 </dataSource> 26 </environment> 27 </environments> 28 <mappers> 29 <package name="com.bjsxt.mapper" /> 30 </mappers> 31 </configuration>