一、mybatis处理CLOB、BLOB类型数据
CLOB：大文本类型；小说啊等大文本的；对应数据库类型不一致，有long等；
BLOB：二进制的，图片；电影、音乐等二进制的；
在mysql中：
blob：
longblob：存储的东西比blob更大；
longtext：存储大文本类型的；
新建t_studeng表：
create table t_student(
id int primary key auto_increment,
name varchar(20),
age int,
pic longblob,
remark longtext
)
项目结构：
1)jdbc.properties:
jdbc.driverClassName=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/test_demo jdbc.username=root jdbc.password=123456
2)mybatis_config.xml:
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 resource="jdbc.properties"/>
7 <!-- 别名 -->
8 <typeAliases>
9 <package name="com.cy.model"/>
10 </typeAliases>
11
12 <environments default="development">
13 <environment id="development">
14 <transactionManager type="JDBC" />
15 <dataSource type="POOLED">
16 <property name="driver" value="${jdbc.driverClassName}" />
17 <property name="url" value="${jdbc.url}" />
18 <property name="username" value="${jdbc.username}" />
19 <property name="password" value="${jdbc.password}" />
20 </dataSource>
21 </environment>
22 <environment id="test">
23 <transactionManager type="JDBC" />
24 <dataSource type="POOLED">
25 <property name="driver" value="${jdbc.driverClassName}" />
26 <property name="url" value="${jdbc.url}" />
27 <property name="username" value="${jdbc.username}" />
28 <property name="password" value="${jdbc.password}" />
29 </dataSource>
30 </environment>
31 </environments>
32
33 <mappers>
34 <package name="com.cy.mapper"/>
35 </mappers>
36 </configuration>
3)Student.java model:
1 package com.cy.model;
2
3 public class Student {
4 private Integer id;
5 private String name;
6 private Integer age;
7 private byte[] pic;
8 private String remark;
9
10 public Integer getId() {
11 return id;
12 }
13 public void setId(Integer id) {
14 this.id = id;
15 }
16 public String getName() {
17 return name;
18 }
19 public void setName(String name) {
20 this.name = name;
21 }
22 public Integer getAge() {
23 return age;
24 }
25 public void setAge(Integer age) {
26 this.age = age;
27 }
28 public byte[] getPic() {
29 return pic;
30 }
31 public void setPic(byte[] pic) {
32 this.pic = pic;
33 }
34 public String getRemark() {
35 return remark;
36 }
37 public void setRemark(String remark) {
38 this.remark = remark;
39 }
40 @Override
41 public String toString() {
42 return "Student [id=" + id + ", name=" + name + ", age=" + age
43 + ", remark=" + remark + "]";
44 }
45
46
47
48 }
4)获取sqlSession：SqlSessionFactoryUtil.java:
1 package com.cy.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 SqlSessionFactoryUtil {
12 private static SqlSessionFactory sqlSessionFactory;
13
14 public static SqlSessionFactory getSqlSessionFactory(){
15 if(sqlSessionFactory==null){
16 InputStream inputStream=null;
17 try {
18 inputStream=Resources.getResourceAsStream("mybatis_config.xml");
19 sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
20 } catch (IOException e) {
21 e.printStackTrace();
22 }
23 }
24
25 return sqlSessionFactory;
26 }
27
28 public static SqlSession openSession(){
29 return getSqlSessionFactory().openSession();
30 }
31 }
5)测试代码：StudentTest.java: service层：
1 package com.cy.service;
2
3 import java.io.File;
4 import java.io.FileInputStream;
5 import java.io.FileOutputStream;
6 import java.io.InputStream;
7 import java.io.OutputStream;
8
9 import org.apache.ibatis.session.SqlSession;
10 import org.junit.After;
11 import org.junit.Before;
12 import org.junit.Test;
13
14 import com.cy.mapper.StudentMapper;
15 import com.cy.model.Student;
16 import com.cy.util.SqlSessionFactoryUtil;
17
18 public class StudentTest {
19 private SqlSession sqlSession=null;
20 private StudentMapper studentMapper=null;
21
22 @Before
23 public void setUp() throws Exception {
24 sqlSession=SqlSessionFactoryUtil.openSession();
25 studentMapper=sqlSession.getMapper(StudentMapper.class);
26 }
27
28 @After
29 public void tearDown() throws Exception {
30 sqlSession.close();
31 }
32
33 @Test
34 public void testInsertStudent(){
35 Student student=new Student();
36 student.setName("zhangsan");
37 student.setAge(14);
38 student.setRemark("很长的文本...");
39 byte []pic=null;
40 try{
41 File file=new File("I://shoot.png");
42 InputStream inputStream=new FileInputStream(file);
43 pic=new byte[inputStream.available()];
44 inputStream.read(pic);
45 inputStream.close();
46 }catch(Exception e){
47 e.printStackTrace();
48 }
49 student.setPic(pic);
50 studentMapper.insertStudent(student);
51 sqlSession.commit();
52 }
53
54 @Test
55 public void testGetStudentById(){
56 Student student=studentMapper.getStudentById(1);
57 System.out.println(student);
58 byte []pic=student.getPic();
59 try{
60 File file=new File("i://boy.png");
61 OutputStream outputStream=new FileOutputStream(file);
62 outputStream.write(pic);
63 outputStream.close();
64 }catch(Exception e){
65 e.printStackTrace();
66 }
67 }
68
69
70
71
72 }
执行testInsertStudent方法后，查看数据库中插入情况：
执行testGetStudentById获取这个记录，将pic保存到I盘 boy.png，已将数据库中的图片，以流的形式写入到I盘中；
6）StudentMapper.java:
1 package com.cy.mapper;
2
3 import com.cy.model.Student;
4
5 public interface StudentMapper {
6
7 //插入
8 public int insertStudent(Student student);
9
10 //根据id获取student
11 public Student getStudentById(Integer id);
12
13 }
7)StudentMapper.xml mapper映射文件：
<?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.cy.mapper.StudentMapper">
<insert id="insertStudent" parameterType="Student">
insert into t_student values(null,#{name},#{age},#{pic},#{remark});
</insert>
<select id="getStudentById" parameterType="Integer" resultType="Student">
select * from t_student where id=#{id}
</select>
</mapper>
二、项目中使用log4j：
在项目中加入log4j的jar包，以及配置log4j.properties:
1)log4j.properties配置文件：
1 log4j.rootLogger=info,appender1,appender2 2 3 log4j.appender.appender1=org.apache.log4j.ConsoleAppender 4 5 log4j.appender.appender2=org.apache.log4j.FileAppender 6 log4j.appender.appender2.File=I:/logFile.txt 7 8 log4j.appender.appender1.layout=org.apache.log4j.TTCCLayout 9 log4j.appender.appender2.layout=org.apache.log4j.TTCCLayout
而且，发现配置文件名必须为log4j.properties;
上面的输入到两个地方：
console；
I盘下面的logFile.txt;
2)测试代码：StudentTest.java:
package com.cy.service;
import org.apache.log4j.Logger;
import org.junit.Test;
public class StudentTest {
private static Logger logger = Logger.getLogger(StudentTest.class);
@Test
public void testLogger(){
logger.info("测试log4j.....");
}
@Test
public void testOtherLogger(){
logger.info("测试other log4j.....");
}
}
运行后console输出：这样信息：
[main] INFO com.cy.service.StudentTest - 测试other log4j.....
查看I盘下面logFile.txt:
时间： 2024-11-03 21:23:07