依赖注入就是对类的属性进行赋值
4.1、环境搭建
创建名为spring_ioc_xml的新module，过程参考3.1节
4.1.1、创建spring配置文件
4.1.2、创建学生类Student
package org.rain.spring.pojo;/** * @author liaojy * @date 2023/7/27 - 22:33 */public class Student { private Integer id; private String name; private Integer age; private String sex; public Student() { } public Student(Integer id, String name, Integer age, String sex) { this.id = id; this.name = name; this.age = age; this.sex = sex; } 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; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } @Override public String toString() { return "Student{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + ", sex='" + sex + '\'' + '}'; }}4.2、setter注入(常用)4.2.1、配置bean
4.2.2、测试
package org.rain.spring.test;import org.junit.Test;import org.rain.spring.pojo.Student;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;/** * @author liaojy * @date 2023/7/27 - 22:43 */public class IOCByXmlTest { @Test public void testDISetter(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("student", Student.class); System.out.println(student); }}4.3、构造器注入4.3.1、配置bean
注意：constructor-arg标签的数量，必须和某一个构造器方法的参数数量一致
4.3.2、测试
@Test public void testDIConstructor(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentTwo", Student.class); System.out.println(student); }4.4、特殊值处理4.4.1、null值4.4.1.1、配置bean
注意：该写法，实际为sex所赋的值是字符串null
4.4.1.2、测试
由控制台日志可知，此时sex的值为null
@Test public void testDIspecial(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentThree", Student.class); System.out.println(student.getSex().toString()); }+++++++++++++++++++++++++++++++++++分割线+++++++++++++++++++++++++++++++++++
由控制台日志可知，此时age的值也为null；所以不配置属性也能实现同样的效果
4.4.2、xml字符值4.4.2.1、方式一：实体
4.4.2.2、方式二：CDATA节
<![CDATA[]]> 4.4.2.3、测试
4.5、为类类型的属性赋值4.5.1、方式一：外部bean（常用）4.5.1.1、创建班级类Clazz
package org.rain.spring.pojo;/** * @author liaojy * @date 2023/7/28 - 7:54 */public class Clazz { private Integer cid; private String cname; public Clazz() { } public Clazz(Integer cid, String cname) { this.cid = cid; this.cname = cname; } public Integer getCid() { return cid; } public void setCid(Integer cid) { this.cid = cid; } public String getCname() { return cname; } public void setCname(String cname) { this.cname = cname; } @Override public String toString() { return "Clazz{" + "cid=" + cid + ", cname='" + cname + '\'' + '}'; }}4.5.1.2、修改Student类
package org.rain.spring.pojo;/** * @author liaojy * @date 2023/7/27 - 22:33 */public class Student { private Integer id; private String name; private Integer age; private String sex; private Clazz clazz; public Student() { } public Student(Integer id, String name, Integer age, String sex, Clazz clazz) { this.id = id; this.name = name; this.age = age; this.sex = sex; this.clazz = clazz; } public Clazz getClazz() { return clazz; } public void setClazz(Clazz clazz) { this.clazz = clazz; } 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; } public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } @Override public String toString() { return "Student{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + ", sex='" + sex + '\'' + ", clazz=" + clazz + '}'; }}4.5.1.3、配置外部bean
4.5.1.4、引用外部bean
4.5.1.5、测试
@Test public void testDIOuterBean(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentfour", Student.class); System.out.println(student); }4.5.2、方式二、级联4.5.2.1、配置bean
4.5.2.2、测试
@Test public void testDICascade(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentFive", Student.class); System.out.println(student); }4.5.3、内部bean（常用）4.5.3.1、配置bean
4.5.3.2、测试
@Test public void testDIInnerBean(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentSix", Student.class); System.out.println(student); }4.6、为数组类型的属性赋值4.6.1、修改Student类
在Student类中添加或修改以下代码：
private String hobby[]; public String[] getHobby() { return hobby; } public void setHobby(String[] hobby) { this.hobby = hobby; } @Override public String toString() { return "Student{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + ", sex='" + sex + '\'' + ", clazz=" + clazz + ", hobby=" + Arrays.toString(hobby) + '}'; }4.6.2、配置bean
游泳 跑步 骑车 4.6.3、测试
@Test public void testDIArray(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentSeven", Student.class); System.out.println(student); }4.7、为List集合类型的属性赋值4.7.1、修改Clazz类
在Clazzt类中添加或修改以下代码：
private List students; public List getStudents() { return students; } public void setStudents(List students) { this.students = students; } @Override public String toString() { return "Clazz{" + "cid=" + cid + ", cname='" + cname + '\'' + ", students=" + students + '}'; }4.7.2、配置bean
<![CDATA[]]> 4.7.3、测试
@Test public void testDIList(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Clazz clazz = applicationContext.getBean("clazzTwo", Clazz.class); System.out.println(clazz); }4.8、为Map集合类型的属性赋值4.8.1、创建教师类Teacher
package org.rain.spring.pojo;/** * @author liaojy * @date 2023/7/30 - 12:10 */public class Teacher { private Integer tid; private String tname; public Teacher() { } public Teacher(Integer tid, String tname) { this.tid = tid; this.tname = tname; } public Integer getTid() { return tid; } public void setTid(Integer tid) { this.tid = tid; } public String getTname() { return tname; } public void setTname(String tname) { this.tname = tname; } @Override public String toString() { return "Teacher{" + "tid=" + tid + ", tname='" + tname + '\'' + '}'; }}4.8.2、修改Student类
在Student类中添加或修改以下代码：
private Map teacherMap; public Map getTeacherMap() { return teacherMap; } public void setTeacherMap(Map teacherMap) { this.teacherMap = teacherMap; } @Override public String toString() { return "Student{" + "id=" + id + ", name='" + name + '\'' + ", age=" + age + ", sex='" + sex + '\'' + ", clazz=" + clazz + ", hobby=" + Arrays.toString(hobby) + ", teacherMap=" + teacherMap + '}'; }4.8.3、配置bean
游泳 跑步 骑车 4.8.4、测试
@Test public void testDIMap(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentEight", Student.class); System.out.println(student); }4.9、为集合类型的属性赋值(解耦引用方式)4.9.1、配置bean
注意：使用util:list、util:map标签必须引入相应的XML命名空间
游泳 跑步 骑车 4.9.2、测试
@Test public void testDIUtil(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentNine", Student.class); System.out.println(student); }4.10、p命名空间(了解)4.10.1、配置bean
注意：p命名空间的依赖注入，本质上是属性方式（setter方法）的依赖注入
4.10.2、测试
@Test public void testDIP(){ ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-ioc.xml"); Student student = applicationContext.getBean("studentTen", Student.class); System.out.println(student); }4.11、引入外部属性文件4.11.1、引入数据库相关依赖
mysql mysql-connector-java 5.1.49 com.alibaba druid 1.0.31 4.11.2、创建外部属性文件
jdbc.driver=com.mysql.jdbc.Driverjdbc.url=jdbc:mysql://localhost:3306/ssm?characterEncoding=utf-8jdbc.username=rootjdbc.password=root4.11.3、配置bean
注意：使用context:property-placeholder标签必须引入相应的XML命名空间
4.11.4、测试
@Test public void testDIOuterFile() throws SQLException { ApplicationContext applicationContext = new ClassPathXmlApplicationContext("spring-datasource"); DruidDataSource datasource = applicationContext.getBean("datasource", DruidDataSource.class); System.out.println(datasource.getConnection()); }