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基于XMl的DI
1.集合属性注入 2.array数组属性注入 3.List<>属性注入 4.Set<>属性注入 5.Map<K,V>属性注入 6.Properties属性注入 7.autowire自动注入 8.SPEL注入
School类
package Part02.collectionDI;/** * Created by futao on 2017/10/10. */public class School { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "School{" + "name='" + name + '\'' + '}'; }} Some类
package Part02.collectionDI;import java.util.*;/** * Created by futao on 2017/10/10. */public class Some { private School[] schools; private List myList; private Set mySet; private Map myMap; private Properties myPro; public void setSchools(School[] schools) { this.schools = schools; } public void setMyList(List myList) { this.myList = myList; } public void setMySet(Set mySet) { this.mySet = mySet; } public void setMyMap(Map myMap) { this.myMap = myMap; } public void setMyPro(Properties myPro) { this.myPro = myPro; } @Override public String toString() { return "Some{" + "schools=" + Arrays.toString(schools) + ", myList=" + myList + ", mySet=" + mySet + ", myMap=" + myMap + ", myPro=" + myPro + '}'; }} 配置文件applicationContextcollectionDI.xml
张三 李四 王五 北京 上海 南昌 上海市 闵行区 吴泾镇 紫竹 数码港
测试
/** * 基于XML的DI-集合属性注入 */ @Test fun test4collections(){ val classPathXmlApplicationContext = ClassPathXmlApplicationContext("applicationContextcollectionDI.xml") val some = classPathXmlApplicationContext.getBean("some") as Some println(GsonBuilder().setPrettyPrinting().create().toJson(some)) } 结果
{ "schools": [ { "name": "Ecjtu" }, { "name": "NCDX" }, { "name": "NCDX" }, { "name": "NCDX" } ], "myList": [ "张三", "李四", "王二" ], "mySet": [ "北京", "上海", "南昌" ], "myMap": { "k1": { "name": "Ecjtu" }, "k2": { "name": "NCDX" }, "k3": { "name": "NCDX" }, "k4": { "name": "NCDX" }, "k5": "wechat" }, "myPro": { "地址3": "吴泾镇", "地址2": "闵行区", "地址1": "上海市", "地址5": "数码港", "地址4": "紫竹" }} School类
package Part02.autoDIbyNameForDomain;/** * Created by futao on 2017/10/10. */public class School { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "School{" + "name='" + name + '\'' + '}'; }} Student类
package Part02.autoDIbyNameForDomain;/** * Created by futao on 2017/10/10. */public class Student { private String name; private int age; private String address; private School school; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public School getSchool() { return school; } public void setSchool(School school) { this.school = school; } public Student() { } public Student(String name, int age, String address, School school) { this.name = name; this.age = age; this.address = address; this.school = school; } @Override public String toString() { return "Student{" + "name='" + name + '\'' + ", age=" + age + ", address='" + address + '\'' + ", school=" + school + '}'; }} applicationContext.xml
测试
/** * 基于XML的DI-byName方式的域属性自动注入 */ @Test fun test4autoDIbyNamefordomain() { val classPathXmlApplicationContext = ClassPathXmlApplicationContext("applicationContextautoDIbyNameForDomain.xml") val student = classPathXmlApplicationContext.getBean("student") as Part02.autoDIbyNameForDomain.Student// serializeNulls()->为null的值也显示出来，setPrettyPrinting()->格式化控制台输出 println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(student)) println(student) } 结果
{ "name": null, "age": 18, "address": "Shanghai", "school": null}Student{name='null', age=18, address='Shanghai', school=null} others
在xml配置文件中，autowire有5种类型，可以在<bean/>元素中使用autowire属性指定
<table>
<tr> <td>模式</td> <td>说明</td> </tr> <tr> <td>no</td> <td>不使用自动装配，必须通过ref元素指定依赖，默认设置。</td> </tr> <tr> <td>byName</td> <td> 根据属性名自动装配。此选项将检查容器并根据名字查找与属性完全一致的bean，并将其与属性自动装配。</td> </tr> <tr> <td>byType</td> <td> 如果容器中存在一个与指定属性类型相同的bean，那么将与该属性自动装配；如果存在多个该类型bean，那么抛出异常，并指出不能使用byType方式进行自动装配；如果没有找到相匹配的bean，则什么事都不发生，也可以通过设置dependency-check="objects"让Spring抛出异常。</td> </tr> <tr> <td>constructor</td> <td>与byType方式类似，不同之处在于它应用于构造器参数。如果容器中没有找到与构造器参数类型一致的bean，那么抛出异常。</td> </tr> <tr> <td>autodetect </td> <td>通过bean类的自省机制（introspection）来决定是使用constructor还是byType方式进行自动装配。如果发现默认的构造器，那么将使用byType方式。 </td> </tr> </table> 可以设置bean使自动装配失效： 采用xml格式配置bean时，将<bean/>元素的autowire-candidate属性设置为false，这样容器在查找自动装配对象时，将不考虑该bean，即它不会被考虑作为其它bean自动装配的候选者，但是该bean本身还是可以使用自动装配来注入其它bean的。 需要注意以下情况：
autowird="byType" (type->A) B extends A A是一个bean 如果此时B也是一个bean，则会报错，该类型（A）的bean不止一个。 因为A a=new B() B类型也可以作为A类型根据autowird="byType"进行注入Person类
package Part02.SPELDI;/** * Created by futao on 2017/10/11. */public class Person { /** * 姓名 */ private String pname; /** * 年龄 */ private int page; /** * 带参构造方法 * * @param pname 姓名 * @param page 年龄 */ public Person(String pname, int page) { this.pname = pname; this.page = page; } public Person() { } public String getPname() { return pname; } public void setPname(String pname) { this.pname = pname; } public int getPage() { return page; } public void setPage(int page) { this.page = page; } @Override public String toString() { return "Person{" + "pname='" + pname + '\'' + ", page=" + page + '}'; } /** * 控制年龄 * * @return */ public int calculateAge() { return page > 25 ? 25 : page; }} Student类
package Part02.SPELDI;/** * Created by futao on 2017/10/12. */public class Student { private String sname; private int sage; public String getSname() { return sname; } public void setSname(String sname) { this.sname = sname; } public int getSage() { return sage; } public void setSage(int sage) { this.sage = sage; } @Override public String toString() { return "Student{" + "sname='" + sname + '\'' + ", sage=" + sage + '}'; }} 配置文件
测试
/** * SPEL注入 */ @Test fun test4SPEL(){ val classPathXmlApplicationContext = ClassPathXmlApplicationContext("applicationContextSPEL.xml") val student = classPathXmlApplicationContext.getBean("student") as Part02.SPELDI.Student val person = classPathXmlApplicationContext.getBean("person") as Person println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(student)) println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(person)) student.sage=666 println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(student)) println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(person)) person.page=999 println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(student)) println(GsonBuilder().serializeNulls().setPrettyPrinting().create().toJson(person)) } 结果
{ "sname": "老三", "sage": 25}{ "pname": "老三", "page": 29}{ "sname": "老三", "sage": 666}{ "pname": "老三", "page": 29}{ "sname": "老三", "sage": 666}{ "pname": "老三", "page": 999} 如果一个类有带参的构造函数，而没有无参的构造函数，那么在注册bean的时候必须使用构造注入。
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