目錄
一、@Value的注意事項
1.不能作用於靜態變量(static);
2.不能作用於常量(final);
3.不能在非註冊的類中使用(類需要被註冊在spring上下文中,如用@Service,@RestController,@Component等);
4.使用這個類時,只能通過依賴注入的方式,用new的方式是不會自動注入這些配置的。
二、錯誤的方式
/**
* 抽象工廠+反射
*/
//不能在非註冊的類中使用(類需要被註冊在spring上下文中,如用@Service,@RestController,@Component等);
public class SimpleAbstractFactory {
@Value("${packName}")
//不能作用於靜態變量(static)
private static String packName;
@Value("${sqlName}")
//不能作用於常量(final);
private final String sqlName;
public IUser CreateUser() throws Exception{
String className=packName+"."+sqlName+"IUser";
return (IUser)Class.forName(className).newInstance();
}
public IDepartment CreateDepartment() throws Exception{
String className=packName+"."+sqlName+"IDepartment";
return (IDepartment)Class.forName(className).newInstance();
}
}
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring-config.xml"})
public class MainToken{
@Test
public void testToken() {
try{
//使用這個類時,只能通過依賴注入的方式,用new的方式是不會自動注入這些配置的。
SimpleAbstractFactory simpleAbstractFactory=new SimpleAbstractFactory();
User user=new User();
Department department=new Department();
IDepartment idp=simpleAbstractFactory.CreateDepartment();
IUser ius=simpleAbstractFactory.CreateUser();
idp.insert(department);
idp.getDepartment(Long.valueOf(1));
ius.insert(user);
ius.getUser(Long.valueOf(1));
}catch(Exception e){
}
}
}
三、正確的方式
/**
* 抽象工廠+反射
*/
@Service
public class SimpleAbstractFactory {
@Value("${packName}")
private String packName;
@Value("${sqlName}")
private String sqlName;
public IUser CreateUser() throws Exception{
String className=packName+"."+sqlName+"IUser";
return (IUser)Class.forName(className).newInstance();
}
public IDepartment CreateDepartment() throws Exception{
String className=packName+"."+sqlName+"IDepartment";
return (IDepartment)Class.forName(className).newInstance();
}
}
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:spring-config.xml"})
public class MainToken {
@Autowired
//使用這個類時,只能通過依賴注入的方式,用new的方式是不會自動注入這些配置的。
private SimpleAbstractFactory simpleAbstractFactory;
@Test
public void testToken() {
try{
User user=new User();
Department department=new Department();
IDepartment idp=simpleAbstractFactory.CreateDepartment();
IUser ius=simpleAbstractFactory.CreateUser();
idp.insert(department);
idp.getDepartment(Long.valueOf(1));
ius.insert(user);
ius.getUser(Long.valueOf(1));
}catch(Exception e){
}
}
}