在调用工具类时，若工具类中含有@Autowired注解，这此工具类对象必须同样使用@Autowired注解，否则工具类中的Spring注入的对象都为空值,这里的HadoopTest就是这样
比如MyConfig类是
配置层
@Component
@ConfigurationProperties(prefix = "project")
public class MyConfig {
private String version;
private String name;
public String getVersion() {
return version;
}
public void setVersion(String version) {
this.version = version;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
HadoopTest类引用了MyConfig
public class HadoopTest {
@Autowired
MyConfig myConfig; //这里用了注入，所以controller层的test类中 HadoopTest hadoopTest=new HadoopTest();是无效的
public void getName() {
System.out.println(myConfig.getName());
}
}
Controller中
@RestController
public class test {
HadoopTest hadoopTest=new HadoopTest();
@GetMapping("hello")
public void hello() {
hadoopTest.getName();
}
}
这样在System.out.println(myConfig.getName());中是找不到myconfig的，我们应该改成
配置层
@Component
@ConfigurationProperties(prefix = "project")
public class MyConfig {
private String version;
private String name;
public String getVersion() {
return version;
}
public void setVersion(String version) {
this.version = version;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
HadoopTest类引用了MyConfig
@Component
public class HadoopTest {
@Autowired
MyConfig myConfig;
public void getName() {
System.out.println(myConfig.getName());
}
}
Controller类中
@RestController
public class test {
@Autowired
HadoopTest hadoopTest;
@GetMapping("hello")
public void hello() {
hadoopTest.getName();
}
}
或者是
配置层
@Compoment
@ConfigurationProperties(prefix = "project")
public class MyConfig {
private String version;
private String name;
public String getVersion() {
return version;
}
public void setVersion(String version) {
this.version = version;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
HadoopTest类引用了MyConfig
public class HadoopTest {
MyConfig myConfig=new Myconfig;
public void getName() {
System.out.println(myConfig.getName());
}
}
Controller类中
@RestController
public class test {
HadoopTest hadoopTest=new HadoopTest();
@GetMapping("hello")
public void hello() {
hadoopTest.getName();
}
}
也就是一条逻辑线上，HadoopTest注入了MyConfig,那么在test中必须也是注入而不是new,原因以后在补充。
补充：1.在第三种情况中，虽然MyConfig被注释了，但是只要不去注入它就没关系。