4
我想知道如何初始化Spring Bean中的字段？下面是几个可能的解决方案：在Spring Beans中初始化字段的正确方法是什么？
1.初始化场直接申报
import org.springframework.stereotype.Component;
@Component
public class DeclarationInit {
private final int field = Integer.MAX_VALUE;
public int getField() {
return field;
}
}
2.初始化领域使用@Value注释
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;
@Component
public class ValueInit {
@Value("#{T(Integer).MAX_VALUE}")
private int field;
public int getField() {
return field;
}
}
3.使用@Autowired注释初始化场
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class AutowiredInit {
private int field;
@Autowired
private void initField() {
field = Integer.MAX_VALUE;
}
public int getField() {
return field;
}
}
使用@PostConstruct注释
import javax.annotation.PostConstruct;
import org.springframework.stereotype.Component;
@Component
public class PostConstructInit {
private int field;
@PostConstruct
private void initField() {
field = Integer.MAX_VALUE;
}
public int getField() {
return field;
}
}
所有测试成功，并且没有显示出任何区别4.初始化字段：
import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.equalTo;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = SomeTestContextConfiguration.class)
public class FieldInitTest {
@Autowired
private DeclarationInit declarationInit;
@Autowired
private ValueInit valueInit;
@Autowired
private AutowiredInit autowiredInit;
@Autowired
private PostConstructInit postConstructInit;
@Test
public void shouldInitializeFieldOnDeclaration() {
assertThat(declarationInit.getField(), equalTo(Integer.MAX_VALUE));
}
@Test
public void shouldInitializeFieldWithValueAnnotation() {
assertThat(valueInit.getField(), equalTo(Integer.MAX_VALUE));
}
@Test
public void shouldInitializeFieldWithAutowiredSetter() {
assertThat(autowiredInit.getField(), equalTo(Integer.MAX_VALUE));
}
@Test
public void shouldInitializeFieldWithPostConstruct() {
assertThat(postConstructInit.getField(), equalTo(Integer.MAX_VALUE));
}
}
此声明彼此相等，或者我应该使用只有他们中的一个或两个都没有？