spring Boot @Autowired注入

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Bspring boot @Autowired使用方式：

1.通过构造器注入
单个

public class TestController (){
private final TestMapper testMapper;
@Autowired
public TestController (TestMapper testMapper) {
this.testMapper= testMapper;
}
}
多个

public class TestController (){
private final TestaMapper testaMapper;
private final TestbMapper testbMapper;
@Autowired
public TestController (TestaMapper testaMapper, TestbMapper testbMapper) {
this.testaMapper= testaMapper;
this.testbMapper= testbMapper;
}
}

弊端：可以看出当需要注入更多的对象时，构造函数的参数值会变得很长。

2.通过setter方法注入

public class TestController (){
private final TestMapper testMapper;
@Autowired
public void setTestMapper(TestMapper testMapper) {
this.testMapper= testMapper;
}
}

弊端：不能将属性设置为final,每个对象的注入都要写对应的setter方法。

3.通过field反射注入

public class TestController (){
@Autowired
private TestMapper testMapper;
｝

弊端：方法最简单。不符合JavaBean规范；不能将属性设置为final；创建的对象时，还可能引起NullPointerException。

使用idea时会提示Field injection is not recommended

作者：十月是妳的谎言
来源：CSDN
原文：https://blog.csdn.net/qq_38904700/article/details/79515049
版权声明：本文为博主原创文章，转载请附上博文链接！