前言
@SuppressWarnings注解屏蔽一些错误警告，但不是代码错误，这个注解可以提高代码的安全性，防止为了解决这个错误警告而造成不可估量的后果
1. 源码
通过学习注解上的源码以及官方文档
可以了解更加透彻
@Target({TYPE, FIELD, METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE})
@Retention(RetentionPolicy.SOURCE)
public @interface SuppressWarnings {
/**
* The set of warnings that are to be suppressed by the compiler in the
* annotated element. Duplicate names are permitted. The second and
* successive occurrences of a name are ignored. The presence of
* unrecognized warning names is <i>not</i> an error: Compilers must
* ignore any warning names they do not recognize. They are, however,
* free to emit a warning if an annotation contains an unrecognized
* warning name.
*
* <p> The string {@code "unchecked"} is used to suppress
* unchecked warnings. Compiler vendors should document the
* additional warning names they support in conjunction with this
* annotation type. They are encouraged to cooperate to ensure
* that the same names work across multiple compilers.
* @return the set of warnings to be suppressed
*/
String[] value();
}通过@SuppressWarnings的源码可知，其注解目标为类、字段、函数、函数入参、构造函数和函数的局部变量
- 用于抑制编译器产生警告信息
2. 抑制警告的值
| 值 | 作用 |
|---|---|
| all | to suppress all warnings （抑制所有警告） |
| boxing | to suppress warnings relative to boxing/unboxing operations （抑制装箱、拆箱操作时候的警告） |
| cast | to suppress warnings relative to cast operations （抑制映射相关的警告） |
| dep-ann | to suppress warnings relative to deprecated annotation （抑制启用注释的警告） |
| deprecation | to suppress warnings relative to deprecation （抑制过期方法警告） |
| fallthrough | to suppress warnings relative to missing breaks in switch statements （抑制确在switch中缺失breaks的警告） |
| finally | to suppress warnings relative to finally block that don’t return （抑制finally模块没有返回的警告） |
| hiding | to suppress warnings relative to locals that hide variable（抑制相对于隐藏变量的局部变量的警告） |
| incomplete-switch | to suppress warnings relative to missing entries in a switch statement (enum case)（忽略没有完整的switch语句） |
| nls | to suppress warnings relative to non-nls string literals（ 忽略非nls格式的字符） |
| null | to suppress warnings relative to null analysis（ 忽略对null的操作） |
| rawtypes | to suppress warnings relative to un-specific types when using generics on class params（ 使用generics时忽略没有指定相应的类型） |
| restriction | to suppress warnings relative to usage of discouraged or forbidden references（ 抑制禁止使用劝阻或禁止引用的警告） |
| serial | to suppress warnings relative to missing serialVersionUID field for a serializable class（ 忽略在serializable类中没有声明serialVersionUID变量） |
| static-access | to suppress warnings relative to incorrect static access（ 抑制不正确的静态访问方式警告） |
| synthetic-access | to suppress warnings relative to unoptimized access from inner classes（ 抑制子类没有按最优方法访问内部类的警告） |
| unchecked | to suppress warnings relative to unchecked operations（ 抑制没有进行类型检查操作的警告） |
| unqualified-field-access | to suppress warnings relative to field access unqualified（ 抑制没有权限访问的域的警告） |
| unused | to suppress warnings relative to unused code（ 抑制没被使用过的代码的警告） |
主要常用的值也就这几个
@SuppressWarnings("unchecked")抑制单类型的警告@SuppressWarnings({"unchecked", "deprecated"})抑制多类型的警告@SuppressWarnings("all")抑制所有类型的警告
deprecation告诉编译器忽略过时的方法或类型检查
2. 代码示列
@SuppressWarnings("all")
@RunWith(SpringRunner.class)
@SpringBootTest
public class UserTest {
//定义StudentMapper
@Autowired
private UserMapper userDao;
@Test
public void testInsertStudent() {
User user = new User();
user.setName("zs");
user.setEmail("zd.com");
user.setAge(20);
int rows = userDao.insert(user);
System.out.println("inserStudent rows:" + rows);
}
}