再看别人写的切面代码时，发现用了一个@SuppressWarning("unused")注解，不知道其含义,先将其作用及各参数用法总结下：
1.@SuppressWarnings是J2SE提供的最后一个批注,字面理解，抑制警告信息，还是很多警告信息，大概是一类的意思，其实后续从参数看，就知道是抑制一类警告信息的意思.
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。专家建议注解应声明在最接近警告发生的位置
2.参数解释
@SuppressWarnings("xxxx") 抑制xxxx类警告信息
@SuppressWarnings(value={"xxxx","yyyy"}) 抑制多类警告信息
下表可用作字典查询
| 参数 | 用途 | |
|---|---|---|
| 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 | 抑制过期方法的警告 |
| fallthrough | to suppress warnings relative to missing breaks in switch statements | 抑制在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 | 本地隐藏未显示的参数警告 |
| 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 | 不支持或禁用的信息警告 |
| 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的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-acces | 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额警告 |