springMvc @ ResponseBody annotation problem

Recent projects need to learn springMvc, the project which is mainly used to annotate the way . Today, write a log in the example used
@ ResponseBody annotation , when there is a problem . , prompt information : The annotation @ RequestBody is disallowed for ; this location.
just learning , looking for a long time, scratching their heads , seeking god pointing. Online ! ! ! Thank you .
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LZ, is this @ ResponseBody it, your image is requestBody, wrong , right
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public String loginForm (@ RequestBody) {

}
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remember. Two things .