怎么处理跨域请求

[rechjq]

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To Reproduce
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1. The code is

2. The error is

Expected behavior
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Environments (please complete the following information):

• OS: [e.g. Linux]
• go-zero version [e.g. 1.2.1]
• goctl version [e.g. 1.2.1, optional]

More description
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[chenquan]

Maybe you can do a search first.

#422