使用正则表达式查找字符串中的字符并替换

Question

When returning a string value from an incoming request in my network based app, I have a string like this 'post http://a.com\\r\\nHost: a.com\\r\\n'

Issue is that the host is always changing so I need to replace it with my defined host. To accomplish that I tried using regex but am stuck trying to find the 'host:a.com' chars in the string and replacing it with a defined valued.

I tried using this example www.javamex.com/tutorials/regular_expressions/search_replace_loop.shtml#.VUWvt541jqB changing the pattern compile to : ([\\\\d]+) but it still remains unchanged.

My goal is to replace given chars in a string with a defined value and returning the new string with the defined value. Any pointers?

EDIT : Sample of a typical incoming request: Post http://example.com\\r\\nHost: example.com\\r\\nConnection: close\\r\\n

Another incoming request might take this form: GET http://example2.net\\r\\nContent-Length: 2\\r\\nConnection: close\\r\\nHost: example2.net\\r\\n

I want to replace it to this forms Post http://example.com\\r\\nHost: mycustomhostvalue.com\\r\\nConnection: close\\r\\n

GET http://example2.net\\r\\nContent-Length: 2\\r\\nConnection: close\\r\\nHost: mycustomhostvalue.com\\r\\n

Answer 1

Use a regex to replace it, like this:

content = content.replaceAll("Host:\\s*(\\w)*\\.\\w*", "Host: newhost.com")

This will replace anything after Host: with newHost.com .

Note: as per comment by cfqueryparam, you may want to usea regex like this to cover .co.uk and such:

Host:\\s*.*?(?=\\\\r\\\\n)