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This article mainly explains the "Java Web development of Chinese garbled code", the content of the explanation is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "Java Web development of Chinese garbled what are" it!

First, it is necessary to understand some basic coding knowledge

Cubic coding of jsp

* phase: JVM compiles .jsp files into .java files. JVM first reads the value of pageEncoding, reads the .jsp file according to that value, and then generates the .java file of UTF-8 from the specified encoding scheme.

The second phase: JVM converts .java files to .class files, from UTF-8 to UTF-8. This process has nothing to do with any encoding settings, and after this stage, .java files are converted to uniform UTF-8-encoded .class files.

The third stage: the server returns the processing result to the browser, and this stage relies on the charset of contentType. If charset is set, the browser will use the specified encoding format for decoding, otherwise the default ISO-8859-1 encoding format will be used for decoding processing.

Encoding settings in jsp

PageEncoding:

In the * phase above, use this value to read the jsp file, which is the same as the jsp file code in order to avoid Chinese clutter; re-encode the server response, that is, the code displayed by the jsp output stream in the browser (not the main function).

ContentType:

Use this value to re-encode the server response, that is, the encoding of the output stream of the jsp displayed in the browser; encode the form get and post request data; use this value to read the jsp file (not the primary role) in the * * phase above.

The coding information of the web page, indicating the coding used to make the page.

Request.setCharacterEncoding ()

Can be used in servlet and jsp pages to set the encoding for client requests to be re-encoded, that is, to encode data submitted in post mode.

Response.setCharacterEncoding ()

It's the same as.

Response.setContentType ()

It's the same as.

Response.setHeader ("Content-Type", "text/html;charset=UTF-8")

Vs.

Same thing.

Note: some of the functions above are the same, there is priority, when reading the jsp file, 1 > 2; when coding the server response, 2 > 1 > 3, in general, 1Person2 are written.

The http request transmits the URL by default with the code "ISO-8859-1".

Second, several situations of Chinese garbled codes and the simplest solutions:

PageEncoding setting error

PageEncoding is set to the encoding type of the jsp file.

The query string contains Chinese

Chinese encoding depends on the browser, chrome is UTF-8,IE and GB2312, this is because the browser does not follow the URI coding specification. There are two solutions:

During the development process, encode the query string in advance

Such as: http://www.baidu.com/demo?demo=%D6%D0%B9%FA (UTF-8 coding)

Add to the doGet () method of Servlet

String value = new String (request.getParameter ("parameterName") .getBytes ("ISO-8859-1"), "browser encoding")

The get and post data in the form contain Chinese

The encoding method in Chinese depends on the charset in contentType above. There are two solutions:

Add request.setCharacterEncoding ("value of charset") to the doPost () method of Servlet; (useful for post only)

Add to the doPost () method of Servlet

String value = new String (request.getParameter ("parameterName") .getBytes ("ISO-8859-1"), "value of charset")

Third, principle

We can solve the garbled problem through the above method, here is the principle:

The data sent from the client to the server needs to be encoded on the client, similar to: String parameterName = "China" .getBytes ("UTF-8") and then send the encoded data to the server.

The client accepts the data, and the function of request.getParameter ("") is to decode the received data, which is decoded by default using ISO-8859-1, which can be set using request.setCharacterEncoding (""), but is only useful for post. If we use the default ISO-8859-1, the code must be garbled, because the encoding and decoding are not consistent, then what to do at this time? this leads to the two solutions above: use request.setCharacterEncoding ("") to change the decoding method of request.getParameter ("") or new String (request.getParameter ("parameterName"). GetBytes ("ISO-8859-1"), "the value of charset") to re-encode and decode the data decoded by request.getParameter ("").

IV. Other

Setting character sets such as response.setContentType () on pages in jsp destroys the page encoding of the jsp container itself, which will cause garbled characters in html, and the script will not be messed up, so setting is not recommended. In the development, page instruction is often used to set the character set.

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