Methods and causes analysis of solving Chinese garbled characters in tomcat logs

Tomcat is an open source Java Web application server that is widely used in Java Web development. When using Tomcat, we often encounter the problem of garbled log output. This article will delve into the reasons why Tomcat logs are garbled and provide solutions.

1. Reasons for garbled logs

1. Character encoding mismatch: Tomcat uses ISO-8859-1 character encoding by default, while the application may use other character encoding methods ( such as UTF-8). When the application outputs logs containing non-ISO-8859-1 characters, the output will be garbled.

2. The default encoding of the operating system does not match: Tomcat will set the IO input and output encoding according to the default encoding of the operating system when starting. If the default encoding of the operating system is inconsistent with the encoding used by the application, the logs will also be garbled.

3. Incorrect log output configuration: Tomcat outputs logs through frameworks such as Log4j or JUL. If the relevant configuration is incorrect, the logs will be garbled.

2. Solution

1. Modify Tomcat character encoding configuration: In Tomcat's configuration file server.xml, find the Connector element, and you can specify the character encoding of the URI by setting the URIEncoding attribute. , usually using UTF-8. An example is as follows:

2. Modify application encoding settings: In the application configuration file, you can set the corresponding character encoding. For example, for applications using the Spring framework, you can add the following code to web.xml:

##

<filter-name>characterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
    <param-name>encoding</param-name>
    <param-value>UTF-8</param-value>
</init-param>

<filter-name>characterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>

Modify the default encoding of the operating system: You can solve the log garbled problem by modifying the default encoding settings of the operating system. For specific steps, please refer to the relevant documentation of the operating system or use a search engine to query.
3. Modify log output configuration: For applications that use frameworks such as Log4j or JUL for log output, you can solve the problem of garbled characters by modifying the corresponding configuration file. For specific configuration methods, please refer to the documentation or official website of the corresponding framework.
4. Use transcoding filter: Add a transcoding filter in web.xml to set the character encoding of both request and response to UTF-8. An example is as follows:

<filter-name>encodingFilter</filter-name>
<filter-class>
    org.apache.catalina.filters.SetCharacterEncodingFilter
</filter-class>
<init-param>
    <param-name>encoding</param-name>
    <param-value>UTF-8</param-value>
</init-param>

<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>

> ;

Summary: Tomcat log garbled problem is caused by character encoding mismatch, operating system default encoding mismatch or incorrect configuration. By setting Tomcat character encoding, application encoding, operating system default encoding or modifying the log output configuration, and using transcoding filters, you can solve the log garbled problem. In actual application development, appropriate solutions should be selected according to specific situations to ensure normal display of log output, which is conducive to problem troubleshooting and system maintenance.

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