UnKnownHostException Reported When Compiling Spring Boot

Symptom

During the Spring Boot compilation, the message "UnKnownHostException" is displayed when www.liquibase.org is accessed. Configure a proxy to solve the problem.

Key Process and Cause Analysis

The host is not mapped. Add proxy configurations to solve the problem.

Conclusion and Solution

1. Open the LiquibaseAutoConfigurationTests.java file.

   vim ./spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/liquibase/LiquibaseAutoConfigurationTests.java

2. Press i to enter the insert mode and modify the file:
   1. Add the following content below line 24:

      import java.util.Properties;

      

   2. Insert the following code in line 76:

        static {
                       Properties props = System.getProperties();
                       props.put("http.proxyHost", "127.0.0.1");
                       props.put("http.proxyPort", "3128");
                       props.put("https.proxyHost", "127.0.0.1");
                       props.put("https.proxyPort", "3128");
               }

      In the preceding example, 127.0.0.1 and 3128 indicate the IP address and port number of the proxy host. Replace them with the actual ones.

      

      

      Run the :set list command to check the format. Spaces are not allowed. Use Tab to indent the code.

3. Press Esc, type :wq!, and press Enter to save the file and exit.
4. Recompile Spring Boot.