Go to the root directory of your project from the filesystem, create a file called build.gradle, and add the following content into the file and save it:

      apply plugin: 'war'
      apply plugin: 'eclipse-wtp'
      repositories {
               mavenCentral() //add central maven repo to your buildfile
      }

      dependencies {

              compile 'org.springframework:spring-webmvc:4.3.0.RELEASE',

                       'javax.servlet:jstl:1.2',
                       'org.springframework:spring-jdbc:4.3.0.RELEASE',
                       'org.hsqldb:hsqldb:2.3.2',
                       'commons-fileupload:commons-fileupload:1.2.2',
                       'org.apache.commons:commons-io:1.3.2',
                       'org.springframework:spring-oxm:4.3.0.RELEASE',
                       'org.codehaus.jackson:jackson-mapper-asl:1.9.10',
                       'com.fasterxml.jackson.core:jackson-databind:2.8.0',
                       'log4j:log4j:1.2.17',
                       'org.springframework.security:spring-security
                        -config:4.1.1.RELEASE',
                       'org.springframework.security:spring-security
                        -web:4.1.1.RELEASE',
                       'org.hibernate:hibernate-validator:5.2.4.Final',
                       'org.springframework.webflow:spring
                        -webflow:2.4.2.RELEASE',
                       'org.apache.tiles:tiles-extras:3.0.5'

                  providedCompile 'javax.servlet:javax.servlet-api:3.1.0'

                  testCompile 'junit:junit:4.12',
                                   'org.springframework:spring
                                    -test:4.3.0.RELEASE',
                                   'javax.servlet:jsp-api:2.0',
                                   'com.jayway.jsonpath:json-path
                                    -assert:2.2.0'
      }

Now go to the root directory of your project from the command prompt and issue the following command:

      > gradle eclipse

Next, open a new workspace in your STS, go to File | Import, select the Existing Projects into Workspace option from the tree list (you can find this option under the General node), and then click on the Next button.

Click on the Browse button to select the root directory and locate your project directory. Click on OK and then on Finish.