Notes:
- You can find information about how to install Thrift in this page: https://thrift.apache.org
- You can find information about the ".thrift" file in this page: https://wiki.apache.org/thrift/Tutorial

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>mtitek.thrift.samples</groupId>
    <artifactId>mtitek-thrift-samples</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.apache.thrift</groupId>
            <artifactId>libthrift</artifactId>
            <version>0.9.3</version>
        </dependency>

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.4</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.thrift.tools</groupId>
                <artifactId>maven-thrift-plugin</artifactId>
                <version>0.1.11</version>

                <executions>
                    <execution>
                        <id>thrift-compile</id>

                        <phase>generate-sources</phase>

                        <goals>
                            <goal>compile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>build-helper-maven-plugin</artifactId>
                <version>1.12</version>

                <executions>
                    <execution>
                        <id>build-helper-add-source</id>

                        <phase>generate-sources</phase>

                        <goals>
                            <goal>add-source</goal>
                        </goals>

                        <configuration>
                            <sources>
                                <source>${project.build.directory}/generated-sources/thrift/</source>
                            </sources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

namespace java mtitek.thrift.samples

/*
 * Constraint.
 */
union Constraint {
    1: required string primaryKey;
    2: required string foreignKey;
    3: required string uniqueKey;
}

/*
 * Column.
 */
struct Column {
    1: required string columnName;
    2: required string dataType;
    3: required bool nullable;
    4: optional map<string, Constraint> constraints;
}

/*
 * Table.
 */
struct Table {
    1: required string tableName;
    2: optional list<Column> columns;
}

/*
 * Schema.
 */
struct Schema {
    1: required string schemaName;
    2: optional list<Table> tables;
}

This sample class uses the generated thrift java classes.

If you build your code using the command "mvn package", Thrift will compile the "sample.thrift" file and generate the java classes:
► target/generated-sources/thrift/mtitek.thrift.samples.Schema
► target/generated-sources/thrift/mtitek.thrift.samples.Table
► target/generated-sources/thrift/mtitek.thrift.samples.Column
► target/generated-sources/thrift/mtitek.thrift.samples.Constraint

package mtitek.thrift.samples;

import java.util.Map;

public class SampleThrift {
    public static void main(String[] args) {
        final Schema schema = initSchema();

        System.out.println("Schema Name: " + schema.getSchemaName());

        if (schema.isSetTables()) {
            for (final Table table : schema.getTables()) {
                System.out.println("Table Name: " + table.getTableName());

                if (table.isSetTableName()) {
                    for (final Column column : table.getColumns()) {
                        System.out.println("Column Name: " + column.getColumnName());
                        System.out.println("Column Data Type: " + column.getDataType());
                        System.out.println("Column isNullable: " + column.isNullable());

                        if (column.isSetConstraints()) {
                            for (final Map.Entry<String, Constraint> entry : column.getConstraints().entrySet()) {
                                final String constraintName = entry.getKey();
                                final Constraint constraint = entry.getValue();

                                if (constraint.isSetPrimaryKey()) {
                                    System.out.println(
                                            "Constraint: {" + constraintName + ":" + constraint.getPrimaryKey() + "}");
                                }

                                if (constraint.isSetForeignKey()) {
                                    System.out.println(
                                            "Constraint: {" + constraintName + ":" + constraint.getForeignKey() + "}");
                                }

                                if (constraint.isSetUniqueKey()) {
                                    System.out.println(
                                            "Constraint: {" + constraintName + ":" + constraint.getUniqueKey() + "}");
                                }
                            }
                        }
                    }
                }
            }
        }
    }

    private static Schema initSchema() {
        final Constraint constraint1 = new Constraint();
        constraint1.setPrimaryKey("primaryKey1");

        final Constraint constraint2 = new Constraint();
        constraint2.setForeignKey("foreignKey1");

        final Constraint constraint3 = new Constraint();
        constraint3.setUniqueKey("uniqueKey1");

        final Column column = new Column();
        column.setColumnName("column1");
        column.setDataType("dataType1");
        column.setNullable(Boolean.TRUE);
        column.putToConstraints("constraint1", constraint1);
        column.putToConstraints("constraint2", constraint2);
        column.putToConstraints("constraint3", constraint3);

        final Table table = new Table();
        table.setTableName("table1");
        table.addToColumns(column);

        final Schema schema = new Schema();
        schema.setSchemaName("schema1");
        schema.addToTables(table);

        return schema;
    }
}