geotools多个FeatureCollection合并

方式1，如果元素的id相同则会被覆盖

    <dependency>
        <groupId>org.geotools</groupId>
        <artifactId>gt-main</artifactId>
        <version>${geotools.version}</version>
    </dependency>

DefaultFeatureCollection collection = new DefaultFeatureCollection();
collection.addAll(featureCollection1);
collection.addAll(featureCollection2);

方式2，即使两个数据集都没有id或者具有相同的id也没有问题

    <dependency>
        <groupId>org.geotools</groupId>
        <artifactId>gt-process-feature</artifactId>
        <version>${geotools.version}</version>
    </dependency>
    <dependency>
        <groupId>org.geotools</groupId>
        <artifactId>gt-process</artifactId>
        <version>${geotools.version}</version>
    </dependency>

UnionFeatureCollection collection = new UnionFeatureCollection();
SimpleFeatureCollection result = collection.execute(featureCollection1, featureCollection2);