谈谈GreenDao的使用心得(创建复杂json数据的实体类)

关于GreenDao的配置,网上是一抓一大把,这个也不多说.今天写的是在项目中使用GreenDao创建实体类的一些问题
如果实体类的结构就只有其参数,没有附带其他实体类(List xxx或者 XXX xxx ),这种实体类创建对应的Dao文件还是很好懂的,只需要给实体类加上注解@Entry,然后点击Android Studio顶部的Build的Make Project编译下就能生成对应的Dao文件
如果是另外一种数据结构,如

{
    "userId": "000",
    "userName": "xxx",
    "age": 20,
    "family": [{
        "userId": "111",
        "userName": "yyy",
        "age": 22
    }]
}

这种数据结构在GsonFormat后的bean类

public class UserBean {


    /**
     * userId : 000
     * userName : xxx
     * age : 20
     * family : [{"userId":"111","userName":"yyy","age":22}]
     */

    private String userId;
    private String userName;
    private int age;
    private List family;

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public List getFamily() {
        return family;
    }

    public void setFamily(List family) {
        this.family = family;
    }

    public static class FamilyBean {
        /**
         * userId : 111
         * userName : yyy
         * age : 22
         */

        private String userId;
        private String userName;
        private int age;

        public String getUserId() {
            return userId;
        }

        public void setUserId(String userId) {
            this.userId = userId;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        public int getAge() {
            return age;
        }

        public void setAge(int age) {
            this.age = age;
        }
    }
}

除了最基本的@Entry,还需要给private List family;
加上@Convert注解,此注解可以让实体类和json字符串相互转换,此时,就需要去创建一个implements PropertyConverter的工具

public class FamilyConverter implements PropertyConverter, String> {


    @Override
    public List convertToEntityProperty(String databaseValue) {
        if (databaseValue == null) {
            return null;
        }
        Type type = new TypeToken>() {
        }.getType();
        List arrayList = new Gson().fromJson(databaseValue, type);
        return arrayList;
    }

    @Override
    public String convertToDatabaseValue(List entityProperty) {
        if (entityProperty == null) {
            return null;

        } else {
            String sb = new Gson().toJson(entityProperty);
            return sb;
        }
    }

}

有了这个工具,就可以处理带有其他实体类的实体类了,
然后给需要转换的加上@Convert注解

@Convert(columnType = String.class, converter = FamilyConverter.class)
    private List family;

最外层得到实体类加上@Entry注解

@Entity
public class UserBean {


    /**
     * userId : 000
     * userName : xxx
     * age : 20
     * family : [{"userId":"111","userName":"yyy","age":22}]
     */

    private String userId;
    private String userName;
    private int age;
    @Convert(columnType = String.class, converter = FamilyConverter.class)
    private List family;

}

最后使用顶部的Build选项里的Make Project重新构建下,GreenDao就会帮我们生成对应的Dao文件,以及实体类中的get、set和两个构造函数了