json存数据库时处理器，jsonHandler/jsonArrayHandler

Posted 2021-06-10 Iversonstear

一、普通对象转Json

1、继承BaseTypeHandler

覆盖setNonNullParameter()，getNullableResult()，getNullableResult()，getNullableResult()方法

public class ObjectJsonHandler<T> extends BaseTypeHandler<T> {

    private Class<T> clazz;
　　

　　 /**构造函数*/
    public ObjectJsonHandler(Class<T> clazz) {
        if (clazz == null) {
            throw new IllegalArgumentException("Type argument cannot be null");
        }
        this.clazz = clazz;
    }

    private NameFilter nameFilter = (object, name, value) -> name;

    /**
     * 设置非空参数
     */
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, JSON.toJSONString(parameter, nameFilter));
    }

    /**
     * 根据列名，获取可以为空的结果
     */
    @Override
    public T getNullableResult(ResultSet rs, String columnName) throws SQLException {
        String sqlJson = rs.getString(columnName);
        if (null != sqlJson) {
            return JSONObject.parseObject(sqlJson, clazz);
        }
        return null;
    }

    /**
     * 根据列索引，获取可以为空的结果
     */
    @Override
    public T getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        String sqlJson = rs.getString(columnIndex);
        if (null != sqlJson) {
            return JSONObject.parseObject(sqlJson, clazz);
        }
        return null;
    }

    @Override
    public T getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        String sqlJson = cs.getString(columnIndex);
        if (null != sqlJson) {
            return JSONObject.parseObject(sqlJson, clazz);
        }
        return null;
    }
}

2、继承ObjectJsonHandler

/**
 * @Author jijiecong
 * @Date 2021/4/20 11:49
 * @Version 1.0
 * @Description 评价扩展字段json处理器
 */
public class EvaluationAttributesJsonHandler extends ObjectJsonHandler<EvaluationAttributesEntity> {

    public EvaluationAttributesJsonHandler() {
        super(EvaluationAttributesEntity.class);
    }

}

 

二、List对象转JsonArray

1、继承BaseTypeHandler

覆盖setNonNullParameter()，getNullableResult()，getNullableResult()，getNullableResult()方法

**
 * ObjectJsonArrayHandler
 * JSONArray处理类
 *
 * @version v1.0.0
 * @date 2020/7/23
 */
public class ObjectJsonArrayHandler<T>  extends BaseTypeHandler<List<T>> {

    private final Class<T> clazz;

    public ObjectJsonArrayHandler(Class<T> clazz) {
        if (clazz == null) {
            throw new IllegalArgumentException("Type argument cannot be null");
        } else {
            this.clazz = clazz;
        }
    }

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, List<T> ts, JdbcType jdbcType) throws SQLException {
        ps.setString(i, JSONArray.toJSONString(ts));
    }

    @Override
    public List<T> getNullableResult(ResultSet rs, String s) throws SQLException {
        String jsonArrayStr = rs.getString(s);
        if (null != jsonArrayStr) {
            return JSONArray.parseArray(jsonArrayStr).toJavaList(clazz);
        }
        return null;
    }

    @Override
    public List<T> getNullableResult(ResultSet rs, int i) throws SQLException {
        String jsonArrayStr = rs.getString(i);
        if (null != jsonArrayStr) {
            return JSONArray.parseArray(jsonArrayStr).toJavaList(clazz);
        }
        return null;
    }

    @Override
    public List<T> getNullableResult(CallableStatement cs, int i) throws SQLException {
        String jsonArrayStr = cs.getString(i);
        if (null != jsonArrayStr) {
            return JSONArray.parseArray(jsonArrayStr).toJavaList(clazz);
        }
        return null;
    }
}

2、继承ObjectJsonArrayHandler

/**
 * StringJsonArrayHandler
 *
 * @version v1.0.0
 * @date 2020/8/11
 */
public class StringJsonArrayHandler extends ObjectJsonArrayHandler<String> {

    public StringJsonArrayHandler(Class<String> clazz) {
        super(String.class);
    }
}