Android Open Source - easydb Entity Processor

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License

The source code is released under:

Apache License

Java Source Code

package com.san.api.easydb;
/*w  ww.ja v  a  2 s.  c o m*/
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Date;

/**
 * 
 * @author Santanu Kumar
 */
public class EntityProcessor {
  /**
   * Return SELECT SQL based on entity class given
   * 
   * @param object
   * @return
   */
  public Entity_Meta getSelectSQL(Object object) throws Exception {

    Field field[] = object.getClass().getDeclaredFields();
    Entity_Meta meta = new Entity_Meta();

    if (!validate(field)) {
      throw new IllegalArgumentException("Invalid entity class.Check table and id field.");
    }
    StringBuilder sbValueSeq = new StringBuilder();
    sbValueSeq.append(" WHERE ");
    String tableName = object.getClass().getSimpleName().toLowerCase(), id = null;
    meta.table_name = tableName;

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        String retValu = callGetterMedhod("getId", object);
        if (retValu.equals("0")) {
          id = null;
        } else {
          id = " WHERE id='" + retValu + "'";
        }
        meta.id = f.getName();
      } else {
        sbValueSeq.append(f.getName()).append("='").append(callGetterMedhod("get" + toCamelCase(f.getName()), object)).append("' and ");
        meta.addField(f);
      }
    }
    String fieldList = sbValueSeq.toString();
    fieldList = fieldList.substring(0, fieldList.lastIndexOf("and"));
    meta.SQL = "SELECT * FROM " + tableName + ((id == null) ? fieldList : id);
    return meta;
  }

  /**
   * Return SELECT SQL based on entity class given
   * 
   * @param object
   * @return
   */
  public Entity_Meta getSelectSQL(Class className) throws Exception {
    Field field[] = className.getDeclaredFields();

    Entity_Meta meta = new Entity_Meta();

    if (!validate(field)) {
      throw new IllegalArgumentException("Invalid entity class.Check table and id field.");
    }

    String tableName = className.getSimpleName().toLowerCase();
    meta.table_name = tableName;

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        meta.id = f.getName();
      } else {
        meta.addField(f);
      }
    }
    meta.SQL = "SELECT * FROM " + tableName;
    return meta;
  }

  /**
   * Return DELETE SQL based on entity class.
   * 
   * @param object
   * @return
   * @throws Exception
   */
  public String getDeleteSQL(Object object) throws Exception {
    Field field[] = object.getClass().getDeclaredFields();

    if (!validate(field)) {
      throw new IllegalArgumentException("Invalid entity class.Check table and id field.");
    }
    StringBuilder sbValueSeq = new StringBuilder();
    String tableName = object.getClass().getSimpleName().toLowerCase(), id = null;

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        String retValu = callGetterMedhod("getId", object);
        if (retValu.equals("0")) {
          id = null;
        } else {
          id = " WHERE id=" + retValu + "";
        }
      } else {
        sbValueSeq.append(f.getName()).append("='").append(callGetterMedhod("get" + toCamelCase(f.getName()), object)).append("' and ");
      }
    }
    String valueList = sbValueSeq.toString();

    if (id != null) {
      return "DELETE FROM " + tableName + id;
    } else {
      return "DELETE FROM " + tableName + " WHERE " + valueList.substring(0, valueList.lastIndexOf("and"));
    }
  }

  /**
   * Return INSERT SQL statement of given entity object.
   * 
   * @param object
   * @return
   * @throws Exception
   */
  public String getInsertSQL(Object object) throws Exception {
    Field field[] = object.getClass().getDeclaredFields();

    if (!validate(field)) {
      throw new IllegalArgumentException("Invalid entity class.Check table and id field.");
    }

    StringBuilder sbFieldSeq = new StringBuilder();
    StringBuilder sbValueSeq = new StringBuilder();

    String tableNam = object.getClass().getSimpleName().toLowerCase();

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        // ignore
      } else {
        sbFieldSeq.append(f.getName()).append(",");
        sbValueSeq.append("'").append(callGetterMedhod("get" + toCamelCase(f.getName()), object)).append("',");
      }
    }
    String fieldList = sbFieldSeq.toString();
    String valueList = sbValueSeq.toString();

    return "INSERT INTO " + tableNam + " (" + fieldList.substring(0, fieldList.lastIndexOf(",")) + ") VALUES(" + valueList.substring(0, valueList.lastIndexOf(",")) + ")";
  }

  /**
   * Return UPDATE SQL based on entity class.
   * 
   * @param object
   * @return
   * @throws Exception
   */
  public String getUpdateSQL(Object object) throws Exception {
    Field field[] = object.getClass().getDeclaredFields();

    if (!validate(field)) {
      throw new IllegalArgumentException("Invalid entity class.Check table and id field.");
    }
    StringBuilder sbValueSeq = new StringBuilder();
    String tableName = object.getClass().getSimpleName().toLowerCase(), id = null;

    sbValueSeq.append(" SET ");

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        String retValu = callGetterMedhod("getId", object);
        if (retValu.equals("0")) {
          id = null;
        } else {
          id = " WHERE id='" + retValu + "'";
        }
      } else {
        sbValueSeq.append(f.getName()).append("='").append(callGetterMedhod("get" + toCamelCase(f.getName()), object)).append("',");
      }
    }
    String valueList = sbValueSeq.toString();
    if (id == null) {
      throw new IllegalArgumentException("Primary id not specified.");
    } else {
      valueList = valueList.substring(0, valueList.lastIndexOf(","));
      return "UPDATE " + tableName + valueList + id;
    }

  }

  /**
   * Call method and returns return value of called method of given object.
   * 
   * @param name
   * @param object
   * @return
   * @throws Exception
   */
  public String callGetterMedhod(String name, Object object) throws Exception {
    Method method = object.getClass().getMethod(name, null);
    Object res = method.invoke(object);
    return res == null ? "NULL" : res.toString();
  }

  /**
   * 
   * @param name
   * @param object
   * @param arg
   * @return
   * @throws Exception
   */
  public Object callGetterMedhod(String name, Object object, int arg) throws Exception {
    Method method = object.getClass().getMethod(name, int.class);
    Object res = method.invoke(object, arg);
    return res;
  }

  /**
   * 
   * @param name
   * @param object
   * @param type
   * @param value
   * @return
   * @throws Exception
   */
  public String callSetterMedhod(String name, Object object, Class type, Object value) throws Exception {
    Method method = object.getClass().getMethod(name, type);
    Object res = method.invoke(object, value);
    return res == null ? "NULL" : res.toString();
  }

  public String getDropSQL(Class cn) {
    return "DROP TABLE IF EXISTS " + cn.getSimpleName().toLowerCase();
  }

  /**
   * Return CREATE SQL based on entity class.
   * 
   * @param className
   * @return
   * @throws Exception
   */
  public String getCreateSQL(Class className) throws Exception {
    Field field[] = className.getDeclaredFields();
    StringBuilder sb = new StringBuilder();

    String tableName = className.getSimpleName().toLowerCase(), id = null;

    for (Field f : field) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        id = "id INTEGER PRIMARY KEY";
      } else {
        sb.append(f.getName()).append(" ").append(getTypeString(f)).append(",");
      }
    }
    String fieldList = sb.toString();
    if (tableName == null) {
      throw new IllegalArgumentException("Entity class not contain table name. req TABLE_NAME with String static field.");
    }
    if (id == null) {
      throw new IllegalArgumentException("Entity class not contain primary key \"id\".");
    }
    String result = "CREATE TABLE " + tableName + "(" + id + "," + fieldList.substring(0, fieldList.lastIndexOf(",")) + ")";
    return result;
  }

  /**
   * Return SQL type of given class field.
   * 
   * @param f
   * @return
   */
  public String getTypeString(Field f) {
    String type = null;
    if (f.getType() == int.class) {
      type = "INTIGER";
    } else if (f.getType() == float.class) {
      type = "REAL";
    } else if (f.getType() == String.class) {
      type = "TEXT";
    } else if (f.getType() == boolean.class) {
      type = "NUMERIC";
    } else if (f.getType() == Date.class) {
      type = "NUMERIC";
    } else if (f.getType() == Object.class) {
      type = "BLOB";
    } else {
      type = "NULL";
    }
    return type;
  }

  /**
   * Entity class validation
   * 
   * @param list
   * @return
   */
  public boolean validate(Field[] list) {
    for (Field f : list) {
      if (f.getName().equalsIgnoreCase("id") && f.getType() == int.class) {
        return true;
      }
    }
    return false;
  }

  /**
   * To camel case of given string
   * 
   * @param s
   * @return
   */
  public String toCamelCase(String s) {
    String[] parts = s.split("_");
    String camelCaseString = "";
    for (String part : parts) {
      camelCaseString = camelCaseString + toProperCase(part);
    }
    return camelCaseString;
  }

  /**
   * first char to upper
   * 
   * @param s
   * @return
   */
  public String toProperCase(String s) {
    return s.substring(0, 1).toUpperCase() + s.substring(1);
  }

  /**
   * Entity meta data class for select
   */
  public static class Entity_Meta {

    String        SQL;
    String        table_name;
    String        id;
    ArrayList<Field>  fieldList;

    public Entity_Meta() {
      fieldList = new ArrayList<Field>();
    }

    public void addField(Field f) {
      fieldList.add(f);
    }

    @Override
    public String toString() {
      return "Entity_Meta{" + "SQL=" + SQL + ", table_name=" + table_name + ", id=" + id + ", fieldList=" + fieldList.size() + '}';
    }
  }
}

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