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接上一节 一起来写个SQLite ORM数据库框架（上） 这节讲下代码实现。
首先有4个注解类：表名注解-Table、主键注解-PrimaryKey、列注解-Column、非数据库字段注解-NotDBColumn。因为篇幅的原因 这里只单独看看新增的实现 其他都类似
列注解类
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Column {String value() default "";String defaultValue() default "";
}列注解对应的对象实体类（ColumnEntity ）：
public class ColumnEntity {/*** 实体类中的属性字段*/private Field field;private String columnName;private String defaultValue;/*** 获取指定对象的当前字段的值* @param entity 获取字段值的对象* @return*/public Object getValue(Object entity) {if(entity != null) {try {//设置属性是可以访问的field.setAccessible(true);return field.get(entity);} catch (IllegalArgumentException e) {e.printStackTrace();} catch (IllegalAccessException e) {e.printStackTrace();}}return null;}/*** 设置指定对象的当前字段的值* @param entity 获取字段值的对象* @return*/public void setValue(Object entity, Cursor cursor) throws Exception{Class<?> fieldType = field.getType();try {int columnIdx = cursor.getColumnIndex(columnName);if(columnIdx == -1) {//当前游标中没有该字段的值return;}field.setAccessible(true);if(fieldType==int.class||fieldType==Integer.class) {field.set(entity, cursor.getInt(columnIdx));return;}if(fieldType==char.class||fieldType==String.class){field.set(entity, cursor.getString(columnIdx));return;}if(fieldType==long.class||fieldType==Long.class){field.set(entity, cursor.getLong(columnIdx));return;}if(fieldType==float.class||fieldType==Float.class){field.set(entity, cursor.getFloat(columnIdx));return;}if(fieldType==double.class||fieldType==Double.class){field.set(entity, cursor.getDouble(columnIdx));return;}} catch (Exception e) {throw e;}}// public Field getField() {
// return field;
// }public void setField(Field field) {this.field = field;}public String getColumnName() {return columnName;}public void setColumnName(String columnName) {this.columnName = columnName;}public String getDefaultValue() {return defaultValue;}public void setDefaultValue(String defaultValue) {this.defaultValue = defaultValue;}
}解析注解映射对象管理类（TableEntityManager ）：
public class TableEntityManager {/*** 每张表的相关信息缓存集合*/private static HashMap<Object, TableEntity> mTableMap = new HashMap<Object, TableEntity>();/*** 获取EntityTable对象*/public static <T> TableEntity getTableEntity(T entity) {return getTableEntity(entity.getClass());}public static <T> TableEntity getTableEntity(Class<?> mClass) {if(mTableMap.containsKey(mClass)) {return mTableMap.get(mClass);} else {return createTableEntity(mClass);}}public static TableEntity createTableEntity(Class<?> mClass) {TableEntity tableEntity = new TableEntity();//设置表名setTableName(tableEntity,mClass);//设置主键和列setColumnList(tableEntity,mClass);mTableMap.put(mClass, tableEntity);return tableEntity;}/*** 解析注解设置表名*/public static void setTableName(TableEntity tableEntity,Class<?> mClass) {Table table = mClass.getAnnotation(Table.class);if(null==table||TextUtils.isEmpty(table.value())) {tableEntity.setTableName(mClass.getSimpleName());}tableEntity.setTableName(table.value());}/*** 解析注解设置主键(PrimaryKeyEntity)*/public static boolean setPrimaryKey(TableEntity tableEntity,Field field){PrimaryKey primaryKey = field.getAnnotation(PrimaryKey.class);if(null == primaryKey) {return false;}if(primaryKey.isAutoGenerate() && field.getType()!=long.class && field.getType()!=int.class){throw new RuntimeException("自增长主键字段类型不正确，请设置自增长字段类型为long或者int");}PrimaryKeyEntity primaryKeyEntity = new PrimaryKeyEntity();primaryKeyEntity.setField(field);if(TextUtils.isEmpty(primaryKey.value())) {//没有通过注解设置列名，默认取字段名称为列名primaryKeyEntity.setColumnName(field.getName());} else {primaryKeyEntity.setColumnName(primaryKey.value());}primaryKeyEntity.setAutoGenerate(primaryKey.isAutoGenerate());//获取是否自动增长tableEntity.setPrimaryKey(primaryKeyEntity);return true;}/*** 解析注解获得字段列名和默认值并封装到 ColumnEntity*/public static void setColumnList(TableEntity tableEntity,Class<?> mClass) {Field[] fields = mClass.getDeclaredFields();List<ColumnEntity> columnList = new ArrayList<ColumnEntity>();ColumnEntity columnEntity = null;for(Field field:fields){if (Modifier.isStatic(field.getModifiers())) {//过滤掉static静态字段continue;}if(field.getType() == Object.class) {//过滤掉非基本类型字段continue;}NotDBColumn notDbColumn = field.getAnnotation(NotDBColumn.class);if(null != notDbColumn) {//非数据库字段不作处理continue;}if(null==tableEntity.getPrimaryKey()){ //判断是否有主键注释 并设置主键if(setPrimaryKey(tableEntity,field)){continue;}}//获取每个字段的注解Column column = field.getAnnotation(Column.class);columnEntity = new ColumnEntity();columnEntity.setField(field);// 解析注解设置列名，默认取字段名称为列名String columnName = field.getName();if(column != null) {if (!TextUtils.isEmpty(column.value())) {columnName = column.value();}if(!TextUtils.isEmpty(column.defaultValue())){columnEntity.setDefaultValue(column.defaultValue());}}columnEntity.setColumnName(columnName);columnList.add(columnEntity);}tableEntity.setColumnList(columnList);}
}拼接SQL语句类（SQLBuilder） 这里说下在拼创建表的sql的时候 我并没有把字段类型拼上 这是由于对于sqllite数据库 它有个特点就是可以是无类型的 意思就是你给它什么类型 它就会存什么类型 所以我省去转化类型的步骤
//拼接插入的sql语句
public static <T> BindSQL getInsertSQL(TableEntity tableEntity,T entity){StringBuilder sql = new StringBuilder();StringBuilder valueSql = new StringBuilder();int size = tableEntity.getColumnList().size();Object[] args = new Object[size+1];sql.append("INSERT INTO ").append(tableEntity.getTableName()).append("(");valueSql.append(" VALUES(");int i = 0;PrimaryKeyEntity primaryKey = tableEntity.getPrimaryKey();if(null!=primaryKey&&!primaryKey.isAutoGenerate()){sql.append(primaryKey.getColumnName()+",");valueSql.append("?,");args[i++] = primaryKey.getValue(entity);}for (ColumnEntity columnEntity:tableEntity.getColumnList()){Object valueObj = columnEntity.getValue(entity);if(null!=valueObj){sql.append(columnEntity.getColumnName());sql.append(",");valueSql.append("?");valueSql.append(",");args[i++] = columnEntity.getValue(entity);}}sql.deleteCharAt(sql.length() - 1);valueSql.deleteCharAt(valueSql.length()-1);sql.append(")");valueSql.append(")");sql.append(valueSql);Object[] args2 = new Object[i];System.arraycopy(args,0,args2,0,i);return new BindSQL(sql.toString(),args2);};
执行数据库操作管理类（SQLExecuteManager ）：
/*** 新增一条数据*/
public <T> long insert(T entity){TableEntity tableEntity = TableEntityManager.getTableEntity(entity);BindSQL bindSQL = SQLBuilder.getInsertSQL(tableEntity,entity);long rowId = insert(bindSQL.getSql(),bindSQL.getBindArgs());return rowId;
}框架入口类（SQLiteDB）
/*** 新增一条数据*/public <T> long insert(T entity){return mSQLExecuteManager.insert(entity);}整个easyDB数据库框架的大体结构就介绍到这里了，大家可以下载源码查看更多实现 ，还有很多不足的地方 比如不支持多数据库，线程安全等 也可以自行扩展。
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