Android SQLiteDatabase类中insert方法所调用的insertWithOnConflict方法的实现

  public long insertWithOnConflict(String table, String nullColumnHack,
            ContentValues initialValues, int conflictAlgorithm) {
        acquireReference();
        try {
            StringBuilder sql = new StringBuilder();
            sql.append("INSERT");
            sql.append(CONFLICT_VALUES[conflictAlgorithm]);
            sql.append(" INTO ");
            sql.append(table);
            sql.append('(');

            Object[] bindArgs = null;
            int size = (initialValues != null && initialValues.size() > 0)
                    ? initialValues.size() : 0;
            if (size > 0) {
                bindArgs = new Object[size];
                int i = 0;
                for (String colName : initialValues.keySet()) {
                    sql.append((i > 0) ? "," : "");
                    sql.append(colName);
                    bindArgs[i++] = initialValues.get(colName);
                }
                sql.append(')');
                sql.append(" VALUES (");
                for (i = 0; i < size; i++) {
                    sql.append((i > 0) ? ",?" : "?");
                }
            } else {
                sql.append(nullColumnHack + ") VALUES (NULL");
            }
            sql.append(')');

            SQLiteStatement statement = new SQLiteStatement(this, sql.toString(), bindArgs);
            try {
                return statement.executeInsert();
            } finally {
                statement.close();
            }
        } finally {
            releaseReference();
        }
    }